Digital Twins

Lifecycle activities for a project include concept development, and continue with design, construction, operation, maintenance, and conclude with project disposal tasks.  In the past, an individual working on a project might be concerned with only one part of the lifecycle, and then hand off the product or ideas to another person working on the next […]

Lifecycle activities for a project include concept development, and continue with design, construction, operation, maintenance, and conclude with project disposal tasks.  In the past, an individual working on a project might be concerned with only one part of the lifecycle, and then hand off the product or ideas to another person working on the next aspect of the lifecycle.  As projects have become more complex, and as hardware and software are being asked to work together more than ever, it is no longer possible to work on some isolated aspect of a complex project; the project must be handled holistically across all phases of the lifecycle, and this requires a new way of doing business. 

Traditional engineering projects would have addressed requirements, design, verification and validation, and then delivered the project to the customer for construction, and eventually ongoing operation and maintenance.  The new paradigm, Digital Engineering, addresses all of the things that Traditional engineering addressed, but continues to be active and relevant throughout the entire remaining Lifecycle of the project.  Digital Engineering is defined (Steven’s Institute of Technology) as ‘‘an integrated digital approach that uses authoritative sources of systems’ data and models as a continuum across disciplines to support lifecycle activities from concept through disposal.

The first phase of the lifecycle is concept development and design. Model Based Systems Engineering (MBSE) supports these preliminary systems engineering activities; requirements, architecture, design, verification, and validation. Physics based models used by other engineering disciplines would then need to be connected to the model in order to assess and monitor operations during the following phases of the lifecycle.  All of these models used holistically would be a Digital Engineering approach to the project.

Many who work the field of digital engineering give the example of producing two distinct products.  In the past, a building project would result in one product, the building itself.  Using the digital engineering approach, we would end up with two distinct products.  The first product would still be the building, but the second product would be a “digital twin”  of the building.

A modern building can be thought of as a System of Systems.  The building is a System, but it is comprised of many subsystems; climate control system, fire control system, electrical system, just to name a few.  Under traditional engineering methods, if there was a problem with one of the subsystems in the building, maintenance people would need to troubleshoot the problem using tools like voltmeters and sledge hammers, identify the best solution, perhaps tear down drywall to access and fix the culprit system, and perhaps ultimately discover that they were “barking up the wrong tree.”  If that is the case, the troubleshooting would start again, and the repair process would be repeated until the problem is ultimately identified and fixed.  This is a cumbersome and expensive process, but it is how we have done business for many years.

With a “digital twin” which resulted from using the Digital Engineering process, one could troubleshoot the problem from a computer, and test potential solutions to see if the outcome would be favorable.  Additionally, Digital Engineering could utilize Artificial Intelligence (AI) with data collected from each subsystem, to alleviate or prevent many problems before they even occur. 

When problem do occur, however, although a solution may solve the immediate problem, it can sometimes cause new problems which need to be addressed.  With the “Digital Twin”, the solution to the problem can be investigated and verified before any repairman grabs his toolbox and starts tearing down walls.  If there are unexpected consequences associate with the repair, it will quickly become evident from the Digital Twin.

The holistic approach of Digital Engineering can have profound impacts on production costs, production schedule, and risk reduction throughout the entire lifecycle of the project.  For these reason, Digital Engineering is rapidly gaining popularity in today’s marketplace.

Anyone wishing to learn more about Digital Engineering should start by learning more about Model Based Systems Engineering.  ATI offers a three-day class that provides an introduction to Model-Based Systems Engineering.  Lectures on proven, state-of-the-art techniques will be reinforced with lessons learned and case studies from the instructor’s own experiences applying MBSE of major DoD acquisition programs, along with in class, live demonstrations using a popular system modeling tool (Cameo Systems Modeler™ by No Magic, Inc.) to create an example model.  The course is valuable to systems engineers, program managers, and anyone else interested in understanding what is required to create a system model, how to use it to support systems engineering activities on a program, and the benefits that can be realized.

To learn more about this the ATI course Model-Based Systems Engineering, and to register for this class, you can go here.  And, as always, to learn more about the other courses available at ATI, go to www.aticourses.com .

Playing Nice in the EMI Sandbox

If you wear a pacemaker, you are probably already aware of the precautions you must take when you are in the vicinity of certain other devises.  For those that may be unaware, there are many devices should never come into contact with the skin above the pacemaker, cordless telephones or electric razors for example.  There […]

If you wear a pacemaker, you are probably already aware of the precautions you must take when you are in the vicinity of certain other devises.  For those that may be unaware, there are many devices should never come into contact with the skin above the pacemaker, cordless telephones or electric razors for example.  There are other devices which should never be within six inches of the pacemaker, Bluetooth emitters for example.  And there are other devices that should never be used in the same room as a pacemaker patient, stun guns for example.  Have you ever wondered why these restrictions exist?

When an electronic device operates, changing electrical currents and voltages cause electromagnetic interference ( EMI ).  This EMI is transmitted into the space around the device, and can cause other proximate devices to malfunction, or to stop functioning all together.  When an engineer designs a device, he must be acutely aware of how much EMI the device will transmit into the surrounding space, and he must also be aware of how much EMI can be present in his own space for his device to operate properly.  The ability to both of these things, is called Electromagnetic Compatibility (EMC).  In order to go to market and sell a device in the US, the FCC must test your device to confirm its emitted EMI is below the regulated threshold, and it also tests to make sure your device continues to operate in the presence of EMI at that threshold.  Said in another way, they ensure your device is Electromagnetically Compliant.  In other countries, the thresholds may be different, and the Testing Agency will be different, but compliance testing will be encountered in every country.

Since formal Compliance Testing by the FCC is a lengthy and expensive proposition, most engineers will try to monitor and test their Electromagnetic Compliance themselves before they contact the FCC for formal testing.  This informal testing by the engineer is critical to ensure that the device design ultimately stays on time and on budget.

In general, if a device is not Electromagnetically Compliant, the FCC will not allow it to go to market.  In some cases, however, the device is not compliant and can not be designed differently.  If the device is considered medically essential, it will be allowed to go to market, with very clear operating restrictions.  This is the case with Pacemakers.

If you want to learn more about the Formal FCC Compliance Testing, or if you want to learn more about how to informally test your device prior to formal testing, or if you want to learn how to design your circuits so that you will pass informal and formal testing, consider taking the upcoming ATI course EMC PCB Design and Integration.  You can learn more about the course, and register for it here.

And, as always, you can look at our other classes, and our upcoming schedule of offerings at www.aticourses.com

What we have here is a failure to communicate ( Systems Engineering )

Although the term “Systems Engineering” dates back to the 1940s, and the concept was practiced even earlier than that, there seems to be a growing emphasis on System Engineering, perhaps because Systems have become more complex in recent times.  During my early years of training and practice as an electrical engineer decades ago, I do […]

Although the term “Systems Engineering” dates back to the 1940s, and the concept was practiced even earlier than that, there seems to be a growing emphasis on System Engineering, perhaps because Systems have become more complex in recent times.  During my early years of training and practice as an electrical engineer decades ago, I do not recall hearing or learning much about Systems Engineering, but it seems to have gotten much more well-deserved attention since then.  Feel free to argue these points if you wish, but this has been my observation.

So, what can go wrong if Systems Engineering principles are ignored?  What could possibly go wrong if you have multiple engineers concentrating on their own aspect of the overall design, and no one paying attention to the overall system?    Take a look at this humorous video and see what can happen…

https://www.youtube.com/watch?v=jAP30crsTzk

But seriously, though…..

One of the best descriptions of Systems Engineering that I have seen is from INCOSE ( International Council on Systems Engineering ).  It says “Systems engineers are at the heart of creating successful new systems. They are responsible for the system concept, architecture, and design. They analyze and manage complexity and risk. They decide how to measure whether the deployed system actually works as intended. They are responsible for a myriad of other facets of system creation. Systems engineering is the discipline that makes their success possible – their tools, techniques, methods, knowledge, standards, principles, and concepts. The launch of successful systems can invariably be traced to innovative and effective systems engineering.”

So, how can today’s busy and overworked engineer learn more about Systems Engineering?  Or, even if you think you already know everything about Systems Engineering, how can you refresh your knowledge so it is more relevant to the workplace of 2019? 

Applied Technology Institute may have exactly what you are looking for.  ATI recently merged with Honourcode, Inc., and now offers a full line of Systems Engineering courses being taught by original Honourcode instructors, including Eric Honour.

 There is still time to register for our next offering of Applied Systems Engineering, being offered in Columbia, Md starting on September 23, 2019.  This course includes a  hands-on class exercise conducted in small groups. Part A analyzes a system concept and requirements, developing specific test requirements,. Part B creates an effective test program and test procedures for the product system. Part C builds the robotic systems per assembly instructions. Part D implements the test program to evaluate the final robots.  It is a really fun and informative in-class exercise.   Here is a cool video of the System Product built in this class.

Please read more about this opportunity at the following link.

https://aticourses.com/training_classes/applied-systems-engineering-m120/

How to Promote Your ATI Course in Social Media

How to Promote Your ATI Course in Social Media LinkedIn for ATI Rocket Scientists   Did you know that for 52% of professionals and executives, their LinkedIn profile is the #1 or #2 search result when someone searches on their name? For ATI instructors, that number is substantially lower – just 17%. One reason is […]
How to Promote Your ATI Course in Social Media LinkedIn for ATI Rocket Scientists   Did you know that for 52% of professionals and executives, their LinkedIn profile is the #1 or #2 search result when someone searches on their name? For ATI instructors, that number is substantially lower – just 17%. One reason is that about 25% of ATI instructors do not have a LinkedIn profile. Others have done so little with their profile that it isn’t included in the first page of search results. If you are not using your LinkedIn profile, you are missing a huge opportunity. When people google you, your LinkedIn profile is likely the first place they go to learn about you. You have little control over what other information might be available on the web about you. But you have complete control over your LinkedIn profile. You can use your profile to tell your story – to give people the exact information you want them to have about your expertise and accomplishments.   Why not take advantage of that to promote your company, your services, and your course? Here are some simple ways to promote your course using LinkedIn… On Your LinkedIn Profile Let’s start by talking about how to include your course on your LinkedIn profile so it is visible anytime someone googles you or visits your profile. 1. Add your role as an instructor. Let people know that this course is one of the ways you share your knowledge. You can include your role as an instructor in several places on your profile:
  • Experience – This is the equivalent of listing your role as a current job. (You can have more than one current job.) Use Applied Technology Institute as the employer. Make sure you drag and drop this role below your full-time position.
  • Summary – Your summary is like a cover letter for your profile – use it to give people an overview of who you are and what you do. You can mention the type of training you do, along with the name of your course.
  • Projects – The Projects section gives you an excellent way to share the course without giving it the same status as a full-time job.
  • Headline – Your Headline comes directly below your name, at the top of your profile. You could add “ATI Instructor” at the end of your current Headline.
Start with an introduction, such as “I teach an intensive course through the Applied Technology Institute on [course title]” and copy/paste the description from your course materials or the ATI website. You can add a link to the course description on the ATI website. This example from Tom Logsdon’s profile, shows how you might phrase it:   Here are some other examples of instructors who include information about their courses on their LinkedIn profile:
  • Buddy Wellborn – His Headline says “Instructor at ATI” and Buddy includes details about the course in his Experience section.
  • D. Lee Fugal – Mentions the course in his Summary and Experience.
  • Jim Jenkins – Courses are included throughout Jim’s profile, including his Headline, Summary, Experience, Projects, and Courses.
  • 2. Link to your course page.
In the Contact Info section of your LinkedIn profile, you can link out to three websites. To add your course, go to Edit Profile, then click on Contact Info (just below your number of connections, next to a Rolodex card icon). Click on the pencil icon to the right of Websites to add a new site. Choose the type of website you are adding. The best option is “Other:” as that allows you to insert your own name for the link. You have 35 characters – you can use a shortened version of your course title or simply “ATI Course.” Then copy/paste the link to the page about your course. This example from Jim Jenkins’ profile shows how a customized link looks:   3. Upload course materials. You can upload course materials to help people better understand the content you cover. You could include PowerPoint presentations (from this course or other training), course handouts (PDFs), videos or graphics. They can be added to your Summary, Experience or Project. You can see an example of an upload above, in Tom Logsdon’s profile. 4. Add skills related to your course. LinkedIn allows you to include up to 50 skills on your profile. If your current list of skills doesn’t include the topics you cover in your course, you might want to add them. Go to the Skills & Endorsements section on your Edit Profile page, then click on Add skill. Start typing and let LinkedIn auto-complete your topic. If your exact topic isn’t included in the suggestions, you can add it. 5. Ask students for recommendations. Are you still in touch with former students who were particularly appreciative of the training you provided in your course? You might want to ask them for a recommendation that you can include on your profile. Here are some tips on asking for recommendations from LinkedIn expert Viveka Von Rosen. 6. Use an exciting background graphic. You can add an image at the top of your profile – perhaps a photo of you teaching the course, a photo of your course materials, a graphic from your presentation, or simply some images related to your topic. You can see an example on Val Traver’s profile. Go to Edit Profile, then run your mouse over the top of the page (just above your name). You will see the option to Edit Background. Click there and upload your image. The ideal size is 1400 pixels by 425. LinkedIn prefers a JPG, PNG or GIF. Of course, only upload an image that you have permission to use.   Share News about Your Course You can also use LinkedIn to attract more attendees to your course every time you teach. 7. When a course date is scheduled, share the news as a status update. This lets your connections know that you are teaching a course – it’s a great way to reach the people who are most likely to be interested and able to make referrals. Go to your LinkedIn home page, and click on the box under your photo that says “Share an update.” Copy and paste the URL of the page on the ATI website that has the course description. Once the section below populates with the ATI Courses logo and the course description, delete the URL. Replace it with a comment such as: “Looking forward to teaching my next course on [title] for @Applied Technology Institute on [date] at [location].” Note that when you finish typing “@Applied Technology Institute” it will give you the option to click on the company name. When you do that ATI will know you are promoting the course, and will be deeply grateful! When people comment on your update, it’s nice to like their comment or reply with a “Thank you!” message. Their comment shares the update with their network, so they are giving your course publicity. If you want to start doing more with status updates, here are some good tips about what to share (and what not to share) from LinkedIn expert Kim Garst. 8. Share the news in LinkedIn Groups. If you have joined any LinkedIn Groups in your areas of expertise, share the news there too. Of course, in a Group you want to phrase the message a little differently. Instead of “Looking forward to teaching…” you might say “Registration is now open for…” or “For everyone interested in [topic], I’m teaching…” You could also ask a thought-provoking question on one of the topics you cover. Here are some tips about how to start an interesting discussion in a LinkedIn Group. 9. Post again if you still have seats available. If the course date is getting close and you are looking for more people to register, you should post again. The text below will work as a status update and in most LinkedIn Groups. “We still have several seats open for my course on [title] on [date] at [location]. If you know of anyone who might be interested, could you please forward this? Thanks. ” “We have had a few last-minute cancellations for my course on [title] on [date] at [location]. Know anyone who might be interested in attending?” 10. Blog about the topic of the course. When you publish blog posts on LinkedIn using their publishing platform, you get even more exposure than with a status update:
  • The blog posts are pushed out to all your connections.
  • They stay visible on your LinkedIn profile, and
  • They are made available to Google and other search engines.
A blog post published on LinkedIn will rank higher than one posted elsewhere, because LinkedIn is such an authority site. So this can give your course considerable exposure. You probably have written articles or have other content relevant to the course. Pick something that is 750-1500 words. To publish it, go to your LinkedIn home page, and click on the link that says “Publish a post.” The interface is very simple – easier than using Microsoft Word. Include an image if you can. You probably have something in your training materials that will be perfect. At the end of the post, add a sentence that says: “To learn more, attend my course on [title].” Link the title to the course description on the ATI website. For more tips about blogging, you are welcome to join ProResource’s online training website. The How to Write Blog Posts for LinkedIn course is free. Take the first step The most important version of your bio in the digital world is your LinkedIn summary. If you only make one change as a result of reading this blog post, it should be to add a strong summary to your LinkedIn profile. Write the summary promoting yourself as an expert in your field, not as a job seeker. Here are some resources that can help: Write the first draft of your profile in a word processing program to spell-check and ensure you are within the required character counts. Then copy/paste it into the appropriate sections of your LinkedIn profile. You will have a stronger profile that tells your story effectively with just an hour or two of work! Contributed by guest blogger Judy Schramm. Schramm is the CEO of ProResource, a marketing agency that works with thought leaders to help them create a powerful and effective presence in social media. ProResource offers done-for-you services as well as social media executive coaching. Contact Judy Schramm at jschramm@proresource.com or 703-824-8482.  

