PPM explanation help

[DONGO]

Hello,

Is there any good explanation out there for what PPM is? I know what the PWM is but not sure about the PPM. I've googled it but I haven't found what I need. Specifically I am building the PWM to PPM converter and want to understand what is going on.
http://www.rcgroups.com/forums/showthread.php?t=744169
A brushed esc for example at 50% throttle would have a 50% duty cycle so the converted PWM would be a high of 1.5ms followed by a 18.5ms low. But what does this output look like in PPM.

Thanks,

Daniel.

[jeffs555]

What you are actually building is a PWM to servo pulse converter. Often times we say PPM when we actually mean servo pulse because it is easier to write. Here is a good explanation. http://www.mp.ttu.ee/risto/rc/electronics/radio/signal.htm

[Endurance]

Dan,

If you understand PWM you are almost there. Just think of PPM as a bunch of PWM signals stacked up. This allows many PWM signals to be sent in the same 20ms frame, you just need some decoder to parse it and re-generate the PWM signals.

http://www.endurance-rc.com/ppmtut.html

[DONGO]

Hey,

Endurance and jeffs555 thanks for the explanation. I got it now.

Daniel.