[ntp:questions] Very large jitter and offsets on GPS ref clock after upgrade to "p5"

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Tue Jan 10 19:12:53 UTC 2012


unruh wrote:
> On 2012-01-10, David J Taylor<david-taylor at blueyonder.co.uk.invalid>  wrote:
>> pulse over the length of line he talks about should be no problem at all
>> (but a microsecond-wide pulse might).  The timing PPS I've seen are in the
>> tens of milliseconds wide.  If there is overshoot, perhaps a capacitor to
>
> Did you mean 10s of ns? The Sure width is about 5-10ns. at the card
> without any line attached. The line could certainly broaden that up to
> about 1us, but ms?
> Even the Garmin 18 is less than a usec.

You're mistaking rise time for pulse width: Not the same thing at all!

Some timing GPSs, like the original Oncore has a very short PPS 
duration, while many/most others seem to be in the 100-200 ms range.

Terje
-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"



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