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he total operation of the system.

An input device may be a knob, a switch, or a slide control. Basically, each of these devices set a particular resistance value that represents a particular type of movement or input. The reality of an input device is emulated in some way at the model depending on the installation.

The input devices are connected to potentiometers or Gyro, which convert the positions or rate into voltages. A fanatical IC called an encoder reads these voltages and produces a stream of pulses that is then sent to the RF section. The pulses are set to specific values as determined by the value of the input device and kept in a stream called a pulse train.

The pulse train is a collection of square wave pulses that are about 300 microseconds in width. For a standard 7-channel transmitter, there will be eight positive going pulses. With all surface controls in neutral and the throttle control at midpoint, all of the pulses will be spaced approximately 1.5 ms apart which is measured from the leading edge of the first pulse to the leading edge of the next and on down the line to the last pulse.[4]

Assume the base line is zero volts and the positive going pulses are at about +5 volts. When the irregular edge of the last pulse in the train drops down to zero volts, the output of the encoder stays at zero volts for a period of time that is called 'sync pause'. After the output has been at zero volts for a period of time, another set of pulses called a 'frame' of information or data is generated. The purpose of the sync pause is to reset the decoder IC in the receiver to start reception of another set of pulses. Most PPM transmitters have a frame period of about 20 ms. [5]

As an input is given, the distance changes between the pulses. If Channel 1 is moved to the full upper extreme, the pulse width will be approximately 2.0 ms wide. The length of time can vary from 1.0 to 2.0 ms depending on the stick position of the radio control system. The pulses are 1.0ms in length when the switch is in the off position and 2.0 ms in length with the switch in the on position. The pulses are 1.0 ms in length when the switch is in the first position, 1.5 ms in length with the switch in the next position and 2.0 ms in length with the switch in the last position.

The sync pause will vary in length so the frame width will be same. The sync pause is long enough so with all controls in an 8-channel system at 2.0 ms, there is still have enough time left in the sync pause to reset the decoder in the receiver.

The RF section is the part of the transmitter that generates the radio signal. The pulse train is translated by the RF section and a particular amplitude or frequency variation is generated to represent the pulse train. The radio signal is sent to the antenna and radiated by the transmitter.

The receiver contains a radio receiver, a decoder, and a servo buss. Each component is accuracy made and each is required for proper translation of the radio signal.

The radio receiver part receives the radio signal. All RF is eliminated from the signal. The signal is then demodulated into a pulse sequence. The decoder generates a large +ve going pulse for each receiver channel. The decoder then transmits the pulse to a particular port or connector on the servo buss.

The servo is the component that actually does t