A real-time signal analysis tool and an offline time-frequency
browser.  It has a built in tone generation capability and it can
play back audio files with a multitude of effects and filters.
Designed for environmental analysis missions that range from
modulation parameter measurements to searching for transient signals
that go bump in the night, baudline combines fast digital signal
processing, versatile high-speed displays, and continuous capture
tools for hunting down and studying elusive signal characteristics.

WWW: http://www.baudline.com/