Small program that computes and plots spectrograms, either in a live window or to disk, with support for stdin input. In theory, you can run any data through it and generate a spectrogram. Read the manpage.
In the AUR (but you want specgram-git because specgram has a bug and won't compile!)
RTL-SDR based spectrum analyzer.
CygnusRFI is an easy-to-use open-source Radio Frequency Interference (RFI) analysis tool, based on Python and GNU Radio Companion (GRC) that is conveniently applicable to any ground station/radio telescope working with a GRC-supported software-defined radio (SDR). In addition to data acquisition, CygnusRFI also carries out automated analysis of the recorded data, producing a series of averaged spectra covering a wide range of frequencies of interest. CygnusRFI is built for ground station operators, radio astronomers, amateur radio operators and anyone who wishes to get an idea of how "radio-quiet" their environment is, using inexpensive instruments like SDRs.
The CLI tool is used to set up scanning runs. Data is graphed as output.