Why engineers are better than everyone else

Applied Technology Institute (ATI Courses) offers a variety of courses on space, communications, defense, sonar, radar, and signal processing. We believe the news summarized below would be of interest to our readers. February 16 marked the beginning of National Engineers week in the U.S.  EDN celebrated engineers with six reasons Why engineers are better than […]
Applied Technology Institute (ATI Courses) offers a variety of courses on space, communications, defense, sonar, radar, and signal processing. We believe the news summarized below would be of interest to our readers. February 16 marked the beginning of National Engineers week in the U.S.  EDN celebrated engineers with six reasons Why engineers are better than everyone else!  The tongue-in-cheek piece elaborated on these engineering qualities:
  • Team work, not cut-throat competition
  • You’re boring at parties
  • Start-ups don’t happen without you
  • Your degree is worth more than the paper it’s printed on
  • Go ahead, argue
  • Others make problems, engineers find solutions.
For the logic, see the entire article (Why engineers are better than everyone else) by Suzanne Deffree, February 20, 2014.  

New INCOSE CSEP Handbook v4.0 to be Released! Pass the CSEP test Now!

New INCOSE Handbook – New CSEP Opportunities The newest INCOSE SE Handbook (version 4.0) is expected this month (June 2015). Now is a great time to plan for the CSEP/ASEP exam best suited to you, because the transition gives you a choice!. Insider Hint – Since the CSEP application process can be long and time […]
New INCOSE Handbook – New CSEP Opportunities The newest INCOSE SE Handbook (version 4.0) is expected this month (June 2015). Now is a great time to plan for the CSEP/ASEP exam best suited to you, because the transition gives you a choice!. Insider Hint – Since the CSEP application process can be long and time intensive, sign up first to become an ASPE. Once you pass the exam, you then can take your time to complete the more demanding CSEP application process. The Handbook was delayed to coincide with the recent release of ISO-15288. Now INCOSE will offer a transition period for you. From now through December 2015, the current exam will continue to be primary, based on Handbook v3.2.2. The new exam will become primary in January 2016 – but the new exam can also be available by special request as early as July. ATI matches the transition with our Certified Systems Engineering Professional (CSEP) Preparation course. You can still take our 2-day course based on Handbook v3.2.2 on July 7-8, 2015 in Chantilly, VA. Or you can expand your knowledge with our new 3-day version based on Handbook 4.0 on September 24-26 (and forward). The new course will cover the significant expansion in the new Handbook (another 50 pages!) and will also include more exercises and activities to help you “seal in” the knowledge for the exam. You can choose! Take the shorter course and get your ASEP/CSEP now, before the change – or take the longer course to get the full set of new knowledge and more learning activities. Either way, you advance your career by gaining the INCOSE certification!  
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ATI’s Fiber Optic Communication Systems Engineering Course

Can You Perform Cost Analysis or Design Fiber Optic Systems? This three-day course investigates the basic aspects of digital and analog fiber-optic communication systems. Topics include sources and receivers, optical fibers and their propagation characteristics, and optical fiber systems. The principles of operation and properties of optoelectronic components, as well as signal guiding characteristics of […]
Can You Perform Cost Analysis or Design Fiber Optic Systems?
This three-day course investigates the basic aspects of digital and analog fiber-optic communication systems. Topics include sources and receivers, optical fibers and their propagation characteristics, and optical fiber systems. The principles of operation and properties of optoelectronic components, as well as signal guiding characteristics of glass fibers are discussed. System design issues include both analog and digital point-to-point optical links and fiber-optic networks. From this course you will obtain the knowledge needed to perform basic fiber-optic communication systems engineering calculations, identify system tradeoffs, and apply this knowledge to modern fiber optic systems. This will enable you to evaluate real systems, communicate effectively with colleagues, and understand the most recent literature in the field of fiber-optic communications. Since 1984, the Applied Technology Institute (ATI) has provided leading-edge public courses and onsite technical training. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. If you or your team is in need of more technical training, then boost your career with the knowledge needed to provide better, faster, and cheaper solutions for these sophisticated systems. Why not take a short course????????????????? ATI short courses are less than a week long and are designed to help you keep your professional knowledge up-to-date. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for an understanding the issues that must be confronted in the use, regulation and development of complex systems. What You Will Learn: • What are the basic elements in analog and digital fiber optic communication systems including fiber-optic components and basic coding schemes? • How fiber properties such as loss, dispersion and non-linearity impact system performance. • How systems are compensated for loss, dispersion and non-linearity. • How a fiber-optic amplifier works and it’s impact on system performance. • How to maximize fiber bandwidth through wavelength division multiplexing. • How is the fiber-optic link budget calculated? • What are typical characteristics of real fiber-optic systems including CATV, gigabit Ethernet, POF data links, RF-antenna remoting systems, long-haul telecommunication links.

Computational Electromagnetics (CEM): New Course from ATI

Video Clip: Click to Watch With this course you will become more of an electromagnetic expert This three-day course teaches the basics of Computational Electromagnetics (CEM) with application examples. Fundamental concepts in the solution of EM radiation and scattering problems are presented. Emphasis is on applying computational methods to practical applications. Students will be able to […]
Maxwell’s Equations in Vector Form
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With this course you will become more of an electromagnetic expert
This three-day course teaches the basics of Computational Electromagnetics (CEM) with application examples. Fundamental concepts in the solution of EM radiation and scattering problems are presented. Emphasis is on applying computational methods to practical applications. Students will be able to identify the most relevant CEM method for various applications, avoid common user pitfalls, understand model validation and correctly interpret results. Students are encouraged to bring their laptop to work examples using the provided FEKO Lite code. You will also learn the importance of model development and meshing, post- processing for scientific visualization and presentation of results. COMPUTATIONAL ELECTROMAGNETICS What You Will Learn: • A review of electromagnetics and antennas with modern applications. • An overview of popular CEM methods with commercial codes as examples • Hands-on experience with FEKO Lite to demonstrate modeling guidelines and common pitfalls. • An understanding of the latest developments in CEM methods and High Performance Computing. Course Outline, Samplers, and Notes Determine for yourself the value of this course before you sign up. See Slide Samples. Participants will receive a complete set of notes, a copy of FEKO and textbook for future reference. You can add notes and more detail based on the in-class interaction. After completion, all students receive a certificate of completion. Please visit our website for more valuable information. About ATI and the Instructors Our mission here at ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Dr. Keefe Coburn is a senior design engineer with the U.S. Army Research Laboratory in Adelphi MD. He has a Bachelor’s degree in Physics from the VA Polytechnic Institute with Masters and Doctoral Degrees from the George Washington University. In his job at the Army Research Lab, he applies CEM tools for antenna design, system integration and system performance analysis. He teaches graduate courses at the Catholic University of America in antenna and remote sensing. He is a member of the IEEE, the Applied Computational Electromagnetics Society, the Union of Radio Scientists and Sigma Xi. He serves on the Configuration Control Board for the Army developed GEMACS code and the ACES Board of Directors. Dates and Locations For the dates and locations of this short course, please see below: May 16-18, 2012 in Columbia, MD Sincerely, The ATI Courses Team P.S Call today for registration at 410-956-8805 or 888-501-2100 or access our website at www.ATIcourses.com. For general questions please email us at ATI@ATIcourses.com or Join, Link, Follow or Share with us at: Join us on Facebook Link to us on LinkedIn Follow us on Twitter Share with us on Slideshare P.P.S. What Happens at ATI does NOT Stay at ATI because our training helps you and your organization remain competitive in this changing world. Please feel free to call Mr. Jenkins personally to discuss your requirements and objectives. He will be glad to explain in detail what ATI can do for you, what it will cost, and what you can expect in results and future performance.

Fundamentals of COTS-Based Systems Engineering Course

C. O. T. S. = Commercial Off-the-Shelf Video Clip: Click to Watch Leveraging Commercial Off-the-Shelf Technology for System Success  This three day course provides a systemic overview of how to use Systems Engineering to plan, manage, and execute projects that have significant Commercial-off-the-Shelf (COTS) content. Modern development programs are increasingly characterized by COTS solutions (both hardware […]
C. O. T. S. = Commercial Off-the-Shelf
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Leveraging Commercial Off-the-Shelf Technology for System Success  This three day course provides a systemic overview of how to use Systems Engineering to plan, manage, and execute projects that have significant Commercial-off-the-Shelf (COTS) content. Modern development programs are increasingly characterized by COTS solutions (both hardware and software) in both the military and commercial domains. The course focuses on the fundamentals of planning, execution, and follow-through that allow for the delivery of excellent and effective COTS-based systems to ensure the needs of all external and internal stakeholders are met. Participants will learn the necessary adjustments to the fundamental principles of Systems Engineering when dealing with COTS technologies. Numerous examples of COTS systems are presented. Practical information and tools are provided that will help the participants deal with issues that inevitably occur in the real word. Extensive in-class exercises are used to stimulate application of the course material. Who Should Attend? • Prime and subcontractor engineers who procure COTS components. • Suppliers who produce and supply COTS components (hardware and software). • Technical team leaders whose responsibilities include COTS technologies. • Program and engineering managers that oversee COTS development efforts. • Government regulators, administrators, and sponsors of COTS procurement efforts. • Military professionals who work with COTS-based systems. For more information: FUNDAMENTALS OF COTS-BASED SYSTEMS ENGINEERING Why not take a short course? Our short courses are less than a week long and are designed to help you keep your professional knowledge up-to-date. This course provides provide a strong foundation for understanding the issues that must be confronted in the procurement and use of COTS systems. Course Outline and Notes This short course is designed for individuals who plan, manage, and execute projects that have significant COTS content. What You Will Learn: • The key characteristics of COTS components. • How to effectively plan and manage a COTS development effort. • How using COTS affects your requirements and design. • How to effectively integrate COTS into your systems. • Effective verification and validation of COTS-based systems. • How to manage your COTS suppliers. • The latest lessons learned from over two decades of COTS developments. After attending the course each student will receive a complete set of lecture notes and an annotated bibliography at the beginning of the class for future reference and can add notes and more detail based on the in-class interaction, as well as a certificate of completion. Please visit our website for more valuable information. About ATI and the Instructors Our mission here at the Applied Technology Institute (ATI) is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. Since 1984, ATI has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. If you or your team is in need of more technical training, then boost your career with the knowledge needed to provide better, faster, and cheaper solutions for sophisticated DoD and NASA systems. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. David D. Walden, ESEP, is an internationally recognized expert in the field of Systems Engineering. He has over 28 years of experience in leadership of systems development as well as in organizational process improvement and quality having worked at McDonnell Douglas and General Dynamics before starting his own consultancy in 2006. He has a BS degree in Electrical Engineering (Valparaiso University) and MS degrees in Electrical Engineering and Computer Science (Washington University in St. Louis) and Management of Technology (University of Minnesota). Mr. Walden is a member of the International Council on Systems Engineering (INCOSE) and is an INCOSE Expert Systems Engineering Professional (ESEP). He is also a member of the Institute of Electrical and Electronics Engineers (IEEE) and Tau Beta Pi. He is the author or coauthor of over 50 technical reports and professional papers/presentations addressing all aspects of Systems Engineering. Dates and Locations The date and location of this course is below: May 8-10, 2012 in Columbia, MD

