Get a modular system for passive sonar signal analysis.
HASAS for Linux (HydroAcoustic Signal Analysis System) is a modular system for passive sonar signal analysis. It can be used for biological research or surveillance, for example. The soundcard is used as input device, and it currently includes all the very basic functionality; beamforming, direction finding, level histogram, LOFAR/DEMON (narrowband spectrogram), wideband spectrogram, and raw audio.