[ntp:hackers] Reduce jitter of refclocks (connected via USB)

David J Taylor david-taylor at blueyonder.co.uk
Tue Mar 15 06:26:23 UTC 2011


> USB by design operates with a 1 ms polling interval, so this is exactly 
> the jitter you should get, best case.
>
> Terje

I once did some casual checks of running NTP with a GPS/PPS source over a 
serial to USB converter, and got the results here:

  http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html#usb

Jitter was in the region of 50 microseconds (Windows XP SP3).  Not quite 
sure how that tallies with a 1 ms polling interval.

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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