Help building custom electrical

Hello,

I am designing and building a flying model and unfortunately have had very little 
experience with non-out-of-the-box electrical systems.

I tried to learn about how my reciever works (Futaba FP-R127DF FM dual conversion) by 
taking a voltage tester to the 3 contacts designated for the servos. I then 
manipulated the lever on the transmitter (Futaba Conquest FP-T4NBF) while keeping an 
eye out for voltage fluctuations on the tester. What I discovered was the voltage 
between the red and black leads held a constant 5.28 volts regardless of the signal 
being recieved. Voltage differences between the white lead was not noticeable.

How does the reciever send a signal to the servo if not by fluctuating voltage? More 
to the point, how can I "read" this signal?