Re: [Discuss-gnuradio] Measuring phase between channels

[Stephen Harrison]

I did an experiment similar to this a year or so ago. I synced all the USRPs to the same 10MHz and PPS. I had pretty good results using libgps to get the GPS time and then using UHD to start streaming on a particular PPS edge on all units. With LFRX boards this will ensure that the DDCs start at the same time and start from zero degrees. I seem to remember there was some small random variation from run to run. If you are just looking for relative changes in phase difference I found this approach works fairly well. 

On Tue, Jun 17, 2014 at 10:36 AM, Martin Braun <address@hidden> wrote:

On 17.06.2014 19:06, David Miller wrote:

Hello,
I want to measure the phase difference between three synchronised USRP
channels (Common Ref & PPS), does software exist to do this, and to what
accuracy, please?
Sorry, this is a bit of a newbie question, and probably already covered!

Sure, the easiest way would simply be to put in a scope, and check by looking -- of course, that's not very accurate.

There's enough math operators in GNU Radio to see the actual phase difference, such as conjugate and multiply, then convert to phase.

Cheers,
Martin

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio