Hi Marcus, > You'll need to look at the API here: > > https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a191b78b00d051d3d51c2f719361c1fb5 > > and here: > > https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a607aee766d21228a7aaabde2771eb46f > > Basically, GRC will generate python code where it calls the > set_rx_freq() method (or set_tx_freq() method), and you need to modify this > code to have set_command_time() and clear_command_time() wrapped > around those operations.
Thank you. As I understand you referenced the USRP driver whereas GRC creates gnuradio objects (e.g.: usrp_source https://www.gnuradio.org/doc/doxygen-3.7.2/classgr_1_1uhd_1_1usrp__source.html ) My dilemma is that I need to set the center frequency of the TX to "fc" and the center frequency of the RX to "2*fc" and its phase relationship should be identical for each "fc" (at least as long the USRP does not power cycle). The gnuradio API als exposes the USRP API you mentioned so I tried: now = self.uhd_usrp_sink_0.get_time_now() self.uhd_usrp_sink_0.set_command_time(now + uhd.time_spec(1)) self.uhd_usrp_source_0.set_command_time(now + uhd.time_spec(1)) self.uhd_usrp_source_0.set_center_freq(2*self.fcenter, 0) self.uhd_usrp_source_0.set_center_freq(2*self.fcenter, 1) self.uhd_usrp_sink_0.set_center_freq(self.fcenter, 0) self.uhd_usrp_source_0.clear_command_time() self.uhd_usrp_sink_0.clear_command_time() But this this the phase still jumps after a frequency change. I also tried this (in order to perform the commands on a single USRP multi object): dev = self.usrp_source_0.get_device() # dev = self.uhd_usrp_sink_0.get_device() should be identical now = dev.get_time_now() dev.set_command_time(now + uhd.time_spec(1)) dev.set_rx_freq(2*self.fcenter) dev.set_tx_freq(self.fcenter) dev.clear_command_time() but it has no effect (it does not even change the center frequencies). And I have also tried to modify Nate's suggestion to different RX/TX frequencies: http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2019-December/061114.html And interestingly the received signal has a frequency shift (approximately 5kHz which is very weird). Any further advice is highly appreciated. Thanks, Luke _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
