Bob,
Shipping will be a bit of an issue as I'm not in the USA.
But the most sensitive voltmeter may be the VC-TCXO so some SW was added
to the GPSDO/Timer/Counter to sweep the dac's while measuring a 10 MHz
signal from a Rb.
This showed the high dac steps are all monotonic and almost equal size.
For the low dac a single step is to small too accurately measure the
frequency difference but again the steps seem to be monotonic.
I'm aware of different way's to measure phase noise. Is there a method
particularly good for GPSDO phase noise measurement?
Erik.
On 5-3-2022 20:50, Bob kb8tq wrote:
Hi
One suggestion on the frequency plot:
TimeLab as you have it set does a “per pixel” process on its charts. You have
a limited screen resolution and a ton of data. You have to do something. There
is no way to display it all.
It’s a good idea to zoom in to some of the “problem regions” and see
what is really going on. This reduces the number of data points that
map to one pixel and potentially changes what you see a bit. The closer you
get to one data point per pixel, the closer you are to “reality” without any
processing potentially getting in the way.
On the DVM, eBay (with some time spent shopping) will sell you a working
6 1/2 digit device for < $100 if you are patient. If you need it now, it’s still
likely to be below $200. Yes it will be a big clunky box that takes up bench
space. It will be HPIB and not serial i/o. The display might be a bit fun in
bright lighting.
While you are shopping, I would get set up for phase noise as well. Often
it can spot issues that are tough to find with a second to second data stream.
The setup does not have to be very fancy or terribly expensive.
Bob
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