WIRELESS HELMET COMMUNICATION SYSTEM

oor YEONG YIH

Universiti Malaysia Sarawak 2000

TIC 5103.2

"2"000 059

Dorang Pcnyerahlln Tesis Universiti Malaysia Sarawnk

RI3a

BORANG PENYERAHAN TESIS'

ludul: Wireless Helmet Communication System

SESI PENGAJIAN: 1999/2000

Saya oar YEONG YIH (HURUF BESAR)

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

I. Hakmilik kertas projek adalah di bawah nama penulis melainkan penulisan sebagai projek bersama dan dibiayai oleh UNIMAS, hakmiliknya adalah kepunyaan UNIMAS.

2. Naskhah salinan di dalam bentuk kertas atau mikro hanya boleh dibuat dengan kebenaran bertulis daripada penulis.

3. Pusat Khidmat Maklwnat Akadernik, UNIMAS dibenarkan membuat salinan untuk pengajian mereka. 4. Kertas projek hanya boleh diterbitkan dengan kebenaran penulis. Bayaran royalti adalah mengikut kadar

yang dipersetujui kelak. 5. * Saya membenarkanltidak membenarkan Perpustakaan membuat salinan kertas projek ini sebagai bahan

pertukaran di antara institusi pengajian tinggi. 6. ** Sila tandakan (.I)

c=:J1 SULTI' (Mengandungi maklwnat yang berdrujah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSlA RASMI 1972).

CJ TERHAD (Mengandungi maklwnat TERHAD yang te1ah ditentukan oleh organisasil badan di mana penyelidikan dijalankan).

~ TIDAK TERHAD

Disahlcan oleh

(TANDATANGAN PENULIS)

Alamat tetap: 205 TAMAN NURI

JALAN DATIJK KUMBAR EN. AL-KHALlD BIN OTHMAN Nama Penyelia

05300 ALOR SETAR KEDAH MALAYSIA

Tarikh: 27 March 2000 Tarikh: 27 March 2000

(TANDATANGAN PENYELlA)

CATATAN Potong yang tidak berkenaan. •• Jika Kertas Projek ini SULIT atau TERHAD, sUa lamplrkan surat daripada pihak berkuasal

organisasl berkenaan dengm menyertakan sekali tempoh kerias projek. lni perlu dikelaskan sebagai SULIT atau TERHAD.

dem A 'i

'resis ini telah dibaca dan disahkan oleh:

I . 4- r 'LO c::ld TarikhEn. Al·Khalid bin Othman

Penyelia

WIRELESS HELMET COMMUNICATION SYSTEM

001 YEONG YIH

Tesis Dikemukakan Kepada Faculti Kejuruteraan, Universiti Malaysia Sarawak

Sebagai Memenuhi Sebahagian daripada Syarat Penganugerahan Sarjana Muda Kejuruteraan

Dengan Kepujian (Kejuruteraan Elektronik dan Telekomunikasi

II

-

To Beloved Family

ACKNOWLEDGEMENT

The Author would like to thank the supervisors, En Al-Khalid bin

Othman, for his extraordinary concern, advice, cooperation and support

throughout his supervision of the thesis project. The Author also would like to

gratitude to his ex-supervisor, En. Thelaha had help author through his ideas

and experiences that contributed to the success of this project. Without his

support and advice, this project might not be done efficiently.

The Author also appreciates the blessings and sacrifices given by the

Author's family members who have been very supportive, loving and

understanding. The Author also would like to thank to all the Author's

lecturers, friends, and classmates, for their assistance, support and advice

throughout the academic year. Finally, the Author would like to thank to all his

faculty staffs for their support and cooperation during his academic year in

UNlMAS.

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I ,..

ABSTRACT

Nowadays, telecommunications systems become very popular. With

today technology, telecommunication systems have reach to the wireless

system. This system is very convenience, which allow users to bring the

communications tool to any place since the transmission medium is through air.

As a motorcyclist, it found that it is very hard to communicate with the pillion

rider during riding. Therefore, with the current wireless communication

technology, this project is designed and develops a wireless helmet

communication, which will improve the condition of communication between

motorcyclist and the pillion rider. In this project design, the features such as

flexibility, and safety are included.

IV

ABSTRAK

Dewasa ini, sistem telekomunikasi semakin popular. Dengan teknologi

yang sedia ada, sistem telekomukasi telah mencapai ke tahap komunikasi

tanpa wayar (wireless). Sistem ini adalah sangat memudahkan kerana

pengguna dapat membawa alat komunikasi ke mana-mana tempat

memandangkan medium penghantaran komunikasi adalah melalui udara.

