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1. Implementation of Manchester and differential Manchester Digital
encoding
BY
Nabil Ali Sharaf Murshed
B.ENG in Electronic engineering,(communication section),
Sudan University of Science &Technology,2002
A Dissertation
Submitted in Partial fulfilment of the Requirements for
The Degree of Master of Engineering
In
Computer Engineering and Networks
Department of computer engineering
Faculty of engineering &technology
University of Gezira
Supervisor: DR.ABDELRASOOL JABAR ALZUBIDI
Jun 2008

2. ‫ملخص‬
‫ي‬
: ‫وهي‬ ‫التشفيرالرقمي‬ ‫انواع‬ ‫من‬ ‫نوعين‬ ‫على‬ ‫البحث‬ ‫هذا‬ ‫حتوى‬
-
Manchester (MANCH) and Differential Manchester (DMANCH)
‫هذه‬ ‫تنفيذ‬ ‫ويتم‬
‫بالكمبيوتر‬ ‫توصيلها‬ ‫يتم‬ ‫بحيث‬ ‫الكترونية‬ ‫دائرة‬ ‫تصميم‬ ‫عبر‬ ‫التقنية‬
‫الرابط‬ ‫عبر‬
D-25
‫الكمبيوتر‬ ‫عبر‬ ‫البيانات‬ ‫ادخال‬ ‫يتم‬ ‫بحيث‬ ‫و‬
( ‫دي‬ ‫نوع‬ ‫قالب‬ ‫شريحتين‬ ‫شرائح‬ ‫اربعة‬ ‫على‬ ‫ايضا‬ ‫الدائرة‬ ‫وتحتوي‬
(D-flip-flops
‫والشريحتين‬
‫هي‬ ‫االخرى‬
Darlington amplifier
‫شريحة‬ ‫من‬ ‫الواردة‬ ‫االشارة‬ ‫تكبير‬ ‫يتم‬ ‫بحيث‬ ‫و‬
D-flip-flops
‫الشريحة‬ ‫بواسطة‬
Darlington amplifier
‫مرحلتين‬ ‫الى‬ ‫الشريحة‬ ‫هذه‬ ‫ربط‬ ‫ويتم‬
(Two relays)
(‫المرحلين‬ ‫توصيل‬ ‫ويتم‬
relays
)
( ‫االشارة‬ ‫راسم‬ ‫جهاز‬ ‫الى‬ ‫حدة‬ ‫على‬ ‫كال‬
(ooscilloscope
‫تقنية‬ ‫تنفيذ‬ ‫يتم‬ ‫االولى‬ ‫الحالة‬ ‫وفي‬ ‫المدخلة‬ ‫للبيانات‬ ‫العرض‬ ‫شاشة‬ ‫يمثل‬ ‫الذي‬
)
(Manchester
‫وفي‬
( ‫تقنية‬ ‫تنفيذ‬ ‫يتم‬ ‫الثانية‬ ‫الحالة‬
(Differential Manchester
‫البحث‬ ‫بهذا‬ ‫ونكون‬
‫الرقمي‬ ‫التشفير‬ ‫تقنيات‬ ‫من‬ ‫نوعين‬ ‫استخدام‬ ‫من‬ ‫عمليا‬ ‫تمكنا‬ ‫قد‬

3. Abstract
This research includes the digital encoding techniques by designed an electronic
circuit by which two types of digital encoding are achieved: Manchester encoding
(MANCH) and Differential Manchester encoding (DMANCH) .
The circuit was designed so that it can be connected to the computer via the D-25
connector where the computer represents the means to input data.
The other two chips are Darlington amplifier chips so that the signal received from
the D-flip flop is amplified by the Darlington amplifier chip which is connected to two
relays representing the above two digital encoding techniques.
The two relays are separately connected to an oscilloscope device which represents
the output display unit for the data input to the computer after implementing one of
the digital encoding techniques described above.
This research allows us to make use of digital encoding practically by inspecting two
types of digital encoding techniques

4. TABLE OF CONTENTS
Dedication............................................................................................................... iii
Acknowledgment......................................................................................................iv
Abstract ....................................................................................................................v
Abstract (Arabic)...................................................................................................vii
Table of contents....................................................................................................viii
List of Figures................................ ...................................................... ...............xiii
List of Tables......................................................................................................... xiv
List of abbreviations............................................................ ...................................xv
CHAPTER ONE INTRODUCTION
1-1 introduction.........................................................................................................1
1-2 Background.........................................................................................................1
1-3 Approach.............................................................................................................2
1-4 Problem definition...............................................................................................2
1-5 Objective of the research................................................ ....................................3
1-6 Research outline..................................................................................................3

