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CHAPTER ONE

1.0 INTRODUCTION

The most recent advancement in technology has really given birth to different development in the field of telecommunication engineering. Provisions have been made by technologist who covers a wide range of humans environment giving solution to humans problems.

In recent time, communication has been unstable in the world which has really affected consistent communication among the people of different countries. Many communication channels were found to be able to cover a certain area leaving majority of other area worth covering out. With the help of the present modern technology who brought about the use of satellite antenna have in a great way curtailed the problems of poor transmission and communication.

Specifically, we are considering a cable television satellite system. A cable television satellite or TV aerial is an antenna specifically designed for the reception of over the air broadcast television signals which are transmitted at frequencies from about 41MHz to 250MHz in the VHF band and 470MHz to 960MHz in the UHF band in different countries.

To cover this range, antennas generally consist of multiple conductors of different lengths which correspond to the wavelength range the antenna is intended to receive. The length of the element of a TV antenna is usually half the wavelength of the signal they are intended to receive. The wavelength of a signal equals the speed of light divided by the frequency.

The design of a television broadcast receiving antenna is the same for the older analog transmission and the digital television DTV transmission which are replacing them.

The cable television satellite system is parabolically shaped. It reflects the signal to the dishs focal point. Mounted on brackets at the dishs focal point is a device called feedhorn. This feedhorn is essentially the front end of a wave guide that gathers the signals at or near the focal point and conducts them to a low noise blockdown convert or LNB. The LNB converts the signals from electromagnetic or radio waves to electrical signal and shift the signal from the downlinked cband and or ku band to the Lband range.

Direct broadcast satellite dishes uses an LNBF which integrates the feedhorn with the LNB a new form of omini directional satellite antennas which does not use a directed parabolic dish and can be used on a mobile platform such as a vehicle that was announced by the University of Waterloo in 2004.

1.1 BACKGROUND OF THE STUDY:

The history and discovery of an antenna system of transmission can be traced back to the first experiment conducted by Michael Faraday around 1830s which involved the coupling of electricity and magnetism.

He slide a magnetic material a magnet actually around the coil of a wire attached to a galvanometer. In doing so, he was actually creating a time varying magnetic field which as a result from Maxwells equation must have had a time varying electric field. The coil attached acted as a loop antenna and received the electromagnetic radiation which was detected by the galvanometer. The work of an antenna interestingly, the concept of electromagnetism has not been thought up at this point.

The first satellite television signal was relayed from Europe to the Telstar satellite over North America in 1962. It was based on the principle of using the highly elliptical Molniya satellite for pre broadcasting and delivering of TV signal to ground downlink stations.

The first commercial North America satellite to carry television was Canadas geostationary Anik which was launched in 1972. AT6, the worlds first experimental educational and direct broadcast satellite was launched in 1974. The first Soviet geostationary satellite to carry direct to home television called Ekran was launched in 1976.

Satellite television is a program delivered by the means of communications satellite and received by an outdoor antenna, usually a parabolic reflector generally referred to as satellite dish and as far as household usage is concerned, and a satellite receiver either in the form of an external set top box or a satellite tuner module built into a TV set. Satellite TV tuner are also available as a card or a USB peripheral to be attached to a personal computer. In many areas of the world, satellite television provides a wide range of channels and services often to areas that are not serviced by terrestrial or cable providers.

Direct broadcast satellite television comes to the general public in two flavors analog and digital. This necessitates either having an analog satellite receiver or a digital satellite receiver. Analog satellite television is being replaced by digital available in a better quality known as high definition television.

1.1. STATEMENT OF PROBLEM:

The following forms the problems that necessitated the research of this project work.

I. High cost of communication receiving equipment in the third world countries

II. The use of outdated and analog receiving satellite equipment which cannot receive all channels.

III. The invention and discovery gap between the whites and the blacks.

1.2. PURPOSE OF THE STUDY:

The purpose of this study is aimed at cloning and installation of a cable television satellite system. It is necessitated by a quest to produce a comparatively cheap free to air antenna that can cover a wide distant and which can work as perfectly as the most recent antenna satellite in the market today.

1.3. OBJECTIVE OF THE STUDY:

Having researched the problem faced by the telecommunication receiving system engineers, the following forms the objective of this study:

I. Cloning a locally made cable television satellite using the Ekran launched in 1976 by the Soviet Union as a case study.

II. Eliminating or atleast curtailing the communication gap between the haves and the have not. That is the rich and the poor.

III. Improving the antenna gain of other already produced antenna by encouraging its correction using this project work as a case study.

