[ntp:questions] GPS clock for Linux
uwe_klein_habertwedt at t-online.de
Sat Sep 13 08:31:29 UTC 2008
Hal Murray wrote:
> In article <ko8qp5-po8.ln1 at klein-habertwedt.de>,
> Uwe Klein <uwe_klein_habertwedt at t-online.de> 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.
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.
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