[time-nuts] PRS-10 input and output calibrations
phk at phk.freebsd.dk
Sun Apr 22 18:44:28 UTC 2012
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.
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