UNIVERSITI PUTRA MALAYSIA

INTERNET - BASED SECURITY AND MONITORING SYSTEM

ISAMELDIN MOHAMMED SULIMAN

FK 1998 10

INTERNET -BASED SECURITY AND MONITORING SYSTEM

By

ISAMELDIN MOHAMMED SULIMAN

Thesis Submitted in Fulfillment of the Requirements for the Degree of Master of Science in the Faculty of

Engineering Universiti Putra Malaysia

November 1998

To my parents and sisters

ACKNOWLEDGEMENTS

I would like to express my sincere thanks to my supervisor Dr. Abd Rahman

Ramli. This thesis would not have been done without his support, encouragement , and

comments. Thanks and appreciation is extended to the members of the supervisory

committee Dr. Mahmud Hassan and Mrs. Roslizah Ali.

I would also like to express my thanks to the staff at the Graduate School Office

for their help and cooperation. My appreciation and gratitude to all of the individuals at

the Department of Computer and Communication System Engineering , who had been

cooperative.

I gratefully ackno wledge the support of Ir. Dr. No nnan Bin Mariun the general

manager of Control and Automation System Center (CA SC ). My thanks and appreciation

to my colleagues at the CA SC for their help and suggestions during the research work.

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TABLE OF CONTENTS

Page

AC KNOWL EDG EM ENT S. . . . . ..... . ............ ............ .. . .. . .. . .... . ............. . III

LI ST O F T ABL ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v u

LI ST O F FIG URES ......................................................... ........... .... Vlll

LI ST O F ABB REVIATION S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

AB ST RACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x u

AB ST RAK . . . . . . .......... .................. .. ... ..................... .............. ..... .. . . XIV

CHAPTER

I INT ROD UCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Benefits ofa Web-Based Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Objectives . . . . . . . . .. . .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . ... . ... 3

Thesis Organisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

II REVI EW ON SEC URIT Y SYST EM S A ND

A LA RM SIGNA LLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Security and Monitoring Technology .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Intrusion Detection and Monitoring Systems . . . . . . . . . . . . . . . . . . . . . . . . . 8

The Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

Internet Telephony . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3

III BAC KG RO UND TH EO RY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

Java Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

Telephone Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6

The Phone Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

IV

On-hook and Off-hook Operation ........................... 17

DTMF Dialing .................................................. 19

TP5088 DTMF Generator .................................... 20

Telephone Line Interface ...................................... 22

Modems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

PC Serial Interfacing ................................................... 23

PIC16C8 4 Microcntroller .............................................. 24

IV SYSTEM ARCHITECTURE ........................................... 25

Introduction ............................................................... 25

General Layout of the Security System ............................. 25

Software Description .................................................... 27

Interface to the Host Machine ................................. 27

Interrupts ........ ................................... ............ ... 27

Data Exchange between C Program and Java Applet ..... 28

The Web Server Installation ............................................ 29

The Communication Program ......................................... 30

Implementing the Interrupt Service Routine (ISR) ................. 31

Creating the Monitor Server ............................................ 34

Implementing the Monitor Client Applet ............................ 37

The infotist Applet ....................................................... 39

HTTP Links to Monitored Locations Applet .. ...................... 42

The Password Apple .. ...... ..... ............ .................. ... ..... ... 44

The Chat System .......................................................... 46

Creating Multithread Chat Server........ ................. ... 47

Building Chat Client Applet ................................... 50

Conclusion ................................................................ 54

V RESULTS AND DISCUSSION ......... ......... . ... .............. . ... 55

System Performance ........ .................... ...................... ... 55

Conclusion ................................................................ 62

v

VI CON CLUSION S AND RECOMMENDA nON S ................. 63

Conclusions ............................................................... 63

Recommendations and Directions for F uture Work s ............ 66

Sensors Unit ...................................................... 67

Control Unit ..................................................... 67

Auto-Dialler Unit ................................. ............ 68

Data Access Arrangement (DAA) ............................ 68

REFERENCES . . . . . . . . . . . . . . ..... .. ... . . . . . . . . . . . . .. .. . .... ... . . . . . .. ... . . . . . . 7 1

APPENDICES .. . . . . . . . . .. . . . . . . . . . .... .. . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . 7 5

A The Communication Program......... ... .................... 7 6

8-1 The Monitor Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 9

8-2 The Monitor Client Applet ............... ....... .... ...... .... 8 3

C The Infolist Applet ............................................ . 9 0

D HTTP Link s Applet ............................................ 9 7

E The Password Applet .......................................... 9 9

F -1 The Chat Server ................................................ 102

F -2 The Chat Client Applet ..... ............. ...................... 107

VITA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

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LIST OF TABLES

Table Page

1 DTMF Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2 Functional Truth Table of TP508 8 DTMF Generator.... . . . 21