ATI’s Top 5 Engineering Course Samplers of 2011

Video Clip: Click to Watch ATI specializes in short course technical training Our mission here at the Applied Technology Institute (ATI) is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced […]
What Are the Tools of Your Trade?
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ATI specializes in short course technical training
Our mission here at the Applied Technology Institute (ATI) is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s Top Five Engineering Courses for 2011 The five engineering courses for 2011 are highlighted below: #1 Practical Statistical Signal Processing – using MATLAB This 4-day course covers signal processing systems for radar, sonar, communications, speech, imaging and other applications based on state-of-the-art computer algorithms. These algorithms include important tasks such as data simulation, parameter estimation, filtering, interpolation, detection, spectral analysis, beamforming, classification, and tracking. Until now these algorithms could only be learned by reading the latest technical journals. This course will take the mystery out of these designs by introducing the algorithms with a minimum of mathematics and illustrating the key ideas via numerous examples using MATLAB. Designed for engineers, scientists, and other professionals who wish to study the practice of statistical signal processing without the headaches, this course will make extensive use of hands-on MATLAB implementations and demonstrations. Attendees will receive a suite of software source code and are encouraged to bring their own laptops to follow along with the demonstrations. Click here for the tutorial #2 Advanced Topics in Digital Signal Processing This four-day course is designed for communication systems engineers, programmers, implementers and managers who need to understand current practice and next generation DSP techniques for upcoming communication systems. DSP is more than mapping legacy analog designs to a DSP implementation. To avoid compromise solution appropriate for an earlier time period, we return to first principles to learn how to apply new technology capabilities to the design of next generation communication systems. Click here for the tutorial #3 Engineering Systems Modeling WithExcel/VBA This two-day course is for engineers, scientists, and others interested in developing custom engineering system models. Principles and practices are established for creating integrated models using Excel and its built-in programming environment, Visual Basic for Applications (VBA). Real-world techniques and tips not found in any other course, book, or other resource are revealed. Step-bystep implementation, instructor-led interactive examples, and integrated participant exercises solidify the concepts introduced. Application examples are demonstrated from the instructor’s experience in unmanned underwater vehicles, LEO spacecraft, cryogenic propulsion systems, aerospace & military power systems, avionics thermal management, and other projects. Click here for the tutorial #4 Wavelets: A Conceptual, Practical Approach Fast Fourier Transforms (FFT) are in wide use and work very well if your signal stays at a constant frequency (“stationary”). But if the signal could vary, have pulses, “blips” or any other kind of interesting behavior then you need Wavelets. Wavelets are remarkable tools that can stretch and move like an amoeba to find the hidden “events” and then simultaneously give you their location, frequency, and shape. Wavelet Transforms allow this and many other capabilities not possible with conventional methods like the FFT. This course is vastly different from traditional math-oriented Wavelet courses or books in that we use examples, figures, and computer demonstrations to show how to understand and work with Wavelets. This is a comprehensive, in-depth, up-to-date treatment of the subject, but from an intuitive, conceptual point of view. We do look at a few key equations from the traditional literature but only AFTER the concepts are demonstrated and understood. If desired, further study from scholarly texts and papers is then made much easier and more palatable when you already understand the fundamental equations and how they relate to the real world. Click here for the tutorial #5 Computational Electromagnetics This 3-day course teaches the basics of CEM with application examples. Fundamental concepts in the solution of EM radiation and scattering problems are presented. Emphasis is on applying computational methods to practical applications. You will develop a working knowledge of popular methods such as the FEM, MOM, FDTD, FIT, and TLM including asymptotic and hybrid methods. Students will then be able to identify the most relevant CEM method for various applications, avoid common user pitfalls, understand model validation and correctly interpret results. Students are encouraged to bring their laptop to work examples using the provided FEKO Lite code. You will learn the importance of model development and meshing, post- processing for scientific visualization and presentation of results. Click here for the tutorial Course Outline, Samplers, and Notes Determine for yourself the value of these or our other courses before you sign up. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending the course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. To see the complete course listing from ATI, click on the links at the bottom of the page. Please visit our website for more valuable information. About ATI and the Instructors Since 1984, ATI has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. ATI short courses are designed to help you keep your professional knowledge up-to-date. Our courses provide you a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the use, regulation and development such complex systems. Our short courses are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will also become aware of the basic vocabulary essential to interact meaningfully with your colleagues. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology.


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RFPs and RFIs: Do You Know What to Always Include and What Should Never Be Included?

Video Clip: Click to Watch How to build solid RFIs and RFPs for complicated systems, which will maximize the number of highly qualified bidders This three-day course on proposal writing is designed for engineers, scientists, project managers and other professionals who design, build, test, buy or sell complex systems. Each topic is illustrated by real-world case studies […]
Video Clip: Click to Watch
How to build solid RFIs and RFPs for complicated systems, which will maximize the number of highly qualified bidders
This three-day course on proposal writing is designed for engineers, scientists, project managers and other professionals who design, build, test, buy or sell complex systems. Each topic is illustrated by real-world case studies discussed by experienced system development and acquisition professionals. Key topics are reinforced with small-team exercises. Over two hundred pages of sample Requests for Proposal (RFP) and Requests for Information (RFI) and are provided. Students assess real RFIs and RFPs in class using checklists and templates provided
Since 1984, the Applied Technology Institute (ATI) has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. If you or your team are in need of more technical training, then boost your career with the knowledge needed to provide better, faster, and cheaper solutions for sophisticated DoD and NASA systems. Why not take a short course? ATI short courses are less than a week long and are designed to help you keep your professional knowledge up-to-date. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the use, regulation and development of complex systems.  What You Will Learn From This Course:
  • What are Requests for Proposal (RFP)?
  • How do they differ from Requests for Information (RFI)?
  • How can they help us cost-effectively buy robust systems that meet not only the specification but also meet the needs and expectations of the end users?
  • What makes “good” RFIs and RFPs?
  • What should always be included and what should never be included in them?
  • What is the one item that, if missing from the RFP, will ensure no reputable firm will bid the job?
  • What is the one thing that inexperienced RFP writers inadvertently do that guts the competitiveness (only one company will bid) and practically guarantees protests of any contract award?
  • What RFP components and features will attract the most qualified bidders?
Course Outline, Samplers, and Notes BUILDING SOLID REQUESTS FOR PROPOSALS After taking this course you will be able to write solid RFPs and RFIs and you will know how a well-crafted one is organized, structured, designed and built by an acquisition/procurement enterprise (either government or a contractor). After attending the course you will receive a full set of detailed notes at the beginning of the class for future reference and can add notes and more detail based on the in-class interaction, as well as a certificate of completion. Please visit our website for more valuable information. About ATI and the Instructors Our mission here at ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Mack McKinney, president and founder of a consulting company, has worked in the defense industry since 1975, first as an Air Force officer for eight years, then with Westinghouse Defense and Northrop Grumman for 16 years, then with a SIGINT company in NY for six years. He now teaches, consults and writes Concepts of Operations for Boeing, Sikorsky, Lockheed Martin Skunk Works, Raytheon Missile Systems, Joint Forces Command and all the uniformed services. He has US patents in radar processing and hyperspectral sensing. Dates and Locations The dates and locations of this short course are below: Jan 31-Feb 2, 2012        Virginia Beach, VA May 1-3, 2012                  Virginia Beach, VA
 

Can Neutrinos Travel Faster Than Light?

Yes, according to the CERN scientists from Geneva. Scientists at the world’s largest physics lab say they have clocked subatomic particles traveling faster than light, a feat that – if true – would break a fundamental pillar of science. The readings have so astounded researchers that they are asking others to independently verify the measurements […]
Yes, according to the CERN scientists from Geneva. Scientists at the world’s largest physics lab say they have clocked subatomic particles traveling faster than light, a feat that – if true – would break a fundamental pillar of science. The readings have so astounded researchers that they are asking others to independently verify the measurements before claiming an actual discovery. “This would be such a sensational discovery if it were true that one has to treat it extremely carefully,” said John Ellis, a theoretical physicist at the European Organization for Nuclear Research, or CERN, who was not involved in the experiment. Nothing is supposed to move faster than light, at least according to Albert Einstein’s special theory of relativity: The famous E (equals) mc2 equation. That stands for energy equals mass times the speed of light squared. But neutrinos – one of the strangest well-known particles in physics – have now been observed smashing past this cosmic speed barrier of 186,282 miles per second (299,792 kilometers). CERN says a neutrino beam fired from a particle accelerator near Geneva to a lab 454 miles (730 kilometers) away in Italy traveled 60 nanoseconds faster than the speed of light. Scientists calculated the margin of error at just 10 nanoseconds, making the difference statistically significant. But given the enormity of the find, they still spent months checking and rechecking their results to make sure there was no flaws in the experiment. The CERN researchers are now looking to the United States and Japan to confirm the results.
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DOD cyber defense plan: secure internet OR government controlled internet?

It is not a secret to anybody that the next new war will be fought (or possibly is being fought) through internet.  Previously the U.S. had determined that cyberattacks could be considered an act of war.  It was disclosed, that in March one of the leading defense contractors was hacked by a foreign intruder who was […]
It is not a secret to anybody that the next new war will be fought (or possibly is being fought) through internet.  Previously the U.S. had determined that cyberattacks could be considered an act of war.  It was disclosed, that in March one of the leading defense contractors was hacked by a foreign intruder who was able to get away with 24,000 files containing information on the newly developed weapons systems.  Read more here   It is obvious that something needs to be done to defend our cyber borders. Nearly $500 million were allocated to DARPA (Defense Advanced Research Projects Agency) to increase the number of cyber-aligned resources. Last week DOD presented its new plan to secure our cyber space. However, the problem will not be easily solved and the issue is highly controversial. Why?  Because to SECURE anything means to CONTROL it. In this case, we are talking about controlling the INTERNET– a worldwide interconnection of computer networks that facilitate the exchange of information among users! A lot of people out there say that if we can’t control our borders how can we possibly “secure” the internet.  Yet others consider the plan to be an intrusion on user’s privacy.   However, if the plan is not put in place here are just a few possible threats we are facing: Espionage and national security breaches Sabotage of military operations Sabotage of the national electrical grid What do you think?  Please comment below…
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Do You Resonate with Shock, Noise and Vibration?

  Video Clip: Click to Watch Two Short Courses from ATI on Vibration, Shock or Noise in Vehicles, Devices, and Equipment If you are concerned with vibration, shock or noise in vehicles, devices, and equipment; then Applied Technology Institute (ATI) short courses maybe for you. Why not take a short course? Our short courses are less […]
Negative Stiffness Vibration Isolator
 
Video Clip: Click to Watch
Two Short Courses from ATI on Vibration, Shock or Noise

in Vehicles, Devices, and Equipment

If you are concerned with vibration, shock or noise in vehicles, devices, and equipment; then Applied Technology Institute (ATI) short courses maybe for you. Why not take a short course? Our short courses are less than a week long and are designed to help you keep your professional knowledge up-to-date. They provide a practical overview of space and defense technologies which furnish a strong foundation for understanding the issues that must be confronted in the use, regulation and development of complex systems. If you are test personnel who conduct or supervise or “contract out” vibration and shock tests, then take the three-day course fundamentals course. It also benefits design, quality and reliability specialists who interface with vibration and shock test activities. If you have some prior acquaintance with vibration or noise fields, then you should sign up for the more advanced four day course. It emphasizes understanding of the relevant phenomena and concepts in order to enable the participants to address a wide range of practical problems insightfully. See sections below for more details on these two short courses from ATI. FUNDAMENTALS OF RANDOM VIBRATION & SHOCK TESTING This three-day course is primarily designed for test personnel who conduct or supervise or “contract out” vibration and shock tests. It also benefits design, quality and reliability specialists who interface with vibration and shock test activities. From this course you will obtain the ability to understand and communicate meaningfully with test personnel, perform basic engineering calculations and evaluate tradeoffs between test equipments’ and procedures. Each student receives the instructor’s brand new, minimal-mathematics, minimal-theory hardbound text Random Vibration & Shock Testing, Measurement, Analysis & Calibration. This 444 page, 4-color book also includes a CDROM with video clips and animations. What you will learn: • How to plan, conduct and evaluate vibration and shock tests and screens. • How to attack vibration and noise problems. • How to make vibration isolation, damping and absorbers work for vibration and noise control. • How noise is generated and radiated, and how it can be reduced. VIBRATION & NOISE CONTROL This course is intended for engineers and scientists concerned with the vibration reduction and quieting of vehicles, devices, and equipment. The course will provide guidance relevant to design, problem solving, and development of improvements. It will emphasize understanding of the relevant phenomena and concepts in order to enable the participants to address a wide range of practical problems insightfully. The instructors will draw on their extensive experience to illustrate the subject matter with examples related to the participant’s specific areas of interest. Although the course will begin with a review and will include some demonstrations, participants ideally should have some prior acquaintance with vibration or noise fields. Each participant will receive a complete set of course notes and the text Noise and Vibration Control Engineering, a $210 value. What you will learn: How to attack vibration and noise problems What means are available for vibration and noise control? How to make vibration isolation, damping, and absorbers work How noise generated and radiated, and how it can be reduced? Course Outline, Samplers, and Notes Determine for yourself the value of these courses before you sign up. • Fundamentals of Random Vibration & Shock Testing course slide sampler • Vibration & Noise Control course slide sampler Our other short courses are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending a course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. Please visit our website for more valuable information. About ATI and the Instructors Since 1984, ATI has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. Our mission here at ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Fundamentals of Random Vibration & Shock Testing course Wayne Tustin has since 1995 been president of a specialized engineering school and consultancy he founded in Santa Barbara, CA. His BSEE degree is from the University of Washington, Seattle. He is a licensed Professional Engineer – Quality in the State of California. Wayne’s first encounter with vibration was at Boeing/Seattle, performing what later came to be called modal tests, on the XB-52 prototype of that highly reliable platform. Subsequently he headed field service and technical training for a manufacturer of electrodynamic shakers, before establishing another specialized school on which he left his name. Wayne has written several books and literally hundreds of articles dealing with practical aspects of vibration and shock measurement and testing. Vibration & Noise Control course Dr. Eric Ungar has specialized in research and consulting in vibration and noise for more than 40 years, published over 200 technical papers, and translated and revised Structure-Borne Sound. He has led short courses at the Pennsylvania State University for over 25 years and has presented numerous seminars worldwide. Dr. Ungar has served as President of the Acoustical Society of America, as President of the Institute of Noise Control Engineering, and as Chairman of the Design Engineering Division of the American Society of Mechanical Engineers. ASME honored him with its Trent-Crede Medal in Shock and Vibration. ASA awarded him the Per Bruel Gold Medal for Noise Control and Acoustics for his work on vibrations of complex structures, structural damping, and isolation. Dr. James Moore has, for the past twenty years, concentrated on the transmission of noise and vibration in complex structures, on improvements of noise and vibration control methods, and on the enhancement of sound quality. He has developed Statistical Energy Analysis models for the investigation of vibrations and noise complex structures as submarines, helicopters, and automobiles and has been instrumental in the acquisition of corresponding data bases. He has participated in the development of active noise control systems, noise reduction coating and signal conditioning means, as well as in the presentation of numerous short courses and industrial training programs. Times, Dates, and Locations Fundamentals of Random Vibration & Shock Testing Sep 20-22, 2011 Detroit, MI Oct 4-6, 2011 Santa Clarita, CA Nov 7-9, 2011 Acton, MA Vibration & Noise Control Sep 26-29, 2011 Boston, MA Mar 12-15, 2012 Columbia, MD Apr 30-May 3, 2012 Boston, MA  

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Largest Tidal Farm To Be Constructed In The Sound Of Islay In Scottland

On March 22, 2011 Scottish Government announced that the world’s largest tidal power project will be built on the Sound Of Islay.  The construction will begin in 2012 and is planned to be completed by 2020.  The project is expected to cost about $85 million and will be capable of powering 5,000 homes.  The facility […]
On March 22, 2011 Scottish Government announced that the world’s largest tidal power project will be built on the Sound Of Islay.  The construction will begin in 2012 and is planned to be completed by 2020.  The project is expected to cost about $85 million and will be capable of powering 5,000 homes.  The facility will have 10 underwater HS100 tidal turbines and  produce 10 megawatt.  This is the large operation of that nature ever undertaken.  The Scottish Government’s goal is to obtain 80% of the energy from renewable sources by 2020.  This will put Scotland among the leaders in marine energy.


