GSM AND GPS BASED CO-ORDINATE SYSTEM FOR ALERT

INTRODUCTION

This proposed work is an attempt to design a tracking unit that

uses the global positioning system to determine the precise

location of a object, person or other asset to which it is attached

and using GSM modem this information can be transmit to

remote user. It can provide tele-monitoring system for inter-

cities transportation vehicles such as taxis and buses. This

system contains single-board embedded system that is equipped

with GPS and GSM modems along with AVR controller that is

installed in the vehicle. During object motion, its location can be

reported by SMS message. A software package is developed to

read, process, analyze and store the incoming SMS messages.

The use of GSM and GPS technologies allows the system to

track object and provides the most up-to-date information about

ongoing trips. If a password like SMS is sent by the owner, it

automatically stops the vehicle or we can use it for different

other work, it can provide real time control. This system finds its

application in real time traffic surveillance. It could be used as a

valuable tool for real time traveler. The current system can be

able to provide monitoring process from anywhere. The purpose

of this system is to design and integrate a new system which is

integrated with GPS- GSM to provide following feature: a)

Location information, b) Real time tracking using SMS, c) track

bus driver activity d) Communication is instantaneous therefore

we can receive running report quickly. It is completely

integrated so that once it is implemented in all vehicles, then it is

easy to track vehicles any time.

Proposed design is cost-effective, reliable and has the function

of accurate tracking. When large object or vehicles were spread

out over ground, the owner corporations often found it difficult

to keep track of what was happening. They required some type

of system to determine where each object was at any given time

and for how long it travelled. Also the need of tracking in

consumer’s vehicle use to prevent any kind of theft because

police can use tracking reports to locate stolen vehicle. GSM

and GPS based tracking system will provide effective, real time

vehicle location, and reporting. A GPS- GSM based tracking

system will inform where your vehicle is and where it has been,

how long it has been. The system uses geographic position and

time information from the Global Positioning Satellites. The

system has an "On- Board Module" which resides in the vehicle

to be tracked. The On-Board module consists of GPS receiver, a

GSM modem and ARM processor. It can provide tele-

monitoring and management system for inter-cities

transportation vehicles such as taxis and buses. During vehicle

motion, its real-time parameters such as location are reported by

SMS message. The system takes advantage of wireless

technology in providing powerful management transportation

engine. The use of GSM and GPS technologies allows the

system to track vehicle and provides the most up-to-date

information about ongoing trips. This system finds its

application in real time traffic surveillance. It could be used as a

valuable tool for real time traveler information, congestion

monitoring, and system evaluation. An intelligent, automated

vehicle tracking system can resolve following problems such as,

late arrivals to scheduled, improper use of company time and

resources, unsafe driving habits, assigned routes, inefficient

dispatching, and passenger’s dissatisfaction. This can lead to

better traffic flow modeling and a better understanding of driver

behavior. This project includes various features like ingenuity,

simplicity of design and easy implementation. It is completely

integrated so that once it is implemented in all vehicles, then it is

easy to track vehicle any time.

THEORETICAL BACKGROUND AND

LITERATURE REVIEW

THEORETICAL BACKGROUND

GSM (Global System for Mobile communications: originally

from GROUPE Spécial Mobile) is the most popular standard for

mobile phones in the world. Its promoter, the GSM Association,

estimates that 80% of the global mobile market uses the

standard. GSM is used by over 3 billion people across more than

212 countries and territories [4]. Its ubiquity makes international

roaming very common between mobile phone operators

enabling subscribers to use their phones in many parts of the

world. GSM differs from its predecessors in that both signaling

and speech channels are digital, and thus is considered a second

generation (2G) mobile phone system [5]. This has also meant

that data communication was easy to build into the system.

GSM ARCHITECTURE

GSM is a complex system and difficult to understand. The

Mobile Station (MS) refers to the mobile equipment [6]. The

Base Station Subsystem controls the radio link with the Mobile

Station. The Network Subsystem performs main functions such

as switching of calls between mobile users, mobility

management operations, and proper operation and setup of a

network [7]. These functions are controlled by the Mobile

Services Switching Center (MSC).

TECHNICAL DETAILS

GSM is a cellular network, which means that mobile phones

connect to it by searching for cells in the immediate vicinity.

