Re: [Discuss-gnuradio] USRP timing offset

[Leonard Foxes]

Thank you Marcus for help!

Now I' m using Usrp with SCFDMA chain. I set_time_now and start_time_now :

uhd_usrp_source.set_time_now (uhd.time_spec_t(time.time()))

uhd_usrp_source.set_start_time(uhd.time_spec_t(time.time()+0.6)) 

uhd_usrp_sink.set_start_time(uhd.time_spec_t(time.time()+0.6)) 

and I haven't time shift.

But I see a lot of "L" (late packet) printed and some "U" (underflow).  How can solve the problem? I have tried to use low sample rate but after few seconds L and U appear.

Thanks

Leo

 

2015-09-02 16:41 GMT+02:00 Leonard Foxes <address@hidden>:

Hi everyone!

I’m new to Gnuradio e USRP. I use a USRP N210 with WBX daughterboards and loop back cable to connect TX e RX. I have tested USRP with a simple flowgraph (sine , usrp_sink , usrp_source) and I have observed that the output signal from usrp_source block  is time shifted. I mean, the usefull output signal starts after 0.0105 seconds. How can avoid this? I have tried to use “issued_stream_cmd”,  setting time_spec=0.0105 s but nothing has changed.

I want to use this USRP in a more complex project and I need to remove this initial time-shift.

I attach a plot of input and output signal and my flowgraph.

Thanks in advance for help,

Leo