UNIVERSITI MALAYSIA SARAWAK

Transcription

1 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 V-] SULIT 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). I I TIDAK TERHAD Disahkan oleh (TA ANG N PENULIS) (TANDATANGAN PENYELIA) Alamat tetap: 1230 KENYALANG PARK, KUCHING, SARAWAK. EN. NORHUZAIMIN Naina Penyelia JULAI Tarikh: 26 MARCH 2004 Tarikh 26 MARCH 2004 CATATAN * ** 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.

2 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: Norhuzaimin Julai Tarikh Penyelia I 2j ý 2ý ý

3 P. KHIDMAT MAKLUMAT AKADEMIK UN IMAS liiiiiiiiiiiiipiiriiiv 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

4 Especially Dedicated To: My Beloved Family; My Late Father, My Mother, Brothers and Sisters, Mau, Lecturers, and Colleagues 11

5 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. 111

6 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. iv

7 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. V

8 TABLE OF CONTENT Page APPROVAL SHEET TITLE PAGE i DEDICATION ii ACKNOWLEDGEMENT iii ABSTRAK iv ABSTRACT V CONTENTS VI LIST OF TABLES LIST OF FIGURES X XI CHAPTER 1: INTRODUCTION Introduction I 1.2 Objectives of Project Project Overview Statement of problems/ Hypothesis History of Optical fiber communication Elements of a Telecommunications System Reflection Refraction Critical Angle 19 vi

9 1.10 How light travels through a Fiber cable Sources of Optical Transmitter Light-emission processes 22 CHAPTER 2: LITERATURE REVIEW Introduction PAM (Pulse Amplitude Modulation) PCM (Pulse Code Modulation) TDM (Time Division Multiplexing) Sampling Theorem Sampling in PAM Sampling Frequency 2.8 Quantization 2.9 Sample/Hold Amplifier Analog to digital converter (ADC) Optical Fiber Communications Channel Attenuation and Distortion Optical Modulation Semiconductor Laser Optical Detectors Noise 52 vii

10 CHAPTER 3: BASIC DESIGN OF OPTICAL COMMUNICATION 56 SYSTEM 3.1 Introduction PAM (Pulse Amplitude Modulation) PCM (Pulse Code Modulation) TDM (Time Division Multiplexing) FDM (Frequency Division Multiplexing) The Transmitter The Transmission Medium Receiver 91 CHAPTER 4: HARDWARE RESULTS 4.1 Introduction 4.2 Information signal Hardware Layout PAM (Pulse Amplitude Modulation) Results PCM (Pulse Code Modulation) Results Analog Transmitter Circuit Results Analog Receiver Circuit Results Digital Transmitter Circuit Results Digital Receiver Circuit Results Summary 127 viii

11 CHAPTER 5: HARDWARE DESIGN Introduction Analog Hardware Design Digital Hardware Design Summary 134 CHAPTER 6: CONCLUSION AND RECOMMENDATION 135 REFERENCES 138 APPENDIX A 140 ix

12 LIST OF TABLES Page Table 5.1 List of Components for Analog System Design 130 Table 5.2 List of Components for Digital System Design 133 X

13 LIST OF FIGURES Page Figure l. 1 Basic Concepts of Optical Fiber Communication Block Diagram 4 Figure 1.2 Total Internal Reflection 9 Figure 1.3a Basic PCM TDM Transmitter Block Diagram 16 Figure 1.3b Basic PCM TDM Receiver Block Diagram 17 Figure 1.4 Examples of Communications Waveforms 18 Figure 2.1 Original Signal and Sampling Signal 26 Figure 2.2 PAM sampled waveform 27 Figure 2.3 Figure 2.4 Figure 2.5 PAM Comcepts PAM Sampling Quantization of Samples Figure 2.6 Analog Signal to be digitized 32 Figure 2.7 Sampling and Reconstruction of the waveform from the sample pulses 35 Figure 2.8 Comparison of Analog to PAM signal 37 Figure 2.9 Companding Versus Expanding 41 Figure 2.1 Oa Analog Signal Optical Modulation 45 Figure 2. I Ob Digital Signal Optical Modulation 46 Figure 2.11 a Analog Signal and Noise 55 Figure 2. l Ob Digital Signal and Noise 55 Figure 3.1 Simulation Result of PAM Sampling (Single Channel) 58 Figure 3.2 Simulation Result for PAM system 59 xi

