The Design And Construction Of Mini Radio Broadcast Transmitter And Audio Console Using Frequency Modulation (Fm) With Power Rating Of 15 Watt

ABSTRACT

The early transmitter for radio broadcasting is so big and bulky that they do occupy numerous spaces. The circuitries are mainly designed with valves, which are big in sizes. With the advent of semiconductor materials such as transistors electronic equipment are now becoming miniaturized such that small transmitters are now becoming handy and compact.

In line with this we choose to design a complete radio broadcasting equipment tat is compact and existence of semiconductor materials.

The system units are of two categories namely: audio console for the processing and mixing of musicals is basically a condenser microphone.

The transmitter unit is where the center frequency is provided. All these were designed to be in compact and small manner. This project is aimed at serving a community using a small and compact radio broadcasting equipment with a power watt of 15watt a community of 1 kilometer in radius should be covered comfortable and the audio production very clear unlike the common noisy FM microphone project.

TABLE OF CONTENTS

TABLE OF CONTENT

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• AIM OF THE PROJECT
• PURPOSE OF THE PROJECT
• OBJECTIVE OF THE PROJECT
• SCOPE OF THE PROJECT
• APPLICATION OF THE PROJECT
• PROBLEM OF THE PROJECT
• LIMITATION OF THE PROJECT
• DEFINITION OF TERMS
• PROJECT ORGANISATION

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 HISTORITICAL BACKGROUND OF THE PROJECT

2.2 REVIEW OF PARTS OF RADIO TRANSMITTER

2.3 REVIEW OF FM BROADCAST BANDS

2.4 MODULATION AND DEMODULATION

2.5 PRE-EMPHASIS AND DE-EMPHASIS

2.6 REVIEW OF MODULATION CHARACTERISTICS

2.7 REVIEW OF MIXING CONSOLE

CHAPTER THREE

3.0 CONSTRUCTION

3.1 BASICS OF FM TRANSMITTER

3.2 BLOCK DIAGRAM OF AN FM TRANSMITTER

3.3 FUNCTION OF FM TRANSMITTER BLOCK

3.4 CIRCUIT DIAGRAM OF THE SYSTEM

3.5 CIRCUIT PARTS

3.6 CIRCUIT OPERATION

3.7 DESCRIPTION OF COMPONENTS USED

CHAPTER FOUR

4.0 RESULT ANALYSIS

4.1 CONSTRUCTION PROCEDURE AND TESTING

4.2 CASING AND PACKAGING

4.3 ASSEMBLING OF SECTIONS

4.4 TESTING OF SYSTEM OPERATION

4.5 INSTALLATION OF THE COMPLETED DESIGN

4.6 SYSTEM TROUBLESHOOTING METHOD

4.7 COST ANALYSIS

CHAPTER FIVE

5.0 CONCLUSION

5.1 RECOMMENDATION

5.2 BIBLIOGRAPH

CHAPTER ONE

1.0                                                        INTRODUCTION

Radio broadcast transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. In addition to their use in broadcasting, transmitters are necessary component parts of many electronic devices that communicate by radio, such as cell phones, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, and spacecraft, radar sets, and navigational beacons. The term transmitter is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits.

The term is popularly used more specifically to refer to a broadcast transmitter, a transmitter used in broadcasting, as in FM radio transmitter. This usage usually includes the transmitter proper, the antenna, and often the building it is housed in.

A transmitter can be a separate piece of electronic equipment, or an electrical circuit within another electronic device. A transmitter and receiver combined in one unit is called a transceiver. The term transmitter is often abbreviated “XMTR” or “TX” in technical documents. The purpose of most transmitters is radio communication of information over a distance. The information is provided to the transmitter in the form of an electronic signal, such as an audio (sound) signal from a microphone. The transmitter combines the information signal to be carried with the radio frequency signal which generates the radio waves, which is often called the carrier. This process is called modulation. The information can be added to the carrier in several different ways, in different types of transmitter.

In a frequency modulation (FM) transmitter, it is added by varying the radio signal’s frequency slightly. Many other types of modulation are used.

The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as cell phones, walkie-talkies, and garage door openers. In more powerful transmitters, the antenna may be located on top of a building or on a separate tower, and connected to the transmitter by a feed line, that is a transmission line.

1.1                                                   AIM OF THE PROJECT

The aim of radio broadcasting is to inform and to entertain the people. Consequently, the properties of the human hearing have to be taken into regard when the quality parameters of the radio broadcasting systems and that of the receivers are specified

1.2                                              PURPOSE OF THE PROJECT

The main purpose of this work is to construct a device that will allow music or other audio content from a portable media player, CD player or other portable audio system to be played through a nearby FM radio. It can either be a capability built into a portable media player, or a portable appliance that plugs into the headphone jack or proprietary output port of a portable media player or video device. The sound is then broadcast through the transmitter on an FM broadcast band frequency and picked up by the receiver. The purpose is generally to allow portable audio devices to make use of the better sound quality of a home audio system or car stereo without requiring a wired connection between them.

