If you don’t care about shortwave frequencies, the PlutoSDR is a great deal. The device is supposed to be an evaluation board for Analog Device’s radio chips, but it does great as a software-defined radio that can receive and transmit and it even runs Linux internally. [SignalsEverywhere] shows how to use it as a spectrum analyzer that works from the command line in the video you can see below.
The software used is Retrogram. Despite the ASCII graphics, the program has many features. You can use simple keystrokes to change the center frequency, the sampling rate, the bandwidth, and more. You can run the software on a Linux host or compile a binary on the box or cross-compile using tools on the Raspberry Pi.
The Pluto connects via USB but looks like a network adapter. That means you can talk to it like a remote computer and software can run on the host computer or directly on the hardware which has an ARM processor (or two, if you hack it).
We noticed on the GitHub site that plans are in the works for generic device support like the ubiquitous RTLSDR dongles. We’d love to see someone pick up that work. There are also plans for mouse tuning, waterfall displays, and HTML output.
We’ve talked about the Pluto before. We’ve also seen [SignalsEverywhere] cover how to connect the Pluto Ethernet.