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eLORAN and UrsaNav: Timing Is Everything
GPS World, March 14, 2012, by Don Jewell
Defense PNT Newsletter, March 2012
The first part of the recent UrsaNav press release says it best:
This week for the first time since August 2010 advanced low frequency (LF) signals, including a new eLORAN, are on the air in North America! As a result of a Cooperative Research and Development Agreement (CRADA) between the United States Coat Guard (USCG) and UrsaNav, Inc. live testing of a wide-area precise timing solution has begun. These initial tests include a comprehensive pallet of signals, including eLoran, that are being evaluated for their ability to provide a robust, wide-area, wireless precise timing alternative that can operate cooperatively with GPS, or during periods of GPS unavailability.
Global government, industry, and academic experts recognize that advanced LF signals, of which eLORAN is just one example, can provide alternative timing — either as a stand-a-lone service, or as a component of an existing PNT service. The high power, virtually jam proof and spoof proof LF signals operate independently of GPS and GNSS, and provide a Universal Coordinated Time (UTC) time reference in the order of tens of nanoseconds. The recognition of the criticality of time to many aspects of our national critical infrastructure has led to establishment of the CRADA to evaluate the benefits of an LF wide-area timing system.
UrsaNav on-air eLORAN tests continue at various sites throughout the United States (CONUS and Alaska). Broadcast demonstrations will test several different frequencies, waveforms, and modulation techniques using evolutionary state-of-the-art technology.
Reception demonstrations of the eLORAN broadcasts are planned at both on- and offshore locations, and will include advanced LF data delivery techniques. Trial results will be presented at national and international conferences. Anyone interested in any part of the testing or interested in making their own measurements are invited to contact UrsaNav.
Partnered with Symmetricom and Nautel, UrsaNav says it has the world’s most advanced LF alternate PNT and data solutions to include the world’s best high-performance eLORAN timing receivers. UrsaNav has partnered with two of the best in the business for timing and transmitters, and this alliance of expertise provides the foundation technology for the best wide-area terrestrial-based alternative to GNSS such as GPS, GLONASS, and Galileo.
That being said, I would add that you should not only consider the UrsaNav LF system as an alternative, but during normal GPS operations as a complimentary and/or augmentation to GPS, and then as a back-up and integrity system when the situation warrants.
As one of my professional colleagues, who is a retired USCG officer and once ran the USCG Navigation Center, stated, “This is a big deal! It is in fact the first and biggest piece of good news about a true PNT (position, navigation, and timing) backup for GPS since Loran-C was killed in the FY2010 budget.
“Not only is this an independent timing backup, but the LF signals can also be used as pseudoranges mixed in with GPS, or if enough transmitters are available, as a fully independent PNT network. In other words, a true backup PNT capability for safety-of-life navigation, for dispatching first responders, and for supporting critical national infrastructures.”
This is a pretty enthusiastic response, even from a LORAN aficionado, and it is indicative of the responses I received whenever I reached out for comments from knowledgeable PNT SMEs (subject matter experts) around the globe.
The response nationally and internationally has been extremely positive as well — especially in light of the recent LightSquared debacle and the now better-understood vulnerabilities of the very low-power GPS signals.
I hoped I would never have to type or have you read that word again, as a noun or a verb, but the whole LightSquared scenario did serve to point out a dire need and shortcoming in the U.S. PNT infrastructure. Fortunately, the proposed UrsaNav eLORAN system appears to be on track to fill that need perfectly.
For the first 32 years that GPS signals were broadcast, LORAN-C served as a critical backup for timing and a less accurate but viable alternative for navigation. In fact, Loran-C, along with GPS and cesium clocks synchronized to UTC, were the only accepted Stratum 1 frequency sources at the time (Stratum 1 frequency sources provide a minimum frequency stability of 1 x 10-11 per day.). Then in 2010 the current U.S. administration was looking for government programs to cut and for some unknown reason they latched onto LORAN-C, which was in a critical state of transition at the time.
LORAN-C has been around since World War II. I among many other aviators used it extensively in Vietnam, and frankly for many countries and users today it is still a totally adequate service. With USCG expertise and support for 52 years, LORAN-C provided unparalleled timing and navigation services around the United States and Canada until the pretender known as GPS came along and dethroned the aging monarch.
