There is another movement to rebuild our former Loran navigation system, both as a backup to the GPS Satellite System and as a usuable lower cost stand alone.
John K5HIP asks “Could AI-Fueled Amateur Radio Rebuild Loran-C?” at:
https://gcaptain.com/could-ai-fueled-amateur-radio-rebuild-loran-c/
Reality is Politics killed Loran, as the proponents of GPS need alternatives swept away.
Some say the entire North American Loran system was less costly than a single GPS Satellite.
I know that for several years I flew behind an avionics system that was multi-sensor gathering & reconciling both GPS and Loran.
Certain an easy option to reconsider.
73
Steve
K9ZW
With Varying Frequency - Amateur Radio Ponderings 
This effort only touches the tip of a major issue within USSC/USCG/DoD – the total lack of forward ‘IF’ thinking.
What IF, most all SAT’s go dead or jammed; how does DoD/USA/World recover from the loss of surveillance and communications capabilities; a crippling Solar CME can do this?
Is DoD/Congress so naïve/arrogant to think China/Russia do not have SAT-killing missiles at the ready to take out strategic orbiting SAT’s?
I was Magellan GPS first Test/MFG/QA Engineer employee #29 in 1989. Magellan made the first hand-held portable GPS unit; final-test was a successful download of a SAT Ephemeris, 2D position fix, and comparing the SAT SQ/GQ to the Test control unit.
Back then GPS 2D (3-SAT) fix window was only four hours long with the window progressing 1hr every day.
We build the GPS units during the day, populating the three rolling test rack 20 holsters to roll out into our Monrovia, CA, parking lot when three SATs were up. That meant final test could come at 0100,2,3,4,5,6… rain/shine, hot/cold to finish the final test so the units could be packed/shipped the next day.
In our new San Dimas, CA location I installed roof-top GPS LNA antennas to my created repeaters then installed ceiling TX antennas within the company negating the parking lot testing. Customer Service, Repair, MFG became much more effective and happy.
By 1990, our final test was a 3D fix since there were so many SATs in orbit. We saw the 100m SA change to 1m for the Gulf war as Magellan units were in most all General Schwarzkopf’s leading vehicles during his successful blitzkrieg.
By 2003, Iraq war – Hussein had purchased GPS Jammers from Russia to thwart any repeat of Schwarzkopf’s highly successful blitzkrieg. The 72hr jammers were parachute dropped onto the Iraq deserts overpowering-jamming the minuscule GPS SAT signal for all Line-of-Site GPS receivers. The Achilles’ heal to GPS is its single frequency, CA/Civilian 1575.42 MHz & P/Mil 1227.60 MHz via Spread Spectrum; a strong FM signal on the frequency will make GPS useless.
So what is DoD/USA backup plan to major/total loss of SATs? NO more surveillance, NO more Internet, NO more +500mi cross-country telephones and maybe total cellphone death, only local TV as Cable TV is dead, GPS services dead, any operation or service that depended on some type if SAT communication’s is greatly impaired or unusable, i.e. navigation or Looking-Glass or Air Force One.
How many cockpits/bridges have working Loran receivers, today? Are old C-Loran radios convertible to e-Loran or is a whole new radio required – at what cost (FCC/FAA accepted)? Is USA govt willing to create e-Loran as a backup?
I found this article that was an interesting read.
Click to access rd81-36.pdf