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Great Questions! Q & A from “How America is Losing the GPS War” (Part 2)

 

Blog Editor’s Note: The Assn of Old Crows sponsored a webinar last week “How America is Losing the GPS War – and risking everything.” The presenter was RNTF President, Dana A. Goward.

For Old Crows, the webinar is archived here (must be an Assn of Old Crows Member.

If you are not an Old Crow, you get a copy of the slides here and the narrative here.

Questions afterward from attendees were amazing and ran well past the allotted time. We even had some emailed in after the webinar.

We had so many questions we are doing this in two parts.

Today the topics are:

eLoran  –  Other Terrestrial Systems  –  GPS & Space Systems  –  Non-RF Navigation  –  DoD Preparation

eLoran

Q. Why was Loran disestablished in 2010?

A. Great question. In 2004 President Bush ordered Dept of Transportation to work with other departments and get a GPS backup capability. In 2008 DHS announced it would transform Loran-C to eLoran to meet this requirement.

Unfortunately, during the transition to the next administration, mid-level officials at OMB took away the recurring funding to operate and transition the system. This was over the objection of virtually every engineer and technologist in government and the President’s PNT Advisory Board. But OMB was closer to the seat of power and was able to make it happen. They “saved” $36M/yr. Obviously too small an issue to argue over.

Why did they do this? Who knows? GPS had been sold for years as the be-all and end-all for navigation. It was going to replace ALL the old navigation systems. The FAA had already decided GPS signals were too fragile to allow disestablishment of the aviation terrestrial navigation system of VORs and DMEs.

Yet GPS continued to be very expensive. There was talk within the government that Loran could not be allowed to stand because it showed a lack of faith in GPS and threatened funding.

This was certainly a very big contributor to Loran termination in Europe. Galileo was a civil vice military/security program, and very expensive. Funding wars were more difficult, and it was even more important to eliminate anything that looked like competition or that might express that Galileo wasn’t the answer to all PNT needs.

Q. How do you feel about eLoran? Is it too late to salvage existing stations?

A. The US government has announced twice, in 2008 and 2015 that it would build an eLoran system to protect GPS signals and users. I know there was a lot of analysis that went into each of those decisions. Also, the President’s PNT Advisory Board has repeatedly recommended and endorsed eLoran.

We at the RNT Foundation, based on our knowledge of the alternatives, are happy to agree with the advisory board and the two government decisions. But action of some kind is needed. If eLoran is the answer, we need to get on with it. If it is not the answer, the feds need to say what the answer is and get on with that.

Regarding the stations, the sites are almost all still owned by the federal government and have reasonable geometry. Based on our testimony, in 2014 Congress prohibited further dismantling and disposal of Loran-C facilities until the government had decided and implemented a backup system for GPS.

In the short term, there are a handful of antennas and transmitter that could allow a 4-6 site timing system to be up and running fairly quickly and inexpensively by reusing them as-is.

In the longer term, these sites which are in a reasonable geometry, no surprise, would make the final timing and eventually navigation system easier and less expensive that it would have been, despite the need for newer/ renovated antennas and transmitters.

Q. What is the precision in regard to positioning of the eLORAN systems?

A. All of its potential has not been tested publicly in the west, so there is not a lot of non-proprietary information. However, the UK had an operational system for a year off their east coast which they certified for maritime use. They found a precision of 50ns and “less than 10m.” Here is an Institute of Navigation paper by the British GLA and UrsaNav that discusses their results.

In the Netherlands, the Dutch Pilots and Reelektronika pioneered their own version of the system with differential corrections and achieved a 5m accuracy. Here is that paper.

Two interesting projects with the one in the UK providing Initial Operating Capability and the Dutch one being a Proof of Concept.

Q. GPS is used for more than location information. It is also a critical timing source. Would loran provide the same support?

A. Yes. DHS had a CRADA for several year examining just that. eLoran timing is being re-examined now by the US government. As mentioned above, accuracy over a substantial distance has been shown to be 50ns or better with differential corrections.

Some of the CRADA results were presented at the Institute of Navigation’s annual PTTI and are available here: https://www.ursanav.com/wp-content/uploads/Resilient-Timing-and-UTC-Service.pdf

Q. In your opinion, what could explain the lack of appetite in many countries for this alternative technology? Only Korea seems really active with the eLORAN.

