Inspectrum: A tool to inspect signals from SDR

If we are using a software defined radio (SDR) device to capture some signals and planning to analyze it later, we might need a good software to visualize the data. The most obvious solution is to use GNURadio Companion itself as it has the required modules to plot waveform, FFT and waterfall graphs. However, today I found another useful tool which we can use to visualize and inspect recorded signals. It is called Inspectrum. Following are the steps to easily install it and try using a dummy data file generated using GnuRadio Companion.

sudo apt-get update
sudo apt-get install inspectrum
sudo apt-get install gnuradio

Now, let's start GnuRadio Companion by using the following command on the terminal.

gnuradio-companion

Create the flow graph shown in the following figure. It reads from a sample Wav file we have stored in our computer and writes it to a new file in the correct format which we need. The file extension of the file we write to should be .cfile in order for the Inspectrum tool to recognize it properly. Let's say our output file name is mydata.cfile.

Flow graph to generate sample data

It's time to try the new tool we wanted to see. Run the following command in the terminal to start Inspectrum with the data file we created.

inspectrum mydata.cfile

Inspectrum window with sample data file