[ntp:questions] Very large jitter and offsets on GPS ref clock after upgrade to "p5"

Thomas Laus lausts at acm.org
Sat Jan 7 15:37:17 UTC 2012


On 2012-01-06, unruh <unruh at invalid.ca> wrote:
> Ssure a pulse can go missing. Eg, your encore pluse is a TTL level pulse
> (0-3 volt transition) and your serial port is marginal with that ( the
> standard for serial ports is basically -5 to +5 volt transition) So
> occasionally the hardware misses the transition. Or there could be some
> high resistance in the line from the encore which meant that the voltage
> level transition was too small. Of the receiver decided that the
> sattelite data was just not good enough to send out a pulse.....
> So yes, pulses could go missing. What worries me more is that 999 ms
> offset at one point, which suggests that the nmea sentence came too late
> and the pulse got associated with the wrong second. (The garmin 18x had
> this trouble a lot apparently).
>
The Oncore Driver 30 does not use the NMEA protocol.  It uses one of
those 'special' non-generic type of commands unique to Motorola receivers. 
Reg Clements is the Type 30 maintainer and is very helpful sharing
his knowledge of Motorola binary in solving problems.

Tom
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