The last section discussed the encoding operation within the transmitter. Accepting that the encoded signal was sucessfully transmitted to the receiver we will address the decoder operation with this article.

The purpose of the decoder is to reverse the operation of the encoder. Its goal is to take the incoming string of pulses, return them to their original pulse length, and send them out to the proper servo.

To understand the basics of this operation let us refer to Figure 1. This is a hypothetical block diagram of a decoder (For you circuit and electronic nuts I know it is not technically correct, but bear with me for now).

To demonstrate the basic operation let us look at the circuits which I have blocked.

Input pulse shaping - This block represents circuitry which would clean up the input pulses

from the receiver.

Lock-out timer - This blocks output is on and is reset with each incoming pulse. It will time out and return to its on state when an input pulse has not been received for a period of time.

Chan x Flip flop - This blocks output will be turned on or off with each input pulse based on the status of the privious block. If the previous block is on it will turn on, if the previous block is off it will turn off (or stay off if it's not on). Its output is positive when turned on.

Notice that the input pulse is applied to all flip-flop blocks.

Now then assuming that all circuits are in their static state, where the lock-out timer is on, and each flip-flop is off, we are ready to start receiving our input string. As covered in encoding, our input string begins with a start pulse and is followed by four pulses spaced to represent the width of the four channel outputs (Refer to figure 2). For this example we will again assume