[time-nuts] 10MHz LTE-Lite - PPS accuracy?

David J Taylor david-taylor at blueyonder.co.uk
Wed Dec 10 11:41:36 EST 2014


Gents-

I don’t know if everyone is aware, but the USB PPS out is basically useless 
on both my units - at least 200us off if not more.

Make sure you’re using the PPS OUT and not trying to measure on the DCD of 
the USB int, as is easy to be drawn to do.

NS
=============================================

Neil,

Thanks for that reminder.  I've been measuring both on the co-ax output pin 
and on the debug header (with the same or very similar results).  The 
difference between my two GPSDO has settled at 170-180 ns.  I suppose I will 
now need a third!

But having the PPS on the DCD over USB is not as useless as you might first 
think, because in tests here using the DCD/PPS over USB produced better 
results with NTP than an internet connection alone.  It is worth checking - 
your results may differ.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 



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