Whether PPM is analog or digital signal has always been a controversial debate. In this article we will discuss the question from a RC stand point.
I summarized the opinions in this forum thread, you can also vote/comment on the topics to support your argument. :)
PPM is a signal protocol used in receivers to talk to flight controllers.
Here are some other arguments from the users…
Bob R. – It’s analog. The signal of each channel is determined by the width of that channels pulse. All channels are sent together in a compressed pulse. At least that’s how I understand it. There is some delay depending on the pulse width which I think is about 27ms for 8 channels. Cleanflight based FC’s usually average three pulse before responding so the delay is 27×3. Serial links don’t have this dilemma.
Aeryck V. L. – it’s analog. if you look at the wave on a scope, it is sinusoidal, its not a sharp 0-1 transition. digital implies the transition from 0 to 1 is instantaneous; a ppm stream shows time (albeit very short).
Greg K. – Wrong, it’s digital. You’re wrong on what defines analog and digital. Its digital. By your definition if you look close enough at any signal its analog. Your definition is wrong. PPM is digital.