Sebagai seorang penunggang motorsikal, penulis mendapati komunikasi antara

penunggang dan pemboncengnya adalah begitu sukar terutamanya ketika

dalam perjalanan. Dengan teknologi yang sedia ada, projek ini adalah untuk

mereka dan memajukan komunikasi tanpa wayar helmet. Dalam projek ini

juga, ciri-ciri rekaan juga merangkumi aspek kefleksibelan dan keselamatan.

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CONTENTS

APPROVAL LEITER

APPROVAL SHEET

PROJECT TITLE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

CONTENT

LIST OF TABLE

LIST OF FIGURE

LIST OF ABBREVIATIONS

Chapter

1 INTRODUCTION

1.1 Background

1.2 Project Overview

1.3 Project Objective

2 LITERATURE REVIEW

2.1 Case Study

VI

Page

iii

IV

V

vi

ix

x

xi

1

1

3

4

5

5

I

2.2 Modulation Technique 7

2.2.1 Introduction 7

2.2.2 Analogue Modulation 10

2.2.8 Linear Modulation 11

2.2.3.1 Amplitude Modulation 11

. 2.2.4 Angle Modulation 11

2.2.4.1 Phase Modulation (PM) 12

2.2.4.2 Frequency Modulation (FM) 12

2.2.5 Comparison Among AM, FM, PM 13

2.3 Transmitter 14

2.3.1 Introduction 14

2.3.2 Microphone: Transmitter Input Device 14

2.3.3 Voltage-controlled Oscillators (VCOs) 15

2.3.4 Frequency Multipliers 16

2.4 Receiver 18

2.4.1 FM Receiver 19

2.4.2 FM Demodulators 24

2.4.3 PPL Demodulators 24

3 CIRCUIT DESIGN 29

3.1 Introduction 29

3.2 Circuit Description 29

3.3 Block Diagram for The Transmitter Circuit 30

3.3.1 Input 31

3.3.2 Modulator 32

Vll

3.:1.:1 AmpliLior 83

3.3.4 Antenna 34

3.4 Circuit Implementation Inside the Helmet :15

4 CIRCUIT ANALYSIS AND TROUBLE SHOOTING 36

4.1 Introduction 36

4.2 Signal Analysis 36

4.3 Carrier Frequency Analysis 41

4.4 Transmitted Distance 43

4.5 Tool for Circuit Simulation 44

5 CONCLUSIONS & FURTHER WORK · 46

5.1 Conclusion 46

5.2 Recommendations 46

Bibliography 50

Vlll

LIST OF TABLE

PageTable

2.1 Comparison of The Helmet Communication

7System

2.2 Comparison Among AM, FM, and PM 12

4.1 Range of Carrier Frequency And The

Amplitude At The Maximum Power Transfer 42

lX

LIST OF FIGURE

Figure

2.1 Family Tree of Modulation Methods

2.2 (a) The VCO Output Waveform for

Switching Comparator Waveform

2.2 (b) The Output Waveform as The Result of

Charge IDischarge of The Capacitor

2.3 An AC Equivalent of a VCO

2.4 Quadruplers

2.5 Block Diagram of Receiver

2.6 Block Diagram For the FM Receiver

2.7 PPL Block Diagram

3.1 The Circuit Design For The Transmitter Part

3.2 Block Diagram for the Transmitter

3.3 Wireless Helmet Communication Design

4.1 (a) Signal Analyses At Each Node of The

-(g) Transistor

4.2 Graph carrier frequency against R9

Page

8

15

16

16

18

18

20

25

29

30

35

37-40

43

x

LIST OF ABBREVIATIONS

AM Amplitude Modulation

PM Phase Modulation

FM Frequency Modulation

ASK Amplitude Shift Keying

FSK Frequency Shift Keying

PAM Pulse Amplitude Modulation

PDM Pulse Duration Modulation

PPM Pulse Position Modulation

t!.M Delta Modulation

PCM Pulse Code Modulation

PPL Phase-Locked Loop

VCO Voltage-Controlled Oscillator

IF Intermediate Frequency

RF Radio Frequency

Xl

CHAPTER 1

INTRODUCTION

1.1 Background

The goal of telecommunications system is to transfer the information

such as voice and data from a point to another. This technology is not only

applied for the long distance communications but it is also applied for the short

distance. Among the examples are walkie-talkie, intercom system, and wireless

microphone system. The walkie-talkie is used widely especially during patrol by

polices offices or security guards. Intercom system had been applied in an

organization such as companies, universities and government departments,

while the wireless microphone is normally used in public addressing system.