MAIN CELLULAR STANDARDS

YEAR STANDARD MOBILE

TELEPHONE

SYSTEM

TECHNO

LOGY

PRIMARY

MARKETS

1981 NMT540 NORDIC MOBILE

TELEPHONY

ANALOG

UE

EUROPE,MIDDL

E EAST

1985 TACS TOTAL ACCESS

COMMUNUNICATION

SYSTEM

ANALOG

UE

EUROPE AND

CHINA

1986 NMT900 NORDIC MOBILE

TELEPHONY

ANALOG

UE

EUROPE,

MIDDLE EAST

1991 GSM GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL WORLD-WIDE

1991 TDMA TIME DIVISION

MULTIPLE ACCESS

DIGITAL AMERICA

1993 CDMA CODE DIVISION

MULTIPLE ACCESS

DIGITAL NORTH

AMERICA,

KOREA

1992 GSM 1800 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL EUROPE

1994 PDC PERSONAL DIGITAL

CELLULAR

DIGITAL JAPAN

1995 PCS 1900 PERSONAL

COMPUTER SERVICES

DIGITAL NORTH

AMERICA

2001 GSM 800 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL NORTH

AMERICA

2006-TILL

DATE

GSM 450 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL WORLD-WIDE

GSM FREQUENCIES

GSM networks operate in a number of different frequency

ranges (separated into GSM frequency ranges for 2G and UMTS

frequency bands for 3G). Most 2G GSM networks operate in the

900 MHz or 1800 MHz bands. Some countries in the Americas

(including Canada and the United States) use the 850 MHz and

1900 MHz bands because the 900 and 1800 MHz frequency

bands were already allocated. Most 3G GSM networks in

Europe operate in the 2100 MHz frequency band [9]

NETWORK STRUCTURE

The network behind the GSM seen by the customer is large and

complicated in order to provide all of the services which are

required.

The Base Station Subsystem (the base stations and their

controllers).

The Network and Switching Subsystem (the part of the

network most similar to a fixed network). This is

sometimes also just called the core network.

The GPRS Core Network (the optional part which allows

packet based Internet connections).

All of the elements in the system combine to produce many

GSM services such as voice calls and SMS.

SUBSCRIBER IDENTITY MODULE (SIM)

One of the key features of GSM is the Subscriber Identity

Module, commonly known as a SIM card. The SIM is a

detachable smart card containing the user's subscription

information and phone book. This allows the user to retain his or

her information after switching handsets [10]. Alternatively, the

user can also change operators while retaining the handset

simply by changing the SIM. Some operators will block this by

allowing the phone to use only a single SIM, or only a SIM

issued by them; this practice is known as SIM locking, and is

illegal in some countries [11].

LITERATURE REVIEW

This project is an implementation to the idea of the wireless

communication between a mobile phone and a microcontroller.

Currently the main work that has been done on this proposed

system is through serial port to the computer but not wireless. If

they want to switch on and off the appliance, they have to go to

the remote area and one /off the appliance. But in this new

design, the systems need not be reprogrammed to control

another home appliance without changing the programming of

microcontroller. The user will send SMS from his phone and he

will be able to control the appliance.

GSM SECURITY

GSM was designed with a moderate level of security. The

system was designed to authenticate the subscriber using a pre-

shared key and challenge-response. Communications between

the subscriber and the base station can be encrypted.

Fig. 2.2 Block Diagram

As we see in the above figure, there are at least three interfacing

circuits, MAX-232 with Microcontroller, LCD display with

microcontroller, and MAX-232 with GSM MODEM.

A BRIEF INTRODUCTION TO AVR

MICROCONTROLLER:

AVR microcontrollers are popular because of their Linux

support and their software like AVRGCC and AVRDUDE. If

you start learning with any microcontroller the cost you have to

pay is the microcontroller cost+software+programmer. If you

compute this then AVR is the best. Atmega8 is available with

Rs.75 and programmer cost is just a printer cable costs Rs.40

with some wires and AVRGCC for Linux and WinaVR2006 for

Windows. It has facilities like inbuilt ADC which is not there in

8051, which will be advantageous for robotics. Software are

easily available for other microcontrollers but they have a limit

of maximum 2K program memory. The project 'embedded

‘Ethernet' have around 10K program memory usage while

WinAVR have no such limitations. The programmer cost of

8051 and pic are above Rs.400(as far as I know). Here I am

going to talk about microcontroller just like a computer running

on parallel port and a C program. I am using the same examples.

Basic thing you have to know how to program the chip and

writing programs for the chip. If you know 8085 then it will be

easy to understand. Anyway I am writing codes in C so that it

will be easy to understand.

When we have to learn about a new computer we have to

familiarize about the machine capability we are using, and we

can do it by studying the internal hardware design (devices

architecture), and also to know about the size, number and the

size of the registers.

A microcontroller is a single chip that contains the

processor (the CPU), non-volatile memory for the program

(ROM or flash), volatile memory for input and output (RAM), a

clock and an I/O control unit. Also called a "computer on a

chip," billions of microcontroller units (MCUs) are embedded

each year in a myriad of products from toys to appliances to

automobiles. For example, a single vehicle can use 70 or more

microcontrollers. The following picture describes a general

block diagram of microcontroller.

