Decoding Time Coded Signals - Where to start?


I have a project which requires me to decode a 4-20mA signal to get 3 values from a sensor.

I have connected the signal wire to a 240ohm resistor connected to ground and I am reading the voltage across the resistor using one of the analog read pins of arduino mega.

Now I need tips on how do I decode this signal? I am completely lost and I am not able to figure out where to start in the first place!

The sensor datasheet can be found here

I am working with the signal mentioned on page number 58.

All help is highly appreciated!

That's an interesting one! I don't think I've ever seen a protocol like this before.
First start by being able to read and recognise a single high/low signal. If you can do that, it's easy to count two or three of them so you know what the sensor is telling you. Reading the actual value it transmits I may assume is not the problem, you have 3000 ms for that.
The high and low periods are 300 ms each, that's a very slow signal. You'll have to look into millis() based timing to write non-blocking code if you want to be able to do anything else in the meantime.

OP's image: