From: Luke Mester
=================================
Luke,
I meant to add - there could be periods of several seconds or even a minute
or more where the receiver loses its view of a sufficient number of
satellites. You will need to place it in a location with a good view of the
sky, preferably a 360 degree horizon view. These devices are very
sensitive, though, and mine work well enough on the top floor of a house,
located in a good VHF location with no local blockages such as industrial
premises or blocks of flats. One of my GPS receivers is located downstairs,
but near a window, and you can see that it likely lost GPS lock just after
02:00 UTC this morning:
http://www.satsignal.eu/mrtg/raspi2_ntp.html
Temperature variations are apparent throughout the plots here:
http://www.satsignal.eu/mrtg/performance_ntp.php
http://www.satsignal.eu/mrtg/performance_disk_temp.php
Heating comes on around 05:30 UTC.
The final accuracy tweak is to compensate for the quantisation of the PPS
signal caused by the finite clock rate in the GPS receiver - sometimes
called sawtooth error. Some GPS receivers will output that error in the
data stream, and you can then correct for it in your software. A good
starting point:
http://www.leapsecond.com/pages/m12/sawtooth.htm
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: [email protected]
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
