[Pool] External device sync / PPS / USB

David J Taylor david-taylor at blueyonder.co.uk
Wed Mar 2 17:32:41 UTC 2011


> As long as we’re on this topic, is it important to distinguish serial
> ports that are connected via an internal (or external) USB bus? Does
> this increase jitter? What if there’s other traffic on the USB bus?
>
> --
> Daniel

Using a Sitecom USB hub which includes a serial port, I made a comparison 
here, Daniel:

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

Yes, it does increase the jitter.  Whilst certainly not as good as a 
direct connection, it's considerably better than a LAN-only connection.

Certainly not "a waste of your time and money" if USB is your only choice, 
but check whether your motherboard has a serial port header and just needs 
the lead to an RS-232 male connector on the back of the PC.  Many 
motherboards do.

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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