ATMEGA16: The ATMEGA16 is a low-power, high-

performance advance RISC 8-bit microcontroller with 32K

bytes of in-system programmable Flash memory. The on-chip

Flash allows the program memory to be reprogrammed in-

system or by a conventional nonvolatile memory pro-grammer.

By combining a versatile 8-bit CPU with in-system

programmable Flash on a monolithic chip, the Atmel

ATMEGA16 is a powerful microcontroller, which provides a

highly flexible and cost-effective solution to many, embedded

control applications. The ATMEGA16 provides the following

standard features: 32K bytes of Flash, 1024 byte of EEPROM &

2KB INTERNAL S RAM ,32 I/O lines, Watchdog timer, two

data pointers, two 16-bit timer/counters, a six-vector two-level

interrupt architecture, a full duplex serial port, on-chip

oscillator,8-channel 10 bit ADC and clock circuitry. In addition,

the ATMEGA16 is designed with static logic for operation

down to zero frequency and supports two software selectable

power saving modes. The Idle Mode stops the CPU while

allowing the RAM, timer/counters, serial port, and interrupt

system to continue functioning. The Power-down mode saves

the RAM con-tents but freezes the oscillator, disabling all other

chip functions until the next interrupt.

BLOCK DIAGRAM

POWER SUPPLY

AVR

MICRO

CONTROLLER

GSM MODEM

LCD

MOBILE PHONEG

P

S

BUZZER

CIRCUIT DIAGRAM

DISCRIPTIONHardware framework for tracking system is shown in Fig 1. System contains high Performance AVR controller, a GPS, and GSM modem and overall system reside into a vehicle. A tracking system will provide effective real time vehicle location reporting .Tracking system will inform where your vehicle is and where it has been, how longer it has been there.

The basic function of in vehicle unite is to acquire, Monitor and transmit the position latitude, longitude, time to management center either at fixed interval or on demand. Microcontroller unit form the heart of tracking unit, which acquires and process the position data from the GPS module. The GPS receiver of vehicle terminal receives and resolves the navigation message broadcasted by GPS position satellites, computes the longitude and latitude of vehicle coordinates, transforms it into the GSM message form by GSM communication controller, and sends the message to monitoring center via the GSM network.

COMPONENT LIST

Name Capacity Quantity

2 Pin Connector Screw 1

2 Pin Connector Male 1

Diode IN40007 4

Regulator 7805 1

Regulator 7812 1

Capacitor 1000µf 1

Capacitor 10µf 1

Ceramic Capacitor 22pf 2

Crystal 11.0592mhz

1

Push Button 1

Relay 12V 1

40 Pin Base 1

16 Pin Base 1

8 Pin Base 1

8051 ATMEGA 1

16

ULN2003 1

LM358 1`

LED 2

LCD Base 16 Pin 1

LCD 16*2 1

Resistance 220Ω 2

Resistance 1k 1

Resistance 10k 1

Variable resistance 100k 2

GPS MODULE 1

GSM MODEM 1

1. POWER SUPPLY :

Power supply is a reference to a source of electrical power. A

device or system that supplies electrical or other types of energy

to an output load or group of loads is called a power supply

unit or PSU. The term is most commonly applied to electrical

energy supplies, less often to mechanical ones, and rarely to

others. Here in our application we need a 5v DC power supply

for all electronics involved in the project. This requires step

down transformer, rectifier, voltage regulator, and filter circuit

for generation of 5v DC power. Here a brief description of all

the components is given as follows:

TRANSFORMER:

transformer is a device that transfers electrical energy from

one circuit to another through inductively coupled conductors —

the transformer's coils or "windings". Except for air-core

transformers, the conductors are commonly wound around a

single iron-rich core, or around separate but magnetically-

coupled cores. A varying current in the first or "primary"

winding creates a varying magnetic field in the core (or cores) of

the transformer. This varying magnetic field induces a varying

electromotive force (EMF) or "voltage" in the "secondary"

winding. This effect is called mutual induction.

If a load is connected to the secondary circuit, electric charge

will flow in the secondary winding of the transformer and

transfer energy from the primary circuit to the load connected in

the secondary circuit.

The secondary induced voltage VS, of an ideal transformer, is

scaled from the primary VP by a factor equal to the ratio of the

number of turns of wire in their respective windings:

By appropriate selection of the numbers of turns, a transformer

thus allows an alternating voltage to be stepped up — by making

NS more than NP — or stepped down, by making it

BASIC PARTS OF A TRANSFORMER

In its most basic form a transformer consists of:

A primary coil or winding.