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LIST OF FIGURES

Figure Page

1 On-hook State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2 Off-hook State .................. ......... ... ...... .................... . ..... 18

3 General Layout of the Security System .............................. ... 26

4 Mechanism for Data Exchange between Java

Applet and C Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5 Algorithm for Implementing the Interrupt Service Routine . . . . . . . . . 32

6 The Communication Program F lowchart . . . . . . . . . . . . ............ ... ... 33

7 Algorithm for Creating the Monitor Server . . . . ... . . . . . . . . . . .. ... . . . . . 35

8 The Monitor Server F lowchart . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . ... .. . 36

9 Algorithm for Creating the Monitor Client ............................. 38

10 The Monitor Client F lowchart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39

11 Algorithm for Infolist Applet . . . . . . . . . . . . . . . . . . .. . .. . . ... .. . . . .. . . . . . . . . . 40

12 The Infolist Applet F lowchart . . . . . . . . . . . . . . . . . . . . . . . . .............. ..... 41

13 The HTTP Link s Applet F lowchart . . . . . .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

14 The Password Applet F lowchart . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . 45

15 The Chat Client/Server Pair . . . . . . . . . . . . .. . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . 47

16 Algorithm for Creation of the Chat Server . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 48

17 The Chat Server F lowchart . . . . . . . . .. . . . . . . .. . . .. .. . . . .. . . . . . . . . . . . . . . . . . . 49

18 Algorithm for Building the Chat Client Applet . . . . . . . . . . . . . . . . . . . . . . . . 52

19 The Chat Client F lowchart . . . .. . . . ... . . . . . . . . . . . . . . ...... .. ............. 53

Vlll

20 The Password Applet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

21 Applet s Execut ion Using Int ernet Explorer 4.01 . ... ... .. .. ...... .... 58

22 Applet s Execut ion Using Hot Java Browser. ...... .. .... ... ......... ... 58

23 Applet s Execut ion Using N et scape N avigat or Gold 3.01 ..... ... .... 59

24 Chat Server Response t o Chat Client s .... .. . . . . . . . . . . . . . . . . . . . ... . . . ... 60

25 The Chat Client Applet . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

26 Block Diagram of t h e Proposed Monit oring Device 67

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LIST OF ABBREVIATIONS

AC Alternating Current

AWT Abstract Windowing Toolk it

CCTV Closed-circuit TV

CGI Common Gateway Interface

CPU Central Processing Unit

DAA Data Access Arrangement

DC Direct Current

DCE Data Communication Equipment

DLAB Divisor Latch Access Bit

DTMF Dual Tone Multi-frequency

DTE Data Terminal Equipment

DTR Data Terminal Ready

EOI End of Interrupt

F IF O F irst In F irst Out

GUI Graphical User Interface

HTML Hypertext Mark up Language

HTTP Hypertext Transfer Protocol

IER Interrupt Enable Register

IRQ Interrupt Request

ISR Interrupt Service Routine

x

JV M

LAN

LED

MSR

OOP

PC

PIC

PSTN

PWS

RI

RISC

ROM

RTS

RTU

SCADA

TCPIIP

UART

URL

WWW

Java V irtual Machine

Local Area Network

Light Emitted Diode

Modem Status Register

Object Oriented Programming

Personal Computer

Programmable Interrupt Controller

Public Switched Telephone Network

Personal Web Server

Ring Indicator

Reduced Instruction Set Computing

Read Only Memory

Request To Send

Remote Terminal Unit

Supervisory Control And Data Acquisition

Transmission Control ProtocollIntemet Protocol

Universal Asynchronous Receiver/Transmitter

Uniform Resource Locator

World Wide Web

Xl

Abstract of thesis submitted to the Senate of Universiti Putra Malaysia in fulfilment of the requirements for the degree of Master of Science.

INTERNET-BASED SECURITY AND MONITORING SYSTEM

By

ISAMELDIN MOHAMMED SULIMAN

NOVEMBER, 1998

Chairman: Abd Rahman Ramli, Ph.D.