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Every Spring, the Pros Get Back to the Fundamentals, Do You?

Video Clip: Click to Watch Spring into Fundamentals with a Short Course from the Applied Technology Institute (ATI) Do you return to the fundamentals of your profession once a year like professional baseball players do? Dictionary.com defines fundamental as: “a basic principle, rule, law, or the like, that serves as the groundwork of a system; essential part: […]
Video Clip: Click to Watch
Spring into Fundamentals with a Short Course from the Applied Technology Institute (ATI) Do you return to the fundamentals of your profession once a year like professional baseball players do? Dictionary.com defines fundamental as: “a basic principle, rule, law, or the like, that serves as the groundwork of a system; essential part: to master the fundamentals of a trade”. Since 1984, the Applied Technology Institute (ATI) has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Some ATI short courses are designed to reinforce fundamental professional knowledge. Our short courses are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time while keeping necessary skills up-to-date. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the use, regulation and development such intricate systems. You will also become aware of the basic vocabulary essential to interact meaningfully with your colleagues. The three courses below emphasize the fundamentals. They are all offered soon or they can be scheduled at your facility. Please see our website for more information. ATI’S FUNDAMENTALS OF RF TECHNOLOGY COURSE This two-day course is designed for engineers that are non specialists in Radio Frequency (RF) engineering, but are involved in the design or analysis of communication systems including digital designers, managers, procurement engineers, etc. The course emphasizes RF fundamentals in terms of physical principles behavioral concepts permitting the student to quickly gain an intuitive understanding of the subject with minimal mathematical complexity. These principles are illustrated using modern examples of wireless components such as Bluetooth, Cell Phone and Paging, and 802.11 Data Communications Systems. What You Will Learn: • How to recognize the physical properties that make RF circuits and systems unique • What the important parameters are that characterize RF circuits • How to interpret RF Engineering performance data • What the considerations are in combining RF circuits into systems • How to evaluate RF Engineering risks such as instabilities, noise, and interference, etc. • How performance assessments can be enhanced with basic engineering tools ATI’S FUNDAMENTALS OF SONAR AND TARGET MOTION ANALYSIS COURSE This three-day course is designed for SONAR systems engineers, combat systems engineers, undersea warfare professionals, and managers who wish to enhance their understanding of this discipline or become familiar with the “big picture” if they work outside of the discipline. Each topic is illustrated by worked numerical examples, using simulated or experimental data for actual undersea acoustic situations and geometries. From this course you will obtain the knowledge and ability to perform basic SONAR and USW systems engineering calculations, identify tradeoffs, interact meaningfully with colleagues, evaluate systems, and understand the literature. What You Will Learn: • What are of the various types of SONAR systems in use on Naval platforms today? • What are the major principles governing their design and operation? • How is the data produced by these systems used operationally to conduct Target Motion Analysis and USW? • What are the typical commercial and scientific uses of SONAR and how do these relate to military use? • What are the other military uses of SONAR systems (i.e. those NOT used to support Target Motion Analysis)? • What are the major cost drivers for undersea acoustic systems? From this course you will obtain the knowledge, skill and ability to configure a communications payload based on its service requirements and technical features. You will understand the engineering processes and device characteristics that determine how the payload is put together and operates in a state-of-the-art telecommunications system to meet user needs. ATI’S FUNDAMENTALS OF SYSTEMS ENGINEERING COURSE Today’s complex systems present difficult challenges to develop. From military systems to aircraft to environmental and electronic control systems, development teams must face the challenges with an arsenal of proven methods. Individual systems are more complex, and systems operate in much closer relationship, requiring a system-of-systems approach to the overall design. This two-day workshop presents the fundamentals of a systems engineering approach to solving complex problems. It covers the underlying attitudes as well as the process definitions that make up systems engineering. The model presented is a research-proven combination of the best existing standards. Participants in this workshop practice the processes on a realistic system development. You Should Attend This Workshop If You Are: • Working in any sort of system development • Project leader or key member in a product development team • Looking for practical methods to use today This Course is Aimed at: • Project leaders, • Technical team leaders, • Design engineers, and • Others participating in system development Course Outline, Samplers, and Notes Determine for yourself the value of our courses before you sign up. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending the course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. Please visit our website for more valuable information. About the Instructors and ATI ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Our mission here at ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. Times, Dates, and Locations For the times, dates and locations of all of our short courses, please access our schedule.


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An Engineer Joke

The optimist says the glass is half full. The pessimist says the glass is half empty. What does the engineer say? The glass is twice as big as it needs to be!

The optimist says the glass is half full.
The pessimist says the glass is half empty.

What does the engineer say?

The glass is twice as big as it needs to be!

Do You Know Enough about Antennas to build one from Scratch?

“Haystack” Antenna Video Clip: Click to Watch ATI has Short Courses Where You can Play with Antennas The Applied Technology Institute (ATI) provides leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. ATI short courses are designed to help you keep your professional knowledge up-to-date. Our courses provide a […]
“Haystack” Antenna
“Haystack” Antenna
Video Clip: Click to Watch
ATI has Short Courses Where You can Play with Antennas
The Applied Technology Institute (ATI) provides leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. ATI short courses are designed to help you keep your professional knowledge up-to-date. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the design, construction and testing of complex radar, microwave and satellite antenna systems and sub-systems. Our short courses are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. Antenna Course Outline, Samplers, and Notes Several antenna related courses are available in 2011: • Antenna Fundamentals – One Day Overview course • Antenna and Antenna Array Fundamentals course • Microwave Antenna Systems & Design course Determine for yourself the value of our courses before you sign up. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending the course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. Please visit our website for more valuable information. About the Instructors and ATI ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Our mission here ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. Times, Dates, and Locations For the times, dates and locations of all of our short courses, please access the links below. Sincerely, The ATI Courses Team P.S. Call today for registration at 410-956-8805 or 888-501-2100 or access our website at www.ATIcourses.com. For general questions please email us at ATI@ATIcourses.com.

ATI Features World Class Instructors for Our Short Courses

Washington, DC Tuesday, November 30, 2010 “Even I Could Learn a Thing or Two from ATI” Video Clip: Click to Watch Since 1984 ATI has provided leading-edge public courses and onsite technical training The short technical courses from the Applied Technology Institute (ATI) are designed to help you keep your professional knowledge up-to-date. Our courses provide […]
Washington, DC
Tuesday, November 30, 2010
“Even I Could Learn a Thing or Two from ATI”
“Even I Could Learn a Thing or Two from ATI”
Video Clip: Click to Watch
Since 1984 ATI has provided leading-edge public courses and onsite technical training
The short technical courses from the Applied Technology Institute (ATI) are designed to help you keep your professional knowledge up-to-date. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the use, regulation and development such complex systems. The classes are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. ABOUT ATI AND THE INSTRUCTORS Our mission here at the ATI is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. For example: Robert Fry worked from 1979 to 2007 at The Johns Hopkins University Applied Physics Laboratory where he was a member of the Principal Professional Staff. He is now working at System Engineering Group (SEG) where he is Corporate Senior Staff and also serves as the company-wide technical advisor. Throughout his career he has been involved in the development of new combat weapon system concepts, development of system requirements, and balancing allocations within the fire control loop between sensing and weapon kinematic capabilities. He has worked on many aspects of the AEGIS combat system including AAW, BMD, AN/SPY-1, and multi-mission requirements development. Missile system development experience includes SM-2, SM-3, SM-6, Patriot, THAAD, HARPOON, AMRAAM, TOMAHAWK, and other missile systems. Robert teaches ATI’s Combat Systems Engineering course Wayne Tustin has been president of Equipment Reliability Institute (ERI), a specialized engineering school and consultancy he founded in Santa Barbara, CA, since 1995. His BSEE degree is from the University of Washington, Seattle. He is a licensed Professional Engineer in the State of California. Wayne’s first encounter with vibration was at Boeing/Seattle, performing what later came to be called modal tests, on the XB-52 prototype of that highly reliable platform. Subsequently he headed field service and technical training for a manufacturer of electrodynamic shakers, before establishing another specialized school on which he left his name. Based on over 50 years of professional experience, Wayne has written several books and literally hundreds of articles dealing with practical aspects of vibration and shock measurement and testing. Wayne teaches ATI’s Fundamentals of Random Vibration & Shock Testing course. Thomas S. Logsdon, M.S For more than 30 years, Thomas S. Logsdon, M. S., has worked on the Navstar GPS and other related technologies at the Naval Ordinance Laboratory, McDonnell Douglas, Lockheed Martin, Boeing Aerospace, and Rockwell International. His research projects and consulting assignments have included the Transit Navigation Satellites, The Tartar and Talos shipboard missiles, and the Navstar GPS. In addition, he has helped put astronauts on the moon and guide their colleagues on rendezvous missions headed toward the Skylab capsule. Some of his more challenging assignments have centered around constellation coverage studies, GPS performance enhancement, military applications, spacecraft survivability, differential navigation, booster rocket guidance using the GPS signals and shipboard attitude determination. Tom Logsdon has taught short courses and lectured in thirty one different countries. He has written and published forty technical papers and journal articles, a dozen of which have dealt with military and civilian radionavigation techniques. He is also the author of twenty nine technical books on various engineering and scientific subjects. These include Understanding the Navstar, Orbital Mechanics: Theory and Applications, Mobile Communication Satellites, and The Navstar Global Positioning System. Courses Mr. Logsdon teaches through ATI include: Understanding Space Fundamentals of Orbital & Launch Mechanics GPS Technology – Solutions for Earth & Space and Strapdown Inertial Navigation Systems COURSE OUTLINE, SAMPLERS, AND NOTES Determine for yourself the value of our courses before you sign up. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending the course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. Please visit our website for more valuable information. DATES, TIMES AND LOCATIONS For the dates and locations of all of our short courses, please access the links below. Sincerely, The ATI Courses Team P.S. Call today for registration at 410-956-8805 or 888-501-2100 or access our website at www.ATIcourses.com. For general questions please email us at ATI@ATIcourses.com.
Mark N. Lewellen
Consultant/Instructor
Washington, DC
240-882-1234

Why Not Give Yourself the Gift of a Short Course this Holiday Season?

Washington, DC Monday, November 29, 2010 Is One of These Yours? Video Clip: Click to Watch When Did You Last do Something for Your Career? Since 1984, the Applied Technology Institute (ATI) has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Our courses provide a practical overview of space […]
Washington, DC
Monday, November 29, 2010
Is One of These Yours?
Is One of These Yours?
Video Clip: Click to Watch
When Did You Last do Something for Your Career?
Since 1984, the Applied Technology Institute (ATI) has provided leading-edge public courses and onsite technical training to DoD and NASA personnel, as well as contractors. Our courses provide a practical overview of space and defense technologies which provide a strong foundation for understanding the issues that must be confronted in the use, regulation and development such complex systems. ATI short courses are designed to help you keep your professional knowledge up-to-date. Our short courses are designed for individuals involved in planning, designing, building, launching, and operating space and defense systems. Whether you are a busy engineer, a technical expert or a project manager, you can enhance your understanding of complex systems in a short time. You will become aware of the basic vocabulary essential to interact meaningfully with your colleagues. Course Outline, Samplers, and Notes Determine for yourself the value of our courses before you sign up. See our samples (See Slide Samples) on some of our courses. Or check out the new ATI channel on YouTube. After attending the course you will receive a full set of detailed notes from the class for future reference, as well as a certificate of completion. Please visit our website for more valuable information. About ATI and the Instructors Our mission here at the Applied Technology Institute (ATI) is to provide expert training and the highest quality professional development in space, communications, defense, sonar, radar, and signal processing. We are not a one-size-fits-all educational facility. Our short classes include both introductory and advanced courses. ATI’s instructors are world-class experts who are the best in the business. They are carefully selected for their ability to clearly explain advanced technology. Dates, Times and Locations For the dates and locations of all of our short courses, please access the links below. Sincerely, The ATI Courses Team P.S Call today for registration at 410-956-8805 or 888-501-2100 or access our website at www.ATIcourses.com. For general questions please email us at ATI@ATIcourses.com.
Mark N. Lewellen
Consultant/Instructor
Washington, DC
240-882-1234

Enabling the sharing of airspace by manned and unmanned aircraft

The Australian Research Centre for Aerospace Automation’s (ARCAA) Smart Skies project, focusing on the development of technology to enable manned and unmanned aircraft to effectively share airspace, is approaching its final milestone. The project, also involving Boeing Research and Technology-Australia, Insitu Pacific and the Queensland Government, is exploring development of three key enabling aviation technologies: […]
The Australian Research Centre for Aerospace Automation’s (ARCAA) Smart Skies project, focusing on the development of technology to enable manned and unmanned aircraft to effectively share airspace, is approaching its final milestone. The project, also involving Boeing Research and Technology-Australia, Insitu Pacific and the Queensland Government, is exploring development of three key enabling aviation technologies: an Automated Separation Management System capable of providing separation assurance in complex airspace environments; Sense and Act systems for manned and unmanned aircraft capable of collision avoidance of dynamic and static obstacles; and a Mobile Aircraft Tracking System (MATS) utilising a cost-effective radar and dependent surveillance systems. The latest flight trials included all of the project elements, including a fixed-wing UAV and a modified Cessna flying in automatic mode, flying collision scenarios with simulated aircraft. The final flight trial will take place in December this year, before project wrap-up and final reports in 2011, and, ultimately, the attempt to commercialise the Smart Skies intellectual property. ARCAA acting director Dr Jonathon Roberts said a new research project was also on the cards. The collision-avoidance research is one of two key areas in which the Civil Aviation Safety Authority (CASA) requires proof that technology in unmanned aircraft can operate in a way equivalent to human pilots. “In the future research we’re trying to hit the next problem: Smart Skies is all about collision avoidance and managing the avoidance of collisions; the next thing that CASA will require will be automatic landing systems,” Dr Roberts said. “So that if you have an engine failure or other catastrophic failure and you have to come down, you’ve got to be able to put it down in a safe place, so these will be vision systems that actually look at the ground and figure out where to land. “That’s the next thing that has to be done before UAVs can fly over populous areas.” The Smart Skies program was recently recognised at the Queensland Engineering Excellence Awards, where it won the ‘Control systems, networks, information processing and telecommunications’ category.

