Audacity is a convenient tool to have a first look at a recording from a software defined radio. It can import raw data files with various data types and has a user interface to zoom and scroll signals in both waveform and spectrogram views. It can also do some basic filtering and resampling.

Audacity, however, does not really understand complex (IQ) signals. It can treat them as stereo audio signals but shows the positive and negative halves of their spectrum on top of each other because it sees the real and imaginary parts as two separate signals. It also doesn't easily do common SDR tasks like AM or FM demodulation. The Nyquist prompt allows doing some special things though, such as rectifying a digital baseband signal to get a spectral line at the symbol rate.

A typical workflow seems to be to make small GNURadio Companion scripts to perform filtering and demodulation and then switching back and forth between Audacity and GRC.

By making some Audacity plugins to do downconversion, filtering and demodulation of IQ recordings, it should be possible to do more of these common tasks using one tool that already has a convenient user interface for things like zooming the signals. This is my attempt at doing that. I'm not sure if it's a good idea at all yet but let's see if it turns out to be useful.

To use the plugins, copy or symlink them to the plugin directory. For example, on Linux: mkdir -p ~/.audacity-files/plug-ins; cd ~/.audacity-files/plug-ins && ln -s ../../path/to/repository/*.ny . If they don't appear in your plug-ins menu yet, go to Effect -> Add/Remove Plug-ins -> New -> select the plugins -> Enable