4 ms·

Wouldn't that require them to match the timestamp somehow?

• dghlsakjg 1y ago
  The receiver derives the time from the signal itself.
  • causality0 1y ago
    Right, so if the timecode in the signal doesn't match the receiving device's internal clock it should know the signal is invalid shouldn't it?
    • dghlsakjg 1y ago
      The time in the device isn’t independent of the received signal. The device typically has a clock that is much less accurate than the timesignal that gets set based on the gps signal. There aren’t many devices that can rival a gps satellite for time accuracy. A spoofed gps signal would not differ enough in time from a real one to tip you off. Further, a big part of the working of GPS is that your location is trilaterated from discrepancies in time from the various signals due to time of flight. The only way to accurately detect a spoofed signal is if you already know your location. (You can infer spoofing using IMUs, or signal analysis, etc… but that is a rare capability at this point)