In this article I would like to address a very common issue that recently a lot of people have been arguing over – is PPM signal analog or digital?

Whilst the argument is not clear cut, there are some compelling arguments from both sides.


It’s Digital:

1. Its Pulse Position Modulation, So its a standard logic pulse(3.3 or 5v), the data is just defined by the position of the pulse in reference to the clock cycle. Similar to PWM. Analog is where a signal varys in voltage, Digital only has two states, on and off, Generally 0v and 3.3 or 5v
2. Digital, 0 and 1 levels only! It is generated digitally… But, as a “protocol” can be decoded both, digital or analogic way… Omho

Although is time dependent, it uses a “fixed time frame” to code/decode, larger pulses are multiple from this timeframe, so the double time can be interpreted as two high pulses and so on…This is a kind of protocol… But the signal amplitude does not carry any info…is pure digital, also you need a digital decoder or a DAC to use the info transmitted, so its a digital thing…
Basically, circuits operating on a saturation and cut levels (two levels only) are Digital.
I thing the fact that we can use a simple passive circuit as DAC, makes the confusion…

3. PPM is digital. The signaling is either 0 or 1. (We all know this). I would state that the PROTOCOL is what makes it convey analog values. Ie. the protocol is time-based, where as SBUS uses fixed time base and serial protocol to convey analog values. Both are digital as they can only transmit ones and zeroes, but they have different protocols.

It’s Analog:

1. Digital is not ever-present, relies on a clock or timing signal and does not vary its strength.

2. Just because it uses high and low wave patterns doesn’t make it digital smile emoticon Digital would be if it read 1 and 0 and turned that back into something. It uses the width which is varying length so instead of a wave form going up and down the length of the on pulse gets longer and shorter. That is where the analog comes in.

What do you think? Please comment below – thanks!

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