[ntp:questions] ntpd - gpsd communication

Uwe Klein uwe at klein-habertwedt.de
Fri Jun 5 07:25:23 UTC 2020


Am 05.06.2020 um 08:36 schrieb ah at avtodoria.ru:
>> This sounds more like bit errors in serial reception.
>> ( i.e errors coming up in all magnitudes.)
>
>> That is reception via NMEA?
>> do you check the NMEA checksum ( Portion after * afair)?
>
> Thank you for response. Yes, that is reception via NMEA. No i didn't check checksum, i think gpsd should check it, am i wrong?
>
> I just write to log data from SHM when it's all OK. And try to use this correct log after some time to make ntpd change the time. If you think i do something not correct please tell me, i'll try to do something else
>
can you enable data logging and produce logs from the GPS instances that 
produce errors? ( all sentences received over some time.)

Just from a single sytem.

As an alternate take a terminal application configured for 4800baud
and for the right serial port and log data via that path.

never used gpsd put did my own solution years ago for a special use case:

https://wiki.tcl-lang.org/page/NTP+plugin+for+a+detachable+nmea+GPS+source

( one app sources NMEA from the device and reflects that into UDP packets.)
    the other part is sinking UDP packets and funneling those
     into NTPD. kind of a primitive gpsd replacement )

Uwe



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