Specs of HK-TR6A remote controller receiver
The HK-TR6A-V2 receiver is designed to drive standard model radio control servos, which require 4.8~6V and a PWM signal that varies in width from 1~2ms at a frequency about 50Hz (20ms frame time). On this receiver the pin next to each channel label is signal, the center pin is Vcc, and the pin closest to the end of the case is Gnd. Power rails are common to all channels. A separate battery port is also provided to feed power into, in case all the channels have servos plugged into them.       

At one time this receiver included a PPM signal stream, but apparently this feature has been removed in the latest units (since 2012?). If yours is an older one then it may have PPM on the 'signal' pin of the battery port (marked BATT). 

Note that PPM (Pulse Position Modulation) and PWM (pulse Width Modulation) are not the same thing. PPM allows several servo channels to be encoded on a single wire. PWM is the signal sent to one servo. Some people also call individual servo pulses 'PPM' but that is not correct. 

How To Read RC Receiver PPM Stream 

Decoding 6 servo channel inputs with an Arduino UNO