From: Gabs Ricalde
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Non-timing receivers could be unsuitable for your requirements, as
some of us have discovered:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#oscillations
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Gabs,
The oscillations I reported are not due to the use of a navigation GPS
receiver. Three things lead me to that conclusion:
1 - the magnitude of the offsets is far greater than would be expected from
the specifications of the navigation receivers.
2 - I replaced the U-blox NEO-6M with a unit based on the MTK3339 module,
but the oscillations continued with visually the same amplitude and
frequency.
3 - I replaced the MKT3339 module with a unit based on the U-blox LEA-6T
timing GPS, but the oscillations continued with visually the same amplitude
and frequency.
[The one obvious difference between the two Raspberry Pi cards is that the
one without oscillations is begin fed with USB data into its USB port,
although that data isn't used by NTP, with gpsd not even running on that PC,
whereas the problem PC has nothing in the USB port. However, while writing
this note, I recall that one of the PCs has X enabled and the other does
not, so better try disabling X as putting a memory stick in the USB port
hasn't made any difference.]
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: [email protected]
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