The schematic diagram shown is that of an encoder for a transmitter.

-first two transistors form a free running multivibrator(flip-flop). Q1 is On and Q2 is Off and vice versa. There is a duty cycle of about 20 milliseconds(MS). Subsequent transistors are timer circuits triggered by the previous Q(Q=transistor). The 5k POT sets the delay when to fire the next Q. When the timer Q turns on, it send a .25MS pulse to shut off the carrier wave of an RF generator.

-So, the TX send a frame of .25MS pulses to clock a decoder at the RX. This schemactic diagram is for a 2 channel system. The three diodes send three pulses and the space between pulses is the time a channel port in the decoder remains on which the servo recognizes and positions itself.

To add more channels, add more timer Qs.