A secondary coil or winding.

A core that supports the coils or windings.

Refer to the transformer circuit in figure as you read the

following explanation: The primary winding is connected to a

60-hertz ac voltage source. The magnetic field (flux) builds up

(expands) and collapses (contracts) about the primary winding.

The expanding and contracting magnetic field around the

primary winding cuts the secondary winding and induces an

alternating voltage into the winding. This voltage causes

alternating current to flow through the load. The voltage may be

stepped up or down depending on the design of the primary and

secondary windings.

THE COMPONENTS OF A TRANSFORMER

Two coils of wire (called windings) are wound on some type of

core material. In some cases the coils of wire are wound on a

cylindrical or rectangular cardboard form. In effect, the core

material is air and the transformer is called an AIR-CORE

TRANSFORMER. Transformers used at low frequencies, such

as 60 hertz and 400 hertz, require a core of low-reluctance

magnetic material, usually iron. This type of transformer is

called an IRON-CORE TRANSFORMER. Most power

transformers are of the iron-core type. The principle parts of a

transformer and their functions are:

The CORE, which provides a path for the magnetic lines of flux.

The PRIMARY WINDING, which receives energy from the ac

source.

The SECONDARY WINDING, which receives energy from the

primary winding and delivers it to the load.

The ENCLOSURE, which protects the above components from

dirt, moisture, and mechanical damage.

BRIDGE RECTIFIER

A bridge rectifier makes use of four diodes in a bridge

arrangement to achieve full-wave rectification. This is a widely

used configuration, both with individual diodes wired as shown

and with single component bridges where the diode bridge is

wired internally.

BASIC OPERATION

According to the conventional model of current flow originally

established by Benjamin Franklin and still followed by most

engineers today, current is assumed to flow through electrical

conductors from the positive to the negative pole. In actuality,

free electrons in a conductor nearly always flow from the

negative to the positive pole. In the vast majority of

applications, however, the actual direction of current flow is

irrelevant. Therefore, in the discussion below the conventional

model is retained.

In the diagrams below, when the input connected to the left

corner of the diamond is positive, and the input connected to the

right corner is negative, current flows from the upper supply

terminal to the right along the red (positive) path to the output,

and returns to the lower supply terminal via the blue (negative)

path.

When the input connected to the left corner is negative, and the

input connected to the right corner is positive, current flows

from the lower supply terminal to the right along the red path to

the output, and returns to the upper supply terminal via the blue

path.

In each case, the upper right output remains positive and lower

right output negative. Since this is true whether the input is AC

or DC, this circuit not only produces a DC output from an AC

input, it can also provide what is sometimes called "reverse

polarity protection". That is, it permits normal functioning of

DC-powered equipment when batteries have been installed

backwards, or when the leads (wires) from a DC power source

have been reversed, and protects the equipment from potential

damage caused by reverse polarity.

Prior to availability of integrated electronics, such a bridge

rectifier was always constructed from discrete components.

Since about 1950, a single four-terminal component containing

the four diodes connected in the bridge configuration became a

standard commercial component and is now available with

various voltage and current ratings.

OUTPUT SMOOTHING

For many applications, especially with single phase AC where

the full-wave bridge serves to convert an AC input into a DC

output, the addition of a capacitor may be desired because the

bridge alone supplies an output of fixed polarity but

continuously varying or "pulsating" magnitude (see diagram

above).

The function of this capacitor, known as a reservoir capacitor (or

smoothing capacitor) is to lessen the variation in (or 'smooth')

the rectified AC output voltage waveform from the bridge. One

explanation of 'smoothing' is that the capacitor provides a low

impedance path to the AC component of the output, reducing the

AC voltage across, and AC current through, the resistive load. In

less technical terms, any drop in the output voltage and current

of the bridge tends to be canceled by loss of charge in the

capacitor. This charge flows out as additional current through

the load. Thus the change of load current and voltage is reduced

relative to what would occur without the capacitor. Increases of

voltage correspondingly store excess charge in the capacitor,

thus moderating the change in output voltage / current.

The simplified circuit shown has a well-deserved reputation for

being dangerous, because, in some applications, the capacitor

can retain a lethal charge after the AC power source is removed.

If supplying a dangerous voltage, a practical circuit should

include a reliable way to safely discharge the capacitor. If the

normal load cannot be guaranteed to perform this function,

perhaps because it can be disconnected, the circuit should

include a bleeder resistor connected as close as practical across

the capacitor. This resistor should consume a current large

enough to discharge the capacitor in a reasonable time, but small

enough to minimize unnecessary power waste.

