Hi there,
I just started using UHD Python API to implement a simple
transmission-reception experiment on an Ettus X310. I have a UBX 160
daughterboard installed on slot B, with its TX (TX/RX port) connected to RX
(RX2 port) directly using a SMA cable and a 30dB attenuator. I plan to transmit
a sequence of waveforms from TX/RX port and to see the waveforms received at
the RX2 port. Ideally the two waveforms should be highly similar with some time
shift in between, but the received waveforms turned out to be not quite right
(see the diagram below, the upper diagram shows the real part of the
transmitted waveform and the lower, the real part of the received.).
Some of the parameters are defined as following:duration = 10 # second, the
time length of the transmitter sending the
waveformscentre_freq=1e8sample_rate=200000num_samples=200000 # number of
samples to be collected by the receiving side.gain_tx=0 #dBgain_rx=20
USRP is defined as:usrp =
uhd.usrp.MultiUSRP()usrp.set_tx_subdev_spec(uhd.usrp.SubdevSpec("B:0"))usrp.set_tx_antenna("TX/RX")
usrp.set_rx_subdev_spec(uhd.usrp.SubdevSpec("B:0"))usrp.set_rx_antenna("RX2")usrp.set_rx_bandwidth(sample_rate,
0)
As the transmission and the reception happen at the same time, they are put in
two separate threads, as below:threads = []rx_thread =
threading.Thread(target=receive_data, args=(usrp, num_samples, centre_freq_rx,
sample_rate, gain_rx))threads.append(rx_thread)rx_thread.start()tx_thread =
threading.Thread(target=usrp.send_waveform, args=(tx_signal, duration,
centre_freq_tx, sample_rate, [0],
gain_tx))threads.append(tx_thread)tx_thread.start()
Here the function, receive_data() in the first thread, is a user-defined (by
me) function, receiving samples using the uhd provided method,
usrp.recv_num_samps() and saving the samples to a .txt file. A little more on
the data format saved in the file, I used np.savetxt() function to save the
samples (a numpy array) to a text file. As the numpy array has a data type of
np.complex64, the real and imaginary of the samples are saved in the same file
in the format of np.float32. I can confirm that 200000 complex samples were
collected in the file saved, which verifies (partially at least) that data
format didn't go wrong.
I have been working on this script for a whole day, but couldn't fix it. I
suspect I didn't configure the usrp variable correctly. Any suggestions would
be appreciated.
Kind regards,Tom
As the transmission and reception happen simultaneously, the Python scritp _______________________________________________
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