Some more info The two GPS do keep their phase stable vs a Rb within +/-10 ns. But the absolute time difference of their PPS pulses was, after a cold start, stable within +/- 20ns but the average value could be up to 100ns and differed after every cold start. The two GPS antenna cables had a length difference of 1 meter, but that should cater for only 5 ns (?) One module is connected to the antenna with only a C, the other has a 1 GHz CLC high pass filter between antenna and module Erik
Op za 30 apr. 2022 om 12:32 schreef Erik Kaashoek <[email protected]>: > The PPS jitter of a cheap Chinese GPS module was measured at about +/- > 10 ns. > But the phase of the PPS compared to a Rb varied substantial more. > To verify if this was possibly due to ionospheric or atmospheric > conditions the time difference between the PPS of two identical modules > using two identical rooftop antenna was measured. Both only used the GPS > constellation. > This showed difference of up to 100 ns. Switching to GPS+GLN did not > make a visible difference. > It was tried to set both GPS modules into fixed position mode but the > reported position still kept moving a bit (within 3 m) and the fixed > mode did not have a visible impact on the time difference variations. > Is a time difference of up to 100 ns to be expected when using two GPS > receivers or is this difference possibly due to bad application or > performance of the cheap Chinese GPS modules > Erik. > _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