Because a bleeder sets a minimum current drain, the regulation

of the circuit, defined as percentage voltage change from

minimum to maximum load, is improved. However in many

cases the improvement is of insignificant magnitude.

The capacitor and the load resistance have a typical time

constant τ = RC where C and R are the capacitance and load

resistance respectively. As long as the load resistor is large

enough so that this time constant is much longer than the time of

one ripple cycle, the above configuration will produce a

smoothed DC voltage across the load.

In some designs, a series resistor at the load side of the capacitor

is added. The smoothing can then be improved by adding

additional stages of capacitor–resistor pairs, often done only for

sub-supplies to critical high-gain circuits that tend to be

sensitive to supply voltage noise.

The idealized waveforms shown above are seen for both voltage

and current when the load on the bridge is resistive. When the

load includes a smoothing capacitor, both the voltage and the

current waveforms will be greatly changed. While the voltage is

smoothed, as described above, current will flow through the

bridge only during the time when the input voltage is greater

than the capacitor voltage. For example, if the load draws an

average current of n Amps, and the diodes conduct for 10% of

the time, the average diode current during conduction must be

10n Amps. This non-sinusoidal current leads to harmonic

distortion and a poor power factor in the AC supply.

In a practical circuit, when a capacitor is directly connected to

the output of a bridge, the bridge diodes must be sized to

withstand the current surge that occurs when the power is turned

on at the peak of the AC voltage and the capacitor is fully

discharged. Sometimes a small series resistor is included before

the capacitor to limit this current, though in most applications

the power supply transformer's resistance is already sufficient.

Output can also be smoothed using a choke and second

capacitor. The choke tends to keep the current (rather than the

voltage) more constant. Due to the relatively high cost of an

effective choke compared to a resistor and capacitor this is not

employed in modern equipment.

Some early console radios created the speaker's constant field

with the current from the high voltage ("B +") power supply,

which was then routed to the consuming circuits, (permanent

magnets were then too weak for good performance) to create the

speaker's constant magnetic field. The speaker field coil thus

performed 2 jobs in one: it acted as a choke, filtering the power

supply, and it produced the magnetic field to operate the

speaker.

REGULATOR IC (78XX)

It is a three pin IC used as a voltage regulator. It converts

unregulated DC current into regulated DC current.

Normally we get fixed output by connecting the voltage

regulator at the output of the filtered DC (see in above diagram).

It can also be used in circuits to get a low DC voltage from a

high DC voltage (for example we use 7805 to get 5V from 12V).

There are two types of voltage regulators 1. fixed voltage

regulators (78xx, 79xx) 2. variable voltage regulators(LM317)

In fixed voltage regulators there is another classification 1. +ve

voltage regulators 2. -ve voltage regulators POSITIVE

VOLTAGE REGULATORS This include 78xx voltage

regulators. The most commonly used ones are 7805 and 7812.

7805 gives fixed 5V DC voltage if input voltage is in (7.5V,

20V).

The Capacitor Filter

The simple capacitor filter is the most basic type of power

supply filter. The application of the simple capacitor filter is

very limited. It is sometimes used on extremely high-voltage,

low-current power supplies for cathode-ray and similar electron

tubes, which require very little load current from the supply. The

capacitor filter is also used where the power-supply ripple

frequency is not critical; this frequency can be relatively high.

The capacitor (C1) shown in figure 4-15 is a simple filter

connected across the output of the rectifier in parallel with the

load.

Full-wave rectifier with a capacitor filter.

When this filter is used, the RC charge time of the filter

capacitor (C1) must be short and the RC discharge time must be

long to eliminate ripple action. In other words, the capacitor

must charge up fast, preferably with no discharge at all. Better

filtering also results when the input frequency is high; therefore,

the full-wave rectifier output is easier to filter than that of the

half-wave rectifier because of its higher frequency.

For you to have a better understanding of the effect that filtering

has on Eavg, a comparison of a rectifier circuit with a filter and

one without a filter is illustrated in views A and B of figure 4-

16. The output waveforms in figure 4-16 represent the unfiltered

and filtered outputs of the half-wave rectifier circuit. Current

pulses flow through the load resistance (RL) each time a diode

conducts. The dashed line indicates the average value of output

voltage. For the half-wave rectifier, Eavg is less than half (or

approximately 0.318) of the peak output voltage. This value is

still much less than that of the applied voltage. With no

capacitor connected across the output of the rectifier circuit, the

waveform in view A has a large pulsating component (ripple)

compared with the average or dc component. When a capacitor

is connected across the output (view B), the average value of

output voltage (Eavg) is increased due to the filtering action of

capacitor C1.

UNFILTERED

Half-wave rectifier with and without filtering.

