Looking into the radio spectrum
Gqrx is a GNU Radio application that allows you to have a nice GUI to set the frequency of your hardware and have a visual representation of the radio spectrum around the set frequency. It also allows you to hear some common modulations, such as narrow- or wide-band FM (WFM), lower and upper side band (LSB and USB), and others.
Let's fire up Gqrx and set up the source (hackrf for hackrf, RTLSDR for RTLSDR, and so on):
Figure 9.3 – Selecting the source: a HackRF example
The following screenshot shows the Gqrx main window:
Figure 9.4 – Gqrx main window
The frequency you are listening to is as follows:
- A: The frequency you are listening to
- B: The frequency delta between the hardware-centering frequency and the part of the captured data the software processing is focusing on
- C: The frequency the hardware is centered on (that is, the frequency it will be capturing...
