PCM and PPM are informational coding schemes. FM, frequency modulation is a way to put that into the air. AM, amplitude modulatin is another. PCM and PPM are just different ways of coding information into the FM or AM signal. They can be used across a wide variety of frequency bands. Common ones are 35, 40, 50 and 72 MHz.

So PCM and PPM are not directly related to FM or AM. I imagine you could use PPM on 2.4 GHz too if you wanted to, but I am not certain of that.

2.4 GHz is a frequency band, like 72 MHz, not a coding scheme. As we have seen, each of the 2.4 GHz providers are using their own special coding scheme. So you can't mix and match receivers with transmitters. PCM is the same way. You have to match brands.

Hope that helps.

What you need to know about receivers
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