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
saidj...@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.griffi...@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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