A freeware Macintosh program for post-run digital signal processing.
http://www.wam.umd.edu/~toh/spectrum/
AutoSignal - Spectral and time domain signal analysis and processing software.
http://www.systat.com/products/AutoSignal/
Some tutorials, references and research on the Kalman filter.
http://www.cs.unc.edu/~welch/kalman/index.html
Information on the use of DSP to track satellites and search for small intensity radio signals, including possible signals from outer space.
http://www.nitehawk.com/rasmit/dsp50.html
for radio communications
http://www.w9gr.com/dsp3.pdf