UNIVERSITI MALAYSIA SARAWAK

R13a

BORANG PENGESAHAN STATUS TESIS

Judul: TWO CHANNELS AUDIO LINKS OVER OPTICAL FIBER

SESI PENGAJIAN: 2003/2004

Saya CYRUS NYAWAI MASON (HURUF BESAR)

mengaku membenarkan tesis * ini disimpan di Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:

I. Tesis adalah hakmilik Universiti Malaysia Sarawak. 2. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan untuk

tujuan pengajian sahaja. 3. Membuat pendigitan untuk membangunkan Pangkalan Data Kandungan Tempatan.

4. Pusat Khidmat Maklurnat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan tesis ini

sebagai bahan pertukaran antara institusi pengajian tinggi. 5. ** Sila tandakan (I) di kotak yang berkenaan

0

I

V-]

I

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972).

(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/ badan di mana penyelidikan dijalankan).

(TA ANG N PENULIS)

Alamat tetap: 1230 KENYALANG PARK,

93300 KUCHING, SARAWAK.

Disahkan oleh

(TANDATANGAN PENYELIA)

EN. NORHUZAIMIN JULAI Naina Penyelia

Tarikh: 26 MARCH 2004

CATATAN * **

Tarikh 26 MARCH 2004

Tesis dimaksudkan sebagai tesis bagi ljazah Doktor Falsafah, Sarjana dan Sarjana Muda. Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT dan TERHAD.

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Laporan Projek Tahun Akhir berikut:

Tajuk: Two Channels Audio Links Over Optical Fiber

Nama penulis: Cyrus Nyawai Mason

Matrik: 5303

telah dibaca dan disahkan oleh:

ý 2ý ý 1-- -- ---------

I 2j Norhuzaimin Julai Tarikh

Penyelia

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P. KHIDMAT MAKLUMAT AKADEMIK UN IMAS

liiiIIIIIIIIIIpIIRIIIV 1000125612

TWO CHANNELS AUDIO LINKS OVER OPTICAL FIBER

CYRUS NYAWAI MASON

This project is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science with Honors

(Electronics and Telecommunications Engineering)

Faculty of Engineering UNIVERSITI MALAYSIA SARAWAK

2004

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Especially Dedicated To: My Beloved Family; My Late Father, My Mother, Brothers and

Sisters, Mau, Lecturers, and Colleagues

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ACKNOWLEDGEMENT

Upon the completion of this project, the author would like to express his highest

appreciation to his supervisor, Encik Norhuzaimin Julai for his cooperation, suggestions,

ideas, and guidance through out the process of finishing the project.

The author would also like to thank his fellow lecturers especially to Encik Kismet

Hong Ping their project coordinator, Encik Ng Liang Yew his mentor, Encik Martin Anyi,

Encik Wan Azlan, Encik Zakaria, who have helped by giving their time to guide, advice and

support in the process of making this project. Without their help this project would not have

been the same.

The author would also like to convey his heartiest appreciation to all his colleagues,

and friends for their help and support.

Last but not least, the author would like to thank his family for their constant support

and understanding. And to those that have help and not mentioned here, their kind assistance

will not be forgotten. God Bless them all.

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ABSTRAK

Two channel audio links over optical fiber merupakan sebuah projek dimana konsep

komunikasi optic dibentangkan dan diapplikasikan. Analisa sistem di simulasikan

menggunakan kedua-dua kaedah perisian dan perkakasan. Perisian yang digunakan untuk

simulasi adalah CommSim dan Matlab. Simulasi di lakukan untuk menganalisa bagaimana

sistem pengkodan/ modulasi dan sistem transmisi optic beroperasi. Isyarat maklumat

dimodulasi dan diubah daripada sebuah isyarat elektrik yang berterusan kepada denyutan

optic untuk transmisi. Isyarat ini kemudiannya diubah kembali kepada isyarat elektrik oleh

penerima, dan kemudiannya di dimodulasikan. Secara am nya, inilah bagaimana two channel

audio link over optical fiber" beroperasi. Walaupun, topik ini hanya merangkumi audio,

sistem ini diharapkan boleh diaplikasikan kepada pelbagai jenis maklumat lain tidak mengira

isyarat digital atau analog.

