[colechristensen]

>Anyone got any leads on Doppler shift detecting equipment?

All radio receivers? Detecting the radio doppler frequency shift for satellites is kinda trivial.

Spoofing/jamming systems also trivially include doppler shifts. The more someone is trying to interfere with your specific location, the harder it is to defeat the spoofing.

[Scoundreller]

Seems like there's a gap for distributed gnss jamming/spoofing detection systems, not unlike what we have for lightning detection and flight tracking.

Unfortunately gpsjam.org relies on ADS-B data and if you don't have a lot of flights (or ads-b receivers) in an area, it leaves a lot of gaps. Plus it's far from real-time.

[colechristensen]

For that you need a custom GPS receiver stack and as well as the technical hurdles of designing the receiver in an expanded way to detect spoofing (by the way it's not just spoofing, in normal circumstances GPS signals will reflect off of things and you'll get perfectly natural "spoofing" which you have to properly reject) you'll also have to deal with the fact that GPS receivers are export controlled unless they meet certain requirements.