Hal Murray wrote: > In article <[EMAIL PROTECTED]>, > Uwe Klein <[EMAIL PROTECTED]> writes: > >>Hal Murray wrote: >> >> >>> There are a lot of low cost USB GPS gizmos that use the >>>SiRF Star III. They suck for timekeeping. >>> >> >>Is there a reason known for this? > > > I assume it's a software bug/feature. The problem is drift/wander > in the offset. The offset changes too slowly for normal > jitter filters to work on it. > http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif connected via serial/nmea or pps?
that looks like some beat frequency effect. But it is much too slow/time too big to be sender and/or receiver uart clocking. > > I forgot to mention another problem with those chipsets. > They have a leap second bug. > http://www.megapathdsl.net/~hmurray/ntp/leap-gps.gif Hmpf > uwe > _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
