Simple FM Demod
This demo project demodulates a live WBFM audio signal from an SDR source. The audio is streamed to the audio sink block so the user can listen to live FM radio.
Find the resource files for this Simple FM Demod project here. The directory contains a saved Pothos GUI topology design:
This panel displays a live plot of the receive spectrum and audio waveform. It has controls for tuning the radio, setting the frontend gain, and audio volume.
This panel contains the demodulation chain which transforms raw IQ samples from the RF spectrum into a single audio channel. This is a very simple FM demod chain with a quadrature demod block and decimating low pass filter. It only supports a single mono audio channel.
The RF frontend is simply a SDR source block with various control blocks for tuning and setting the frontend gain. We tested this project with an RTL SDR dongle. Other hardware should work, however, sample rates and frontend gain may need to be fiddled with.