Now, that may sound like a natural sequence of events, except that LORAN-C was in metamorphosis, 80% of the way through the process actually, of morphing into a new digital (1990s era technology) LORAN know as eLORAN or enhanced LORAN with better, more reliable transmitters, smaller receivers, and a virtually jam-proof signal structure. Many likened the legacy eLORAN to a strong ground-based GPS with coded signals for security. All that was in place and 80% complete when the whole process was killed by an administration with a strong Luddite orientation and subsequently the bean counters pulled the plug in 2010, despite recommendations to complete eLoran from both the Department of Transportation’s Positioning and Navigation (PosNav) Committee and the Department of Homeland Security Geospatial Committee and the strong personal support of the DOT Undersecretary for Policy and the DHS Deputy Undersecretary for Preparedness and National Protection and Programs. My sources tell me the Office of Management and Budget (OMB) was determined to do away with Loran-C and facilitated its ultimate demise. An unfortunate theme we have seen played out much too often: Non-technical people forcing ill-advised technical decisions. In a country whose greatness has always been its technical acumen, willingness to take risks, and self-assurance, OMB stands as a chilling element of focus today…but, that’s a subject for a future article.
Since that time the U.S. Coast Guard spent more money dismantling the legacy LORAN-C infrastructure and antennas than it would have taken to complete the 20% upgrade for a full transition to eLORAN. Taking down the Port Clarence, Alaska, tower, the video of which was a YouTube favorite for many weeks, cost an estimated $8 million. The destruction of the towers in Attu (right), Shoal Cove and St. Paul were probably on average $5 million each. With the tower removal in Baudette, Minnesota, the cost of removing Loran towers to date cost close to $25 million. One could argue that the administration created some jobs in these “shovel-ready” tower tear downs, but I have no doubt that a better use of the funding would have been to deliver a robust positioning, navigation, and timing backup for the nation. But alas that is ancient history in the technology world, a whole 18 months to be exact.
Then along comes the Lone Rang… I mean Chuck Schue, the CEO and president of UrsaNav, which is a small company originally founded by Charles “Chuck” Schue, because frankly he has always been interested in navigation. Chuck is a former ION (Institute of Navigation) Washington, D.C., Section Chair and is a current member of the ION Council. Chuck is also a retired USCG officer and his last job in the USCG was as Commanding Officer of the Loran Support Unit, providing direct support to a large portion of the functions supported by the USCG Navigation Center (NAVCEN). So it is no accident that Chuck and UrsaNav saw the gaping hole for GPS support that was created when LORAN-C and the legacy eLORAN programs were unceremoniously put on the chopping block. Now UrsaNav with their new 2012 version of eLORAN and the help of the USCG, through a CRADA, have stepped in to fill a very real need.
In my opinion (pun intended) their timing could not have been better. LightSquared is hopefully behind us along with the threat of losing GPS capabilities and all GPS P&T (positioning and timing) enables without a viable backup. This is definitely not a scenario any sane person wants to see happen again and fortunately UrsaNav LF timing and eLORAN can provide a critical back-up, augmentation and integrity check while simultaneously providing the USG with a security blanket, as Linus would say.
The USCG-UrsaNav CRADA
Before considering reactions from other USG agencies and then international reactions to the UrsaNav program, maybe it would be best, in case any of you are wondering, to describe the function of the subject CRADA since it has been mentioned several times.
In February 2012 the U.S. Coast Guard Research & Development Center (R&DCEN) announced it had entered into a Cooperative Research and Development Agreement (CRADA) with UrsaNav to research, evaluate, and document at least one alternative to the Global Positioning System (GPS) as a means of providing precise time. The alternative under consideration is a wireless technical approach for providing precise time using U.S. government facilities and frequency authorizations.
While this is a very general statement and does not give much away, it is meant to be that way since it is, after all, an R&D effort and general statements give you the most leeway when considering options and trade space.
CRADAs are authorized by the Federal Technology Transfer Act to promote the transfer of technology to the private sector for commercial use as well as specified research and/or development efforts that are consistent with the mission of the federal parties to the CRADA. The federal party or parties (USCG) agree with one or more non-federal parties (UrsaNav) to share research resources, but the federal party does not contribute funding.
This means that the USCG and UrsaNav are sharing R&D efforts, data, and even non-monetary resources, but the USG is not providing any funding to UrsaNav for the project. So UrsaNav is footing the bill; at the same time, it has access to USG data and resources, to include buildings and transmitting towers, for example, and UrsaNav knows it has at least generated interest among government and commercial users for LF timing signals.