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ABSTRACT

Two channel audio links over optical fiber is a project where the concepts of optical

communication is discussed and applied. A system analysis of the system is simulated both by

using software and hardware simulation. The programs used to simulate the analysis are the

Commsim and MatLab software. Simulation is done to analyze how an encoding/ modulation

system and optical transmission system operates. Information signals are modulated and

converted from continuous electrical signals to pulses of optical signal for transmission. Then

the received signals are converted back to electrical signal by the receiver and demodulated.

Basically this is the operation of the two channel audio link over optical fiber. Although the

topic only refers to audio, this system is hopefully applicable to any information source for

transmission either digital or analog.

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TABLE OF CONTENT

APPROVAL SHEET

TITLE PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRAK

ABSTRACT

CONTENTS

LIST OF TABLES

LIST OF FIGURES

CHAPTER 1: INTRODUCTION

1.1 Introduction

1.2 Objectives of Project

1.3 Project Overview

1.4 Statement of problems/ Hypothesis

1.1 History of Optical fiber communication

1.6 Elements of a Telecommunications System

1.7 Reflection

1.8 Refraction

1.9 Critical Angle

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1.10 How light travels through a Fiber cable

1.11 Sources of Optical Transmitter

1.12 Light-emission processes

CHAPTER 2: LITERATURE REVIEW

2.1 Introduction

2.2 PAM (Pulse Amplitude Modulation)

2.3 PCM (Pulse Code Modulation)

2.4 TDM (Time Division Multiplexing)

2.5 Sampling Theorem

2.6 Sampling in PAM

2.7 Sampling Frequency

2.8 Quantization

2.9 Sample/Hold Amplifier

2.10 Analog to digital converter (ADC)

2.11 Optical Fiber Communications

2.12 Channel Attenuation and Distortion

2.13 Optical Modulation

2.14 Semiconductor Laser

2.15 Optical Detectors

2.16 Noise

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CHAPTER 3: BASIC DESIGN OF OPTICAL COMMUNICATION 56

SYSTEM

3.1 Introduction 56

3.2 PAM (Pulse Amplitude Modulation)

3.3 PCM (Pulse Code Modulation)

3.4 TDM (Time Division Multiplexing)

3.5 FDM (Frequency Division Multiplexing)

3.6 The Transmitter

3.7 The Transmission Medium

3.8 Receiver

CHAPTER 4: HARDWARE RESULTS

4.1 Introduction

4.2 Information signal

4.3 Hardware Layout

4.4 PAM (Pulse Amplitude Modulation) Results

4.5 PCM (Pulse Code Modulation) Results

4.6 Analog Transmitter Circuit Results

4.7 Analog Receiver Circuit Results

4.8 Digital Transmitter Circuit Results

4.9 Digital Receiver Circuit Results

4.10 Summary

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CHAPTER 5: HARDWARE DESIGN

5.1 Introduction

5.2 Analog Hardware Design

5.3 Digital Hardware Design

5.4 Summary

CHAPTER 6: CONCLUSION AND RECOMMENDATION

REFERENCES

APPENDIX A

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LIST OF TABLES

Table 5.1 List of Components for Analog System Design

Table 5.2 List of Components for Digital System Design

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LIST OF FIGURES

Figure l. 1

Figure 1.2

Page

Basic Concepts of Optical Fiber Communication Block Diagram 4

Total Internal Reflection 9

Figure 1.3a Basic PCM TDM Transmitter Block Diagram

Figure 1.3b

Figure 1.4

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 2.8

Figure 2.9

Figure 2.1 Oa

Figure 2. I Ob

Figure 2.11 a

Figure 2. l Ob

Figure 3.1

Figure 3.2

Basic PCM TDM Receiver Block Diagram

Examples of Communications Waveforms

Original Signal and Sampling Signal

PAM sampled waveform

PAM Comcepts

PAM Sampling

Quantization of Samples

Analog Signal to be digitized

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Sampling and Reconstruction of the waveform from the sample pulses 35

Comparison of Analog to PAM signal

Companding Versus Expanding

Analog Signal Optical Modulation

Digital Signal Optical Modulation

Analog Signal and Noise

Digital Signal and Noise

Simulation Result of PAM Sampling (Single Channel)

