[time-nuts] How to measure Allan Deviation?
Didier Juges
didier at cox.net
Mon Oct 23 04:02:33 UTC 2006
Bruce,
Thanks for the reminder. That was my intention. I was planning to use a
74HC74, and whatever dividers I can get my hands on. I am not looking
forward to daisy chain seven 7490s, so I will probably try something
else. With the D flip-flop, the dividers don't really matter, as long as
the delay is below 100nS.
I need to find the best way to go from the 10 MHz sinewave to the
divider, probably through an LM119 comparator with modest hysteresis.
The need for a low jitter divider is the same for the GPS disciplined
oscillator, so I should be able to reuse the divider for my frequency
standard.
Thanks
Didier
Dr Bruce Griffiths wrote:
> Didier
>
> If you are going to use a PPS divider to divide the oscillator frequency
> down to 1Hz, you will need to measure the inherent jitter of the divider
> to ensure that it doesn't degrade the measurement resolution. It may be
> necessary to resynchronise the divided output using a fast D flipflop to
> reduce the inherent divider jitter to less than the 20ps resolution of
> the 5370.
>
> Bruce
>
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