With the revolutions of the telecommunications systems, the cable

telecommunication system had been replaced by the wireless communication

systems. This make communications possible everywhere and anywhere

because the transmission medium is no longer using wire or cable, but using the

microwave, air, and infrared as the medium. This factor makes the system

convenience to be applied in anyplace .

In Lhia thesis, the research will focus on wireless helmet communications

part. Tho technology of helmet communications was not a latest t;echIlolo~y.

This is because this technology had heen applied at the present time, some of

the examples are pilot helmets in aircraft system, and motor racing helmet. In

this thesis, the application of the wireless helmet communicatioml will be

focusing on the communications between the motorcyclist and the pillion rider.

As we all known, wearing the helmet is a must for both motorcycle rider

and pillion in countries such as Malaysia, Singapore, Hong Kong and United

Kingdom. The purpose of wearing helmet is to protect the motorcyclist head

from injury. If a person having a serious head injury, the casualty might face

the critical condition such as coma, and whole life paralyze or even died on the

spot. However, wearing helmet during driving has caused some difficulty for

motorcyclist and the pillion especially in communicating with each other. In

this case, the motorcyclist need to turn his head back while communicate with

the pillion rider. This might also increase the possibility of the accident

occurrence. With this system (wireless helmet communications system), the

communication between motorcyclist and the pillion will be convincible. The

motorcyclist doesn't need to hold the equipment (such as hand phone) during

communications, as the equipment is a part of the helmet system. In other

word, the wireless communication system is an extra safety measurement for

the motorcyclist and the pillion.

In this thesis, the helmet communications between motorcyclist and the

pillion maybe different with the aircraft pilot helmets and motor racing helmet.

For pilot helmet, its helmet is a part of the aircraft system where there is a wire

2

connecLcd betw(l n the helmet and the system, while for the motor racing

helmet communication system, the communications system is the simpl(~ x

system, which the motorcyclist can only receive the signal from his counterpart

or the manager only.

1.2 Project Overview

Briefly, the communications circuit that implement in this thesis is

using frequency modulation (FM) modulation and demodulation technique in

the transmitter and receiver respectively. In this project, more attention is

given on the transmitter part. This is because commercial receiver (radio) can

be used in the receiver if the transmitted signal falls in the broadcasting range,

which is in between 88MHz to 108MHz. When a motorcyclist speaks, the voice

signal will be modulated and transmitted. The pillion will receive the signal

through receiver, which will demodulate the RF signal to original signal

waveform. Since the motorcyclist and the pillion sit very close, the estimated

distance for this wireless system is around one foot apart. The suggested

voltage is 3V or using two AA batteries because the distance for this system is

short (around one foot). The transmit range must be limited because the

conversation is just between the motorcyclist and pillion only, and it shouldn't

be received by third party.

As the summary, this wireless helmet communications system consist

two major part, which are:

1. A Transmitter

2. A Receiver

3

1.3 Project Objective

The objective of this project is to facilitate the communication between

rider and the pillion. For this purpose, the full duplex wireless helmet

communication system will be designed. In transmitter part, the wireless FM

microphone is being implemented. The advantages of using the FM microphone

as the transmitter is:

• The device for using this technique is more economical compare to other

technique. For example, using microwave frequency might be useful but the

cost for device is much more expensive.

• The normal radio can be used as the receiver part if the modulating signal is

in the broadcasting frequency range.

• This transmission method is using the wireless technology. This means that

it is convenience for both motorcyclist and the pillion.

However there is a disadvantage by implement this method, where other

people who is near the spot could receive the signal when they tuning the radio.

This hardware product will make the communication between

motorcyclist and the pillion easier. This product might be an extra safety

measurement for the motorcyclist in the future.

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Chapter 2

LITERATURE REVIEW

2.1 Case Study

Besides helmet communication system for the motorcyclist, there are

some fields of profession using the helmet as the communications tool. Among

those profession are pilot, motor racing team, divers, and astronauts.

For pilot helmet design, its helmet is a part of the aircraft system. There

is a wire connected between the helmet and the aircraft system. This system

using couple wire as the transmission medium and the transmission mode is

full duplex system. Compare to motor racing helmet communication system, the

transmission mode is the simplex system, which the motorcyclist can only

receive the signal from his counterpart or the manager only. In this

transmission part, radio signal is used and the transmission medium is air. For

astronauts, their helmet communication is using the radio signal, which can

transmit through the vacuum. The used transmission mode in this system is

half duplex, which seem to be an extension of the walkie-talkie system. For the

diver helmet system, the helmet communication system receives the signal

through the cable, which contains the couple wire. This cable is also supplying

5

Transmission Descri (l bon

Mode

Pilot

Mediumtype

The wire connected to the

I aircraft system

racing

Full duplex Couple wire

The system design is similar

team

SimplexAir

to "walkman"

Astronaut The system is an extension

I of the walkie-talkie

Diver

Half DuplexVacuum

Half Duplex The connected cable to the

helmet contain couple wire

Infra-red

Couple wire

The system is link by

infrared

Air

Full Duplex

Full Duplex The wireless full duplex

system, where free space as

. I the transmission medium.

