There are three ways of sending a signal from your transmitter to the receiver.

1) AM, or Amplitude Modulation, is the old way. It is very susceptible to interference, just like your old AM music radio is. Do not fly an expensive aircraft with an AM radio. Sooner or later you WILL get shot down by interference.

2) FM, or Frequency Modulation, is better. FM is much less susceptible to interference than the old AM radios, but it still has limitations. The FM signal is open to interpretation, so to speak, when its analog signal is reconverted back to a motion by the receiver. This results in a little bit of “drift” in the servo position. In other words, the servo may not center in exactly the same position every time you let go of the stick. The drift can be as much as several degrees at the servo. In sport planes this is not noticeable. In your well set-up pattern plane, it is very noticeable and intolerable. Leave FM to the sport flyers, where it belongs.

3) PCM, or Pulse Code Modulation, is the best we currently have. It uses the same old Frequency Modulation, but instead of sending an analog signal open to interpretation, it sends a precise digital code, with zero error. Center is always center, period.

PCM is the radio system you want for competition.