Simulation Result for PAM system

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Figure 3.3

Figure 3.4

Figure 3.5a

Figure 3.5b

Figure 3.6

Figure 3.7a

Figure 3.7b

Figure 3.8

Figure 3.9a

Figure 3.9b

Figure 3.10

Figure 3.11

Figure 3.12a

Figure 3.12b

Figure 3.13

Figure 3.14

Figure 3.15a

Figure 3.15b

Figure 3.16

Figure 3.17a

Diagram of Simulation PAM and TDM System

PAM System Simulation Input signal

Sampled I kHz Signal

Sampled 2 kHz Signal

Multiplexed Sampled Signal

Demultiplexed I kHz Signal

Demultiplexed 2 kHz Signal

Simulation Output Signals

Channel 1 Comparison of Input to Output Signal

Channel 2 Comparison of Input to Output Signal

Diagram of Simulation PCM and TDM System

PCM Simulation Input Signals

Sampled Channel 1 Signal (PCM Simulation)

Sampled Channel 2 Signal (PCM Simulation)

Sample and Hold Signal (Both Channels)

Digital Representations of Sampled Signals in Parallel Form

Serial Digital Representation (Binary) of Channel I

Serial Digital Representation (Binary) of Channel 2

Multiplexed Digital Signals of Channel 1 and Channel 2

Channel 1 Demultiplexed Signal

Figure 3.17b Channel 2 Demultiplexed Signal

Figure 3.18a Channel 1 Received Parallel Digital Signal

Figure 3.18b Channel 2 Received Parallel Digital Signal

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Figure 3.19a Channel I Converted Digital Signal into Analog Form Signal 72

Figure 3.19b Channel 2 Converted Digital Signal into Analog Form Signal 72

Figure 3.20a When Gain is Applied to Channel 1 Signal 73

Figure 3.20b When Gain is Applied to Channel 2 Signal 73

Figure 3.21 a Sample and Hold Signal Channel 1 PCM Simulation 74

Figure 3.21 b Sample and Hold Signal Channel 2 PCM Simulation 74

Figure 3.22 PCM Simulation Output Signal 75

Figure 3.23a Comparison of Input to Output Channel 1 PCM Simulation Results 75

Figure 3.23b Comparison of Input to Output Channel 2 PCM Simulation Results 76

Figure 3.24 Input and Output of PCM System Simulation 76

Figure 3.25 Concepts of FDM System (Transmitter) 79

Figure 3.26 Concepts of FDM System (Receiver) 79

Figure 3.27 Diagram OF FDM System Simulation 80

Figure 3.28 FDM Simulation Input Signals 81

Figure 3.29 Channel 1, IV DC Component Added Signal and Original Signal 81

Figure 3.30 Channel 2, IV DC Component Added Signal and Original Signal 82

Figure 3.31 a Amplitude Modulation Signal of Channel 1 82

Figure 3.3 lb Amplitude Modulation Signal of Channel 2 83

Figure 3.32 Compound Signal of Channel 1 and Channel 2 Added Together 83

Figure 3.33 Signals Obtained by Passing the Compound Signal through a Lowpass 84

and a Highpass Filter

Figure 3.34a Absolute Value of AM I kHz Signal 84

Figure 3.34b Absolute Value of AM 2 kHz Signal 85

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Figure 3.35a FDM Simulation Obtained 1 kHz Output Signal 85