Table 2.1: Comparison of The Helmet Communication System

J Modulation Technique

1.J.1 Introduction

For human, the range of voice frequency that can detect is in the range

10Hz to 20kHz. If the transmitted voice signal is in the original form, then we

receive the noise if there is other transmitted signal. Modulation technique

7

had been introduced the telecommunication system. Modulation refers to

changes produced by in the baseband to facilitate its transmission. Generally.

the signal cannot be transmitted usefully without modification. There are two

distinct classes method, which are:

• Frequency translation: moving the whole baseband up to a much higher

frequency range

• Digitizing: changing the baseband to digital form, usually binary, by

sampling

Even both methods above are named as modulation, but the second

(digitizing) keeps the signal in a baseband frequency region of different

bandwidth. These categories can subdivide into the specific modulation types

related by the techniques used in the family tree of modulations method in the

figure 2.1.

To choose a suitable modulation technique, it is influence by:

• The characteristics of message signal such as in the analog form, binary,

or digital form

• The characteristics of the channel such as power, and the bandwidth

needed

• The performance of desired from overall communication system

especially the reliability, accuracy and quality

• The use to be made of the transmission data

• The economic factors or the cost needed

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All modulation

I I Frequency translation Sampling

I

Analogue m Binary

r1l Not Quantized

I

Quantized

II AM FM PM ASK FSK PSK PAM PDM PPM .6.M peM

Figure 2.1: Family Tree of Modulation Methods

Among the five factors stated above, the first three factors can be

explained theoretically while two last factors, it can be developed through

sufficient insight by experience in proper perspective for a particle application.

In this project, the analogue modulation might be suitable compare to

the digital modulation. This is because the message signal for the voice data is

in the analog form. To digitalize an analog signal, the technique of sampling

and coding is needed. This will cause the transmitter and receiver circuits

become more complex. Undoubtedly, transmission through digital modulation

might be more reliable since the noise corruption very much less likely. But if

considering the transmission distance (one foot) the noise corruption might be

Jesser compare to the long distance transmission such as mobile phone.

9

2.2.2 Analogue Modulation

In analogue modulation a continuously varying analogue baseband

signal changes some aspect of a carrier signal so that, when sent though a

transmission system, the baseband can be recovered intact from the carrier.

Two basic types of analog modulation are continuous-wave modulation and

pulse modulation. The carrier usually assumed to be in sinusoidal form. For a

sinusoidal carrier, a general modulated carrier can be represented

mathematically as:

Xc =Ec cos ( roc t + <Pc )(2-1)

Where Ec: Carrier Amplitude

Ole: Carrier Frequency

<Pc: Carrier Phase Shift

A further general classification occurs if the carrier is rewritten as:

Vc =Ec cos ( ec) (2-2)

For the equation above, we found that there are two types of modulating

signal, which are linear modulation and the angle modulation. The result of

linear modulation occurred if we fix the angular of carrier, ec where the carrier

frequency, m and the carrier phase, In is fixed to the constant. c ~c

10

the

modulation

2.2.4

Linear Modulation

Generally, by setting the instantaneous phase deviation <Pc (t) to Z8ro,

modulation will represent a linear modulated carrier. This will only

occurred if there is a change the carrier amplitude, E in equation 2-2 . As the c

technique is changing with the carrier amplitude, therefore

Amplitude Modulation (AM) is the only linear modulation technique.

2.2.3.1Amplitude Modulation (AM)

The AM results when a dc bias A is added to m (t), message signal, prior

to the modulation process. The result of the dc bias is that a carrier component

present in the transmitted signal as:

Xc =[A + m(t)]Ec cos cot (2-3)

Angle Modulation

To generate angle modulation, the value of amplitude for modulated

carrier is fixed while either the phase or the time derivative of the phase carrier

varied linearly with the message signal Ec' 'rhus the general angle-

modulated signal is given by:

Xc = Ec cos [cot + cp(t)] (2-4)

The instantaneous phase of Xc is defined as

8i (t) =roc t + cp(t) (2-5)

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