Hello,
I’m a student trying to use the USRP with the TVRX board to do a simple
FM
stereo receiver. I previously wrote a MATLAB model of a FM transmitter
and
receiver, and I wanted to use real data in my model. I’ve been modifying
the
wideband fm example to record data from the TVRX board by basically
inserting some of the l1_record.py code like this:
self.dst = gr.file_sink(gr.sizeof_gr_complex, ‘data.txt’)
self.head = gr.head(gr.sizeof_gr_complex, 800000)
self.connect(self.u, self.head, self.dst)
Then, I use a script written to convert the binary data file into a
MATLAB
vector. However, the recorded data is not meaningful to me. When
plotting
the data, instead of seeing some kind of waveform, I see what looks
similar
to a NRZI waveform. If you wish to see what I am seeing, here is a
screenshot of the data: http://web.ics.purdue.edu/~jpendlum/usrpdata.bmp
It is also important to note that the example wideband FM code runs
flawlessly. I can tune to local radio stations and listen to them.
These are the questions that I’ve tried very hard to answer, but I can’t
seem to figure out:
2. Is the recorded data in some kind of encoded format, and if so, what
is
this format?
3. If not, then what am I doing incorrectly in my record script?
If anyone could help, I would greatly appreciate it. Thanks.
Jon Pendlum