[time-nuts] Re: Tuning a GPSDO loop for optimal disturbance handling

[Erik Kaashoek]

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
>