Reflections and Hope for GNSS

December 10, 2014  - By
Image: GPS World

For me, 2014 marks 40 years of my long association with the positioning, navigation and timing (PNT) gold standard we call the global positioning system (GPS), and I find it only prudent and natural to reflect on what has, for many, been a tumultuous 12 months.

In this regard, I find that I am not alone. Many seasoned veterans (who, unfortunately, by necessity must remain anonymous) have taken the opportunity to take pen in hand and jot down a few of their thoughts for my perusal and cogitation. Not to digress, but I find that many of us of a certain age, when we wish to convey our considered thoughts privately to a trusted colleague, more often than not accomplish said task with a fountain pen and luxurious heavy linen writing stock or in a private conversation, versus email and quick messages on social media.

In putting the following thoughts together, I have availed myself of those thoughtfully scribed missives from trusted colleagues. The following conveys some thoughts to contemplate on current tactical and strategic PNT matters.

Political SMEs

Without a doubt, the most troubling, or certainly discussed, topics this year have revolved around the spurious thoughts, rhetoric and unfortunate resulting public statements by PNT neophytes in positions of power whom, not being from the most lucid generation, seem to believe that GPS or GNSS are vulnerable and should be replaced — end of discussion — no further thought given to the problem other than surely something will come along to replace it — and preferably overnight, at that. Obviously, I am incredulous and find the statements to be nothing more than political hype purveyed by luddites that are essentially technically hapless and clueless. Alas, some are in positions of power where they are frequently and regrettably quoted in the press. Lamentably, the technically clueless parameter rarely keeps them from speaking their — if you will pardon the over-generous appellation — mind.

Rather than merely complain about political appointees and their hapless, uninformed ramblings, as it is after all a national pastime, I will follow the edict and sage advice of a fellow thinker, mentor and Eminence Grise, General Pete Piotrowski (USAF, Ret.) who pontificated to a young executive officer over four decades ago, “Never come to me with a problem, as problems are nothing more than opportunities waiting to be recognized — so come to me with opportunities and implementation plans that are actionable.”

Applying that astute and long-remembered advice to our GNSS opportunity leaves us with an essentially technical and actionable way ahead. There can be no question that GPS or GNSS should remain as the baseline bedrock for all PNT solutions while technology provides ample opportunities for enhancements, augmentations and verifications, not merely inadequate substitutions. As one of my colleagues at the Royal Institute of Navigation stated recently, “Truly robust position, navigation and timing will always require a combination of dissimilar PNT technologies.” The top three that come to mind are:

  1. eLoran
  2. Inertial systems
  3. All signals available

At the risk of belaboring the obvious for my regular, informed readers, let’s take a brief look at each supporting opportunity.


eLoran in many forms has been around for decades longer than many users realize, and was just months away from being fully implemented in 2010 (more than 80% complete) when it was unceremoniously, all politics aside, abruptly curtailed by those technical luminaries in the OMB (Office of Management and Budget) and the current administration. Since that time companies and countries around the globe, except for the United States of course, have charted their own course for eLORAN both as an independent PNT system and as an augmentation, enhancement and backup to GNSS with accuracies and availability (essentially not capable of being jammed) that rival and exceed most any other non-GNSS PNT system available today.

In Rotterdam earlier this year, I saw firsthand and wrote about an eDLoran or differential eLORAN system,that, “with modern monitoring can result in consistent horizontal accuracies approaching five meters on a moving platform.” eLORAN has shown the capability to broadcast continuously with several thousand watts of low frequency signal power and provide a PNT system that is reliable and accurate, while essentially making it ludicrous to try and jam or intentionally interfere with GNSS signals. The two systems utilized jointly, GNSS and eLORAN, are an unbeatable combination.

I am currently contractually embargoed, but hope to write more about some amazing new eLoran receivers in the New Year. However, I can legally say now that I have recently been made aware of two separate multi-GNSS-eLoran receivers that are both affordable and portable. More than that I cannot say, but just think about what that means when you consider there are fully operational eLoran transmitters literally scattered around the globe today, except for the United States, of course. An embarrassing situation that hopefully our Congress will remedy soon.

Some exceptional multi-PNT devices, which I am allowed to mention, are the UrsaNav UN-155 Resilient PNT receivers from Chuck Shue and company. These innovative new products utilize PNT information from multiple sources including GNSS, eLoran, and maritime medium-frequency beacon systems. The UN-155 contains an embedded computer for easy updating of software and algorithms for resilient PNT, and provides a robust navigation and timing output. While this is not yet a portable unit, miniaturization is all the rage.

Inertial Systems

Which is a great segue to our next opportunity, MEMS (micro-electro-mechanical sensors) inertial devices. These are routinely and historically described as devices capable of providing tightly coupled integration of GPS precise point positioning (PPP) and MEMS-based inertial systems. While the tightly coupled descriptor essentially involves Kalman filters and shared positioning data descriptors and fields, there have recently been cogent arguments for an independent non-tightly coupled MEMS inertial device as well, perhaps even both types of devices coupled to a multi-GNSS device with eLORAN.

Think about it only momentarily and the advantages become obvious for both approaches, and even more so for a combined approach. Again, I am prohibited from providing too many details, due to upcoming press releases and device announcements from major players in the field, but 2015 appears to be promising for new and innovative inertial integration technologies. Suffice it to say, the U.S. Army is enamored with this approach, as well they should be, with the key for the U.S. military being a sustainable low-cost MEMS-inertial . . . and there my tale of new advancements must end — for now.

