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 UHD.

Implemented functions:
- Set USRP frequency, RF gain and bandwidth (250k, 500k, 1M, 2m or 4M)
- 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

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

I have also made some modifications to the gr-qtgui code (enable grid, nicer colors and less vertical space) which are avaialble 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