Just to persue discussion on this, and to clarify something, my method of reading the dsp will not work very well. It actually outputs the Amplitude of the wave tone at any moment. This WILL NOT give a clean "on-off" pattern when fed morse code.

The more I think about it, you probably need to use something like Fourier Analysis on the signal, to map out the on-off tone pattern. A nice article on this is at Analyzing wave files with Perl which uses PDL and PDL::FFT to do it.