Lo Phase alignment


I’m trying to compensate for carrier mismatch and would like to use both rx channels from the LimeSDR Usb with the same LO Frequency, but the phase difference at startup is random.

I Stumbled upon Application for using the 2 RX channels simultaneously witch is related to my problem, it mentions the PhaseAlignment branch of LimeSuite, but the branch is 4 years old and apparently never was merged to master.

I don’t know enough about the internals to merge the branches myself. Is there any chance someone could merge the branches?

Thanks in advance

Reading the thread you pointed to, it was merged on 2018-03-07

You are right.

However my channels aren’t aligned. I confirmed this by continuously measuring the intensity of packages sent from a single LimeSDR Mini at the same position with the same amplitude over a couple of minutes. There is a carrier mismatch resulting in a ~0.2Hz Beat, however the offset is typically about 90° which I think can only result from a phase offset in the Lo Frequencies of the two channels.

Is there any way to manually align the two Channels?

I tested it with the last commit of the PhaseAlignment branch. I’m fairly impressed the C API remained stable over the course of four years and it seems to work without downgrading the Gateware. The beat is not a clean sinus, it seems the Lo frequency is continually getting aligned. I can’t make out any offset between the channels.

So I guess the functionality got broken again some time since the merge.

However as I was only doing some measurements and statistics on them which now work properly I’m satisfied.