[cyanoacry]

Neat, it's always really cool to see folks get their feet wet in the DSP field! (Props to the author for trying to get through the dense Wikipedia pages.)

Minor correction for the author: this isn't amplitude-shift keying, and the way to tell is to look at how demodulation works. The detection code asks if a sample is negative or positive, but "how large is this sample?" is never asked. An ASK demodulator effectively thresholds the signal on amplitude and in the simplest case this boils down to "is there a signal or not?"

The implemented code has some flavor of phase-shift keying (the inversion of a sine wave flips the phase 180 degrees), but since there isn't guaranteed to be a steady carrier, it seems like it'd be hard to decode as a pure PSK. The all-sample offset (constant above or below zero) can also be treated in a way as a PSK process, with the carrier being DC (0Hz).