Key Features:
- No of Chapter: 5
- No of Pages: 53
- Graphs
- Tables
- Images
Abstract:
Optical communication is one of the most widely used technologies in field of telecommunication now days. However, the vulnerability of Free Space Optic (FSO) towards atmospheric conditions
like rainfall has become a main issue towards its implementation. Many studies conducted to estimate the climatological effects on FSO links are based on link centered in temperate and tropical regions. This however, has not been considered in this part of the world. Hence, this project aims at making analysis on the performance of FSO links in Akure, Nigeria. This analysis is based
on the use of Arduino to send data bits serially via a laser diode to the receiving Arduino for processing of the bit error rate (BER), carried out under controlled rain conditions using a rainfall
simulator with rainfall data obtained from The Department of Meteorology, The Federal University of Technology, Akure. The BER is observed to increase with increase in distance of rain along the FSO link path, having error rate of up to 0.35 at distance of 250cm.
Table of Content:
CERTIFICATION ..........................................................................................................................II
DEDICATION.............................................................................................................................. III
ACKNOWLEDGEMENT............................................................................................................IV
ABSTRACT................................................................................................................................... V
TABLE OF CONTENTS.............................................................................................................. VI
LIST OF TABLES..................................................................................................................... VIII
LIST OF FIGURES ......................................................................................................................IX
CHAPTER ONE............................................................................................................................. 1
1.1 BACKGROUND OF STUDY ......................................................................................... 1
1.2 MOTIVATION ................................................................................................................ 3
1.3 PROBLEM STATEMENT .............................................................................................. 4
1.4 AIM AND OBJECTIVES................................................................................................ 5
1.4.1 AIM........................................................................................................................... 5
1.4.2 OBJECTIVES........................................................................................................... 5
1.5 JUSTIFICATION OF PROJECT..................................................................................... 5
1.6 SCOPE OF RESEARCH ................................................................................................. 6
1.7 CONTRIBUTION TO KNOWLEDGE........................................................................... 6
CHAPTER TWO ............................................................................................................................ 7
2.1 HISTORY OF FREE SPACE OPTICS ........................................................................... 7
2.1.1 ALEXANDER GRAHAM BELL’S DISCOVERY................................................. 7
2.2 RAIN ATTENUATION PREDICTION MODEL........................................................... 8
2.3 BASAHEL’S RAIN RATE MEASUREMENTS.......................................................... 11
2.3.1 DERIVATION OF PATH LENGTH REDUCTION FACTOR ............................ 11
CHAPTER THREE ...................................................................................................................... 14
3.1 SERIAL COMMUNICATION...................................................................................... 14
3.1.1 SERIAL TRANSMISSION WITH ARDUINO ..................................................... 16
3.1.2 ASYNCHRONOUS SERIAL TRANSMISSION PROTOCOL............................ 16
3.2 TRANSMITTER............................................................................................................ 17
3.2.1 HAMMING CODE................................................................................................. 22
3.2.2 MANCHESTER CODE.......................................................................................... 23
3.3 RECEIVER .................................................................................................................... 25
3.4 DESIGN AND IMPLEMENTATION........................................................................... 30
3.4.1 TRANSMITTER AND RECEIVER ...................................................................... 30
3.4.2 RAINFALL SIMULATOR .................................................................................... 36
CHAPTER FOUR......................................................................................................................... 38
CHAPTER FIVE .......................................................................................................................... 42
5.1 CONCLUSION .............................................................................................................. 42
5.2 CHALLENGES ENCOUNTERED ............................................................................... 42
5.3 RECOMMENDATION ................................................................................................. 43
REFERENCES ............................................................................................................................. 44
Introduction:
Free Space Optics (FSO) is atechnology, which uses laser (light amplification by stimulated emission of radiation) as a medium of transmission between transmitter and receiver, frequently called fibreless optics. The transmitter converts the electrical signals into optical signals and sends it through the atmosphere (free space), modulation from a laser beam is used to send optical binary information. The Receiver converts the optical signal back to an electrical signal. FSO is a line of sight (LOS) emerging technology that has a great chance to complement the traditional wireless communications. Communication is theoretically possible as long as the line of sight between the transmitter and the receiver is clear, and as long as the transmitted power is high enough to overcome atmospheric attenuation. FSO is in reality an alternative method of transmitting information from one place to another by sending pulse of light in Terahertz spectrum.With the increase in usage of high speed internet, video-conferencing, live streaming etc., the bandwidth and capacity requirements are increasing drastically leading to congestion in conventionally used radio frequency (RF) spectrum and arising a need to shift from RF carrier to optical carrier.
US military and NASA, and being used for more than three decades in various forms to provide fast communication links originally developed FSO. The latest fourth-generation FSO lasers are 100 per cent class 1m eye-safe technology. These systems offer excellent automatic power-level control, and eliminate short-distance optical saturation.It is similar to fiber optic communications in that modulated laser light transmits data. Instead of containing the pulses of light within a glass fiber, these transmitted in a narrow beam through the atmosphere made it become an optimal solution for last-mile connection because of the capability in transmitting higher speed of data, which is up to 2.5Gbps. The motivation for FSO is to eliminate the effort of installing fiber optic cable, time, cost and yet maintaining the data rates up to 1Gb/s and beyond for transmission of voice, video and data services. Light travels through air faster than it does through glass, so it is fair to classify FSO as optical communications at the speed of light.
Fiber optic communications, which is the most reliable solution for optical communications, is one of the backbones in most cities. However, the cost to digging and laying down the fiber cable are huge. Furthermore, the time of deployments is also economically too expensive. It is also quiet difficult to relocate fiber cable once it is already being deployed (Ramasarma, 2002). Last-mile access; to lay cables of users in the last mile is very costly for service providers as the cost of digging to lay fiber is so high and it would make sense to lay as much fiber as possible.
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