A. There is actually quite an appetite! Russia, China, South Korea, and Saudi Arabia, of course as they never shut their Loran-C down. S. Korea is upgrading to eLoran and we have seen indications that Russia and/or China are doing so also.

The rest of the world has taken note of what Russia, China, and North Korea have been doing with spoofing and jamming. As it happens, our founding member, UrsaNav, Inc., is quite involved assisting several countries in their pursuit of eLoran technology.

Also, there has been substantial interest in the UK, Canada, and the US.

United Kingdom – The UK worked very hard over several years with the four other European nations to keep Loran-C going and convert what was once known as the Northern European Loran System to eLoran, but to no avail. The UK continues to operate its lone eLoran transmitter as a timing reference. My understanding is they are considering reviving an eLoran PNT service, either with assets entirely in the UK or in concert with nearby countries. Besides its complete diversity with space-based systems, eLoran has the added attribute of sovereignty: no dependence on “foreign” GNSS or other solutions for critical national PNT infrastructure.

Canada – Several groups in Canada have shown interest in eLoran, especially for operations at high latitudes and underwater and under ice. When the US shut down its stations in 2010, it was probably easier for Canada to shut down also rather than build more stations. Besides, GPS was free and good. What could possibly go wrong?

United States – As I mentioned before, the US has announced twice already that it would implement an eLoran system to provide a terrestrial augment for GPS. So clearly the US is interested also. Unfortunately it has been fumbling with a bureaucratic structure that (1) is very resistant to admitting it made a mistake, and (2) wants to avoid any hint that an expensive satellite program needs a terrestrial component.

I suspect that if the US decides for the third time that eLoran should be part of the answer and implements it, other nations will eagerly adopt that idea also.

Q. According to my understanding, to obtain positioning accuracy better than 10 m., ASF and differential stations are required. How can we get ASF maps at a reasonable cost for a country as large as Canada? (The UK has developed its own tool.)

A. ASF corrections can be modeled and/or measured. With appropriate tools and available terrain information, very accurate ASF models can be generated. Today’s models are quite sophisticated, and have been validated against measured data. Measurements can be made using vehicles, vessels, or aircraft to cover wide areas quickly. Additionally, measurements can be made against GNSS information as long as it is available and trustworthy. There is considerable expertise available in this area.

Academic and government research conducted in the US, UK, and Europe have shown that ASF variations for an area over the course of a year are regular and predictable. Most corrections are associated with localized weather conditions. These changes are easily offset using differential Loran, the same techniques that are used with differential GNSS (whether ground-based or space-based). So, if Google Maps/street view were to measure eLoran signals and GPS signals at the same time as they were making their yearly rounds of all the neighborhoods, you would be able to have very precise measurements. When combined with the meteorological and other information from differential stations, the eLoran match to map would be quite accurate. Google Maps/street view may not cover non-metropolitan areas quite as often, or ever. However, if GNSS were not available or trustworthy, then eLoran could be expected to provide 10-20m position accuracy and far better than 500 nanosecond timing accuracy.

 

Other Terrestrial Systems

Q. Was it a mistake to decommission the Omega system?

A. Probably not, since Loran-C was still around in many places to complement GPS.

I was a great fan of Omega at one point as it provided navigation when I was flying Coast Guard helicopters in the Caribbean in the late 70’s.

Omega was a VLF system accurate to within a mile and a half. Not bad at all if you were over the water and looking for land, or even a boat that needed a medical evaluation. But not near the kind of precision that we have become used to and need for most applications today.

What is a mistake is not continuing to explore possible improvements to legacy technology. DARPA is trying to rectify that now with their STOIC VLF navigation program.

Imagine if we had not continued to develop radar, TV, radio, telephones, and GPS. Where would we be today?

Q. How mature/robust is the Russian scorpion system and how is it networked?

A. I don’t know. We found information about it in an obscure US govt military journal on foreign militaries several years ago. It had some embedded links, but they don’t work any longer.

If I had to guess, it would be that Skorpion is probably a bit like the US Air Force’s Loran-D (deployable) from the 1970’s. An air transportable set of containerized generators, transmitters, and folding towers that can be fairly quickly assembled in theater.