IV. To produce a free to air satellite that can easily be purchased by all.

1.4. SIGNIFICANCE OF THE STUDY:

The cable television satellite system should be able to cover all the areas within the country or province where it is mounted.

It should also be able to cover both the VHF and UHF requirement and as well be able to receive foreign channels which are comparatively cheap as the original prototype or case study.

1.5. SCOPE OF THE STUDY:

The focal point of this work is to clone and install a cable television satellite, highlighting its objective and operational characteristics.

The study covers only the receiving part of communication where antennas are used to intercept mobile frequency channels in the air. The type of antenna receiving system covered here is a parabolic antenna which is designed to receive microwaves from communication satellites which transmit or broadcast such as a satellite television.

1.6. BLOCK DIAGRAM:

Fig. 1.0 block diagram of a cable television satellite system

Figure1.0 represents a block diagram of the cable television satellite system. It is made up of three units namely; satellite antenna unit, the decoder/receiver unit and the television unit.

A modular approach was adopted here in which the installation and cloning was incorporated namely; the antenna dish, the receiver/decoder and the television unit.

These subunits would be cloned, installed and tested separately when all are confirmed to be working properly, they should be appropriately connected.

Integrated circuit IC chips should be used in the cloning so as to reduce and enhance compatibility of the equipment and reliability

1.7. LIMITATION OF THE STUDY

1 FINANCIAL CONSTRAINT: sourcing for more information from diverse sources is limited to do, lack of money to extract more information through available sources in Nigeria.

2 TIME FACTOR: the time given to the researcher to source and write this project work was not enough because of other academic activities such as reading for exam and test.

3 COMPANY POLICY: the policies guiding the organization that have some information needed for the research work are restricted to give certain company files to the public who have no direct contribution to the well being of the company/organization.

4 MATERIAL FACTOR: the materials required for the cloning of the cable television satellite are limited because of this, alternative materials was used which may result in the constructed work not performing as expected.

1.8. DEFINITION OF OPERATIONAL TERMS

a RADIO WAVES: These are a type of electromagnetic radiation with wavelength spectrum longer than infrared light. Radio waves have frequencies from 300GHZ to as low as 3KHZ and corresponding wavelength from one millimeter to 100 kilometers. Like all other electromagnetic waves, they travel at the speed of light.

b VHF: the abbreviation stands for very high frequency. It is the radio frequency range from 30MHZ to 300MHZ.

c RECEIVER/ DECODER: Commonly found in radio television cable and satellite broadcasting facilities, the IRD is generally used for the reception of contribution feeds that are intended for receiving antenna system.

d TELEVISION: This is a telecommunication medium for transmitting and receiving moving images that can be monochrome black and white or coloured with or without accompanying sound.

e ANTENNA: This is an electrical device which converts electrical current into radio waves and vice versa. It is usually used with a radio transmitter or radio receiver.

f BANDWIDTH: An antennas bandwidth specifies the range of frequencies over which its performance does not suffer due to poor impedance.

g ANTENNA GAIN: This is a parameter which measures the degree of directivity of the antennas radiation pattern. It is also known as the power gain.

h POLARIZATION: The polarization of an antenna is the orientation of the electric field EPlane of the radio wave with respect to the earths surface and it is determined by the physical structure of the antenna and by its orientation.

i WAVELENGHT: This is defined as the ratio of the velocity of the antennas electromagnetic waves to the frequency of the waves

j IMPEDANCE MATCHING: This is the maximum power transfer for matching the impedance of an antenna system as seen looking into the transmission line to the complex conjugate of the receiver or transmitter.

k SKEW: This refers to the angle of the electric field.

l AZIMUTH: This refers to the rotation of the whole satellite dish assembly around a vertical axis or supporting pole.

m ELEVATION: This refers to the look or upward angle between the dish pointing direction and the local horizontal plane.

n RESISTANCE: This is the opposition that is offered by a resistor against the flow of current in a circuit.

o INTEGRATED CIRCUIT IC: It is a complete electronic circuit in which both the active and passive components are fabricated on a tiny single chip of silicon.

p SIGNAL LEAKAGE: This is the passage of electromagnetic fields through the shield of a cable and occurs in both directions.

q SLEW RATE: This is the maximum rate of change of the output usually quoted in Volts per seconds or microseconds.

r DIPLEXER: A diplexer is a passive device that implements frequency domain multiplexing.

s MOTORDRIVEN DISH: A dish that is mounted on a pole and driven by a stepper motor or a servo can be controlled and rotated to face any satellite Position in the sky

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