Faculty: Engineering

This study describes a remote monitoring and security system based on the

Internet. It is intended to investigate the possibilities of using the integration of the

Internet and telephone lines in providing solution to security problems by

conveying alarm signals from remote monitored locations. A homepage was

developed to allow selected users to get monitoring and security information. A

special purpose web server was designed to handle the system. This web server

which is acting as a central monitoring station will supply the system's users with

information reporting any intrusion at remote monitored locations

The system utilised the existing telephone network , which is cost-effective

and user friendly in alarm transmission from remote monitored location. An internal

modem was used to maintain interface between the telephone line and the web

server. A communication program developed using C language was responsible for

xii

data capturing from the modem through the serial port and providing them to the

web server. Java language was used for developing a server program that is running

in the back ground to enable data provided by the communication program to be put

on the Internet for access. A graphical user interface (J ava applets) was

implemented to allow users to access the system.

The results of applying this approach showed the possibilities of using the

integration of the Internet and telephone lines in conveying alarm signals and

control command. It also emphasised the import ance of Java language in

developing software programs for Internet-based systems. F urthermore, C language

is still required to fill the low-level interface gap that was not supported by Java

language. F inally, the application described in this study demonstrated that the

Internet can be used not only for information exchange and retrieval, but also used

as a communication medium for monitoring and controlling of remote physical

environments.

xiii

Abstrak tesis yang dikemukan kepada Senat Universiti Putra Malaysia untuk ijazah Master Sains

SISTEM KESELAMATAN DAN PEMANTAUAN BERASASKAN INTERNET

Oleh:

ISAMELDIN MOHAMED SULIMAN

NOVEMBER, 1998

Pengerusi: Abd Rahman Ramli, P.hD.

Fakulti: Kejuruteraan

Kajian ini menerangkan satu sistem pemantauan dan keselamatan jarak jauh

menggunakan internet. Tujuan kajian adalah untuk menyiasat kemungkinan

menggunakan integrasi talian telefon dan Internet untuk menyelesaikan masalah

keselamatan dengan menghantar isyarat penggera dari lokasi jauh. Halaman web

dibangunkan untuk membenarkan pengguna mendapatkan maklumat bagi pemantauan

dan keselamatan. Komputer perumah (pelayan WWW) bertindak sebagai stesen

pemantauan pusat yang menyediakan kawalan keselamatan dan laporan maklumat

keadaan sistem pengguna di lokasi pemantauan pada jarak jauh. Satu pelayan web dibina

khusus untuk mengawal sistem ini.

Sistem ini menggunakan rangkaian telefon yang sedia ada, yang mana ia lebih kos

efektif dan senang dipakai dalam penghantaran isyarat penggera dari lokasi jauh. Satu

modem dalaman digunakan untuk mengantaramukakan tali an telefon dengan pelayan

web. Program komunikasi yang dibangunkan dalam bahasa C bertanggungjawab untuk

xiv

mendapatkan data dari modem melalui pangkalan bersiri dan menghantar data itu kepada

pelayan web. Bahasa Java digunakan untuk membangunkan satu program pelayan yang

lari pada latar belakang supaya data yang diberi oleh program komunikasi boleh

dipaparkan pada internet untuk dicapai. Satu pengantara bergrafik (Java Applet)

dibangunkan supaya pengguna boleh mencapai sistem tersebut.

Keputusan daripada perlaksanaan kaedah ini menunjukkan kemungkinan untuk

mengguna integrasi internet dan talian telefon dalam menghantar isyarat penggera dan

arahan kawalan. Ia juga menitikberatkan kepentingan bahasa Java dalam pembangunan

peri sian untuk sistem berasaskan internet. Selanjutnya, bahasa C masih diperlukan untuk

memenuhi ruang aras rendah yang tidak dapat dilakukan oleh bahasa Java. Secara

kesimpulan, kajian yang diterangkan ini telah membuktikan bahawa internet boleh

digunakan bukan hanya kepada pertukaran maklumat dan capaian, tetapi ianya boleh

digunakan sebagai perantara komunikasi untuk pemantauan dan kawalan persekitaran

fizikal pada j arak yang j auh.

xv

CHAPTER I

INTRODUCTION

Computer network s and data communications are of great importance in today's

information society. Data communications is used to extend the power of computers and

allow computer facilities to be accessed at remote sites. The emergence of advanced

network ing capabilities and the availability of software and information components

mak es it easier to implement network ed data acquisition systems that is used to support

a wide range of applications lik e telemedicine (Koblas and Stienbak k , 19 9 4) ,

teleconferencing (Kirstein, 19 9 4) , control (Rovetta et at., 19 9 6) , and industrial

applications.

