Hey Tom, I guess "scrambled" wasn't really the best word to describe the problem. :) What I basically meant was that there was a lot of static, and I couldn't really differentiate the radio signal from the noise when I played it back. Apparently, I hadn't set up the script to the correct sampling rate, but once I got that fixed, the script worked like a charm.
Thank you! On Fri, Jun 12, 2015 at 8:38 AM, Tom Rondeau <t...@trondeau.com> wrote: > On Thu, Jun 11, 2015 at 7:17 PM, Nick Harrison <hnick...@gmail.com> wrote: > >> Hi everyone, >> >> I recently started playing around with gnuradio, and being the beginner >> that I am, wanted to begin by listening to a close by radio station. I >> basically followed the instructions on >> http://www.trondeau.com/gr-tutorial/ and used the uhd_rx_cfile with the >> following command: >> >> >> *uhd_rx_cfile -a "addr=192.168.10.2" -g 0 -f 97.1M --samp-rate=500k -N >> 5000000 radio_sample_97.1Mhz.32fc* >> Below you can find the image of the IQ data and the PSD that I got when I >> used *gr_plot_psd_c * >> http://imgur.com/kFpqK25 >> >> But when I used the fm_demod.py to playback the captured data, it comes >> out completely scrambled. Am I missing something here? >> > > > What do you mean by "scrambled"? That can mean a handful of different > things in this domain. > > Also, you set the gain to 0; you might want to increase that, though it > looks like the PSD is showing a decent amount of signal. > > When plotting the image the way you did, skip into the file a few thousand > samples (pass -s 4000 to the gr_plot_psd_c script) to skip the start-up > transients, which are obscuring the signal. > > You also are bringing the signal in at 500 ksps. Make sure that the script > to play back the FM signal is set up for that (it should be based on that > tutorial page, but you'll want to verify). > > Tom > >
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