In these articles I have tried to de-mystify some of the theory behind model

electrics. Some of this is extremely complex I have tried to give you a feel

of what goes on and hopefully answer some of the questions I have been asked

in the club house.

I will start with the older systems.


FM/AM radio control systems operate on a small bandwidth

on relatively low frequencies (27, 35, 36, 40, 41 or 72Mhz).

They work just like a regular AM or FM radio - sending out a signal

that is picked up by the receiver and then sent to the servos.

This tiny allocation of bandwidth for each RC channel  is like walking

down a narrow path. You can't walk very quickly because it's such

a squeeze to get past the bushes either side of your path.

Also if you run into another person  on that narrow path you won’t be

able to get past.


In transmitter terms this means you can't send the

control information between transmitter and receiver very quickly.

and any other signal on the  frequency you're using will result in

interference (glitches or lock-out).

With careful channel management this system has served us well for decades, until the arrival of the 2ghz band with FASST  and DSM.

The theory behind these system is beyond the scope of this article but I

have given a much simplified explanation in 2Ghz DSM FHSS.