Use gps for clock correction

[Harald Koenig]

On Aug 14, Russell Sears wrote:

> > GPS would be perfect for updating time, cause the time sent is more 
> > exact then the times, you can get by any other way. What about ntpd, can 
> > it handle gps-data?
> 
> http://time.qnan.org/

ntp has full gps/nmea support, even with PPS:

    http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html
    http://www.eecis.udel.edu/~mills/ntp/html/refclock.html

> Does the FR have access to the PPS signal from the GPS chip?  That might 

if not, please add that feature request for GTA03++ !

is there a chance to solder a wire from ublox to some free digital input line
which can trigger an interrupt (serial handshake line or similar) for gta02 ?
having PPS would be really nice...

> I wonder how hard it would be to add GSM time broadcast support to NTP...

I've been told that time quality of GSM is (or at least has been?) _very_ bad,
(errors from seconds to minutes, at least on germany) ?!?  
not exactly what you'd expect as time source for ntp then ;-)


Harald
-- 
"I hope to die                                      ___       _____
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Donald E. Knuth, 02-Oct-2001 in Tuebingen.        <_/  /  /OOOOOOOOOOO\
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Harald Koenig                                           //  /     \\  \
koenig at tat.physik.uni-tuebingen.de                     ^^^^^       ^^^^^