When I first saw the UrsaNav announcement, I immediately thought of the DOT and FAA, since they have been trying to think of ways to provide a common, non-GNSS, distributed timing backup for all their facilities and customers as part of their efforts to develop an alternate PNT (APNT) capability. One of the APNT alternatives is considering distributing time to air traffic control facilities and aircraft through their ground-based DME (distance measuring equipment) facilities. For the non-aviators among you, DME signals allow aircraft to determine their distance from a DME location. Properly equipped aircraft (primarily commercial and high-end general aviation) can use ranging from multiple DMEs to actually determine their position and follow area navigation (RNAV) procedures for more effective routing and flexibility. In order to utilize the DMEs as a ground-based, high-power (1000 W) equivalent of a satellite constellation will require each DME facility to be synchronized in time to around 30 nanoseconds or better. Now, with the possibility of an eLORAN time standard with a huge booming, virtually jam-proof and spoof-proof signal, across the CONUS and Alaska, this FAA alternative solution could be greatly facilitated. While the FAA also has the option to use GPS time, or time from its own WAAS ground-based clock ensemble, or WAAS retransmitted time combined with GPS time for remote locations and to back it all up and provide an integrity check, the availability of an eLoran alternative is certainly worthy of FAA APNT consideration. The FAA’s distribution problems would be solved, and since both GPS and eLORAN have the capability for encoded signals, the integrity (information assurance) and security problems are solved as well. Comparison of the vulnerable GNSS signal with the robust eLoran timing signal could alert an operator to possible spoofing or even a less sinister loss of integrity event. So this is a win/win for the FAA and several other critical national agencies and infrastructures that must remain nameless for security purposes.
What makes the UrsaNav solution so promising and frankly exciting is that they are not conducting these experiments and demonstrations in isolation. For the past few months UrsaNav has been working with the Lighthouse Authorities of the United Kingdom and Northern Ireland as well as Chronos Technology, a world leader in GNSS jamming and interference detection, in Great Britain. To determine how the UrsaNav eLORAN program is progressing internationally, who are you going to call? Personally, if it concerns GPS, time, and the UK, there are two people who immediately come to mind: Dr. David Last and Martin Bransby.
Professor David Last is a consultant engineer and internationally renowned expert witness specializing in radio navigation and communications systems. David is a Professor Emeritus (that means he is at least as old as I am) at the University of Bangor, Wales, and Past-President of the Royal Institute of Navigation (RIN), the equivalent of the U.S. ION, but RIN has only been around since 1947. David acts as a consultant on radionavigation and communications to companies and to governmental and international organizations worldwide and is active as an expert witness, especially in forensic matters concerning GPS.
Both David and Martin are highly qualified SMEs and BLUF, or bottom line up front; their praise for the UrsaNav initiative could not be higher.
According to Professor Last, “…a ‘sky-free’ timing service like the one UrsaNav will hopefully soon be radiating in the United States is already available across the British Isles and adjacent parts of Europe. The eLORAN system uses the GLAs’ prototype eLoran system plus GPS/eLoran timing receivers from UrsaNav and Chronos Technology.
“The prototype eLoran service has been running 24/7 since January 2008, serving the eastern half of Britain and the North Sea. It now delivers 10-meter (~30 feet) navigation accuracy in the approaches to Harwich and Felixstowe, the UK’s major container ports, where a prototype full differential service has been in place since mid-2010.
“In addition, the UK transmissions support a prototype robust, nationwide data channel that will benefit in future from the techniques currently being developed by UrsaNav to expand the data capacity of eLoran-compatible LF transmissions.
“This is all part of the resurgence of terrestrial LF services in response to the vulnerability of GPS and all other GNSS (read LightSquared). The GLAs are leading this movement to adopt eLoran as the terrestrial complement at sea and supporting the use of the new eLoran transmissions for sky-free complementary navigation, timing, data, and tracking of land vehicles. And the neat thing about LF timing and data is that a single station serves a large area. So the UK station delivers data across the UK and timing even more widely. This appeals to all sorts of folks who aren’t interested in navigation. But once enough timing and data stations are on the air, you get back navigation!”