14 Figure 3.3 Diagram of Simulation PAM and TDM System 60 Figure 3.4 PAM System Simulation Input signal 60 Figure 3.5a Sampled I khz Signal 61 Figure 3.5b Sampled 2 khz Signal 61 Figure 3.6 Multiplexed Sampled Signal 61 Figure 3.7a Demultiplexed I khz Signal 62 Figure 3.7b Demultiplexed 2 khz Signal 62 Figure 3.8 Simulation Output Signals 63 Figure 3.9a Channel 1 Comparison of Input to Output Signal 63 Figure 3.9b Channel 2 Comparison of Input to Output Signal 63 Figure 3.10 Figure 3.11 Figure 3.12a Figure 3.12b Diagram of Simulation PCM and TDM System PCM Simulation Input Signals Sampled Channel 1 Signal (PCM Simulation) Sampled Channel 2 Signal (PCM Simulation) Figure 3.13 Sample and Hold Signal (Both Channels) 67 Figure 3.14 Digital Representations of Sampled Signals in Parallel Form 68 Figure 3.15a Serial Digital Representation (Binary) of Channel I 68 Figure 3.15b Serial Digital Representation (Binary) of Channel 2 69 Figure 3.16 Multiplexed Digital Signals of Channel 1 and Channel 2 69 Figure 3.17a Channel 1 Demultiplexed Signal 70 Figure 3.17b Channel 2 Demultiplexed Signal 70 Figure 3.18a Channel 1 Received Parallel Digital Signal 71 Figure 3.18b Channel 2 Received Parallel Digital Signal 71 xii

15 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 xiii

16 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 94 Figure 4.2b Figure 4.3 Figure 4.4 Figure 4.5 Closer View of the 2 khz Signal HPS I Channel PAM System Layout HPS 2 Channels PAM System Layout Analog Optical Transmitter Figure 4.6 Digital Optical Transmitter 98 Figure 4.7 Analog Optical Receiver 99 Figure 4.8 Digital Optical Receiver 99 Figure 4.10 HPS 2 Channel PCM System Layout 100 Figure 4.11 Sampled PAM Signal Hardware Results 101 Figure 4.12 Sampling Signal Hardware Results 102 Figure 4.13 Sample and Hold Signal Hardware Results 103 Figure 4.14 Sample and Hold Sampling Signal Hardware Result 103 Figure 4.15 Receiver Sample and Hold Signal Hardware Result 104 xiv

17 Figure 4.16 After passing through the Low pass Filter Hardware Result 105 Figure 4.17 Multiplexed Sampled Signal (1 and 2 khz) Hardware Result 106 Figure 4.18 Sample and Hold Multiplexed Signal Hardware Result 106 Figure 4.19 Demultiplexed Channel 2 Signal (2 khz) Hardware Result 107 Figure 4.20 Hardware Result Output of Channel Figure 4.21 Serial Digital Converted Analog Signal Hardware Results 109 Figure 4.22 Synchronizing Signal Added to PCM Signal Hardware Result 110 Figure 4.23 Multiplexed (Channel I and 2) signal PCM Hardware Result 111 Figure 4.24 DAC output Multiplexed (Channel 1 and 2) signal Hardware Result 112 Figure 4.25 Demutliplexed, Sample and Hold Signal Channel 2 Hardware Result 112 Figure 4.26 Output Signal of Channel 2 PCM System Hardware Result 113 Figure 4.27 Figure 4.28 Figure 4.29 PAM Single Channel Prepared For Optical Transmission PAM Dual Channel Prepared for Optical Transmission Added DC Offset Single Channel Signal Figure 4.30 Added DC Offset Dual Channel Signal 116 Figure 4.31 Optical Transmitter Signal (Single Channel) 116 Figure 4.32 Optical Transmitter Signal (Dual Channel) 117 Figure 4.33 Preamplifier Signal (Single Channel) 118 Figure 4.34 Preamplifier Signal(Dual Channel) 1 18 Figure 4.35 DC Offset and Voltage Adjusted Signal (Single Channel) 119 Figure 4.36 DC Offset and Voltage Adjusted Signal (Dual Channel) 119 Figure 4.37 Sample and Hold Amplifier Signal Passed From The Optical Reciever 120 (Single Channel) xv

18 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 126 Figure 4.47 Figure 5.1 Figure 5.2 Figure 5.3 The Reproduced Signal at the Receiver End Analog Transmitter Circuit Design Analog Receiver Circuit Design Digital Transceiver Circuit Design xvi

19 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. I

20 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: 2

21 Start Research ý Fiber Optics Communication Hardware Software ir-77 77ýi I ý Reciever Transmitter Simulation Analogue Digital Analogue Digital Analogue Digital f_ t Literature Review Design Build i Run Test Outcome Sucessfull? No Yes Compile Result and Submit Report 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 3

22 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 Fibre-Optic"/. Reciever Cable /s Information Decoder Filter Amplifier JJ` f /ý output Pho ocell or light detector Figure!. I Basic Concepts of Optical Fiber Communication Block Diagram 4

23 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. IV. To produce a Literature review of on the topic of Two-Channel audio link over Optical Fiber. 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. 5

24 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 6