[time-nuts] Advantages of GNSS ???

[Bob kb8tq]

Hi

They go absolutely crazy updating nav….. but they only come up with the timing correction once a second.

From the latest version of the F9T Manual UBX-19005590 - R02  on page 43: 
The recommended configuration when using the UBX-TIM-TP message is to set both the measurement rate (CFG-RATE-MEAS) and the time pulse frequency (CFG-TP-*) to 1Hz.

Since the rate of UBX-TIM-TP is bound to 1 Hz, more than one UBX-TIM-TP message can appear between two pulses if the time pulse frequency is set lower than 1 Hz. In this case all UBX-TIM-TP messages in between a time pulse T1 and T2 belong to T2 and the last UBX- TIM-TP before T2 reports the most accurate quantization error. In general, if the time pulse rate is not configured to 1 Hz, there will not be a single UBX-TIM-TP message for each time pulse. 

Sorry if the quote comes through a bit garbled. Sometimes this cut and paste stuff does not quite do the trick. 
Indeed it’s not 100% clear what they are doing from the docs. They say this and that here and there. The 
bottom line is still that you can only trust the sawtooth offset data to be correct at the one second point. 

Bob

> On Jul 7, 2019, at 8:42 AM, Leo Bodnar <leo at leobodnar.com> wrote:
> 
> Correction on all Ublox receivers including F9P is done at navigation rate which can be set as high as 20Hz.
> Leo
> 
>> From: Bob kb8tq <kb8tq at n1k.org>
>> Frequency of any GNSS output on the F9P is limited by the accuracy of the time pulse. 
>> Correction is only done once a second.
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.