[time-nuts] First success with very simple, very low cost GPSDO, under $8
hmurray at megapathdsl.net
Thu Apr 10 06:18:20 UTC 2014
tvb at LeapSecond.com said:
> You only need enough bits to cover the worst case OCXO frequency drift or
> the worst case GPS jitter error, per second. For example, if your OCXO stays
> accurate to 1 ppm it can't possibly drift more than 1 us per second.
> Similarly, it's a safe assumption that your GPS 1PPS stays within 1 us of
> correct time. Therefore, the maximum number of 100 ns ticks you will be off
> in any second is +/-10. So even a 8-bit counter is enough. Does this make
> sense now?
Am I confused or did you forget to add the 2 errors to cover the case when
they both happen during the same second? 2 us or a count of 20 is still
tiny, even for an 8 bit counter.
These are my opinions. I hate spam.
More information about the Time-nuts_lists.febo.com