Sorta working! (was Re: RTL2832 questions)

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Jeff Gustafson ncjeffgus at
Tue May 8 19:52:23 UTC 2012

	I git pull'd the newest code today and the NFM seems to do something
now. I suspect something is wrong with the sampling rate somewhere. The
voices are like recordings played too fast and the audio is jumpy.
	I'm using the file called fm_rx.grc. It has widgets for changing the
max deviation, etc. I replaced the default usrp source with the rtl
	The default sampling rate in the grc file is 250k.
	Also, has anyone else had issues with the system halting when running
gnuradio with a rtl dongle? I've had it happen on two different systems
so far. 

On Mon, 2012-05-07 at 11:10 -0700, Jeff Gustafson wrote:
> Hi all,
> 	First of all, props to the person that found out how to put the RTL
> chip into a SDR compatible mode! I've been wanting to play around with
> SDR and, specifically, P25 for a while now. Finally an inexpensive way
> to get my feet wet.
> 	My question is probably a bit of a noob question. I have successfully
> received a broadcast FM radio station with the RTL dongle. The problem
> is that I can't seem to decode anything else. I tried to receive some
> ham radio (NFM) transmissions from my radio and I didn't get any sound.
> The white noise blanked out, the scope in gnuradio spiked up, but no
> real demodulation. Would someone be willing to share a .grc file they
> know will decode NFM with the gr-osmosdr/rtl-sdr driver?
> 	I tried taking some files that used the USRP driver and swapping out
> the USRP driver with the osmosdr/rtl driver, but no go. Could it be that
> I don't have all the sampling rates and decimation rates set correctly?
> ...Jeff

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