FM - is an analog signal from transmitter to receiver AND analog representation of positions of the control sticks.
PPM (and PCM) is an analog signal from transmitter to receiver AND digital representation of positions of the control sticks.
Other things being equal PPM and PCM will allow more precise control of the model (and PCM is more precise of these two).
Hope this helps.
It doesn't help at all, because it is utterly and fundamentally wrong in every respect.
The radio modulation we use is FSK, a subset of FM. It is a binary, not an analogue signal and in that respect it behaves as if it is digital. It does nothing to represent the stick positions, the data it contains does that. The data can be analogue binary PPM, or digital binary PCM.
PCM is not an analogue signal. PPM is analogue, PCM is digital i.e the data has been quantized to base 2. PPM and PCM are data signals, not radio signals and must not be confused with FM though PPM often is.
"PPM and PCM will allow more precise control" More precise than what?
"PCM is more precise of these two". Wrong, PPM has greater precision. PCM systems have either 512 or 1024 psoitions that they can operate to. In theory analogue PPM has an infinite number, in practice it is limited by the sensitivity of the pots and the operation of the encoders. In a previous thread some months ago I quoted the numbers being generated by my analogue Tx through the Rx to a signal counter and showed that in PPM I was generating a precision of greater than 1200 steps, in other words around 20% better precision than PCM.
Harry