[ntp:questions] GPS clock for Linux

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Fri Sep 12 20:42:38 UTC 2008


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.
  http://www.megapathdsl.net/~hmurray/ntp/GPSSiRF-off.gif

I forgot to mention another problem with those chipsets.
They have a leap second bug.
  http://www.megapathdsl.net/~hmurray/ntp/leap-gps.gif


-- 
These are my opinions, not necessarily my employer's.  I hate spam.




More information about the questions mailing list