[time-nuts] Best test setup?

[Bruce Griffiths]

That relies on the internal arming of the 5370B which isnt all that 
stable in that the time interval between successive measurements doesnt 
have great stability and one actually has to measure this by other means.

Using an external arm signal with known repetition rate that is 
synchronised to the zero crossing of the start input avoids this problem.

The actual requirement is that the phase difference doesnt change by 
more than the period of the stop input signal between successive 
measurements.
Unwrapping of the phase measurements (adding or subtracting one period 
of the stop frequency when required) can then be done unambiguously.
The sample rate depends on the arm frequency (set the divider 
appropriately) ie one can set the arm frequency to any value for which 
the 5370B doesn't lose measurements.


Bruce

SAIDJACK at aol.com wrote:
> If both sources drift less than 100ns max (pk to pk) at 10MHz,  then their
> 10MHz outputs can be used directly to start/stop the 5370B.
>
> Choose a cable length, and a rise/fall trigger so as to measure as close to
>   50ns as possible, so the signals can drift up or down from that 50ns
> average.
>
> The advantage is getting many (up to 20 samples per second or more) rather
> than just 1 sample per second.
>
> bye,
> Said
>
>
> In a message dated 12/29/2009 11:04:49 Pacific Standard Time,
> bruce.griffiths at xtra.co.nz writes:
>
> For most  caesium standards and for some GPSDOs the jitter of the PPS
> output exceeds  the jitter of the 5370B so using the PPS output to arm
> the 5370B reduces  the measurement noise over the setup where the PPS
> output is used to start  (or stop) the  5370B.
>
> Bruce
>
>
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