On 15/08/11 05:36, Paul Cianciolo wrote:
Hello
I have a properly working Keithly 776 Frequency counter that has the TIC using
the A and B inputs.
I have z3801 that is considered my house reference, that 10 MHz output goes to
the A input.
A double oven RAKON oscillator is connected to the is connected to the B input
Both signals are square waves.
Using a frequency comparator the Rakon oscillator is adjusted to 1 part in 10-8
I was assuming that I would see on the FReq Counter a display in degrees a
number between 0 360 that was constantly cycling
The whole reason for this post and my previous one is to get sample out of the
counter in terms of a voltage, log these voltages, manipulate them and then
try to graph the results to try and duplicate Allan Variance and Deviations
even if only in a very crude manner for now.
There is an analog output in the back of the counter.
Does this seem feasable? Or maybe there is another counter that would work
better
Thank you again for any help
A recommended setup is to:
1) Trigger measurement by the PPS
2) Use the reference 10 MHz as start of TIC
3) Use the DUT 10 MHz as stop of TIC
4) Log measured time interval start->stop using preferably digital output
Pick up TimeLab to do the post-processing.
If you can't trigger the measurement as described, then using the PPS as
start signal can be used. You depend much more on the particular GPSDO
then (a topic in itself).
If you can't do digital readout over RS232 or GPIB then using that
analog tap is possible, but now you need to have a DMM synchronised to
the measurements. Possible, but a little more complex.
Cheers,
Magnus
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