D'oh! Took me long enough to notice that the optfir block generates coefficients, but isn't the filter itself. Putting it into the pipeline directly was a bad idea.
So I have transmitter and receiver, and they run without errors... they just aren't giving me what I expect. The filtered sum of sine waves at 320 Hz, 440 Hz, and 650 Hz, when given a passband of 340 Hz and stopband of 800 Hz should produce roughly the 320 Hz sine wave (perhaps with some attenuated elements of the other signals). However, it doesn't appear to be doing so. When played at a sampling rate of 32000, the speakers produce more of a popping sound. Which is still periodic, but isn't a sine wave. The output file is stored as an attachement (which can be viewed in a hex editor or played with audio_play.py), as is the latest revision of the code. Any thoughts? ~ Francesco http://www.nabble.com/file/p22174207/filtered_reception.dat filtered_reception.dat http://www.nabble.com/file/p22174207/usrp_wfm_rcv_filt_nogui.py usrp_wfm_rcv_filt_nogui.py http://www.nabble.com/file/p22174207/wfm_tx_multisignal.py wfm_tx_multisignal.py Francesco B. wrote: > > Hey all, > > I was wondering, is there anything in particular that's peculiar about > using a filter to isolate one sine wave out of three that are being > transmitted over FM? I've attempted adding another FIR (optfir) filter > post-demod, but connecting it to the pipeline produces a long list of > small floats in the terminal (filter coefficients, perhaps?), and then the > program terminates. Otherwise, the program is identical to > usrp_wfm_rcv_nogui.py. It runs as normal when the filter is commented out, > outputting all signals at a specific FM frequency to the sound card. > However, I don't accomplish my task with that. > > What's the proper method for filtering signals, then? It looked fairly > straightforward, but perhaps optfir doesn't function as I was expecting it > to. My code is attached. > > http://www.nabble.com/file/p22029608/usrp_wfm_rcv_filt_nogui.py > usrp_wfm_rcv_filt_nogui.py > -- View this message in context: http://www.nabble.com/Filtering-USRP-FM-Reception-tp22029608p22174207.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