The FM transmitter plugs into the audio output of audio devices and converts the audio output into an FM radio signal, which can then be picked up by appliances such as car or portable radios.

1.3                                             OBJECTIVE OF THE PROJECT

The objective of this work is to design and construct an FM broadcast transmitter which transmits a frequency modulated signal to an fm radio. That is, to construct a device that can broadcast signals on an FM broadcast band and picked up by the receiver.

1.4                                          LIMITATIONS OF THE PROJECT

• The relatively low power output of FM transmitters sometimes makes it unsuitable for use in some large urban areas because of the number of other radio signals. This is compounded by the fact that strong FM signals can bleed over into neighboring frequencies making the frequencies unusable with the transmitter. Removing a car’s radio antenna has been found to significantly improve transmitter reception.^[1] Some frequencies below 88.1 have even been supported as reception frequencies on some car stereos, and some indegeneous FM transmitters even take advantage of those unused frequencies which are generally more reliable as no frequency below 88.1 is used for mainstream broadcasters in the US.
• Some models which connect via ports other than the headphone jack have no means of controlling the volume, which can force the sound to transmit out from the device harshly (causing over modulation, audio distortion and possible radio interference), or too low. In theory a device could use an automatic level control or audio limiter circuit to overcome this problem although there are few (if any) devices with such a facility available out on the market yet.

1.5                                      APPLICATIONS OF THE PROJECT

• FM transmitters used in many different environments. Some of the more popular uses are churches, sporting events, fitness centers, homes, cars, correctional facilities and holiday light shows.
• Public address systems use a mixing console to set microphones to an appropriate level, and can add in recorded sounds into the mix. A major requirement is to minimize audio feedback.
• Most bands use a mixing console to combine musical instruments and vocals.
• Radio broadcasts use a mixing desk to select audio from different sources, such as CD players, telephones, remote feeds, or prerecorded advertisements. These consoles, often referred to as “air-boards” are apt to have many fewer controls than mixers designed for live or studio production mixing, dropping pan/balance, EQ, and multi-bus monitoring/aux feed knobs in favor of cue and output bus selectors, since, in a radio studio, nearly all sources are either prerecorded or preadjusted.
• Dub producers/engineers such as Lee “Scratch” Perry were perhaps the first musicians to use a mixing board as a musical instrument.
• Noise music musicians may create feedback loops within mixers, creating an instrument known as a no-input mixer. The tones generated from a no-input mixer are created by connecting an output of the mixer into an input channel and manipulating the pitch with the mixer’s dials.
  • SCOPE OF THE PROJET

FM radio broadcasting stations are operating in the very high frequency (VHF) range. The VHF range and FM are used for high quality audio broadcasting. This is not only due to the bandwidth available here but also to the signal-to-noise ratio and the dynamic range of FM transmission which are much better than those of AM transmission. Under optimal conditions, a 45-50 dB dynamic range can be achieved so that the signals need not be compressed as much as when AM is used

FM transmitter is basically a VHF colipits oscillator capable of transmitting sound or music to any standard FM receiver. The circuit works on a D.C source which makes it for a pure rectification. FM transmitter also has a capacitor microphone which picks up very weak sound signals, and discrete components such as: Transistor, Diode, Resistor, Capacitor and Inductor.

• This project transmits frequency on 100MHz± 5%. The transmitting distance is l00metres. It is powered with 5volt – 15volts D.C battery using suitable F.M receiver tuned to the transmitting frequency of this project. F.M Transmitter can be used as cordless microphones, mobile phone and for public address purposes.

1.7                                           SIGNIFICANCE OF THE STUDY

The project signifies a lot in the electronic communication system which telecommunication is the vital aspect which is usually demonstrated through radio communication system the frequency modulation transmitter is applied in a lot of instance frequency modulation is used in FM radio stations scattered all over the country whose advantage is paramount compared to its counterpart AM modulation frequency modulation transmitted is equally used in a miniaturized from as wireless morpheme.

1.8                                              PROBLEM OF THE PROJECT

Beside several favourable features, cost is the only drawback of FM transmissions in the VHF range. Since in this range the waves propagate line-in-sight (the transmitter and the receiver antenna have ‘to see’ each other), the area covered by one transmitter is small. This is so even in such relatively small countries as Hungary. To cover the whole country with the program, several transmitters have to be installed which is especially expensive if stereo programs have also to be transmitted since the receiving area of the stereo signal with the same signal-to-noise ratio as that of the mono signal is even smaller.

1.8                                                  DEFINITION OF TERMS

FM    –                  Frequency Modulation

VHF  –                  Very High Frequency (30MHz to 300MHz)

UHF  –                  Ultra High Frequency (300MHz to 3GHz)

VFO  –                  Variable Frequency Oscillator

VCO –                  Voltage Controlled Oscillator

PLL  –                  Phase Locked Loop

Oscillator –                    device that generates a frequency

1.9                                        PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to the project. In this chapter, the background, significance, objective limitation and problem of the study were discussed.

Chapter two is on literature review of the study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.