AUVs Cannot Fly Through Red Tape.

This was forwarded by Mark Lewellan,  ATI’s AUS instructor. It shows the cost-savings of using a small AUV to take accident overview photos. However, in general, the red tape makes this difficult to do in both the US and Canada.   It looks like a bug equipped with a camera, but the small Ontario Provincial […]
This was forwarded by Mark Lewellan,  ATI’s AUS instructor. It shows the cost-savings of using a small AUV to take accident overview photos. However, in general, the red tape makes this difficult to do in both the US and Canada.   OPP Identification Constable Marc Sharpe operates an unmanned aerial vehicle used at crime scenes It looks like a bug equipped with a camera, but the small Ontario Provincial Police unmanned aircraft is making history as one of the first aerial drones being regularly used in North America by law enforcement officials. The battery-powered craft, which can stay airborne for about 15 minutes at a time, has been used at homicides and other incidents in northwestern Ontario to take aerial photos for use in court. It has helped reduce costs, too, as the provincial police would have otherwise brought in a helicopter or rented an aircraft. “We’ve saved over $30,000 the 11 times we used it,” says Const. Marc Sharpe, who operates the mini-helicopter. Aerial drones are usually associated with the military on overseas missions such as in Afghanistan and Iraq. But the remote-controlled aircraft are also starting to be used by police and firefighters in Europe and by various companies in Australia. Read more: http://www.nationalpost.com/news/story.html?id=2226289#ixzz0XWTiVWS6

The Global Positioning System

The Global Positioning System A National Resource by Robert A. Nelson On a recent trip to visit the Jet Propulsion Laboratory, I flew from Washington, DC to Los Angeles on a new Boeing 747-400 airplane. The geographical position of the plane and its relation to nearby cities was displayed throughout the flight on a video […]

The Global Positioning System

A National Resource

by Robert A. Nelson On a recent trip to visit the Jet Propulsion Laboratory, I flew from Washington, DC to Los Angeles on a new Boeing 747-400 airplane. The geographical position of the plane and its relation to nearby cities was displayed throughout the flight on a video screen in the passenger cabin. When I arrived in Los Angeles, I rented a car that was equipped with a navigator. The navigator guided me to my hotel in Pasadena, displaying my position on a map and verbally giving me directions with messages like “freeway exit ahead on the right followed by a left turn.” When I reached the hotel, it announced that I had arrived at my destination. Later, when I was to join a colleague for dinner, I found the restaurant listed in a menu and the navigator took me there. This remarkable navigation capability is made possible by the Global Positioning System (GPS). It was originally designed jointly by the U.S. Navy and the U.S. Air Force to permit the determination of position and time for military troops and guided missiles. However, GPS has also become the basis for position and time measurement by scientific laboratories and a wide spectrum of applications in a multi-billion dollar commercial industry. Roughly one million receivers are manufactured each year and the total GPS market is expected to approach $ 10 billion by the end of next year. The story of GPS and its principles of measurement are the subjects of this article. EARLY METHODS OF NAVIGATION The shape and size of the earth has been known from the time of antiquity. The fact that the earth is a sphere was well known to educated people as long ago as the fourth century BC. In his book On the Heavens, Aristotle gave two scientifically correct arguments. First, the shadow of the earth projected on the moon during a lunar eclipse appears to be curved. Second, the elevations of stars change as one travels north or south, while certain stars visible in Egypt cannot be seen at all from Greece. The actual radius of the earth was determined within one percent by Eratosthenes in about 230 BC. He knew that the sun was directly overhead at noon on the summer solstice in Syene (Aswan, Egypt), since on that day it illuminated the water of a deep well. At the same time, he measured the length of the shadow cast by a column on the grounds of the library at Alexandria, which was nearly due north. The distance between Alexandria and Syene had been well established by professional runners and camel caravans. Thus Eratosthenes was able to compute the earth’s radius from the difference in latitude that he inferred from his measurement. In terms of modern units of length, he arrived at the figure of about 6400 km. By comparison, the actual mean radius is 6371 km (the earth is not precisely spherical, as the polar radius is 21 km less than the equatorial radius of 6378 km). The ability to determine one’s position on the earth was the next major problem to be addressed. In the second century, AD the Greek astronomer Claudius Ptolemy prepared a geographical atlas, in which he estimated the latitude and longitude of principal cities of the Mediterranean world. Ptolemy is most famous, however, for his geocentric theory of planetary motion, which was the basis for astronomical catalogs until Nicholas Copernicus published his heliocentric theory in 1543. Historically, methods of navigation over the earth’s surface have involved the angular measurement of star positions to determine latitude. The latitude of one’s position is equal to the elevation of the pole star. The position of the pole star on the celestial sphere is only temporary, however, due to precession of the earth’s axis of rotation through a circle of radius 23.5 over a period of 26,000 years. At the time of Julius Caesar, there was no star sufficiently close to the north celestial pole to be called a pole star. In 13,000 years, the star Vega will be near the pole. It is perhaps not a coincidence that mariners did not venture far from visible land until the era of Christopher Columbus, when true north could be determined using the star we now call Polaris. Even then the star’s diurnal rotation caused an apparent variation of the compass needle. Polaris in 1492 described a radius of about 3.5 about the celestial pole, compared to 1 today. At sea, however, Columbus and his contemporarie s depended primarily on the mariner’s compass and dead reckoning. The determination of longitude was much more difficult. Longitude is obtained astronomically from the difference between the observed time of a celestial event, such as an eclipse, and the corresponding time tabulated for a reference location. For each hour of difference in time, the difference in longitude is 15 degrees. Columbus himself attempted to estimate his longitude on his fourth voyage to the New World by observing the time of a lunar eclipse as seen from the harbor of Santa Gloria in Jamaica on February 29, 1504. In his distinguished biography Admiral of the Ocean Sea, Samuel Eliot Morrison states that Columbus measured the duration of the eclipse with an hour-glass and determined his position as nine hours and fifteen minutes west of Cadiz, Spain, according to the predicted eclipse time in an almanac he carried aboard his ship. Over the preceding year, while his ship was marooned in the harbor, Columbus had determined the latitude of Santa Gloria by numerous observations of the pole star. He made out his latitude to be 18, which was in error by less than half a degree and was one of the best recorded observations of latitude in the early sixteenth century, but his estimated longitude was off by some 38 degrees. Columbus also made legendary use of this eclipse by threatening the natives with the disfavor of God, as indicated by a portent from Heaven, if they did not bring desperately needed provisions to his men. When the eclipse arrived as predicted, the natives pleaded for the Admiral’s intervention, promising to furnish all the food that was needed. New knowledge of the universe was revealed by Galileo Galilei in his book The Starry Messenger. This book, published in Venice in 1610, reported the telescopic discoveries of hundreds of new stars, the craters on the moon, the phases of Venus, the rings of Saturn, sunspots, and the four inner satellites of Jupiter. Galileo suggested using the eclipses of Jupiter’s satellites as a celestial clock for the practical determination of longitude, but the calculation of an accurate ephemeris and the difficulty of observing the satellites from the deck of a rolling ship prevented use of this method at sea. Nevertheless, James Bradley, the third Astronomer Royal of England, successfully applied the technique in 1726 to determine the longitudes of Lisbon and New York with considerable accuracy. Inability to measure longitude at sea had the potential of catastrophic consequences for sailing vessels exploring the new world, carrying cargo, and conquering new territories. Shipwrecks were common. On October 22, 1707 a fleet of twenty-one ships under the command of Admiral Sir Clowdisley Shovell was returning to England after an unsuccessful military attack on Toulon in the Mediterranean. As the fleet approached the English Channel in dense fog, the flagship and three others foundered on the coastal rocks and nearly two thousand men perished. Stunned by this unprecedented loss, the British government in 1714 offered a prize of £20,000 for a method to determine longitude at sea within a half a degree. The scientific establishment believed that the solution would be obtained from observations of the moon. The German cartographer Tobias Mayer, aided by new mathematical methods developed by Leonard Euler, offered improved tables of the moon in 1757. The recorded position of the moon at a given time as seen from a reference meridian could be compared with its position at the local time to determine the angular position west or east. Just as the astronomical method appeared to achieve realization, the British craftsman John Harrison provided a different solution through his invention of the marine chronometer. The story of Harrison’s clock has been recounted in Dava Sobel’s popular book, Longitude. Both methods were tested by sea trials. The lunar tables permitted the determination of longitude within four minutes of arc, but with Harrison’s chronometer the precision was only one minute of arc. Ultimately, portions of the prize money were awarded to Mayer’s widow, Euler, and Harrison. In the twentieth century, with the development of radio transmitters, another class of navigation aids was created using terrestrial radio beacons, including Loran and Omega. Finally, the technology of artificial satellites made possible navigation and position determination using line of sight signals involving the measurement of Doppler shift or phase difference. TRANSIT Transit, the Navy Navigation Satellite System, was conceived in the late 1950s and deployed in the mid-1960s. It was finally retired in 1996 after nearly 33 years of service. The Transit system was developed because of the need to provide accurate navigation data for Polaris missile submarines. As related in an historical perspective by Bradford Parkinson, et al. in the journal Navigation (Spring 1995), the concept was suggested by the predictable but dramatic Doppler frequency shifts from the first Sputnik satellite, launched by the Soviet Union in October, 1957. The Doppler-shifted signals enabled a determination of the orbit using data recorded at one site during a single pass of the satellite. Conversely, if a satellite’s orbit were already known, a radio receiver’s position could be determined from the same Doppler measurements. The Transit system was composed of six satellites in nearly circular, polar orbits at an altitude of 1075 km. The period of revolution was 107 minutes. The system employed essentially the same Doppler data used to track the Sputnik satellite. However, the orbits of the Transit satellites were precisely determined by tracking them at widely spaced fixed sites. Under favorable conditions, the rms accuracy was 35 to 100 meters. The main problem with Transit was the large gaps in coverage. Users had to interpolate their positions between passes. GLOBAL POSITIONING SYSTEM The success of Transit stimulated both the U.S. Navy and the U.S. Air Force to investigate more advanced versions of a space-based navigation system with enhanced capabilities. Recognizing the need for a combined effort, the Deputy Secretary of Defense established a Joint Program Office in 1973. The NAVSTAR Global Positioning System (GPS) was thus created. In contrast to Transit, GPS provides continuous coverage. Also, rather than Doppler shift, satellite range is determined from phase difference. There are two types of observables. One is pseudorange, which is the offset between a pseudorandom noise (PRN) coded signal from the satellite and a replica code generated in the user’s receiver, multiplied by the speed of light. The other is accumulated delta range (ADR), which is a measure of carrier phase. The determination of position may be described as the process of triangulation using the measured range between the user and four or more satellites. The ranges are inferred from the time of propagation of the satellite signals. Four satellites are required to determine the three coordinates of position and time. The time is involved in the correction to the receiver clock and is ultimately eliminated from the measurement of position. High precision is made possible through the use of atomic clocks carried on-board the satellites. Each satellite has two cesium clocks and two rubidium clocks, which maintain time with a precision of a few parts in 1013 or 1014 over a few hours, or better than 10 nanoseconds. In terms of the distance traversed by an electromagnetic signal at the speed of light, each nanosecond corresponds to about 30 centimeters. Thus the precision of GPS clocks permits a real time measurement of distance to within a few meters. With post-processed carrier phase measurements, a precision of a few centimeters can be achieved. The design of the GPS constellation had the fundamental requirement that at least four satellites must be visible at all times from any point on earth. The tradeoffs included visibility, the need to pass over the ground control stations in the United States, cost, and sparing efficiency. The orbital configuration approved in 1973 was a total of 24 satellites, consisting of 8 satellites plus one spare in each of three equally spaced orbital planes. The orbital radius was 26,562 km, corresponding to a period of revolution of 12 sidereal hours, with repeating ground traces. Each satellite arrived over a given point four minutes earlier each day. A common orbital inclination of 63 was selected to maximize the on-orbit payload mass with launches from the Western Test Range. This configuration ensured between 6 and 11 satellites in view at any time. As envisioned ten years later, the inclination was reduced to 55 and the number of planes was increased to six. The constellation would consist of 18 primary satellites, which represents the absolute minimum number of satellites required to provide continuous global coverage with at least four satellites in view at any point on the earth. In addition, there would be 3 on-orbit spares. The operational system, as presently deployed, consists of 21 primary satellites and 3 on-orbit spares, comprising four satellites in each of six orbital planes. Each orbital plane is inclined at 55. This constellation improves on the “18 plus 3” satellite constellation by more fully integrating the three active spares. SPACE SEGMENT There have been several generations of GPS satellites. The Block I satellites, built by Rockwell International, were launched between 1978 and 1985. They consisted of eleven prototype satellites, including one launch failure, that validated the system concept. The ten successful satellites had an average lifetime of 8.76 years. The Block II and Block IIA satellites were also built by Rockwell International. Block II consists of nine satellites launched between 1989 and 1990. Block IIA, deployed between 1990 and 1997, consists of 19 satellites with several navigation enhancements. In April 1995, GPS was declared fully operational with a constellation of 24 operational spacecraft and a completed ground segment. The 28 Block II/IIA satellites have exceeded their specified mission duration of 6 years and are expected to have an average lifetime of more than 10 years. Block IIR comprises 20 replacement satellites that incorporate autonomous navigation based on crosslink ranging. These satellites are being manufactured by Lockheed Martin. The first launch in 1997 resulted in a launch failure. The first IIR satellite to reach orbit was also launched in 1997. The second GPS 2R satellite was successfully launched aboard a Delta 2 rocket on October 7, 1999. One to four more launches are anticipated over the next year. The fourth generation of satellites is the Block II follow-on (Block IIF). This program includes the procurement of 33 satellites and the operation and support of a new GPS operational control segment. The Block IIF program was awarded to Rockwell (now a part of Boeing). Further details may be found in a special issue of the Proceedings of the IEEE for January, 1999. CONTROL SEGMENT The Master Control Station for GPS is located at Schriever Air Force Base in Colorado Springs, CO. The MCS maintains the satellite constellation and performs the stationkeeping and attitude control maneuvers. It also determines the orbit and clock parameters with a Kalman filter using measurements from five monitor stations distributed around the world. The orbit error is about 1.5 meters. GPS orbits are derived independently by various scientific organizations using carrier phase and post-processing. The state of the art is exemplified by the work of the International GPS Service (IGS), which produces orbits with an accuracy of approximately 3 centimeters within two weeks. The system time reference is managed by the U.S. Naval Observatory in Washington, DC. GPS time is measured from Saturday/Sunday midnight at the beginning of the week. The GPS time scale is a composite “paper clock” that is synchronized to keep step with Coordinated Universal Time (UTC) and International Atomic Time (TAI). However, UTC differs from TAI by an integral number of leap seconds to maintain correspondence with the rotation of the earth, whereas GPS time does not include leap seconds. The origin of GPS time is midnight on January 5/6, 1980 (UTC). At present, TAI is ahead of UTC by 32 seconds, TAI is ahead of GPS by 19 seconds, and GPS is ahead of UTC by 13 seconds. Only 1,024 weeks were allotted from the origin before the system time is reset to zero because 10 bits are allocated for the calendar function (1,024 is the tenth power of 2). Thus the first GPS rollover occurred at midnight on August 21, 1999. The next GPS rollover will take place May 25, 2019. SIGNAL STRUCTURE The satellite position at any time is computed in the user’s receiver from the navigation message that is contained in a 50 bps data stream. The orbit is represented for each one hour period by a set of 15 Keplerian orbital elements, with harmonic coefficients arising from perturbations, and is updated every four hours. This data stream is modulated by each of two code division multiple access, or spread spectrum, pseudorandom noise (PRN) codes: the coarse/acquisition C/A code (sometimes called the clear/access code) and the precision P code. The P code can be encrypted to produce a secure signal called the Y code. This feature is known as the Anti-Spoof (AS) mode, which is intended to defeat deception jamming by adversaries. The C/A code is used for satellite acquisition and for position determination by civil receivers. The P(Y) code is used by military and other authorized receivers. The C/A code is a Gold code of register size 10, which has a sequence length of 1023 chips and a chipping rate of 1.023 MHz and thus repeats itself every 1 millisecond. (The term “chip” is used instead of “bit” to indicate that the PRN code contains no information.) The P code is a long code of length 2.3547 x 1014 chips with a chipping rate of 10 times the C/A code, or 10.23 MHz. At this rate, the P code has a period of 38.058 weeks, but it is truncated on a weekly basis so that 38 segments are available for the constellation. Each satellite uses a different member of the C/A Gold code family and a different one-week segment of the P code sequence. The GPS satellites transmit signals at two carrier frequencies: the L1 component with a center frequency of 1575.42 MHz, and the L2 component with a center frequency of 1227.60 MHz. These frequencies are derived from the master clock frequency of 10.23 MHz, with L1 = 154 x 10.23 MHz and L2 = 120 x 10.23 MHz. The L1 frequency transmits both the P code and the C/A code, while the L2 frequency transmits only the P code. The second P code frequency permits a dual-frequency measurement of the ionospheric group delay. The P-code receiver has a two-sigma rms horizontal position error of about 5 meters. The single frequency C/A code user must model the ionospheric delay with less accuracy. In addition, the C/A code is intentionally degraded by a technique called Selective Availability (SA), which introduces errors of 50 to 100 meters by dithering the satellite clock data. Through differential GPS measurements, however, position accuracy can be improved by reducing SA and environmental errors. The transmitted signal from a GPS satellite has right hand circular polarization. According to the GPS Interface Control Document, the specified minimum signal strength at an elevation angle of 5 into a linearly polarized receiver antenna with a gain of 3 dB (approximately equivalent to a circularly polarized antenna with a gain of 0 dB) is – 160 dBW for the L1 C/A code, – 163 dBW for the L1 P code, and – 166 dBW for the L2 P code. The L2 signal is transmitted at a lower power level since it is used primarily for the ionospheric delay correction. PSEUDORANGE The fundamental measurement in the Global Positioning System is pseudorange. The user equipment receives the PRN code from a satellite and, having identified the satellite, generates a replica code. The phase by which the replica code must be shifted in the receiver to maintain maximum correlation with the satellite code, multiplied by the speed of light, is approximately equal to the satellite range. It is called the pseudorange because the measurement must be corrected by a variety of factors to obtain the true range. The corrections that must be applied include signal propagation delays caused by the ionosphere and the troposphere, the space vehicle clock error, and the user’s receiver clock error. The ionosphere correction is obtained either by measurement of dispersion using the two frequencies L1 and L2 or by calculation from a mathematical model, but the tropospheric delay must be calculated since the troposphere is nondispersive. The true geometric distance to each satellite is obtained by applying these corrections to the measured pseudorange. Other error sources and modeling errors continue to be investigated. For example, a recent modification of the Kalman filter has led to improved performance. Studies have also shown that solar radiation pressure models may need revision and there is some new evidence that the earth’s magnetic field may contribute to a small orbit period variation in the satellite clock frequencies. CARRIER PHASE Carrier phase is used to perform measurements with a precision that greatly exceeds those based on pseudorange. However, a carrier phase measurement must resolve an integral cycle ambiguity whereas the pseudorange is unambiguous. The wavelength of the L1 carrier is about 19 centimeters. Thus with a cycle resolution of one percent, a differential measurement at the level of a few millimeters is theoretically possible. This technique has important applications to geodesy and analogous scientific programs. RELATIVITY The precision of GPS measurements is so great that it requires the application of Albert Einstein’s special and general theories of relativity for the reduction of its measurements. Professor Carroll Alley of the University of Maryland once articulated the significance of this fact at a scientific conference devoted to time measurement in 1979. He said, “I think it is appropriate … to realize that the first practical application of Einstein’s ideas in actual engineering situations are with us in the fact that clocks are now so stable that one must take these small effects into account in a variety of systems that are now undergoing development or are actually in use in comparing time worldwide. It is no longer a matter of scientific interest and scientific application, but it has moved into the realm of engineering necessity.” According to relativity theory, a moving clock appears to run slow with respect to a similar clock that is at rest. This effect is called “time dilation.” In addition, a clock in a weaker gravitational potential appears to run fast in comparison to one that is in a stronger gravitational potential. This gravitational effect is known in general as the “red shift” (only in this case it is actually a “blue shift”). GPS satellites revolve around the earth with a velocity of 3.874 km/s at an altitude of 20,184 km. Thus on account of the its velocity, a satellite clock appears to run slow by 7 microseconds per day when compared to a clock on the earth’s surface. But on account of the difference in gravitational potential, the satellite clock appears to run fast by 45 microseconds per day. The net effect is that the clock appears to run fast by 38 microseconds per day. This is an enormous rate difference for an atomic clock with a precision of a few nanoseconds. Thus to compensate for this large secular rate, the clocks are given a rate offset prior to satellite launch of – 4.465 parts in 1010 from their nominal frequency of 10.23 MHz so that on average they appear to run at the same rate as a clock on the ground. The actual frequency of the satellite clocks before launch is thus 10.22999999543 MHz. Although the GPS satellite orbits are nominally circular, there is always some residual eccentricity. The eccentricity causes the orbit to be slightly elliptical, and the velocity and altitude vary over one revolution. Thus, although the principal velocity and gravitational effects have been compensated by a rate offset, there remains a slight residual variation that is proportional to the eccentricity. For example, with an orbital eccentricity of 0.02 there is a relativistic sinusoidal variation in the apparent clock time having an amplitude of 46 nanoseconds. This correction must be calculated and taken into account in the GPS receiver. The displacement of a receiver on the surface of the earth due to the earth’s rotation in inertial space during the time of flight of the signal must also be taken into account. This is a third relativistic effect that is due to the universality of the speed of light. The maximum correction occurs when the receiver is on the equator and the satellite is on the horizon. The time of flight of a GPS signal from the satellite to a receiver on the earth is then 86 milliseconds and the correction to the range measurement resulting from the receiver displacement is 133 nanoseconds. An analogous correction must be applied by a receiver on a moving platform, such as an aircraft or another satellite. This effect, as interpreted by an observer in the rotating frame of reference of the earth, is called the Sagnac effect. It is also the basis for a laser ring gyro in an inertial navigation system. GPS MODERNIZATION In 1996, a Presidential Decision Directive stated the president would review the issue of Selective Availability in 2000 with the objective of discontinuing SA no later than 2006. In addition, both the L1 and L2 GPS signals would be made available to civil users and a new civil 10.23 MHz signal would be authorized. To satisfy the needs of aviation, the third civil frequency, known as L5, would be centered at 1176.45 MHz, in the Aeronautical Radio Navigation Services (ARNS) band, subject to approval at the World Radio Conference in 2000. According to Keith McDonald in an article on GPS modernization published in the September, 1999 GPS World, with SA removed the civil GPS accuracy would be improved to about 10 to 30 meters. With the addition of a second frequency for ionospheric group delay corrections, the civil accuracy would become about 5 to 10 meters. A third frequency would permit the creation of two beat frequencies that would yield one-meter accuracy in real time. A variety of other enhancements are under consideration, including increased power, the addition of a new military code at the L1 and L2 frequencies, additional ground stations, more frequent uploads, and an increase in the number of satellites. These policy initiatives are driven by the dual needs of maintaining national security while supporting the growing dependence on GPS by commercial industry. When these upgrades would begin to be implemented in the Block IIR and IIF satellites depends on GPS funding. Besides providing position, GPS is a reference for time with an accuracy of 10 nanoseconds or better. Its broadcast time signals are used for national defense, commercial, and scientific purposes. The precision and universal availability of GPS time has produced a paradigm shift in time measurement and dissemination, with GPS evolving from a secondary source to a fundamental reference in itself. The international community wants assurance that it can rely on the availability of GPS and continued U.S. support for the system. The Russian Global Navigation Satellite System (GLONASS) has been an alternative, but economic conditions in Russia have threatened its continued viability. Consequently, the European Union is considering the creation of a navigation system of its own, called Galileo, to avoide relying on the U.S. GPS and Russian GLONASS programs. The Global Positioning System is a vital national resource. Over the past thirty years it has made the transition from concept to reality, representing today an operational system on which the entire world has become dependent. Both technical improvements and an enlightened national policy will be necessary to ensure its continued growth into the twenty-first century. ____________________________________________ Dr. Robert A. Nelson, P.E. is president of Satellite Engineering Research Corporation, a satellite engineering consulting firm in Bethesda, Maryland, a Lecturer in the Department of Aerospace Engineering at the University of Maryland and Technical Editor of Via Satellite magazine. Dr. Nelson is the instructor for the ATI course Satellite Communications Systems Engineering. Please see our Schedule for dates and locations.