Figure 3.35b FDM Simulation Obtained 2 kHz Output Signal 86

Figure 3.36a Comparison of Input to Output Channel I FDM simulation Result 86

Figure 3.36b Comparison of Input to Output Channel 2 FDM simulation Result 87

Figure 3.37 Input and output OF FDM Simulation 87

Figure 3.38 MAtLAb Results for the DC added and no DC added Components 88

Figure 3.39 Magnitude Spectrum of the Modulated Waveform 89

Figure 4.1 a Hardware 1 kHz Signal 93

Figure 4.1 b Closer View of the 1 kHz Signal 94

Figure 4.2a Hardware 2 kHz Signal

Figure 4.2b Closer View of the 2 kHz Signal

Figure 4.3 HPS I Channel PAM System Layout

Figure 4.4 HPS 2 Channels PAM System Layout

Figure 4.5 Analog Optical Transmitter

Figure 4.6 Digital Optical Transmitter

Figure 4.7 Analog Optical Receiver

Figure 4.8 Digital Optical Receiver

Figure 4.10 HPS 2 Channel PCM System Layout

Figure 4.11 Sampled PAM Signal Hardware Results

Figure 4.12 Sampling Signal Hardware Results

Figure 4.13 Sample and Hold Signal Hardware Results

Figure 4.14 Sample and Hold Sampling Signal Hardware Result

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Figure 4.15 Receiver Sample and Hold Signal Hardware Result 104

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Figure 4.16

Figure 4.17

Figure 4.18

Figure 4.19

Figure 4.20

Figure 4.21

Figure 4.22

Figure 4.23

Figure 4.24

Figure 4.25

Figure 4.26

Figure 4.27

Figure 4.28

Figure 4.29

Figure 4.30

Figure 4.31

Figure 4.32

Figure 4.33

After passing through the Low pass Filter Hardware Result 105

Multiplexed Sampled Signal (1 and 2 kHz) Hardware Result 106

Sample and Hold Multiplexed Signal Hardware Result

Demultiplexed Channel 2 Signal (2 kHz) Hardware Result

Hardware Result Output of Channel 2

Serial Digital Converted Analog Signal Hardware Results

Synchronizing Signal Added to PCM Signal Hardware Result 110

Multiplexed (Channel I and 2) signal PCM Hardware Result 111

DAC output Multiplexed (Channel 1 and 2) signal Hardware Result 112

Demutliplexed, Sample and Hold Signal Channel 2 Hardware Result 112

Output Signal of Channel 2 PCM System Hardware Result 113

PAM Single Channel Prepared For Optical Transmission

PAM Dual Channel Prepared for Optical Transmission

Added DC Offset Single Channel Signal

Added DC Offset Dual Channel Signal

Optical Transmitter Signal (Single Channel)

Optical Transmitter Signal (Dual Channel)

Preamplifier Signal (Single Channel)

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Figure 4.34 Preamplifier Signal(Dual Channel) 1 18

Figure 4.35

Figure 4.36

Figure 4.37

DC Offset and Voltage Adjusted Signal (Single Channel)

DC Offset and Voltage Adjusted Signal (Dual Channel)

Sample and Hold Amplifier Signal Passed From The Optical Reciever 120

(Single Channel)

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Figure 4.38 Sample and Hold Amplifier Signal Passed From The Optical Reciever 120

(Dual Channel)

Figure 4.39 Output Signal of PAM Optical Transmitter System (Single Channel) 121

Figure 4.40 Output Signal of PAM Optical Transmitter System (Dual Channel) 122

Figure 4.41 PCM Signal Passed Through a Schmitt Trigger (Single Channel) 123

Figure 4.42 PCM Signal Passed Through a Schmitt Trigger (Dual Channel) 123

Figure 4.43 Received Signal at The Comparator Circuit 124

Figure 4.44 Received Signal at The Schmitt Trigger 125

Figure 4.45 Received Signal at the DAC 126

Figure 4.46 Received Signal at the Sample and Hold Amplifier

Figure 4.47 The Reproduced Signal at the Receiver End

Figure 5.1 Analog Transmitter Circuit Design

Figure 5.2 Analog Receiver Circuit Design

Figure 5.3 Digital Transceiver Circuit Design

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CHAPTER 1

INTRODUCTION

1.1 Introduction

This project is done to design an affordable, reliable and an acceptable quality optical

fiber audio link system which could be used on all audio inputs. The design should be

exceptionally simple and yet capable of transmitting and receiving an acceptable quality

sound output.

The technology of using optical signals to carry audio information is currently

available only in high-end entertainment systems such as the 5.1 (5 channel directions and I

subwoofer) surround sound systems for computer systems, sound systems for game consoles

such as SONY Playstation2 and various other entertainment system produced by Japanese

companies. The use of optical transmission to carry audio signals is becoming more and more

popular due to the quality of the sound it produces, which is less susceptible to transmission

noise due to electromagnetic flux especially in copper cables. The drawback of this

technology is the high price tag it carries. To overcome the problem of high price and make

the technology affordable, the circuit could be designed and built ourselves.

