Should PCM receivers really cost more?
Harry, interference is interference. . be it a resonance from two nearby sources, hi-energy saturation from a bad ignition, or just being too far away from the transmitter with a low-power transmitter on the same frequency near the plane. When a receiver attempts to improve it's sensitivity by "widening" it's receptive window (as you described) it also opens the possibility of interference from adjacent frequencies. I don't like that idea, as it sounds like an accident waiting to happen. I look at it this way. . if your signal to the receiver is that weak where an IPD receiver has to widen it's bandwidth (or any other receiver has to do it either), then you are too far out anyway. If you are being jammed by another transmitter on the same frequency, no amount of "sensitivity increase' is going to matter. Every receiver can be blanked by RF interference from ignitions and other sources. No amount of special circuits or different types of modulation/encryption can change that.
By the very nature of PPM coding (as admitted by yourself) all information is lost or garbled when the receiver loses signal or is jammed, even partially. PCM (yes I know how it works), however, still gets part of the signal and can "function" up to the limit of being totally blanked out. IPD, as you described it, is still limited by the characteristics of FM/PPM (PWM???), and then throws in a "failsafe" on top of it all.
It may work, you may like it, but I consider the shortcomings (as described by you) to be less desirable than PCM's foibles (lockout can be a pain) I didn't like IPD when it first came out. . I still don't like it.