I can convert PWM to duty cycle since each frame starts with a rising edge. Then I count the on time, off time and take the ratio to find duty cycle.
However, for PPM signal, there is no start of frame or end of frame so I am stuck. That is even with the assumption that frame length is known.
There are some modules that claim they can convert PPM to Analog. One of them is PT01A WingXine which can convert PPM to Analog AND vice verse, there is only 1 single IC on there so I was wondering how it functions.
Best Answer
According to Tech-FAQ you are correct.
Figure 1. Signal encoded with pulse amplitude, pulse density, pulse position and pulse code modulation.
From the Tech-FAQ article:
Further down the article they continue:
The Wikipedia article Pulse position modulation gives food for though (but not much else) when it states
An article on PCB Heaven explains several different PPM schemes. The last one looks the simplest for analog signal transmission without a clock.
Figure 2. This simple analog PPM scheme can reconstruct the signal without the original clock but notice that the number of samples decreases for high voltages.
That complete article is worth a read.
Figure 3. The board and close-up of the setting jumpers.
The board does seem to support PPM but without a datasheet it's not certain.