DESIGN AND CONSTRUCTING OF A 2W FM TRANSMITTER

CHAPTER ONE

1.0 INTRODUCTION:

Information transmission is very vital to human life just as the early men used sticks to produce sound which indicates the location of each other as they wander about also down to the middle era when town criers came into play for the same information propagation to be transmitted from one point to another with the aid of radio communication which necessities the application of radio transmission and receiving.

A radio transmitter is a device whose major function is to send information intelligence from one point to another in most cases the information to be transmitted are voice music and code signals. However, the transmission of radio signal is done with the aid of electrical resonance. This is when the frequency of the receiver is equal to the incoming one from the transmitter resonance is observed which is the totality of radio communication. The researchers of this project work embarked on this topic because in frequency modulation FM transmitter, the transmitted radio signal is less distorted than other wave bands like amplitude modulation and short wave band. T he frequency on the tuning dial ranges from 88MHZ to 108MHZ.

In transmitter configuration, a sound is fed at the microphone which is the transducer that converts the physical sound into the electrical signal which is usually amplified by the first electric circuit audio frequency amplifier class A whose output is fed into a modulator which fields a frequency modulated output fed into the final stage radio frequency amplifier class C then to the antenna which radiates the radio signal into the atmosphere. All these process were because audio frequency signal cannot be radiated out from antenna directly because transmission at audio frequency is not particle. This is because of audio frequency signal.

I.They have reactively short range

II.If everybody starts transmitting the low frequency directly, mutual interference will render all of them ineffective.

III.The size of antenna required for this will be too large.

1.1. CONCEPT OF MODULATION AND DEMODULATION:

Modulation is technically the process of combining an audio frequency signal low frequency signal with a high frequency oscillator. However, the audio frequency signal which is being transmitted is superimposed on the carrier wave that transports it to the output of the radio frequency amplifier into the antenna.

This audio frequency signal otherwise called the modulating signal is being amplified by the radio frequency amplifier in order to overcome air impedance as it travels from the transmitter to the receiver.

1.4 PURPOSE OF THE STUDY:

The purpose of the study is aimed at designing and constructing a 2W FM transmitter. The project idea was necessitated by a quest to produce a comparatively cheap FM transmitter which can be used for transmission within a distance of 2KM as well as for practical and academic purposes.

1.5 OBJECTIVE OF THE STUDY:

The objective of this project is to construct an electrically operated system known as FM transmitter capable of transmitting a frequency modulated signal with a little or no distortion into the atmosphere for dissemination. It is also aimed at preparing graduating students into seasonal research activities that will carry them along during their professional practice as engineers.