I have been testing USRP and Gnu Radio for a while and it’s been a very
interesting, educational experience.
One of the important things for me is to get capture to / playback from
file capability to work.
I simplified usrp_rx_cfile.py a bit and essentially what my script does
usrp.source_c --> gr.head --> gr.file_sink
It produces huge files (with complex samples, I understand) which I
intend to “play” back through LFTX
daughterboard. So, another script does something like:
gr.file_source (gr.sizeof_complex, fname,true)
-----> usrp.sink_c (0, interp)
Gain on the LFTX is set to -1.02 dB - as read by self.u.pga(0). The
problem is that I donâ€™t get any signal
from LFTX although I can see the expected spectrum in the FFT window
(which is connected in parallel
to the same stream). The signal is digital radio transmission with
estimated S/N around 40 dB.
Since the spectrum matches what I had seen when tuning the radio with
some receiver script which also
provided FFT window, I assume data stream is OK. Just to check my
hardware I tried usrp_siggen.py
and checked the outputs of LFTX with an oscilloscope. I could see the
expected sine wave nicely
phase shifted by pi/2. Hardware is OK, but somehow my â€œplaybackâ€ script
doesnâ€™t want to push data out.
Do you have any suggestions?