For your edification and to help me better understand the new MEMS gyros and inertial units, a well-known GPS-savvy Stanford University professor emeritus recently stated, “Don, think of it this way, the rotation of a MEMS gyro component exerts perpendicular coriolis force on a resonating proof mass and the displacement is measured capacitively and converted to algorithmic terms for inputs to a Kalman filter or to an independent display for the user as required. Our desire is that, in the near future, both operations will transpire simultaneously and independently. Simple, right?”

Of course it’s not simple or we would all have them in our iPhones, I thought. Then it hit me, we do have accelerometers in our iPhones, as well as basic gyroscopic functions. There are applications today that make use of these devices as highly evolved pedometers capable of correcting and tracking our position inside GPS-denied environments, such as underground, in dense urban environments and deep inside buildings. Not to be flippant, but it appears there is an “app for that,” and 2015 holds the promise for even better technology for PNT device integration. Stay tuned.

All Signals Available

Which brings us to one of my favorite topics — all signals available. As simple as this concept seems to be, as in “are you smarter than a fifth grader?”, I was briefed earlier this year along with several of my fellow technical SME (subject-matter expert) journalists by one of those interim pseudo-technical political appointees that wants to replace GPS/GNSS. Be assured it was a very serious briefing and venue, no clown costumes in sight. The appointee briefed — with a straight face, no less — that current government PNT receivers would have a difficult time with GEO (Geostationary Earth Orbit) versus MEO (Medium Earth Orbit) PNT signals simply because of the physics involved. To which, channeling John Belushi in Continental Divide, I very ungraciously and forthrightly replied, “Difficult physics such as the physics employed daily in my iPhone 6+, which is a multi-GNSS device, utilizing MEO and GEO GNSS signals globally, which are integrated with inputs from ground transmitters and onboard accelerometers. You mean those difficult physics?” Can you picture speechless?

Consider that the iPhone 6+ today incorporates multi-GNSS signals (GPS and GLONASS) plus WAAS and EGNOS, which are GEO PNT transmitters — bent pipes, if you will. The iPhone utilizes and fully integrates PNT signals from space, terrestrial signals from cellular towers, and Wi-Fi computer networks, as well as onboard accelerometers in an area of real estate roughly the size of a quarter.

Trimble navigation has a fixed commercial PNT unit today, about the size of a softball, that does all this and much more while parsing 129 separate GNSS signals globally, which allow it to determine its position to the centimeter and reject all signals that try to deviate from the known truth set. Plus, it transmits all known positioning parameters, utilized and automatically rejected, to a website. So I submit that our opportunities for PNT today are not restrained by technology, but by atrocious limitations imposed by politicians masquerading as subject-matter experts. Someday I may deign to tell you how I really feel. Allow me to caveat my remarks by saying there are some wonderfully competent government technologists that I have the pleasure to work with on a regular basis, and I applaud their acumen, dedication and hard work.

Fight Back

The question remains: How do we fight back against the pseudo-technical pols and their pronouncements concerning the future of PNT? The solution is simple. Educate yourself concerning the art of the possible. Read a book on the subject. I have recommended many fine references over the years. By all means, for the most up-to-date information, read fine publications like GPS World, and of course, I humbly commend my column to you, if you are so inclined. Education may not be the only panacea, but historically, the more we know about a subject, the less likely we are to fall for the falderal and spin routinely spewed forth by the technically clueless with a political agenda.

To paraphrase Winston Churchill, who once said, when he was encouraging his neophyte code breakers at Bletchley Park to be more well read, “Read a single book on any single subject and you will know more about that subject than most of the world.” I would add a single caveat from Harry Potter’s creator:

Books are like mirrors: if a fool looks in, you cannot expect a genius to look out.

—J.K. Rowling

Stay with me, and we will explore all these opportunities and more in the coming New Year. Fortunately, hope springs eternal.

Until next time, Merry Christmas, Happy New Year, happy navigating and remember: GPS is brought to you courtesy of the United States Air Force.






This article is tagged with and posted in Defense, Opinions

About the Author: Don Jewell

Don Jewell served 30 years in the United States Air Force, as an aviator and a space subject-matter expert. Don’s involvement with GPS and other critical space systems began with their inception, either as a test system evaluator or user. He served two command assignments at Schriever AFB, the home of GPS, and retired as Deputy Chief Scientist for Air Force Space Command. Don also served as a Politico Military Affairs Officer during the Reagan administration, working with 32 foreign embassies and serving as a Foreign Disclosure Officer making critical export control decisions concerning sophisticated military hardware and software. After retiring from the USAF, Don served seven years as the senior space marketer and subject-matter expert for two of the largest government contractors dealing in space software and hardware. Don currently serves on two independent GPS review teams he helped found, and on three independent assessment teams at the Institute for Defense Analyses, dealing with critical issues for the U.S. government. Don has served on numerous Air Force and Defense Scientific Advisory Boards. He writes and speaks extensively on technical issues concerning the U.S. government. Don earned his Bachelor’s degree and MBA; the Ph.D. is in progress.

1 Comment on "Reflections and Hope for GNSS"

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  1. R. Peter DeLong says:

    I especially agree with your comments on eLoran. I still hadn’t gotten over the cancellation of Omega when they decided to ditch Loran.