The PPM Encoder I've just bought produces the sum signal between 0V and -4V, I think that is called a 'negative shift'. I need to have a mirrored sum signal, between 0V and +4V ('positive shift', if I'm right).
So, how do I make the Encoder to work that way?
Among the features it is mentioned, that the 'shift' is user selectable, but in the (three years old) manual the topic is not discussed.
Sounds like you got burned by an oddball device. AFAIK you'll have to buy a proper PPM encoder if you actually need one.
The encoder is from here, the DIY Drones Store. I've downloaded the manual from the Store also. I don't think the device is old. It has the newer chip, not like the one mentioned in the manual. Actually, that is one of the reasons I don't want to start changing the FW.
I think that is a firmware issue then. Sorry I'm not more help. 3DR support can probably help you.