[time-nuts] 1 pps correction

[Azelio Boriani]

Said,
how complex is your 20pS time interval counter? Is it analog, FPGA,
something else (if you can disclose some info, of course)?

On Sat, Mar 31, 2012 at 11:44 PM, Hal Murray <hmurray at megapathdsl.net>wrote:

>
> martyn at ptsyst.com said:
> > I’ve seen that the peak to peak jitter is reduced from something like 27
> ns
> > to < 10 ns.
>
> > Is this a reduction of just the jitter, or is the actual accuracy to UTC
> > also improved by this amount.
>
> Have you read the hanging-bridges paper?
>  Tom Clark and Rick Hambly: Timing for VLBI
>  http://gpstime.com/files/tow-time2009.pdf
> I think that is the key to understanding this area.
>
> If you could average over many sawtooth cycles, you should get an accurate
> answer.
>
> The problem is that you don't get to pick how many cycles fit into your
> averaging time.  The sawtooth pattern is the beat between two frequencies.
> One of them is drifting with time/temperature.  If you are unlucky, the
> beat
> frequency can be very very low.
>
> The sawtooth correction lets you correct on a cycle-by-cycle basis.  You
> don't need to average over many samples.
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>