Dont let the marketing mumbo jumbo get to you.

PPM is an analogue signal. That means that it has a higher resolution that 1024 PCM. PPM would probably be a 10240000000000000000 PCM equavilent. Since it is analogue.

That said, being analogue PPM cannto distinguish between noise and signal, so singnal to noise ratio that is too high completly destroys the incoming data and your servo dont go where you want them to go.

PCM on the other hand is digital. Which means the actual servo position is more or less where you want it to go. The 60 degrees of travel is divided (quantised is teh correct term) into 512 or 1024 positions and then that position is sent as a number. So the resolution (or precision if you prefer) is either 0.117 or 0.0585 degrees in PCM. You would think that that makes it inferior to PPM and on those grounds it does. However the fact that it has been quantized and then modulated into a digital signal means that the actual signal is more easily differentiated from noise then our analogue PPM equvialent. So then when the signal starts to deteriorate the PPM servo's go just about anywhere while the PCM ones go close enought to where you want them not to make a difference.

The PPM vs PCM argument is the exact same as the vinyl vs CD one. Vinyl reproduces the music more accurate, but can your ears really tell the difference however your ears sure can hear those minute scratches on the vinyl!

I hope that makes sense - I find it hard to explain what I took four years in university to learn!