Re: Issue with Ettus B200minis...

On 26/01/2025 19:29, bob@cx2.com wrote:
> Hi Everyone
>
> I am attempting to use two B200 minis at the same time to measure
> differences in amplitude and phase from a single signal over coax cable and
> a 3dB splitter. I am using gnu radio companion to run this radio setup. I am
> splitting a PPS signal and running to both radios.
>
> I am having issues in the measured phase difference. It seems that either
> radio is not locking to the reference (PPS), and the phase for the measured
> signal continues to vary as a function of time.
>
> I have attempted the following:
> . Use a 10MHz reference from my signal generator
> . Running gnu radio as admin
> . Issue a state timer using various delay, trigger, cycle time
> settings
> . Using various sample rates and Rx IBW
>
> Also, using a simulated source in gnu radio does produce the expected
> result. However, when I switch back to the radios the results are variable
> again. I'm beginning to think there might be an issue with the radios but
> would like to open a discussion to see what else we can try to get this
> setup going...
>
> Thanks,
>
> Bob
>
>
The way that the external-clock "servo" works in the B20x-minis does NOT
result in mutual phase-coherence
  between the two radios.

If you're measuring two signals, you'd do better with a B210, and using
both channels.