[ntp:questions] Re: Generating a PPS output.

John Pettitt jpp at cloudview.com
Sun May 28 23:32:46 UTC 2006


Alexander Fisher wrote:

>>From what I understand, the key to getting sub ms NTP accuracy is very
> low and symmetric network latency.  I've then just got to figure out how
> to not lose any more accuracy when generating the PPS out.
> 
> 

The other key when using PC hardware is not not have the box doing anything else.   A machine
running from a memory file system booted from flash and with no other jobs has a much better jitter
than one that's processing packets or doing disk I/O for other apps.

You might want to look at the Soekris 4501 single board computer the Elan CPU has some built in
timers that may well be able to use to generate your PPS in hardware.  If you really want it to be
accurate replacing the xtal with an ovenized version will improving things dramatically.

Everything you need to know about the Elan CPU is here
http://www.amd.com/epd/processors/4.32bitcont/14.lan5xxfam/24.lansc520/index.html



John




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