FILTERED

The value of the capacitor is fairly large (several microfarads),

thus it presents a relatively low reactance to the pulsating current

and it stores a substantial charge.

The rate of charge for the capacitor is limited only by the

resistance of the conducting diode, which is relatively low.

Therefore, the RC charge time of the circuit is relatively short.

As a result, when the pulsating voltage is first applied to the

circuit, the capacitor charges rapidly and almost reaches the

peak value of the rectified voltage within the first few cycles.

The capacitor attempts to charge to the peak value of the

rectified voltage anytime a diode is conducting, and tends to

retain its charge when the rectifier output falls to zero. (The

capacitor cannot discharge immediately.) The capacitor slowly

discharges through the load resistance (RL) during the time the

rectifier is non-conducting.

The rate of discharge of the capacitor is determined by the value

of capacitance and the value of the load resistance. If the

capacitance and load-resistance values are large, the RC

discharge time for the circuit is relatively long.

A comparison of the waveforms shown in figure 4-16 (view A

and view B) illustrates that the addition of C1 to the circuit

results in an increase in the average of the output voltage (Eavg)

and a reduction in the amplitude of the ripple component (Er)

which is normally present across the load resistance.

Now, let's consider a complete cycle of operation using a half-

wave rectifier, a capacitive filter (C1), and a load resistor (RL).

As shown in view A of figure 4-17, the capacitive filter (C1) is

assumed to be large enough to ensure a small reactance to the

pulsating rectified current. The resistance of RL is assumed to be

much greater than the reactance of C1 at the input frequency.

When the circuit is energized, the diode conducts on the positive

half cycle and current flows through the circuit, allowing C1 to

charge. C1 will charge to approximately the peak value of the

input voltage. (The charge is less than the peak value because of

the voltage drop across the diode (D1)). In view A of the figure,

the charge on C1 is indicated by the heavy solid line on the

waveform. As illustrated in view B, the diode cannot conduct on

the negative half cycle because the anode of D1 is negative with

respect to the cathode. During this interval, C1 discharges

through the load resistor (RL). The discharge of C1 produces the

downward slope as indicated by the solid line on the waveform

in view B. In contrast to the abrupt fall of the applied ac voltage

from peak value to zero, the voltage across C1 (and thus across

RL) during the discharge period gradually decreases until the

time of the next half cycle of rectifier operation. Keep in mind

that for good filtering, the filter capacitor should charge up as

fast as possible and discharge as little as possible.

Figure 4-17A. - Capacitor filter circuit (positive and negative

half cycles). POSITIVE HALF-CYCLE

Figure 4-17B. - Capacitor filter circuit (positive and negative

half cycles). NEGATIVE HALF-CYCLE

Since practical values of C1 and RL ensure a more or less

gradual decrease of the discharge voltage, a substantial charge

remains on the capacitor at the time of the next half cycle of

operation. As a result, no current can flow through the diode

until the rising ac input voltage at the anode of the diode exceeds

the voltage on the charge remaining on C1. The charge on C1 is

the cathode potential of the diode. When the potential on the

anode exceeds the potential on the cathode (the charge on C1),

the diode again conducts, and C1 begins to charge to

approximately the peak value of the applied voltage.

After the capacitor has charged to its peak value, the diode will

cut off and the capacitor will start to discharge. Since the fall of

the ac input voltage on the anode is considerably more rapid

than the decrease on the capacitor voltage, the cathode quickly

become more positive than the anode, and the diode ceases to

conduct.

Operation of the simple capacitor filter using a full-wave

rectifier is basically the same as that discussed for the half-wave

rectifier. Referring to figure 4-18, you should notice that

because one of the diodes is always conducting on. either

alternation, the filter capacitor charges and discharges during

each half cycle. (Note that each diode conducts only for that

portion of time when the peak secondary voltage is greater than

the charge across the capacitor.)

Figure 4-18. - Full-wave rectifier (with capacitor filter).

Another thing to keep in mind is that the ripple component (E r)

of the output voltage is an ac voltage and the average output

voltage (Eavg) is the dc component of the output. Since the filter

capacitor offers a relatively low impedance to ac, the majority of

the ac component flows through the filter capacitor. The ac

component is therefore bypassed (shunted) around the load

resistance, and the entire dc component (or Eavg) flows through

the load resistance. This statement can be clarified by using the

formula for XC in a half-wave and full-wave rectifier. First, you

must establish some values for the circuit.

As you can see from the calculations, by doubling the frequency

of the rectifier, you reduce the impedance of the capacitor by

one-half. This allows the ac component to pass through the

capacitor more easily. As a result, a full-wave rectifier output is

much easier to filter than that of a half-wave rectifier.

