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by teeray1 days ago |
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upvoteby ianburrell3 hours ago|
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eLoran has been proposed as more accurate version of LORAN competitive with GPS.

The Wikipedia page says that China has deployed an eLoran network but I can't tell if used for navigation or just high-precision timing.

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upvoteby throw0101d11 hours ago|
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See UK and France:

* https://insidegnss.com/uk-and-france-renew-ties-resilient-pn...

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upvoteby budman11 days ago|
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LORAN can be jammed.
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upvoteby leonidasrup10 hours ago|
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"In trials conducted by the General Lighthouse Authorities of UK and Ireland, a 1.5W radio jammer was able to knock out GPS signals over a range of 30 kilometers. However, to do the same to the Loran system, you'd need a 40ft tower — and around 25kW of juice to power it."

https://www.engadget.com/2013-01-21-uk-eloran-navigation-sys...

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upvoteby teeray1 days ago|
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Well certainly, no one thing is impervious. But if you have GPS, LORAN, VORs, NDBs, astronavigation, etc. you have many more options at your disposal and present a much more complex attack target.
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upvoteby butvacuum11 hours ago|
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It's 2026: we have more ways to defeat jamming, or make it irrelevant, at unit costs trivial for commercial and most private applications. 1) atomic clocks can be smaller than a closed fist and allow GPS to work with 3 satalites with ocassional drops to 2. 2) the same clocks can be used to filter out radio sources from the wrong direction. 3) star navigation (commercial is often above weather, most weather is clear in some IR bands) 4) Terain following (easy to store maps now) 5) Inertial. 6) magnetic

When combined it is very hard to break the position fix. I expect the issue with the system is it's a military tech. with all it's that'll associated legal problems. After all. it'd bypass most the protections built into GPS modules.

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upvoteby wbl10 hours ago|
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And the military has JDAM with HOJ as a solution for jamming
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upvoteby butvacuum7 hours ago|
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I was thinking G-man and a suprise helicopter on your lawn. The government hasn't made a spectical of throwing the book at a jammer recently.
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upvoteby mschuster9110 hours ago|
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> astronavigation

Good luck finding a pilot trained on doing this, or an aircraft with high enough window cutouts that allow for the use of a sextant. Old Boeings had them [1], but no modern aircraft does.

I think even among navies you'll be hard pressed to find a navigator who still can do astronavigation. IIRC even the US Navy discontinued astronavigation, but recently-ish reintroduced training for it again.

[1] https://virginflightdeck.blogspot.com/2010_09_01_archive.htm...

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upvoteby leonidasrup10 hours ago|
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In the 21st century you don't do astronavigation by hand, you use cameras, computers and software.

Astro-inertial guidance is used for example in submarine-launched ballistic missiles.

"Astro-inertial guidance, or stellar-inertial guidance, is a sensor fusion-information fusion of inertial guidance and celestial navigation. It is usually employed on submarine-launched ballistic missiles. Unlike silo-based intercontinental ballistic missiles, whose launch point does not move and thus can serve as a reference, SLBMs are launched from moving submarines, which complicates the necessary navigational calculations and increases circular error probable. Stellar-inertial guidance is used to correct small position and velocity errors that result from launch condition uncertainties due to errors in the submarine navigation system and errors that may have accumulated in the guidance system during the flight due to imperfect instrument calibration."

https://en.wikipedia.org/wiki/Missile_guidance

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upvoteby mschuster916 hours ago|
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Yeah but good luck getting that approved for new airliner designs, much less retrofitting it into existing airliners. For the older ones, you'd probably need to rework half their computers.
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upvoteby teeray10 hours ago|
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> Good luck finding a pilot trained on doing this

Not necessary. ICBMs have been able to do this autonomously for a very long time [0]

[0] https://en.wikipedia.org/wiki/Celestial_navigation

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upvoteby jacquesm11 hours ago|
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Not so simple. For one the distances to the transmitter are much smaller, for another the amount of power available to the transmitters is pretty much whatever you want to hook it up to, whereas GPS satellites are on a pretty strict power budget. On the reception side the power levels are many orders of magnitude apart.
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upvoteby cyberax11 hours ago|
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Not really. It uses 2MHz band, with the wavelength of around 160m.

This means that it's easy to receive via a ferrite bar antenna but hard to transmit. You need an antenna of at least around 40m size for that to be efficient.

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upvoteby lstodd10 hours ago|
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Even a 160m guy-wire tower is cheap. 40m.. my friend installed 32m one just to have better internets, not exactly out of pocket cash, but nothing compared to say swapping a car.
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upvoteby cyberax9 hours ago|
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Sure, but such an antenna will be extremely conspicuous and easy to triangulate. You can't install it covertly.

Meanwhile, GPS can be jammed or spoofed with a briefcase-sized device for a couple of kilometers around you.

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upvoteby laruss51 days ago|
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[dead]
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