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Ghost ships, crop circles, and soft gold: A GPS mystery in Shanghai
- rbanffy 7y agoI'd think the circular pattern comes from slight timing differences (they look like a regular sine-wave-like oscillation) between the multiple satellites being spoofed as if the transmitters were not completely in sync. Disclaimer: it's a guess - this is NOT my expertise.
- Pick-A-Hill2019 7y agoA pretty darn good guess rbanffy. The spoofed signal is a 'hacked' re-transmission of a valid GPS signal rebroadcast by local high powered ground based stations. The basic concept is that you (via a Sat dish) receive a valid GPS signal while blasting out a wide band RF signal to mask/overwhelm a local GPS receiver. 'Splatting' the airwaves and then retransmitting a delayed GPS signal is enough to flick a location by miles. Being able to decode, alter and then re-transcribe (including checksums) the GPS data stream to an over saturated local receiver is .... doable (at a nation state level). The circular patterns are a rounding of the reflection from three (possibly four) retransmitting stations.
- basicplus2 7y agoperhaps they need to start using something like the Airborne Collision Avoidance System https://en.m.wikipedia.org/wiki/Airborne_collision_avoidance_system https://en.m.wikipedia.org/wiki/Airborne_collision_avoidance...
- Pick-A-Hill2019 7y agoThere is / was a working solution to this called LORAN-C that is being phased out. The accuracy isn't all that great (60 ft / 18 metres at best) but can be used to provide a 'disagree' alert to navigation systems. ( https://en.wikipedia.org/wiki/LORAN-C#The_future_of_LORAN https://en.wikipedia.org/wiki/LORAN-C#The_future_of_LORAN )