I am using a FP-R127DF Futaba dual conversion FM 7 channel receiver. With 4 s3151 servos, and a Futaba 401 gyro with one s9254 servo.
What is the diffrence between ppm and pcm, I think i know the diffrence between these and pccm. these do not use the electronic mixing functions on the head. correct.
Please help to explain which is which and why.
Along with what the Shuttle plus is.

Christian,

I think you are getting a couple different subjects confused. I believe what you are referring to as "PCCM" is the CCPM (cyclic/collective pitch mixing) used on helicopters. The electronic type of CCPM uses 3 (or 4) servos to control the swashplate movement by the way of mixing functions within the transmitter. Your Shuttle Plus does not use the electronic CCPM mix.

PPM (Pulse Position Modulation) and PCM (Pulse Code Modulation) are a totally different subject referring to the type of modulation used to transmit the signal from transmitter to receiver and is not specific to a type of plane or heli. [link=http://www.dubai*********.org/ppm_or_pcm_or_ipd.htm]PPM or PCM or IPD(New)[/link] is a good description of the differences between these 2 systems. Your Futaba 7C transmitter can be switched to transmit using either PPM or PCM. This is saved in each different model memory, so you can have different types of receivers in each model. The receivers only operate on one type of modulation or the other.

Hope this helped.
Keith

long story short, PCM is more reliable.

ppm is basically fm

3d type,

Both PPM and PCM operate on the FM band. The difference is in the type of modulation.

Keith

Um, FM is NOT a band! 72MHz is the band! FM is a MODULATION type, and both PCM and PPM use FM modulation. Within that MODULATION, the digital signal must be ENCODED. There are two ways - PPM and PCM. PPM works by varying a pulse in time to equate to a value - IE, the time from one pulse to the next defines the servo position setting. In PCM, a digital value is sent over a series of pulses. Since this is a true digital signal, error checking also takes place in that if the signal is mangled by a stray pulse (interference) the RX will know and can throw out that frame. In PPM, no error checking can occur, and the errant (noise) pulse results in a glitch in your output. As such, when PPM gets close to maximum range, it will glitch like a bugger. On a PCM system, it will just feel sluggish to repond until it quits altogether (PCM lockout). The sluggishness is harder to notice than the glitches (but unlike glitching, it can't crash you) so if you are not closely in tune to your model, you MAY get in trouble with lockout in PCM, but in reality, this is rare - normally, you will lose sight of it before it would lock out.

- Tim

good explanation, tim. thx.

You are absolutely correct, Tim. I guess I shouldn't have been trying to reply after 4 hours sleep in the last 3 days.[]

Thanks for the correction.
Keith

Tim must have had more than 4 hours sleep!!!hehe

Great reply thanks for sharing