On 12/08/2019 05:19 PM, Lukas Haase wrote:
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.
So, you're trying to measure the 2nd-harmonic energy of the TX signal?
What frequencies are involved here?
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