Within the Internet, the World Wide Web (WWW) has become the standard

integrative platform to access Internet services. It provides an effective mechanism for

distributing and sharing information. WWW offers a suitable infrastructure that integrate

computer-based services from multiple platforms and provides flexible and effective

tools for examining and monitoring remote physical environments. The adoption of new

Web-based systems will allow for higher level of interaction between users at remote

clients and servers.

2

The design and installation of security systems employs a wide variety of

techniques, often involving special types of equipment and materials designed for

specific applications (Traister, 1990). Advanced electronics has allowed security

systems to become highly efficient and flexible. Alarm signal transmission is the most

import ant part of an intruder detection system, therefore different types of

communication systems have been used for alarm signalling. Telephone lines over the

years have proved extremely reliable which provides a practical solution consistent with

both security and costing. Moreover, the introduction of microcontrollers will increase

the security considerably.

The work described in this study is an attempt that has been made to use the

integration of the Internet and telephone lines in security systems. The intense interest in

propert y protection and personal safety has made security systems highly desirable.

Monitoring services are needed for several reasons; some of which include house

location, away of home, or the desire of greater peace of mind.

The thesis outlines an approach used to build reasonably interactive security

system, which uses WWW-downloadable Java applet that interact with remote server. It

presents the benefits brought and limitations imposed by using the WWW and Java

language in developing real-time applications. The security system is a tangible example

of how modem technology can be used to provide security services.

3

Benefits of a Web-Based Environment

Within the past few years, the profile of the Internet has changed from that of

network connecting modest number of research institutions to a back bone connecting

individuals, government agencies, an d corporations in an emerging information

infrastructure (Larnm and Reed, 1 996) . The rapid growth of the WWW made it the most

convenient way to access information in the Internet. Moreover, the emergence of Java

language as an effective tool for extending functionality and improving performance of

the Web will facilitate utilising the Internet in building real-time applications.

The protection of property against attack s is the aim of any security procedure.

Many types of security systems are used to support protection of human property, which

range from private protection (homes) to public protection (firms) . These systems are

continuously scanning the area under monitoring, look ing for intruders and reporting

whenever intrusion is detected. Integrating this type of systems in the Internet, which has

the ability to provide many services (communication, multimedia capabilities, etc.) will

enhance security system in several ways. F or example, the multimedia capability of the

Internet could be used to supply visual and audio information to a security guard at a

central monitoring station as well as security system users around the world.

Objectives

The objectives of the Internet-based security and monitoring system are as

follows:

4

1. To investigate the possibilities of using the integration of the Internet and telephone

lines in providing solution to security problems by conveying alarm signals from

remote monitored locations.

2. To establish a web server that acts as a central monitoring station to receive alarm

signals and to enable information to be put on the Internet for access.

3 . To implement a graphical user interface (Java applets) to allow users to access the

web server.

Thesis Organisation

The thesis consists of six chapters. Chapter I presents a short introduction and

objectives of the project. In Chapter II a literature review on security systems and alarm

signalling is provided. Chapter III gives theoretical back ground of the tools that are used

in building the system. Chapter IV gives a general description of the system. It also

provides methods used for the software development. The system's performance and

results are discussed in chapter V . Finally, the thesis is concluded in Chapter V I, which

summ arises the conclusions and directions of future efforts.

CHAPTER II

REVIEW ON SECURITY SYSTEMS AND ALARM SIGNALLING

Introduction

The need for security systems in all types of buildings becomes a necessity with

the increase in crime rate. Alarm and monitoring systems can be used to prevent crime.

By protecting places such as homes, office, and buildings using alarm systems, security

guards and patrol officers can spend more time in areas with high crime rates and with

fewer premises protected by alarm systems. This chapter will review the components of

security and monitoring systems, and illustrate different methods and techniques that

have been used in designing and building of security systems.

Security and Monitoring Technology

Security and monitoring systems were originally introduced as a means to protect

people and property by drawing attention to a problem in its beginning stages so that the

problem can be controlled through quick action. The use of electricity and electronics in

the fight against crime is not new. When electricity was put to practical use around the

5

6

later part of the last century, methods were devised to use door bells, entrance detectors,

and manually operated fire alarms for signalling devices (Traister, 1990). In 1858,

Edwin began the first central office burglar alarm system (Cunningham, 1988).

The two basic signal circuits that were used for security and fire alarm systems

are open and closed circuit. The advantage of the open circuit technique was the reduced

cost in providing alarm protection. However it has certain drawback as a wire to one of

the sensors could be cut and there would no means of detecting it. To avoid difficulties

of the open circuit (Capel, 1989), the closed circuit technique came into general use. In

the early 1960s, closed circuit TV (CCTV) was introduced (Fennelly, 1997) to provide a

useful supplement to an intruder alarm system, particularly in large building complexes.

