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