International System Units

The International System of Units Its History and Use in Science and Industry by Robert A. Nelson On September 23, 1999 the Mars Climate Orbiter was lost during an orbit injection maneuver when the spacecraft crashed onto the surface of Mars. The principal cause of the mishap was traced to a thruster calibration table, in […]

The International System of Units

Its History and Use in Science and Industry

by Robert A. Nelson On September 23, 1999 the Mars Climate Orbiter was lost during an orbit injection maneuver when the spacecraft crashed onto the surface of Mars. The principal cause of the mishap was traced to a thruster calibration table, in which British units instead of metric units were used. The software for celestial navigation at the Jet Propulsion Laboratory expected the thruster impulse data to be expressed in newton seconds, but Lockheed Martin Astronautics in Denver, which built the orbiter, provided the values in pound-force seconds, causing the impulse to be interpreted as roughly one-fourth its actual value. The Mars spacecraft incident renews a controversy that has existed in the United States since the beginning of the space program regarding the use of metric or British units of measurement. To put the issue into perspective, this article reviews the history of the metric system and its modern version, the International System of Units (SI). The origin and evolution of the metric units, and the role they have played in the United States, will be summarized. Technical details and definitions will be provided for reference. Finally, the use of metric units in the satellite industry will be examined. ORIGIN OF THE METRIC SYSTEM The metric system was one of many reforms introduced in France during the period between 1789 and 1799, known as the French Revolution. The need for reform in the system of weights and measures, as in other affairs, had long been recognized. No other aspect of applied science affects the course of human activity so directly and universally. Prior to the metric system, there had existed in France a disorderly variety of measures, such as for length, volume, or mass, that were arbitrary in size and variable from one town to the next. In Paris the unit of length was the Pied de Roi and the unit of mass was the Livre poids de marc. These units could be traced back to Charlemagne. However, all attempts to impose the “Parisian” units on the whole country were fruitless, as they were opposed by the guilds and nobles who benefited from the confusion. The advocates of reform sought to guarantee the uniformity and permanence of the units of measure by taking them from properties derived from nature. In 1670, the abbe Gabriel Mouton of Lyons proposed a unit of length equal to one minute of arc on the earth’s surface, which he divided into decimal fractions. He suggested a pendulum of specified period as a means of preserving one of these submultiples. The conditions required for the creation of a new measurement system were made possible by the French Revolution, an event that was initially provoked by a national financial crisis. In 1787 King Louis XVI convened the Estates General, an institution that had last met in 1614, for the purpose of imposing new taxes to avert a state of bankruptcy. As they assembled in 1789, the commoners, representing the Third Estate, declared themselves to be the only legitimate representatives of the people, and succeeded in having the clergy and nobility join them in the formation of the National Assembly. Over the next two years, they drafted a new constitution. In 1790, Charles-Maurice de Talleyrand, Bishop of Autun, presented to the National Assembly a plan to devise a system of units based on the length of a pendulum beating seconds at latitude 45. The new order was envisioned as an “enterprise whose result should belong some day to the whole world.” He sought, but failed to obtain, the collaboration of England, which was concurrently considering a similar proposal by Sir John Riggs Miller. The two founding principles were that the system would be based on scientific observation and that it would be a decimal system. A distinguished commission of the French Academy of Sciences, including J. L. Lagrange and Pierre Simon Laplace, considered the unit of length. Rejecting the seconds pendulum as insufficiently precise, the commission defined the unit, given the name metre in 1793, as one ten millionth of a quarter of the earth’s meridian passing through Paris. The proposal was accepted by the National Assembly on March 26, 1791. The definition of the meter reflected the extensive interest of French scientists in the figure of the earth. Surveys in Lapland by Maupertuis in 1736 and in France by LaCaille in 1740 had refined the value of the earth’s radius and established definitively that the shape of the earth is oblate. To determine the length of the meter, a new survey was conducted by the astronomers Jean Baptiste Delambre and P.F.A. Mechain between Dunkirk, in France on the English Channel, and Barcelona, Spain, on the coast of the Mediterranean Sea. This work was begun in 1792 and completed in 1798, enduring the hardships of the “reign of terror” and the turmoil of revolution. We now know that the quadrant of the earth is 10 001 957 meters instead of exactly 10 000 000 meters as originally planned. The principal source of error was the assumed value of the earth’s flattening used in correcting for oblateness. The unit of volume, the pinte (later renamed the litre), was defined as the volume of a cube having a side equal to one-tenth of a meter. The unit of mass, the grave (later renamed the kilogramme), was defined as the mass of one pinte of distilled water at the temperature of melting ice. In addition, the centigrade scale for temperature was adopted, with fixed points at 0 C and 100 C representing the freezing and boiling points of water (now replaced by the Celsius scale). The work to determine the unit of mass was begun by Lavoisier and Hauy and was completed by Gineau and Fabbroni. They discovered that the maximum density of water occurs at 4 C, and not at 0 C as had been supposed, so the definition of the kilogram was amended to specify the temperature of maximum density. We now know that the intended mass was 0.999972 kg, i.e., 1000.028 cm3 instead of exactly 1000 cm3 for the volume of 1 kilogram of pure water at 4 C. On August 1, 1793 the National Convention, which by then ruled France, issued a decree adopting the preliminary definitions and terms. The “methodical” nomenclature, specifying fractions and multiples of the units by Latin prefixes, was chosen in favor of the “common” nomenclature, involving separate names. A new calendar was also introduced in September, 1793. Its origin was designated retroactively as September 22, 1792 to commemorate the overthrow of the monarchy and the inception of the Republic of France. The French Revolutionary Calendar consisted of twelve months of thirty days each, concluded by a five or six day holiday. The months were given poetic names that suggested the prevailing seasons. Each month was divided into three ten-day weeks, or decades. The day itself was divided into decimal fractions, with ten hours per day and 100 minutes per hour. The calendar was politically, rather than scientifically, motivated, since it was intended to weaken the influence of Christianity. It was abolished by Napoleon in 1806 in return for recognition by the Church of his authority as emperor of France. Although the calendar reform remained in effect for twelve years, the new method of keeping the time of day required the replacement of valued clocks and timepieces and was never actually used in practice. The metric system was officially adopted on April 7, 1795. The government issued a decree (Loi du 18 germinal, an III) formalizing the adoption of the definitions and terms that are in use today. A brass bar was made by Lenoir to represent the provisional meter, obtained from the survey of LaCaille, and a provisional standard for the kilogram was derived. In 1799 permanent standards for the meter and kilogram made from platinum were constructed based on the new survey by Delambre and Mechain. The full length of the meter bar represented the unit. These standards were deposited in the Archives of the Republic. They became official by an act of December 10, 1799. During the Napoleonic era, several regressive acts were passed that temporarily revived old traditions. Thus in spite of its auspicious beginning, the metric system was not quickly adopted in France. Although the system continued to be taught in the schools, lack of funds prevented the distribution of secondary standards. Finally, after a three year transition period, the metric system became compulsory throughout France as of January 1, 1840. REACTION IN THE UNITED STATES The importance of a uniform system of weights and measures was recognized in the United States, as in France. Article I, Section 8, of the U.S. Constitution provides that Congress shall have the power “to coin money … and fix the standard of weights and measures.” However, although the progressive concept of decimal coinage was introduced, the early American settlers both retained and cultivated the customs and tools of their British heritage, including the measures of length and mass. In contrast to the French Revolution, the “American Revolution” was not a revolution at all, but was rather a war of independence. In 1790, President George Washington referred the subject of weights and measures to his Secretary of State, Thomas Jefferson. In a report submitted to the House of Representatives, Jefferson considered two alternatives: if the existing measures were retained they could be rendered more simple and uniform, or if a new system were adopted, he favored a decimal system based on the principle of the seconds pendulum. As it was eventually formulated, Jefferson did not endorse the metric system, primarily because the metric unit of length could not be checked without a sizable scientific operation on European soil. The political situation at the turn of the eighteenth century also made consideration of the metric system impractical. Although France under Louis XVI had supported the colonies in the war with England, by 1797 there was manifest hostility. The revolutionary climate in France was viewed by the external world with a mixture of curiosity and alarm. The National Convention had been replaced by the Directory, and French officials who had been sympathetic to the United States either had been executed or were in exile. In addition, a treaty negotiated with England by John Jay in 1795 regarding settlement of the Northwest Territories and trade with the British West Indies was interpreted by France as evidence of an Anglo-American alliance. France retaliated by permitting her ships to prey upon American merchant vessels and Federalist President John Adams prepared for a French invasion. Thus in 1798, when dignitaries from foreign countries were assembled in Paris to learn of France’s progress with metrological reform, the United States was not invited. A definitive investigation was prepared in 1821 by Secretary of State John Quincy Adams that was to remove the issue from further consideration for the next forty-five years. He found that the standards of length, volume, and mass used throughout the 22 states of the Union were already substantially uniform, unlike the disparate measures that had existed in France prior to the French Revolution. Moreover, it was not at all evident that the metric system would be permanent, since even in France its use was sporadic and, in fact, the consistent terminology had been repealed in 1812 by Napoleon. Therefore, if the metric system failed to win support in early America, it was not for want of recognition. Serious consideration of the metric system did not occur again until after the Civil War. In 1866, upon the advice of the National Academy of Sciences, the metric system was made legal by the Thirty-Ninth Congress. The Act was signed into law on July 28 by President Andrew Johnson. TREATY OF THE METER A series of international expositions in the middle of the nineteenth century enabled the French government to promote the metric system for world use. Between 1870 and 1872, with an interruption caused by the Franco-Prussian War, an international meeting of scientists was held to consider the design of new international metric standards that would replace the meter and kilogram of the French Archives. A Diplomatic Conference on the Meter was convened to ratify the scientific decisions. Formal international approval was secured by the Treaty of the Meter, signed in Paris by the delegates of 17 countries, including the United States, on May 20,1875. The treaty established the International Bureau of Weights and Measures (BIPM). It also provided for the creation of an International Committee for Weights and Measures (CIPM) to run the Bureau and the General Conference on Weights and Measures (CGPM) as the formal diplomatic body that would ratify changes as the need arose. The French government offered the Pavillon de Breteuil, once a small royal palace, to serve as headquarters for the Bureau in Sevres, France near Paris. The grounds of the estate form a tiny international enclave within French territory. A total of 30 meter bars and 43 kilogram cylinders were manufactured from a single ingot of an alloy of 90 percent platinum and 10 percent iridium by Johnson, Mathey and Company of London. The original meter and kilogram of the French Archives in their existing states were taken as the points of departure. The standards were intercompared at the International Bureau between 1886 and 1889. One meter bar and one kilogram cylinder were selected as the international prototypes. The remaining standards were distributed to the signatories. The work was approved by the First General Conference on Weights and Measures in 1889. The United States received meters 21 and 27 and kilograms 4 and 20. On January 2, 1890 the seals to the shipping cases for meter 27 and kilogram 20 were broken in an official ceremony at the White House with President Benjamin Harrison presiding. The standards were deposited in the Office of Weights and Measures of the U.S. Coast and Geodetic Survey. U.S. CUSTOMARY UNITS The U.S. customary units were tied to the British and French units by a variety of indirect comparisons. Troy weight was the standard for the minting of coins. Congress could be ambivalent about nonuniformity in standards for trade, but it could not tolerate nonuniformity in its standards for money. Therefore, in 1827 a brass copy of the British troy pound of 1758 was secured by Ambassador to England and former Secretary of the Treasury, Albert Gallatin. This standard was kept in the Philadelphia mint and lesser copies were made and distributed to other mints. The troy pound of the Philadelphia mint was virtually the primary standard for commercial transactions until 1857 and remained the standard for coins until 1911. The semi-official standards used in commerce for a quarter century may be attributed to Ferdinand Hassler, who was appointed superintendent of the newly organized Coast Survey in 1807. In 1832 the Treasury Department directed Hassler to construct and distribute to the states standards of length, mass, and volume, and balances by which masses might be compared. As the standard of length, Hassler adopted the Troughton scale, an 82-inch brass bar made by Troughton of London for the Coast Survey that Hassler had brought back from Europe in 1815. The distance between the 27th and 63rd engraved lines on a silver inlay scale down the center of the bar was taken to be equal to the British yard. The standard of mass was the avoirdupois pound, derived from the troy pound of the Philadelphia mint by the ratio 7000 grains to 5760 grains. It was represented by a brass knob weight that Hassler constructed and marked with a star. Thus it has come to be known as the “star” pound. The system of weights and measures in Great Britain had been in use since the reign of Queen Elizabeth I. Following a reform begun in 1824, the imperial standard avoirdupois pound was made the standard of mass in 1844 and the imperial standard yard was adopted in 1855. The imperial standards were made legal by an Act of Parliament in 1855 and are preserved in the Board of Trade in London. The United States received copies of the British imperial pound and yard, which became the official U.S. standards from 1857 until 1893. When the metric system was made lawful in the United States in 1866, a companion resolution was passed to distribute metric standards to the states. The Treasury Department had in its possession several copies derived from the meter and kilogram of the French Archives. These included the “Committee” meter and kilogram, which were an iron end standard and a brass cylinder with knob copied from the French prototypes, that Hassler had brought with him when he immigrated to the United States in 1805. He had received them as a gift from his friend, J.G. Tralles, who was the Swiss representative to the French metric convocation in 1798 and a member of its committee on weights and measures. Also available were the “Arago” meter and kilogram, named after the French physicist who certified them. They were purchased by the United States in 1821 through Albert Gallatin, then minister to France. The Committee meter and the Arago kilogram were used as the prototypes for brass metric standards that were distributed to the states. In 1893, under a directive from Thomas C. Mendenhall, Superintendent of Standard Weights and Measures of the Coast and Geodetic Survey, the U.S. customary units were redefined in terms of the metric units. The primary standards of length and mass adopted were prototype meter No. 27 and prototype kilogram No. 20 that the United States had received in 1889 as a signatory to the Treaty of the Meter. The yard was defined as 3600/3937 meter and the avoirdupois pound-mass was defined as 0.4535924277 kilogram. The conversion for mass was based on a comparison between the British imperial standard pound and the international prototype kilogram performed in 1883. These definitions were used by the National Bureau of Standards (now the National Institute of Standards and Technology) from its founding in 1901 until 1959. On July 1, 1959 the definitions were fixed by international agreement among the English-speaking countries to be 1 yard = 0.9144 meter and 1 pound-mass = 0.45359237 kilogram exactly. The definition of the yard is equivalent to the relations 1 foot = 0.3048 meter and 1 inch = 2.54 centimeters exactly. The derived unit of force in the British system is the pound-force (lbf), which is defined as the weight of one pound-mass (lbm) at a hypothetical location where the acceleration of gravity has the standard value 9.80665 m/s2 exactly. Thus, 1 lbf = 0.45359237 kg x 9.80665 m/s2 = 4.448 N approximately. The slug (sl) is the mass that receives an acceleration of one foot per second squared under a force of one pound-force. Thus 1 sl = (1 lbf)/(1 ft/s2) = (4.448 N)/(0.3048 m/s2) = 14.59 kg = 32.17 lbm approximately. THE ELECTRICAL UNITS The theories of electricity and magnetism developed and matured during the early 1800s as fundamental discoveries were made by Oersted, Ampere, Faraday, and many others. The possibility of making magnetic measurements in terms of mechanical units, that is in “absolute measure,” was first pointed out by Gauss in 1833. His analysis was carried further to cover electrical phenomena by Weber, who in 1851 discussed a method by which a complete set of