ORIGINAL: BMT
Because the RX has no way of knowing which is a valid pulse if the "valid" pulse is within the margins specified. Even if it does go outside there is no way to know if the previous "good" pulse was valid either, so the failsafe hold hold could be anywhere... It is beyond me that R/C mnf can ignore the many years of theory and practice on this subject. PCM is the only way to have a reliable failsafe. PERIOD.
Having said that it is quite possible to under bench conditions demonstrate to the uninformed that the two systems are equal, which is probably why there are a few believers.
Hi Andre!
That is what we call a "fart in the phonebooth"!! I have heard from other old timers than things like this IPD have been around for a long time, but I never heard it described like you have.
No flames or bashing, I just have never understood even the CLAIM that IPD could perform the same as PCM.