Q. Would D-GPS be integrated into a possible future Nav system of systems?

A. The US has elected to disestablish the differential GPS (DGPS) system as similar services are available from the satellite-based Wide Area Augmentation System (WASS). We have urged the government to retain the DGPS sites for future use to support nav systems, but have not had a response.

 

GPS & Space Systems

Q. Does GPS Modernization provide an advantage with multiple civilian signals (L2C & L5) and M-Code?

A. Only slightly. Most civil users will not notice any improvements. M-code will provide a marginal improvement, but it just for military users with special equipment.

Q. Does the current WAAS system that augments GPS for thing like ADS-B and maybe farming have a potential to help the robustness somehow? Encryption?

A. Kinda.

Logan Scott proposed putting an encrypted authentication signal on WAAS in 2003, and the Air Force Research Laboratory has recently said they would look into it. Doing so would provide some additional resilience for those who purchased new receivers that had that capability.

But WAAS isn’t a stand-alone system and can’t be used without the base GPS signals. So the “robustness” added would be only marginal.

 

Non-Radio Frequency Navigation

Q. Is there a way to not rely on radio signals for navigation and positioning altogether?

A. Absolutely, the Boy Scouts do it all the time with a map and compass. The Earth’s magnetic field, gravimetrics, optical recognition, quantum clocks, inertials, and more are continuously being investigated. But it always comes back to a question of accuracy and the ability to integrate with other systems. And if you are also looking to also protect networks and other technology, none of these have a timing signal that can be used for synchronization.

Also, many things that would solve problems locally, or in metropolitan environments, would not work in moving transportation (e.g., aircraft, vessels, vehicles) and might not be cost effective in suburban or rural areas.

Q. WRT not radio based, INS and RLG worked pretty good, to a point. Can they be pushed to be better with today’s newer technologies, or where we a t a limit? Currently they tend to degrade over time, but is that being investigated?

A. Perhaps, but they haven’t yet. Beyond that, I don’t know enough about these to comment further.

Inertial systems, like most others, are constantly improving, but they are still not small enough or accurate enough (because they drift over time) to be used in a standalone configuration. Even the most accurate inertial navigation system, such as those used in submarines, must still be synchronized periodically to eliminate drift.

It is important to keep in mind that inertial systems do not know where they are until they are told (i.e., initialized and periodically updated). Similarly, high performance oscillators (clocks), except for the most sophisticated, large, complex, and expensive ones that make up the world’s time base, do not know what time it is until they are told (i.e., initialized and periodically updated). This is why wide-area, wireless solutions, such as GNSS or eLoran are so important. They are primary sources of positioning and timing information that provide those services without initialization and are accurate for long periods without updating.

Q. Are there any efforts in developing magnetic positioning currently? How does magnetic positioning stack with navigation systems?

A. I have seen a couple papers over the last year about using the Earth’s magnetic field for positioning and navigation. The big challenges that I can see are refining position to an acceptable accuracy, and that the magnetosphere keeps moving.

Q. What would you consider the State-of-the-Art for internal guidance systems (e.g. inertial guidance)?

A. Sorry, this is outside my area of expertise.

 

DoD Preparation

Q. If we know that we are vulnerable in all these areas in the EMS including GPS, then why is our military not really training to REAL degraded operations. Russia said they were prepared to fight with no signals available. And why is the DOD not prioritizing these things? They know it’s an issue.

A. If the military isn’t training to real degraded operations, it might be because they can’t complete the exercise. A 2018 paper in “Joint Forces Quarterly” said:

“In recent exercises, white cell teams quickly restored denied space services and capabilities to allow progress in order to meet training objectives….an unwillingness to play out the scenarios in a denied or degraded environment that warfighters can expect to experience during actual conflict. This is a clear indicator of the critical dependence U.S. forces have on space. Yet the U.S. military operates daily with the expectation that it will not experience long-term denial of space effects.”

I am sure that, in some cases, forces are training for degraded ops.  But I wonder how far that goes. Are land-mobile radios impacted?  IT networks?  Or is it just the ability to navigate with GPS?

As to whether or how DoD is prioritizing this, I cannot say.

Brad P

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