Remember, the smaller the XC of the filter capacitor with respect

to the load resistance, the better the filtering action. Since

the largest possible capacitor will provide the best filtering.

Remember, also, that the load resistance is an important

consideration. If load resistance is made small, the load current

increases, and the average value of output voltage (Eavg)

decreases. The RC discharge time constant is a direct function of

the value of the load resistance; therefore, the rate of capacitor

voltage discharge is a direct function of the current through the

load. The greater the load current, the more rapid the discharge

of the capacitor, and the lower the average value of output

voltage. For this reason, the simple capacitive filter is seldom

used with rectifier circuits that must supply a relatively large

load current. Using the simple capacitive filter in conjunction

with a full-wave or bridge rectifier provides improved filtering

because the increased ripple frequency decreases the capacitive

reactance of the filter capacitor.

CIRCUIT DIAGRAM OF POWER SUPPLY

DIODE

The diode is a p-n junction device. Diode is the component

used to control the flow of the current in any one direction. The

diode widely works in forward bias.

Diode When the current flows from the P to N direction. Then it

is in forward bias. The Zener diode is used in reverse bias

function i.e. N to P direction. Visually the identification of the

diode`s terminal can be done by identifying he silver/black line.

The silver/black line is the negative terminal (cathode) and the

other terminal is the positive terminal (cathode).

APPLICATION

•Diodes: Rectification, free-wheeling, etc

•Zener diode: Voltage control, regulator etc.

•Tunnel diode: Control the current flow, snobbier circuit, etc

RESISTORS

The flow of charge through any material encounters an

opposing force similar in many respects to mechanical

friction .this opposing force is called resistance of the

material .in some electric circuit resistance is deliberately

introduced in form of resistor. Resistor used fall in three

categories , only two of which are color coded which are metal

film and carbon film resistor .the third category is the wire

wound type ,where value are generally printed on the vitreous

paint finish of the component. Resistors are in ohms and are

represented in Greek letter omega, looks as an upturned

horseshoe. Most electronic circuit require resistors to make them

work properly and it is obliviously important to find out

something about the different types of resistors available.

Resistance is measured in ohms, the symbol for ohm is an

omega ohm. 1 ohm is quite small for electronics so resistances

are often given in kohm and Mohm.

Resistors used in electronics can have resistances as low as 0.1

ohm or as high as 10 Mohm.

FUNCTION

Resistor restrict the flow of electric current, for example a

resistor is placed in series with a light-emitting diode(LED) to

limit the current passing through the LED.

TYPES OF RESISTORS

FIXED VALUE RESISTORS

It includes two types of resistors as carbon film and metal

film .These two types are explained under

CARBON FILM RESISTORS

During manufacture, at in film of carbon is deposited onto a

small ceramic rod. The resistive coating is spiraled away in an

automatic machine until the resistance between there two ends

of the rods is as close as possible to the correct value. Metal

leads and end caps are added, the resistors is covered with an

insulating coating and finally painted with colored bands to

indicate the resistor value

Carbon Film Resistors

Another example for a Carbon 22000 Ohms or 22 Kilo-Ohms

also known as 22K at 5% tolerance: Band 1 = Red, 1st digit

Band 2 = Red, 2nd digit Band 3 = Orange, 3rd digit, multiply

with zeros, in this case 3 zero's Band 4 = Gold, Tolerance, 5%

METAL FILM RESISTORS

Metal film and metal oxides resistors are made in a similar way,

but can be made more accurately to within ±2% or ±1% of their

nominal vale there are some difference in performance between

these resistor types, but none which affects their use in simple

circuit.

WIRE WOUND RESISTOR

A wire wound resistor is made of metal resistance wire, and

because of this, they can be manufactured to precise values.

Also, high wattage resistors can be made by using a thick wire

material. Wire wound resistors cannot be used for high

frequency circuits. Coils are used in high frequency circuit. Wire

wound resistors in a ceramic case, strengthened with special

cement. They have very high power rating, from 1 or 2 watts to

dozens of watts. These resistors can become extremely hot when

used for high power application, and this must be taken into

account when designing the circuit.

TESTING

Resistors are checked with an ohm meter/millimeter. For a

defective resistor the ohm-meter shows infinite high reading.

CAPACITORS

In a way, a capacitor is a little like a battery. Although they

work in completely different ways, capacitors and batteries both

store electrical energy. If you have read How Batteries Work ,

then you know that a battery has two terminals. Inside the

battery, chemical reactions produce electrons on one terminal

and absorb electrons at the other terminal.

