You can get the synchronize two USRPs with an external reference or a USRP MIMO <https://www.ettus.com/product/details/MIMO-CBL> cable, and specifying the time to start streaming for both.
-John On Thu, Jan 3, 2013 at 11:18 PM, LD Zhang <[email protected]> wrote: > Hi Folks,**** > > ** ** > > We are testing 2 USRP N210 units with data gathering (using GRC source and > file sink). The command from the host to the N210 is sent at the > approximately simultaneous time (referenced to system NTP time). However, > the samples gathered from the 2 units appear to differ by as much as > 0.4-0.5 seconds! The intention is to gather data at the 2 units at > approximately the same time as the pre-programmed system time commands. The > gathering is done with the top_block.py code generated from GRC. What > happens inside the USRP appears to be beyond my control here. So the > natural thing to do here is to time-stamp the samples with host computer > system time. I hope that we don’t have to use an external reference for the > USRP. Isn’t there an internal USRP clock that is continuously counting. If > we can get the USRP clock counts to tie together the samples counts and the > host computer system time, we would be in good shape. Is this a good idea? > **** > > ** ** > > Your thoughts and help are appreciated.**** > > ** ** > > LD Zhang**** > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
_______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