In an effort to improve security systems, multiplexing circuits were used to transmit

multiple alarm signals using a common carrier. Another major improvement in security

systems was the change from analogue to digital data transmission which made it

possible to apply the capabilities of digital computers for security systems (Hopf, 1979).

Security alarms consists of several functional parts. Sensors to detect the action

or penetration of an intruder, control unit that is used to receive, process and transmit

alarm signal to a central station, communication medium, and a central monitoring

station that operates for 24 hours a day to supervise, record, and maintain alarms

(Fennelly, 1997). When an alarm or monitoring information is to be transmitted, the

medium of communication can be in the form of:

7

1. Power line. The power mains are used to transfer alarm signal from the monitored

locations to the central station. The use of power lines as the transmission medium in

a facility could significantly reduce cabling costs (Halbig, et at., 1994).

2 . Cabling. A dedicated cabling system is run from the protected location to the central

monitoring station. The disadvantage of the direct cabling system is the high cost of

the dedicated line.

3. Telephone. The most common cost-effective form of alarm monitoring has been via

telephone lines. If an alarm device wishes to communicate with the central station, it

will instruct the dialler to dial the monitoring station reporting the alarm

information.

4. Radio signal transmission. This method takes the alarm signal from the protected

locations and sends it via radio frequency to a central monitoring station.

Supervisory Control And Data Acquisition (SCADA) is an industrial

measurement and control system consisting of a central host usually called a master

station, one or more remote terminal units (RTU) , communication medium and a

collection of software used to monitor and control remote located data field elements.

SCADA applications includes monitoring and control services for fire, security, building

management as well as meter reading and control for utilities such as gas, water and

electricity. The overall performance of SCADA system depends on satisfactory

performance of the integral data communication links (Bruce and Lee, 1994). SCADA

covers large geographic areas and rely on variety of communication interfaces between

RTU's and the master station. Transmission of data could take place over the power

8

line, radio frequency link, twisted pair network in addition to a normal telephone line.

The data acquisition is accomplished by RTV's scanning the field input connected to the

R TV to detect alarm conditions, and if an alarm is detected it will be sent to the master

station. SCADA carry out all necessary analysis and control, and then display this data

on a number of operator screens.

Intrusion Detection and Monitoring Systems

In the past, security systems that implemented CCTV were forced to use

expensive television equipment. However, Christoffersen (1990) showed that the PC­

based CCTV system is a highly functional alternative to conventional video system

equipment as it could offer reduced cost and reduced amount of software and hardware

maintenance besides the equipment is of compact size. According to Barry (1993),

improved capacity links have enabled the development of high data sensors such as

remotely controlled camera and imaging units. Laura (1994) showed that a storage area

can be monitored by collecting a basis image representing the monitored area and then

continuously monitoring the area to detect changes in the monitored area.

In many video surveillance applications used for intrusion detection, a variety of

factors lead to some errors like varying illumination conditions, small camera motion,

rain, etc. Michael, et al. (1996) solved these problems by applying compression

techniques to transmit video images to a surveillance centre using digital network.

Although sending video images to the central monitoring station eliminates false alarms

9

by allowing central station operators to see what is happening inside the protected area,

the video images and detection results have to be transmitted to the surveillance centre.

Therefore an individual transmission channel is required for each sensor connected to

the monitoring centre. In addition, as the video signal is transmitted, the connection

needs high bandwidth, as a result the costs increase with the distance and number of

connections.

Centralised monitoring and security systems have been in use for many years but

increasing demands for expansion, flexibility and system integrity along with the cost

have exceeded the capabilities of the traditional systems. Key to the establishment of

security systems is a robust and well designed communications network. However. a

separate communication networks for security only is expensive and not necessary

(William, 1989). A new concept has been developed which allows for sharing resources

to provide security measures in a cost-effective manner. The most important resource

which may be shared is the data network. Johnson, et al. ( 1994) developed a remote

monitoring system by utilising network cable to collect data from sensors and store them

in storage medium. These data are remotely monitored via telephone. They concluded

that number of technologies could be combined to introduce new approaches to provide

unattended remote monitoring of facilities.

Another technique of alarm signalling is the utilisation of optical fibres which

are used to communicate restricted data, transmit CCTV pictures and detect intruders

moving across restricted areas. Hawkes ( 1995) described a study on a fibre optic