[time-nuts] PRS-10 input and output calibrations
azelio.boriani at screen.it
Sun Apr 22 21:40:50 UTC 2012
That is very interesting in my opinion and, for those who have access to
more than one PRS10, further investigation should be done. I had a new
PRS10 and, just out-of-the-box, it locked (not instantly, of course) to the
On Sun, Apr 22, 2012 at 10:47 PM, <bg at lysator.liu.se> wrote:
> With factory default settings with 2 PRS-10s, connecting 1PPS_out from one
> unit to 1PPS_in on the other, would not align the 1PPS_out pulses. They
> were off by several hundred of ns. It was probably an operator error
> somewhere. We just did not find the error in the time frame we had
> > 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.
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