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by avianlyric 462 days ago
No. The US stopped degrading civilian GPS accuracy in 2001[1]. Although the US retains the ability to degrade civilian GPS in specific target areas.

Regardless, if you’re building a long range missile, you need some ability for it to navigate. If you’re not using GPS, then what would you use instead? Additionally there’s nothing preventing you from using multiple navigation systems in tandem and fusing the results together, which is almost certainly what these missile do.

Sensor fusion reduces the impact of stuff like GPS jamming, but certainly doesn’t eliminate it. The over all system will be less accurate with fewer inputs, and if you’re the one faced with a high speed missile flying at you, I suspect you’ll take every edge you can get, regardless of how small the impact might be.

[1] https://en.m.wikipedia.org/wiki/Error_analysis_for_the_Globa...
2 comments
hollerith 462 days ago
>Regardless, if you’re building a long range missile, you need some ability for it to navigate. If you’re not using GPS, then what would you use instead?

US ICBMs and submarine-launched ballistic missiles use a combination of inertial and celestial navigation: in space of course there are no clouds to obscure the stars:

https://en.wikipedia.org/wiki/Celestial_navigation#:~:text=I...

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lupusreal 462 days ago
Many cruise missiles use terrain contour mapping. In principle at least it seems like it should work for airplanes too.
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avianlyric 448 days ago
Doesn't really work if you're trying to navigate over an ocean. Cruise missile also operate over relatively short distances (1,000km - 5,000km, most being 1,000km - 3,000km) compared to long haul flights, plus they also fly at very low altitudes (which helps them avoid enemy radar) which makes terrain contour mapping easier.

Not to mention, if you're designing a cruise missile, you're not that bother about how your navigation system might interfere with other aircraft, or ground systems in the area. I doubt having thousands of planes flying around shooting radar straight down at the ground would work particularly well.

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