Experimental AM, FM and SSB software receiver implemented using GNU Radio and Qt GUI toolkit.

To run this application you need to have GNU Radio 3.3 with gr-qtgui component installed, as well as a USRP1. Of course, it can be modified to use USRP2 or you can try the UHD branch. I do recommend using the UHD branch because that is where I do most of the development and it has features that are not available in the 'master'.

Implemented functions:
 * Set USRP frequency, RF gain and bandwidth (250k, 500k, 1M, 2M or 4M)
 * Select USRP subdevice and antenna on the command line
 * Show USRP spectrum
 * Variable bandpass filter
 * AM, SSB, FNN and FMW demodulators
 * AGC in AM and SSB modes
 * One click recording of audio into .wav file and playback of last recorded audio file

To start the receiver execute the gqrx.py Python script. Use -h to see a list of command line options.

If you have problems with audio while changing receiver settings at runtime you can try to apply this patch: https://gist.github.com/664132 (note that this fix has been applied to GNU Radio since December 2010).

I have also made some modifications to the gr-qtgui code in order to enable grid, have nicer colors and take up less vertical space to better fit on laptop screens. These changes are available in this patch: https://gist.github.com/668462. This is not mandatory though, just part of the experiment.

You can modify the GUI by opening the gqrx_qtgui.ui file in Qt Designer. If you make changes you have to recompile the UI code using:

pyuic4 gqrx_qtgui.ui -o gqrx_qtgui.py