absolute units might be developed. In 1861 a committee of the British Association for the Advancement of Science, that included William Thomson (later Lord Kelvin), James Clerk Maxwell, and James Prescott Joule, undertook a comprehensive study of electrical measurements. This committee introduced the concept of a system of units. Four equations were sufficient to determine the units of charge q, current I, voltage V, and resistance R. These were either Coulomb’s force law for charges or Ampere’s force law for currents, the relation between charge and current q = I t, Ohm’s law V = I R, and the equation for electrical work W = V q = I 2 R t, where t is time. A fundamental principle was that the system should be coherent. That is, the system is founded upon certain base units for length, mass, and time, and derived units are obtained as products or quotients without requiring numerical factors. The meter, gram, and mean solar second were selected as base units. In 1873 a second committee recommended a centimeter-gram-second (CGS) system of units because in this system the density of water is unity. Two parallel systems of units were devised, the electrostatic and electromagnetic subsystems, depending on whether the law of force for electric charges or for electric currents was taken as fundamental. The ratio of the electrostatic to the electromagnetic unit of charge or current was a fundamental experimental constant c. The committee also conducted research on electrical standards. It issued a wire resistance standard, the “B.A. unit,” which soon became known as the “ohm.” The idea of naming units after eminent scientists was due to Sir Charles Bright and Latimer Clark. At the time, electricity and magnetism were essentially two distinct branches of experimental physics. However, in a series of papers published between 1856 and 1865, Maxwell created a unified theory based on the field concept introduced by Faraday. He predicted the existence of electromagnetic waves and identified the “ratio of the units” c with the speed of light. In 1888, Heinrich Hertz verified Maxwell’s prediction by generating and detecting electromagnetic waves at microwave frequencies in the laboratory. He also greatly simplified the theory by eliminating unnecessary physical assumptions. Thus the form of Maxwell’s equations as they are known to physicists and engineers today is due to Hertz. (Oliver Heaviside made similar modifications and introduced the use of vectors.) In addition, Hertz combined the electrostatic and electromagnetic CGS units into a single system related by the speed of light c, which he called the “Gaussian” system of units. The recommendations of the B.A. committees were adopted by the First International Electrical Congress in Paris in 1881. Five “practical” electrical units were defined as certain powers of 10 of the CGS units: the ohm, farad, volt, ampere, and coulomb. In 1889, the Second Congress added the joule, watt, and a unit of inductance, later given the name henry. In 1901, Giorgi demonstrated that the practical electrical units and the MKS mechanical units could be incorporated into a single coherent system by (1) selecting the meter, kilogram, and second as the base units for mechanical quantities; (2) expanding the number of base units to four, including one of an electrical nature; and (3) assigning physical dimensions to the permeability of free space 0, with a numerical value of 4 x107 in a “rationalized” system or 107 in an “unrationalized” system. (The term “rationalized,” due to Heaviside, concerned where factors of 4 should logically appear in the equations based on symmetry.) The last assumption implied that the magnetic flux density B and magnetic field H, which are related in vacuum by the equation B = 0 H, are physically distinct with different units, whereas in the Gaussian system they are of the same character and are dimensionally equivalent. An analogous situation occurs for the electric fields D and Ethat are related by D = 0 E, where 0 is the permittivity of free space given by c2 = 1 / 0 0. In 1908, an International Conference on Electrical Units and Standards held in London adopted independent, easily reproducible primary electrical standards for resistance and current, represented by a column of mercury and a silver coulombmeter, respectively. These so-called “international” units went into effect in 1911, but they soon became obsolete with the growth of the national standards laboratories and the increased application of electrical measure-ments to other fields of science. With the recognition of the need for further international coopera-tion, the 6th CGPM amended the Treaty of the Meter in 1921 to cover the units of electricity and photometry and the 7th CGPM created the Consultative Committee for Electricity (CCE) in 1927. By the 8th CGPM in 1933 there was a universal desire to replace the “international” electrical units with “absolute” units. Therefore, the International Electrotechnical Commission (IEC) recommended to the CCE an absolute system of units based on Giorgi’s proposals, with the practical electrical units incorporated into a comprehensive MKS system. The choice of the fourth unit was left undecided. At the meeting of the CCE in September 1935, the delegate from England, J.E. Sears, presented a note that set the course for future action. He proposed that the ampere be selected as the base unit for electricity, defined in terms of the force per unit length between two long parallel wires. The unit could be preserved in the form of wire coils for resistance and Weston cells for voltage by calibration with a current balance. This recommendation was unanimously accepted by the CCE and was adopted by the CIPM. Further progress was halted by the intervention of World War II. Finally, in 1946, by authority given to it by the CGPM in 1933, the CIPM officially adopted the MKS practical system of absolute electrical units to take effect January 1, 1948. INTERNATIONAL SYSTEM OF UNITS (SI) By 1948 the General Conference on Weights and Measures was responsible for the units and standards of length, mass, electricity, photometry, temperature, and ionizing radiation. At this time, the next major phase in the evolution of the metric system was begun. It was initiated by a request of the International Union of Pure and Applied Physics “to adopt for international use a practical international system of units.” Thus the 9th CGPM decided to define a complete list of derived units. Derived units had not been considered previously because they do not require independent standards. Also, the CGPM brought within its province the unit of time, which had been the prerogative of astronomers. The work was started by the 10th CGPM in 1954 and was completed by the 11th CGPM in 1960. During this period there was an extensive revision and simplification of the metric unit definitions, symbols, and terminology. The kelvin and candela were added as base units for thermodynamic temperature and luminous intensity, and in 1971 the mole was added as a nineth base unit for amount of substance. The modern metric system is known as the International System of Units, with the international abbreviation SI. It is founded on the nine base units, summarized in Table 1, that by convention are regarded as dimensionally independent. All other units are derived units, formed coherently by multiplying and dividing units within the system without the use of numerical factors. Some derived units, including those with special names, are listed in Table 2. For example, the unit of force is the newton, which is equal to a kilogram meter per second squared, and the unit of energy is the joule, equal to a newton meter. The expression of multiples and submultiples of SI units is facilitated by the use of prefixes, listed in Table 3. (Additional information is available on the Internet at the websites of the International Bureau of Weights and Measures at http://www.bipm.fr and the National Institute of Standards and Technology at http://physics.nist.gov/cuu .) METRIC STANDARDS One must distinguish a unit, which is an abstract idealization, and a standard, which is the physical embodiment of the unit. Since the origin of the metric system, the standards have undergone several revisions to reflect increased precision as the science of metrology has advanced. The meter. The international prototype meter standard of 1889 was a platinum-iridium bar with an X-shaped cross section. The meter was defined by the distance between two engraved lines on the top surface of the bridge instead of the distance between the end faces. The meter was derived from the meter of the French Archives in its existing state and reference to the earth was abandoned. The permanence of the international prototype was verified by comparison with three companion bars, called “check standards.” In addition, there were nine measurements in terms of the red line of cadmium between 1892 and 1942. The first of these measurements was carried out by A. A. Michelson using the interferometer which he invented. For this work, Michelson received the Nobel Prize in physics in 1907. Improvements in monochro-matic light sources resulted in a new standard based on a well-defined wavelength of light. A single atomic isotope with an even atomic number and an even mass number is an ideal spectral standard because it eliminates complexity and hyperfine structure. Also, Doppler broadening is minimized by using a gas of heavy atoms in a lamp operated at a low temperature. Thus a particular orange krypton-86 line was chosen, whose wavelength was obtained by direct comparison with the cadmium wavelength. In 1960, the 11th CGPM defined the meter as the length equal to 1 650 763.73 wavelengths of this spectral line. Research on lasers at the Boulder, CO laboratory of the National Bureau of Standards contributed to another revision of the meter. The wavelength and frequency of a stabilized helium-neon laser beam were measured independently to determine the speed of light. The wavelength was obtained by comparison with the krypton wavelength and the frequency was determined by a series of measurements traceable to the cesium atomic standard for the second. The principal source of error was in the profile of the krypton spectral line representing the meter itself. Consequently, in 1983 the 17th CGPM adopted a new definition of the meter based on this measurement as “the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second.” The effect of this definition is to fix the speed of light at exactly 299 792 458 m/s. Thus experimental methods previously interpreted as measurements of the speed of light c (or equivalently, the permittivity of free space 0) have become calibrations of length. The kilogram. In 1889 the international prototype kilogram was adopted as the standard for mass. The prototype kilogram is a platinum-iridium cylinder with equal height and diameter of 3.9 cm and slightly rounded edges. For a cylinder, these dimensions present the smallest surface area to volume ratio to minimize wear. The standard is carefully preserved in a vault at the International Bureau of Weights and Measures and is used only on rare occasions. It remains the standard today. The kilogram is the only unit still defined in terms of an arbitrary artifact instead of a natural phenomenon. The second. Historically, the unit of time, the second, was defined in terms of the period of rotation of the earth on its axis as 1/86 400 of a mean solar day. Meaning “second minute,” it was first applied to timekeeping in about the nineteenth century when pendulum clocks were invented that could maintain time to this precision. By the twentieth century, astronomers realized that the rotation of the earth is not constant. Due to gravitational tidal forces produced by the moon on the shallow seas, the length of the day is increasing by about 1.4 milliseconds per century. The effect can be measured by comparing the computed paths of ancient solar eclipses on the assumption of uniform rotation with the recorded locations on earth where they were actually observed. Consequently, in 1956 the second was redefined in terms of the period of revolution of the earth about the sun for the epoch 1900, as represented by the Tables of the Sun computed by the astronomer Simon Newcomb of the U.S. Naval Observatory in Washington, DC. The operational significance of this definition was to adopt the linear coefficient in Newcomb’s formula for the mean longitude of the sun to determine the unit of time. The rapid development of atomic clocks soon permitted yet another definition. Accordingly, in 1967 the 13th CGPM defined the second as “the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two ground states of the cesium-133 atom.” This definition was based on observations of the moon, whose ephemeris is tied indirectly to the apparent motion of the sun, and was equivalent to the previous definition within the limits of experimental uncertainty. The ampere. The unit of electric current, the ampere, is defined as that constant current which, if maintained in each of two parallel, infinitely long wires with a separation of 1 meter in vacuum, would produce a force per unit length between them equal to 2 x 10-7 N/m. This formal definition serves to establish the value of the constant 0 as 4 x 107 N/A2 exactly. Although the base unit for electricity is the ampere, the electrical units are maintained through the volt and the ohm. In the past, the practical representation of the volt was a group of Weston saturated cadmium-sulfate electrochemical standard cells. A primary calibration experiment involved the measurement of the force between two coils of an “ampere balance” to determine the current, while the cell voltage was compared to the potential difference across a known resistance. The ohm was represented by a wire-wound standard resistor. Its resistance was measured against the impedance of an inductor or a capacitor at a known frequency. The inductance can be calculated from the geometrical dimensions alone. From about 1960, a so-called Thompson-Lampard calculable capacitor has been used, in which only a single measurement of length is required. Since the early 1970s, the volt has been maintained by means of the Josephson effect, a quantum mechanical tunneling phenomenon discovered by Brian Josephson in 1962. A Josephson junction may be formed by two superconducting niobium films separated by an oxide insulating layer. If the Josephson junction is irradiated by microwaves at frequency f and the bias current is progressively increased, the current-voltage characteristic is a step function, in which the dc bias voltage increases discontinuously at discrete voltage intervals equal to f / KJ , where KJ = 2 e / h is the Josephson constant, h is Planck’s constant, and e is the elementary charge. The ohm is now realized by the quantum Hall effect, a characteristic of a two-dimensional electron gas discovered by Klaus von Klitzing in 1980. In a device such as a silicon metal-oxide-semiconductor field-effect transistor (MOSFET), the Hall voltage VH for a fixed current I increases in discrete steps as the gate voltage is increased. The Hall resistance, or RH = VH / I , is equal to an integral fraction of the von Klitzing constant, given by RK = h / e2 = 0 c / 2 , where is the fine structure constant. In practice, RK can be measured in terms of a laboratory resistance standard, whose resistance is obtained by comparison with the impedance of a calculable capacitor, or it can be obtained indirectly from. A new method to determine the relation between the mechanical and electromagnetic units that has shown much promise is by means of a “watt balance,” which has greater precision than an ordinary ampere balance. In this experiment, a current I is passed through a test coil suspended in the magnetic field of a larger coil so that the force F balances a known weight mg. Next the test coil is moved axially through the magnetic field and the velocity v and induced voltage V are measured. By the equivalence of mechanical and electrical power, F v = V I. The magnetic field and apparatus geometry drop out of the calculation. The voltage V is measured in terms of the Josephson constant KJ while the current I is calibrated by the voltage across a resistance known in terms of the von Klitzing constant RK. The experiment determines KJ 2 RK (and thus h), which yields KJ if RK is assumed to be known in terms of the SI ohm. The Josephson and quantum Hall effects provide highly uniform and conveniently reproducible quantum mechanical standards for the volt and the ohm. For the purpose of practical engineering metrology, conventional values for the Josephson constant and the von Klitzing constant were adopted by international agreement starting January 1, 1990. These values are KJ-90 = 483 597.9 GHz/V and RK-90 = 25 812.807 exactly. The best experimental SI values, obtained as part of an overall least squares adjustment of the fundamental constants completed in 1998, differ only slightly from these conventional values. METRIC UNITS IN INDUSTRY The International System of Units (SI) has become the fundamental basis of scientific measurement worldwide. It is also used for everyday commerce in virtually every country of the world but the United States. Congress has passed legislation to encourage use of the metric system, including the Metric Conversion Act of 1975 and the Omnibus Trade and Competitiveness Act of 1988, but progress has been slow. The space program should have been the leader in the use of metric units in the United States and would have been an excellent model for education. Education in the United States equips you greatly to handle the complicated task of trying to recognize synonym. Burt Edelson, Director of the Institute for Advanced Space Research at George Washington University and former Associate Administrator of NASA, recalls that “in the mid-‘80s, NASA made a valiant attempt to convert to the metric system” in the initial phase of the international space station program. However, he continued, “when the time came to issue production contracts, the contractors raised such a hue cry over the costs and difficulties of conversion that the initiative was dropped. The international partners were unhappy, but their concerns were shunted aside. No one ever suspected that a measurement conversion error could cause a failure in a future space project.” Economic pressure to compete in an international environment is a strong motive for contractors to use metric units. Barry Taylor, head of the Fundamental Constants Data Center of the National Institute of Standards and Technology and U.S. representative to the Consultative Committee on Units of the CIPM, expects that the greatest stimulus for metrication will come from industries with global markets. “Manufacturers are moving steadily ahead on SI for foreign markets,” he says. Indeed, most satellite design technical literature does use metric units, including meters for length, kilograms for mass, and newtons for force, because of the influence of international partners, suppliers, and customers. CONCLUSION As we begin the new millennium, there should be a renewed national effort to promote the use of SI metric units throughout industry, and to assist the general public in becoming familiar with the system and using it regularly. The schools have taught the metric system in science classes for decades. It is time to put aside the customary units of the industrial revolution and to adopt the measures of precise science in all aspects of modern engineering and commerce, including the United States space program and the satellite industry.

