Thread: FM or PCM??
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Old 02-12-2004, 01:43 PM
  #22  
AirBearMA
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Default RE: FM or PCM??

There are pros and cons of PCM.

PRO
PCM will reject data frames that aren't received with valid checksums. If you are just getting a bad frame once in a while, only the bad frame is rejected and the last known good frame data is applied to the servos. If you get a number of bad consecutive data frames in a row, the PCM receiver will drive the servos to failsafe position (ASSUMING FAILSAFE POSITIONS ARE PROGRAMMED BEFOREHAND).

CON
Because PCM will reject sporadic bad frames without giving any indication to the user (servo jitter) when you range check a model that has a marginal interference problem (RFI from a Gas Ignition System or some Glow Drivers), you would never know you had a problem.

I fly primarily with PCM receivers BUT when I've done major work on a plane or am setting up a new plane (especially Gas),
I do my initial range checks (with and without the engine running) with a FM (PPM) receiver. If everything checks out good, I then install my PCM receiver.