>>How about using count... or an internal timer?
I am not sure how to do that with the signal im getting.
forget the frequency, from your picture, it's only the dutycycle that change.

>>what's the most important? the frequency or the duty cycle?
In this case I think its the frequency that matters. But I don't know how to get the freq from picbasic.
to get frequency, you could use COUNT, but in your case it should always be the same.