ORIGINAL: evan-RCU
That's not really true both pulse code modulation and frequencey code modulation are susectible to the same interference, with fail safe off you'll have basically the same amount of interference either way. Then the only difference is that a PCM reciever can cost three times the amount as a normal FM. Not a big deal if you have one helo but if you have multiple recievers the cost adds up.
Well all I know is when I tried connecting my RadioSouth glow starter to the remote, all the servos would jitter (including throttle). With that, I didn't dare start the engine. After emailing RadioSouth a few times, they suggested a PCM receiver. After the switch, the problem went away.
So, I have no idea the difference in PPM and PCM (other than the basics of signal format) but I can say for sure, there was a big difference for me. As far as I'm concerned, there IS a difference between the two and it WAS worth it to change. I do not fly with FailSafe enabled.
Good Luck,
d.tipton