CHAPTER ONE

INTRODUCTION

The vehicle system control using telemetry application is all about using a radio wave to control and activate certain events such as the car horn, car head light, car ignition (starter) and car air conditioner etc.

          This is achieved by using various tone frequencies by using an encoder via a radio frequency transmitter (low power) that provides the carrier frequency for these tones.

          At the receiver end demultiplexing and decoding of these tone takes place via a detector/receiver stage. The output of the encoder is used to turn on a relay switch, which inturn connects power source to either the car engine, horn or lamp etc.

          The application of thus project include space exploration, where lunar vehicles are controlled from earth station by using satellite as the medium of transfer of signals.

          In the military warfare, unmanned air crafts, missiles and even armoured tanks are controlled these days by using the pinaple of telemetry applications. Other areas include GSM, where a subscriber has the total control of his telephone calls conversation through the BTS (Base Transmission or Transceiver Station). Its application are so vast and large that they are too numerous to mention.

BLOCK DIAGRAM FOR TRANSMITTER CONTROL UNIT

            BLOCK DIAGRAM FOR RECEIVER CONTROL UNIT

          Telemetry system has two units the transmitter and receiver. The link between the two unit is radio wave. The transmitter sends tones of different frequencies the receiver receives the tones.

TRANSMITTER

Transmitter is a device that process and possibly encode information, so as to make it suitable for transmission and subsequent reception. In a transmitter the information modulates the carrier. It superimposed an a light frequency since wave modulation varies from one system to another and may be high or low levels. Modulations is of three types amplitude modulation, frequency modulation and pulse modulation or combination of these.

FREQUENCY MODULATION:

Frequency modulation is a system in which the amplitude of the modulated carrier is constant while its frequency and rate of change are varied by the modulating signal. Frequency modulation is much more immune to noise than amplitude modulation noise vector is superimposed on the carrier.