RCU Forums - Quick Q

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Whats the differance between AM and FM and what is PCM?

Tony,
AM is amplitude modulation
FM is frequency modulation
PCM is pulse coded modulation over FM signal.

Modulation how you vary the signal to communicate with the receiver
With PCM a code is transmitted to the receiver. The special code is what the receiver acts on. If the signal is lost long enough, the receiver goes into failsafe mode. Thats basicly it. PCM receivers can only be used with a matching brand radio with the same version of PCM.

Dave

So pcm is better than am or fm?

Tony,
PCM is coded FM and is safer then plain FM or AM. If it wasn't better,would the $2,500 radios be using it? I use PCM for the more expensive planes.

Dave

Quote:

ORIGINAL: davewallace
PCM is coded FM and is safer then plain FM or AM. If it wasn't better,would the $2,500 radios be using it?

PCM is an option on the expensive radios, just as it is on many less expensive radios. That doesn't mean it's better, however. Failsafe and the rejection of improper bits of data are the main selling points for PCM. Want to take bets on the percentage of PCM setups out there with an improper/unsafe failsafe setting? Using the wrong failsafe configuration or no configuration can certainly make a model more dangerous than PPM interference.

It's really a personal preference question. Each technology has it's plusses and minuses, and most people just think "costs more, must be better." You'll have to make up your own mind, Tony, based on how much you want to spend and what the RF conditions where you fly are like.