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A Two Channel Audio Links over Optical Fiber is currently only available to a few in

the current market due to its high price. The Two Channel Audio Links over Optical Fiber is

divided in to two main categories;

1. Analogue Two Channel Audio Links over Optical Fiber and,

2. Digital Two Channel Audio Links over Optical Fiber

The quality of the output depends entirely on the transmission method itself. Analogue

transmission would produce an output which is generally of poor quality compared to that of

digital transmission, as the transmitted signal could be affected by noise and could not be

processed to produce a good output. As for the digital transmission, the sound expected

should be better than its counterpart, as digital signal is influenced less by noise.

The end product could also be used as other means of communication systems such as

that of an Intercom or even a Telephone. The numbers of applications are almost limitless in

the field of communications.

The method used to produce the end product is concluded on the next page in the form

of a flow chart:

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Start

Research

ý

Reciever Analogue

Fiber Optics Communication Hardware

ir-77 77ýi Digital

Transmitter Analogue Digital

f_ t

I

Literature Review

Design

Build

i Run Test

Outcome Sucessfull?

Yes

Compile Result and Submit Report

ý Simulation

Analogue

No

Digital

Towards the end of this project is expected to be a design for both the analogue and

digital optical fiber link transmitter and receiver. The circuit design is hopefully to be able to

carry and give an output of audio signals which is of acceptable quality. By using optical

fiber, noise due to atmospheric interference could be reduced to a minimum; flux from using

copper cables as a medium could be eliminated entirely giving a better high fidelity audio

Software

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signal. The circuit could also be used as an optical fiber link transceiver circuit in other

telecommunication applications such as that of an intercom, possibly that of a telephone

system and maybe even that of a networking system. The circuit is targeted on producing an

affordable optical telecommunication system which doesn't compromise on quality and

reliability.

Information Input

Codec or

Converter Light source transmitter

Reciever

Information output

light detector

Fibre-Optic"/. Cable /s

f /ý

Figure!. I Basic Concepts of Optical Fiber Communication Block Diagram

4

Decoder Filter Amplifier JJ`

Pho ocell or

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1.2 Objectives of Project

The objectives of this project are:

1. To identify and accumulate data on the Two-Channel Audio Link over Optical Fiber

systems principles and basics.

II. To explain the functionality and operations of a Two Channel Audio Link over Optical

Fiber systems.

III. To produce a Literature review of on the topic of Two-Channel audio link over Optical

Fiber.

IV. To manipulate the data gathered to design a working circuit of a Two Channel Audio

Link over Optical Fiber Systems for both Analogue and Digital.

V. To simulate the operations of a Two Channel Audio Link Over Optical Fiber for both

Analogue and Digital.

VI. To compile the necessary data gathered from research and simulation to design a

working transceiver circuit of a Two Channel Audio Link over Optical Fiber.

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1.3 Project Overview

The purpose of this project is to identify and accumulate data on the principles and basics

of how to design and produce a Two-Channel Audio Link over Optical Fiber systems.

Principles of optical communication are important in analyzing and designing of a optical

communications systems.

After all principles and basics needed in optical fiber communication systems are

gathered, the functionality and operations of sections and devices in a Two Channel Audio

Link over Optical Fiber systems is later explained. Explanation of these theorems is important

to explain the functions of each part of the circuit used in the design of the circuit.

This information is then used to produce a Literature review of on the topic of Two-

Channel audio link over Optical Fiber covering the topic of both transmission and receiving

circuit theorems. These data is then manipulated to design a working circuit of a Two Channel

Audio Link over Optical Fiber Systems for both Analogue and Digital circuit.

Both circuits will be design accordingly to the analysis done on the topic of optical

communications. When a circuit is designed, the circuit is then simulated; this is done to test

the operations of a Two Channel Audio Link Over Optical Fiber for both Analogue and

Digital are working the way that it is expected to.

When all data is complete from research and simulation, then the data is compiled

accordingly to design a working transceiver circuit of a Two Channel Audio Link over

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