Hi Marcus,
I did what you suggested by wrapping the timed commands as follows:
For the TX side (what you sent me in for_pavan.py):
self.uhd_usrp_source_0.set_time_unknown_pps(uhd.time_spec())
now = self.uhd_usrp_source_0.get_time_now()
start_time = now + uhd.time_spec(.5)
self.uhd_usrp_source_0.set_command_time(start_time)
self.uhd_usrp_source_0.set_clock_source("external", 0)
self.uhd_usrp_source_0.set_time_source("external", 0)
self.uhd_usrp_source_0.set_clock_source("external", 1)
self.uhd_usrp_source_0.set_time_source("external", 1)
self.uhd_usrp_source_0.set_samp_rate(samp_rate)
self.uhd_usrp_source_0.set_time_unknown_pps(uhd.time_spec())
self.uhd_usrp_source_0.set_center_freq(rx_center_freq, 0)
self.uhd_usrp_source_0.set_normalized_gain(rx_gain, 0)
self.uhd_usrp_source_0.set_antenna(Antenna_sel, 0)
self.uhd_usrp_source_0.set_center_freq(rx_center_freq, 1)
self.uhd_usrp_source_0.set_normalized_gain(rx_gain, 1)
self.uhd_usrp_source_0.set_antenna("TX/RX", 1)
self.uhd_usrp_source_0.clear_command_time()
And for the RX side (B210_Phase_Viewer.py):
self.uhd_usrp_sink_0.set_time_unknown_pps(uhd.time_spec())
now = self.uhd_usrp_sink_0.get_time_now()
start_time = now + uhd.time_spec(.5)
self.uhd_usrp_sink_0.set_command_time(start_time)
self.uhd_usrp_sink_0.set_clock_source("external", 0)
self.uhd_usrp_sink_0.set_time_source("external", 0)
self.uhd_usrp_sink_0.set_subdev_spec("A:0", 0)
self.uhd_usrp_sink_0.set_clock_source("external", 1)
self.uhd_usrp_sink_0.set_time_source("external", 1)
self.uhd_usrp_sink_0.set_subdev_spec("A:0", 1)
self.uhd_usrp_sink_0.set_samp_rate(samp_rate)
self.uhd_usrp_sink_0.set_center_freq(915e6, 0)
self.uhd_usrp_sink_0.set_gain(1.5, 0)
self.uhd_usrp_sink_0.set_center_freq(915e6, 1)
self.uhd_usrp_sink_0.set_gain(1.5, 1)
self.uhd_usrp_sink_0.clear_command_time()
However, it still does not work when I have the phase viewer running and stop and restart the for_pavan.py flowgraph. I had a run of three straight where the phase offset was around 11 degrees, but then afterward it started fluctuating again (-140, 45, 81 degrees, etc.).