Thread: FM or PCM??
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Old 02-11-2004, 04:25 PM
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JohnW
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Default RE: FM or PCM??

Highflight: Dude, you need to reeamine you facts, your point are totally off base and in some cases totally wrong. IPD is a slick system and I have nothing against Multiplex, but you obviously don't understand how IPD works becasue every argument you gave against PCM would apply to IPD too!

"The ONLY advantage to PCM is failsafe"
Not true, PCM offers error checking on every frame. This means that minor glitches are smoothed out. IPD does somehing very similar but in a slighty different way. PCM also has better range than PPM systems and yes I have personally checked it and it is a lot more than 10%. Range equates to noise rejection. It is not the fact that I can now fly 2 miles away as opposed to one, but that my RX is better able to reject interference. This means PCM is less likely to have problems in the first place.

"The disadvantage of PCM is that the RX can kick into failsafe repeatedly and mask a frequency glitch problem." Dude, what do you think IPD does during a "glitch problem" as you put it. Same thing as PCM. IPD first masks the problem and then goes into failsafe.

"If you see that you get hit a couple of times witn PPM, you land and figure things out. With PCM, you don't know what's going on until it's too late." What happens is BOTH PCM and IPD get mushy, and eventually you have no active control as failsafes are engaged... this applies to BOTH systems. If you pay attention, it is very easy to detect PCM and IPD glitches. But I suppose you are right that it is very easy to see PPM glitches... I typically watch for a sudden snap that rips the wings off, or a full throttle spin into the ground, or an out of control full throttle taxing plane eating planes and people as it races thru the pits.

IPD has NOT made PCM obsolete... that is why JR and Futaba still use PCM. Why? Becasue IPD offers no functional gain over PCM becasue they are basically identical. The diff is IPD works with a standard PPM signal, which means you can use any PPM TX with them. This is IPDs strong suit. It also means Multiplex opened thier RX up to a larger market... hum, looks to me like it was a marketing decision, not a superior tech decision.

" I can fly ANY manufacturer's receivers with my EVO as opposed to HAVING to match brands with PCM. " What? You know IPD is in the RX, not the TX. I can fly any RX (assuming futaba shift) with my PCM radio too...I just reset the TX for PPM by pushing a button.
If you don't use the Multiplex IPD RX, you don't have IPD so why would you want to use another brand of RX anyway with your Evo?