XJet

This is understandable because for a long time all RC gear was AM.

Then, as the necessary components became readily available and cheap, some manufacturers switched to FM, which offered superior performance.

For a long time RC users had the choice of AM or FM.

Then one smart manufacturer decided to use the power of microprocessors to convert the transmitter stick positions into binary numbers and transmit those numbers instead of a set of simple pulses. This was PCM.

So, the common conception was that really old gear was AM, contemporary gear was FM, and the really new "state of the art" stuff was PCM.

Now that AM has largely disappeared, people still describe the remaining two systems as FM and PCM -- even though both actually use frequency modulation.

I realise that most of us oldies know this already -- but that was for the benefit of newbies who might still be a little confused.