Table 1. SI Base Units



Quantity                                      Unit       
                                       Name        Symbol       

length                                 meter       m
mass                                   kilogram    kg
time	                               second      s
electric current                       ampere      A
thermodynamic temperature              kelvin      K
amount of substance                    mole        mol
luminous intensity                     candela     cd


         

Table 2. Examples of SI Derived Units


	
Quantity                                Unit              
                        Special Name   Symbol	Equivalent    

plane angle             radian	       rad      1
solid angle             steradian      sr       1
angular velocity                                rad/s
angular acceleration                            rad/2 
frequency               hertz          Hz       s-1
speed, velocity                                 m/s
acceleration                                    m/s2 
force	                newton	       N        kg m/s2 
pressure, stress        pascal	       Pa       N/m2 
energy, work, heat      joule	       J        kg m2 /s2,  N m
power	                watt           W        kg m2/s3,  J/s
power flux density                              W/m2
linear momentum, impulse                        kg m/s,  N s
angular momentum                                kg m2/s,  N m s
electric charge         coulomb        C        A s
electric potential, emf	volt           V        W/A,  J/C	
magnetic flux           weber          Wb       V s
resistance              ohm                     V/A
conductance             siemens        S        A/V,  -1
inductance              henry          H        Wb/A
capacitance             farad          F        C/V
electric field strength                         V/m,  N/C
electric displacement                           C/m2
magnetic field strength                         A/m
magnetic flux density   tesla          T        Wb/m2,  N/(A m)
Celsius temperature     degree Celsius C        K
luminous flux           lumen          lm       cd sr
illuminance             lux            lx       lm/m2
radioactivity           becquerel      Bq       s-1


       

Table 3. SI Prefixes


	
Factor   Prefix   Symbol   Factor   Prefix   Symbol         

1024      yotta     Y      10-1      deci       d
1021      zetta     Z      10-2      centi      c
1018      exa       E      10-3      milli      m
1015      peta      P      10-6      micro	
1012      tera      T      10-9      nano       n
109       giga      G      10-12     pico       p
106       mega      M      10-15     femto      f
103       kilo      k      10-18     atto       a	
102       hecto     h      10-21     zepto      z
101       deka      d      10-24     yocto      yze