Re: [Discuss-gnuradio] USRP time synchronization

[Derek Kozel]

Hi Petr,

You'll have to use timed commands for starting your transmissions. This can be done in GRC, but requires writing some code to issue the commands. Usually I find it easier to add the commands to the generated Python if I'm not changing the application very often.

Here's a C++ example that shows timed stream commands. You'd need to use these for both the transmit and reception side.
https://github.com/EttusResearch/uhd/blob/master/host/examples/test_timed_commands.cpp#L111

Regards,
Derek

On 10/04/2019 14:18, Horký Petr wrote:

Dear GNU Radio users,

I have a simple program,  Signal source (square) -> USRP SINK     USRP SOURCE - > TIME SINK.  

If I plot Tx/Rx signals in a Time sink, I see, that there is a time differnce, which is OK. But each time I start the program, the time difference changes (As shown in a picture in attachements).

What can I do? I tried to change Sync, Clock rate, Clock Source, Time source....everything. But still the delay is changing each time I execute my program.

If the delay was not random I could just substract that. This causes me problems in every radar program, since I need precise time measurements.

Regards

Petr 

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