Fletch124

My Feedback: (7)

Hey guys well i'm really thinking that i will be getting a JR 6102 but i don't what the difference is between the FM and PCM versions. What exactly does FM and PCM mean? thanks everyone

Fletch124

My Feedback: (7)

anyone?

khodges

My Feedback: (1)

PCM is a digitized FM transmission (Pulse Code Modulation). Lessens the chance for interference, also most (if not all) PCM radios have failsafe capability built in as programmable feature, can set parameters for each flight control individually.

Fletch124

My Feedback: (7)

So do you think thats it worth the extra $20-30? Do you think it will save me money down the road. Plus theres alot of people at my club and well i'm the only one of Ch.45 i think so again do you think its worth the extra $$$?

BillS

Failsafe when set on throttle will at least let you know when interference occurs. It has saved three airframes for me over the years. I don’t fly well enough to know the difference between a wind gust and interference.

It appears that many FM (PPM) systems will hard over servos on interference and PCM will simply leave servos at last known position, which seems safer.

Experience has shown that soon someone will show up on your frequency. He will probably be a beginner without a full understanding of the antiquated pin control system.

JohnVH

My Feedback: (38)

Id say for that small amount, go PCM, its main advantage is setting up the failsafe, PCM still gets inteference, you just cant see it as easily as FM

mglavin

My Feedback: (31)

PCM is of FM... Both PCM and PPM use FM (frequency modulation) as the medium to transmit a signal or carrier wave. The difference is the codes schemes employed PCM (Pulse Code Modulation) or PPM (Pulse Position Modulation).

For the few bucks difference the PCM RX is worth owning IMO. If you need a PPM RX they are reasonably priced and there is always the new IPD stuff on the market, which is very cost effective.

PCM is able to work through more noise than PPM and when PCM is hit KNOWN parameters or results occur in the event of interference. With PPM anything can and will happen with no absolutes. Each has its merit IMO.

Obviously there is a lot more to all this than I describe, PCM uses a micro-processor in the RX to determine if the signal received is valid and acts pro-actively to ignore bad frames or engages failsafe or hold modes. PCM RX's must be used exclusively with the OEM TX, or is brand specific. Most modern TX's have the ability to transmit PPM and or PCM. The only difference is weather or not a PCM or PPM RX is utilized.

There is also the new intelligent pulse decoding RX's on the market known as IPD or DSR and others. This code scheme works with all PPM TX's and offers similar functionality to PCM, this maybe the wave of the future.

Do a search here on RCU, you'll find this topic comes up regularly.

khodges

My Feedback: (1)

How much is your plane worth? Also, AMA is considering requiring failsafes for any planes flying at sanctioned events. You can add them as aftermarket, but if your radio is already equipped, it will save $$ then.