Peter Reilley suggests a backup to GPS using terrestrial transmitters. This idea has been around since the early days of GPS. The terrestrial transmitters were called "pseudo-satellites", or "pseudolites" for short. The big problem with this idea is that the GPS signal format has a narrow dynamic range. The signal strength from a terrestrial transmitter varies widely (inverse square law) from positions near the transmitter to positions far away. The variation in any practical system is larger than the GPS signal format can handle. This is called the "near-far problem". For an extensive discussion of the pseudolite concept, including the near-far problem, see my dissertation. You can find it with a web search for my full name and the word "pseudolites".
Cheers! --Stu _______________________________________________ time-nuts mailing list -- email@example.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.