[time-nuts] GPSDO and PPS measurement precision

Lars Walenius lars.walenius at hotmail.com
Fri Jun 3 12:23:22 EDT 2016


Using Tom van Baak´s GPSDO simulator is very informative as it can limit the TIC resolution.

Shera´s design is much more complicated than the 42ns resolution as it depends on the noise in the 24MHz oscillator. With an oscillator with enough noise during a 30 sec period it might be below 10ns eq. resolution all times? With a better oscillator it might have a ”hanging bridge” now and then.


Från: Attila Kinali<mailto:attila at kinali.ch>
Skickat: den 3 juni 2016 18:01
Till: Discussion of precise time and frequency measurement<mailto:time-nuts at febo.com>
Ämne: [time-nuts] GPSDO and PPS measurement precision


With all the talk about GPSDOs going on in the last couple of months,
I started to wonder how much precision in the measurments is actually
needed. On one hand, we have the old GPSDO designs, like Shera's,
that offer a resolution in the 40ns range. On the other hand, we
have modern designs, that measure the PPS down to <100ps.

How much does the accuracy/stability improve using higher resolution?
Does anyone have data on that? If not, would someone be willing to
measure one of the better GPSDO's by artifically decreasing its
resolution in software and see what happends to the ADEV/MDEV/TDEV?

I am willing to give a hand with the data analysis, but I don't have
the equipment to do such a measurement.

                        Attila Kinali

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