Now, Martin Bransby is the R&RNAV (Research and Radionavigation) manager for the General Lighthouse Authorities (GLAs) of the UK & Ireland. Which simply means he is a senior engineering manager and program manager with extensive experience in R&D of highly technical assets, such as maritime aids to navigation, radar, C4ISTAR, and tactical data links, and he is the official GLA POC working the eLORAN program in the UK and Ireland, which he indicates is progressing extremely well. So well, in fact, the GLAs awarded a 15-year contract to provide a state-of-the-art eLORAN service to improve the safety of mariners in the UK and Western Europe. The service contract includes R&D work and the operation of an eLORAN service through 2022.
Support: The Good News
Back on this side of the pond, my sources at the USNO (U.S. Naval Observatory) our resource for Coordinated Universal Time or UTC are supportive of the UrsaNav eLORAN effort. A senior source, who prefers to remain anonymous, stated that the USNO will support any USG terrestrial time distribution system that may emerge from the UrsaNav eLORAN effort by providing the underlying timing reference “UTC (USNO).” However, to achieve true GPS independence, my source would like to see either fiber-optic or two-way satellite time transfer (TWSTT) utilized to sync the eLORAN ground transmitters. And in the end higher power, GPS independence, and good indoor reception are probably the greatest advantages. My source is looking forward to the results of this initial demonstration by UrsaNav and the USCG.
According to Chuck Schue, UrsaNav, anticipated this USNO preference and is working with Symmetricom on a TWSTT while also developing a TWLFTT, or two-way low-frequency time transfer capability, which allows for time transfer from a UTC source such as USNO or NIST that is completely sky-free.
The Bad News
We’ve all heard the Biblical phrase that originated in Matthew concerning “the right hand not knowing what the left hand is doing.” In this instance, where eLORAN is concerned, the USCG may have adopted that as a program motto.
Note: The real motto of course is Semper Paratus, and the brave men and women of the USCG live up to it everyday.
Originally in the Unites States, CONUS, and Alaska, there were 24 LORAN-C transmitters with towers between 600 and 1350 feet tall; add the towers supporting the Joint U.S.-Canadian LORAN-C system plus the LORAN-C Support Unit tower, and there were a total of 30 huge LORAN-C towers with all the accompanying support structures for the transmitters, support crews, etc. Today, there are only 25 towers remaining — as the USCG engineers are in the process of dismantling the LORAN-C infrastructure — five towers in the last 18 months.
As often happens in a large distributed organization, though Headquarters (CG-5) supports the eLORAN CRADA with UrsaNav and fully realizes that future eLORAN deployment depends on reuse of existing infrastructure, the civil engineering support organization gets its money and develops its project lists separately. Consequently the antenna towers at Attu (located at the end of the Aleutian chain) and Port Clarence (situated well north of Nome) have come down, as have the towers in St. Paul (in the Pribilof Islands, northern Bering Sea) and Shoal Cove (located in SE Alaska, near Ketchikan). Only two towers remain in Alaska; one in Kodiak (adjacent to the USAF-Alaska launch facility) and one at Tok Junction (on the ALCAN Highway, southeast of Fairbanks). Within CONUS, the USCG engineers are in the process of dismantling the facilities in Baudette — which is just about as isolated as some of the sites in Alaska.
The operational problem is that while the much more powerful and economical energy-scavenging transmitters from UrsaNav’s partner Nautel, and new wave forms being produced by UrsaNav, probably only need to utilize 8-10 towers — the system is that much better and more powerful — no one knows where they need to be located until more tests are conducted. So how do the USCG engineers know which ones to dismantle? Obviously they don’t and there’s the rub, plus if the system is really successful and the data portion is a success, there could be a need for even more towers. Solution — the R&D guys (RH) need to coordinate with the engineering crews (LH) and put a hiatus on dismantling LORAN-C towers and the associated infrastructure, unless they pose a safety hazard, until the outcome of the CRADA and subsequent acquisition decisions have been made.
Seriously, the USCG and UrsaNav are heroes for initiating the CRADA, and my hat is off to them for realizing the critical need for eLORAN, but seriously, somebody pick up a phone and call the engineers, call the Commandant, call somebody that can put the tower demolitions on hold.
The bottom line is UrsaNav and the USCG are to be congratulated for their foresight and planning. Let’s hope the eLORAN demonstrations continue to be successful and that a contract is forthcoming quickly before we, and the powers that be, forget the LightSquared lessons learned…like we would ever let that happen.
All in all, this is a win/win proposition for the USCG, the USG, and for GPS users everywhere. Stay tuned for more on this topic.
While you are reading this I will be attending the Munich Satellite Summit in Germany, so guess what my topic will be next month?
Until next time, happy navigating.