Here is a really great toy. With a little bit of software, you can make this simple starter kit do about anything. I started with a RTTY modem, which evolved into a BAYCOM type packet modem, and that evolved into a KISS packet modem, and I finally wrote a complete TNC program( with plain Kermit for a terminal program). To give anybody( even those without a DSK ) an idea of what can be done, download this CW demo program. It uses a data file to supply the data that the DSK normally would supply via the serial port. Be sure to start it with the .BAT file.
Digital filters are a basic building block for DSP systems, yet it is not
intuitive how they work. Everyone needs a
program that designs filters. These programs design and simulate digital
filters. The design code is from public domain Fortran code that I converted
to C, and I confess I don't understand the algorithms, the simulation code
is all my fault. ( Source code included ).