I liked the code because it's using clear comments and simplifying FHSS for beginners.
It'd be great if you can help us to implement the receiver for this modulator. (either in code or in more explanation).
Appreciate your help..
I think your program is not correct because in output amplitude of frequency hopped signal is varrying which should be constant because it is fsk techniques . So amplitude will be constant. Plzz check it once again....