5. CHAPTER TWO DIGITAL TO DIGITAL ENCODING
2-1Introduction..........................................................................................................5
2.2Digital to digital encoding................................................................................... 6
2.2.1Unipolar..........................................................................................................7
2.2.2Polar................................................................................................................9
2.2.2.1nonreturn to zero (NRZ) encoding...................................... ...................10
2.2.2.2 Return to zero (RZ)...................................................................................12
2.2.2.3Biphase......................................................................................................13
2.2. 3 Bipolar........................................................................................................16
CHAPTER THREE MANCHESTER and DIFFERENTIAL MANCHESTER
3. Biphase…………………………………………………………………………17
3.1 Manchester encoding......................................................................................17
3.1.1features............................................................................... ..........................17
3.1.2description....................................................................................................18
3.1.3 Summary......................................................................................................18
3.1.4 Conventions for representations of data........................................... ..........19
3.1.5 Shortcomings..................................................................................... .........20
3.1.6 In summary..................................................................................................21
3.2. Differential Manchester encoding................................................................... 21
3.3 Bi phase pros and cons............................................................................ .........25

6. CHAPTER FOUR INTERFACING TO COMPUTER
4.1 Interfacing concepts...........................................................................................26
4.1.1 Sensors as Input ………………………………………………………….28
4.1.2Analog to Digital Converter (A/D) …………..……….…………………..29
4.1.3 Digital to Analog Converter (D/A)……… ……….……… ..… ………..29
4.1.4 Interfacing outputs………………………………………………………..29
4.1.5 Interfacing Digital Inputs…………………………….………...................30
4.2 Serial Interfacing...............................................................................................32
4.2.1 Types of serial interface …………………………………………………. 32
4.2.2 Interface the serial/RS232 port…………………………….……………. ..33
4.3 parallel Interface................................................................................................38
4.3.1 Introduction to parallel ports…………………………................................38
4.3.2 Parallel Ports Types…………………………………………......................39
4.3.3 Other Parallel Ports……………………………………………...................39
4.3.4 PC 1/0 Controller Card………………………………………………........40
4.3.5Demultiplexer (demux)………………… ……………………........... .........40
4.3.6 Hardware Properties…………………………………………………... ….41
4.3.7 port addresses…………………………………………………….…. …..42
4.4 PC Buses……………………………………………………………………....43
4.4.1 ISA bus……………………………………………………………………..44

7. 4.4.2 ELSA bus…….…………….……………..……….………………………..46
4.4.3 PCI
bus…………….………....………..……..…….………………..........47
CHAPTER FIVE HARDWARE DESIGN
5.1 D-25 male connector.........................................................................................48
5.2 HD74LS373...................................................................................................... 49
5.2.1Features...................................................................................................... 50
5.2.2 Pin arrangement..................................................................................... 51
5.2.3function table............................................................................................51
5.2.4 Block Diagram.........................................................................................52
5.3ULN2003A............................................................................................. .......... 52
5.3.1Description.................................................................... ........................... 52
5.3.2 Pin connection........................................................... ..............................53
5.4 Relay..................................................................................................................54
5 .4.1Choosing a Relay................................................. .................................... 55
5.4.2Protection diodes for
relays…………………………….………………. 56 5.4.3Reed
Relays…………………………… …….….. …….……………….57 5.4.4Relays and
transistors compared……… ………….. …………………..58
5.4.5Advantages of relay…………………………… ….…………………….58
5.4.6 Disadvantages of relays……………………………………..………….58
5.5 Design steps………………………………… ………………….…..…… .....59
5.5.1step no 1………………………………………………………..…..……..59

8. 5.5.2 step no 2………………………………………………………….….....…60
5.5.3 step no 3………………………………………………………………..…60
5.5.4 step no 4 ………………………………………………………..…...........61
5.5.5 step no 5…………………………………………………………………..61
5.5.6 step no 6………………………………………………..……………........62
CHAPTER SIX SOFTWARE
6.1. Definition…………………………………………..........................................64
6.2 Flowchart………………………………………………………….………... ..65
CHAPTER SEVEN RESULT AND DISCUSSION
Result and Discussion..............................................................................................67
Practical circuit…………………………………………………………….……..68
CHAPTER EIGHT CONCLUSION AND RECOMMENDATION
8.1Conclusion ……………………………………………………………….……69
8-2 Recommendation …………………………………………………………... ..69
REFERENCES……………………………………………………………………71
APPENDIX
A: CODE………………………………………..………….…………………… .72
B: HD74LS373……………………………………………..……………………..75
C:ULN2003A……………………………………………………………………..83
.