Agowre

The 433Mhz RF module uses a technique called Amplitude Shift Keying or ASK thereby the amplitude or the level of the carrier wave is changed in response to the incoming data signal. ASK uses a finite number of amplitudes, in a way that each of them is assigned to a unique pattern of binary digits. Each pattern of bits forms the symbol that is represented by the particular amplitude, and the demodulator determines the amplitude of the received signal and maps it back to the symbol it represents.
As far as I am concerned, it is the root cause of the variation in the duty cycles given by a specific pulse train in the 433Mhz RF receiver module. In fact, the receiver represents each pattern of bits with a pulse wave comprising more than one fixed duty cycle to do with the pulse duration and the period. For me, it was really awkward to deal with sampling over the duty cycles in order to recognize symbols. It is now done!