[time-nuts] PRS-10 input and output calibrations

Azelio Boriani azelio.boriani at screen.it
Sun Apr 22 20:04:52 UTC 2012


  Björn, what do you mean with "We never got one to track the other in a
reliable way"?
Thai is, how can it be that a PRS10 cannot track another PRS10? What do you
get when trying to track one with the other?

On Sun, Apr 22, 2012 at 8:44 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>wrote:

> In message <4F93F032.2040608 at rubidium.dyndns.org>, Magnus Danielson
> writes:
>
> >The input calibration would be something in the similar way,
>
> What I did:
>
> Detune an OCXO slightly (I actually have a 9.99997 MHz OCXO from
> IsoTemp), feed it to PPSDIV, disable the discipline code in the
> PRS10, collect the measured input time stamps over some hours.
>
> Either you get a nice ramp, or you get som kind of demented staircase,
> in which case you try to figure out which of the calibration constants
> to mess with.
>
> An alternative is to feed the PRS10 output to a HP333x Synthesizer
> and have that generate your 10-epsilon MHz for the PPSdiv.
>
> This general "vernier" method can be used to measure all sorts of tricky
> stuff, from interrupt latencies in operating system kernels to
> stuff like the above.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
> _______________________________________________
> 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.
>



More information about the Time-nuts_lists.febo.com mailing list