[time-nuts] Measuring 10 MHz accurately.
bruce.griffiths at xtra.co.nz
Wed May 7 20:30:47 EDT 2008
Brooke Clarke wrote:
> Hi Ulrich:
> The SR620 has a 1 kHz Reference output that's derived from the 10 MHz external
> clock input. It also has a Gate/Arm function.
> Appendix B in the PRS10 Manual explains how to use these two features to make
> 1,000 time interval measurements per second thus averaging the 20 ps one shot
> way down. http://www.prc68.com/I/PRS10.shtml
> The time interval armed 1,000 times per second and the difference between zero
> crossings of a pair of 10 MHz signals are measured. So the range of
> measurement is 100 ns before rollover. I think at least one of the test
> signals needs to be 10 MHz to drive the external clock input to get the 1 kHz
> reference. But you could use Toms PIC divider to generate a 1 kHz signal from
> about any test signal and use the same method.
> Have Fun,
> Brooke Clarke
What about the effect of the phase modulation of the 1kHz output by the
100Hz, 10Hz, 1Hz outputs due to simultaneous switching effects from such
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