ESC signal connections
 

I have a 3ph BLDC speed controller with only a thin red and a thin black wire for the speed control signal.
It has the usual thick red and black battery wires.
I am used to three control wires, (red +5V, white signal, black ground), that plug directly into the receiver.
Before I start fiddling and it ends in tears.. can anyone shed some light on this two wire control signal arrangement?

Probably a controller with an optocoupler connection/interface.
Make, type, pictures?

You're welcome.