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Comment on Without GPS: EU researchers develop satellite-independent navigation system

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tal@lemmy.today ⁨1⁩ ⁨month⁩ ago

I’m sure not, but even without looking at any technical details, it will have at least a couple benefits:

First, it’s short range. GPS satellites are in geosynchronous orbit, which is a pretty high orbit. Wikipedia says about 22,000 miles away. For GPS, the jammer is going to be far closer than the legitimate signal.
Second, I’m guessing — though we’ll see — that this is going to be a civilian system, and I suppose that they could even try to mandate that militaries not use it. GPS was, from the beginning, a military system, and there are weapons being used in Ukraine that use it for guidance. Unless you’re solely out to be a dick — which isn’t impossible — probably not a lot of benefit to stomping on civilian-only frequencies.

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nulluser@lemmy.world ⁨1⁩ ⁨month⁩ ago
Nitpick: GPS satellites are not in geosynchronous orbit and are at about 12,540 miles up.

en.m.wikipedia.org/…/Global_Positioning_System

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dogslayeggs@lemmy.world ⁨1⁩ ⁨month⁩ ago
GPS and Galileo satellites are in MEO, not GEO. GEO is a very specific altitude to keep a satellite directly over the same spot on Earth at all times (synced to the spin of Earth). MEO, on the other hand, is a wide range of altitudes roughly half the altitude of GEO. GPS sits right around 9800 nautical miles, which is 11200 miles. That’s still really far away, so your point stays the same. Galileo is in a similar orbit, I think around 200 miles lower but I can’t remember. GLONASS is there, too. Beidou from China has birds in both MEO and GEO. QZSS from Japan uses one GEO bird and three birds in a highly inclined orbit at GEO altitude.

Your two points are good. I think a third point would be that this is a different RF spectrum, while GPS and Galileo are on roughly the same RF spectrum. Jamming GPS and Galileo at the same time isn’t difficult. Jamming a very different RF spectrum at the same time is much harder.

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Overspark@feddit.nl ⁨1⁩ ⁨month⁩ ago
Regarding the second point, militaries have a long history of using civilian products (see GPS in the gulf war for example) if they don’t have enough of the expensive stuff, which will lead to incentive to jam the civilian stuff as well. The article suggests that this system should be more resilient against simple jamming though.

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