Hi,
I've recently been working with a coded CW radar system that just loops over a fairly long IQ vector. It works all fine for a while, but after a few days, the transmission timing has drifted away from where it should be. I'm comparing the leading edge of the transmit waveform with the PPS provided to the USRP to detect drifting of the waveform. I'm wondering what could cause this. While the drifting occurs both when I see the letters U and L, and sometimes when I don't see them at all (this is correlated with the GPSDO losing lock).
First of all, is there any way to ask the uhd_usrp_sink if there have been overflows or underflows that cause a need for resyncronizing?
Second, what would be the optimal method to implement a continuously repeating IQ vector fed to a uhd_usrp_sink block that needs to stay in sync? On receive, sample counting works, so I would assume this to be the case also on receive.
juha
hftx.py