BASIC

Like a battery, a capacitor has two terminals. Inside the

capacitor, the terminals connect to two metal plates separated by

a dielectric. The dielectric can be air, paper, plastic or anything

else that does not conduct electricity and keeps the plates from

touching each other. You can easily make a capacitor from two

pieces of aluminum foil and a piece of paper. It won't be a

particularly good capacitor in terms of its storage capacity, but it

will work.

In an electronic circuit, a capacitor is shown like this:

When you connect a capacitor to a battery, here’s what happens:

•The plate on the capacitor that attaches to the negative terminal

of the battery accepts electrons that the battery is producing.

•The plate on the capacitor that attaches to the positive terminal

of the battery loses electrons to the battery.

TESTING

To test the capacitors, either analog meters or specia

l digital meters with the specified function are used. The non-

electrolyte capacitor can be tested by using the digital meter.

Multi – meter mode : Continuity Positive probe : One end

Negative probe : Second end Display : `0`(beep sound

occur) `OL` Result : Faulty OK

LED

LED falls within the family of P-N junction devices. The light

emitting diode (LED) is a diode that will give off visible light

when it is energized. In any forward biased P-N junction there

is, with in the structure and primarily close to the junction, a

recombination of hole and electrons. This recombination

requires that the energy possessed by the unbound free electron

be transferred to another state. The process of giving off light by

applying an electrical source is called electroluminescence.

LED is a component used for indication. All the functions being

carried out are displayed by led .The LED is diode which glows

when the current is being flown through it in forward bias

condition. The LEDs are available in the round shell and also in

the flat shells. The positive leg is longer than negative leg.

GSM Modem

A GSM modem is a wireless modem that works with a GSM

wireless network. A wireless modem behaves like a dial-up

modem. The main difference between them is that a dial-up

modem sends and receives data through a fixed telephone line

while a wireless modem sends and receives data through radio

waves. Like a GSM mobile phone, a GSM modem requires a

SIM card from a wireless carrier in order to operate [11].

Accessing GSM MODEM using Microsoft HyperTerminal

Microsoft HyperTerminal is a small program that comes with

Microsoft Windows. We use it to send AT commands to the

GSM modem. It can be found at Start -> Programs ->

Accessories -> Communications -> HyperTerminal. Before

programming our SMS application, it is required to check if the

GSM modem and SIM card are working properly first [12]. The

MS HyperTerminal is a handy tool when it comes to testing the

GSM device. It is a good idea to test the GSM devices

beforehand. When a problem occurs, sometimes it is difficult to

tell what causes the problem. The cause can be the program, the

GSM device or the SIM card. If GSM device and SIM card with

MS HyperTerminal are operating properly, then it is very likely

that the problem is caused by the program or other hardware

[12]. For Linux users, Mincom can be used instead of

HyperTerminal.

TESTING OF GSM MODEM

To use MS HyperTerminal to send AT commands to the GSM

modem, the following procedure is followed

1. I put a valid SIM (MTN) card into the GSM modem. I obtain

a SIM card by subscribing to the GSM service of a wireless

network operator.

2. No need to install any driver for the GSM modem

3. Then I set up MS HyperTerminal by selecting Start ->

Programs -> Accessories -> Communications ->

HyperTerminal.

4. In the Connection Description dialog box (as shown in the

screenshot given below), I enter any file name and choose an

icon I like for the connection. Then I click the OK button.

. In the Connect To dialog box, choose the COM port that your

mobile phone or GSM modem is connecting to in the Connect

using combo box. I choose COM1 because my mobile phone is

connected to the COM1 port. Then click the OK button. Type

"AT" in the main window. A response "OK" will be returned

from the mobile phone or GSM modem. Type "AT+CPIN?" in

the main window. The AT command "AT+CPIN?" is used to

query whether the mobile phone or GSM modem is waiting for a

PIN (personal identification number, i.e. password). If the

response is "+CPIN: READY", it means the SIM card does not

require a PIN and it is ready for use. If my SIM card requires a

PIN, you need to set the PIN with the AT command

"AT+CPIN=<PIN>".

[

LIST OF IMPORTANT AT COMMANDS

After successfully testing the MODEM for its correct

operational state, I then set the MODEM parameters like Baud

rate, Echo off etc to enable easier access via a microcontroller

which I used in this project. The following are the

ATCOMMAND used for programming the gsm modem

Example: Changing and saving parameters

AT+IPR=9600[Enter] Transfer rate to 9600bps

AT&W [Enter] save parameters

AT+CMGF means convert the message to machine instruction

format

AT+CPMS means selection of SMS memory

AT+CMGR means read message from a given memory location

AT+CMGD means delete message from a given memory

location.

Microcontroller – Modem Interfacing

DTE and DCE

The terms DTE and DCE are very common in the data

communications market. DTE is short for Data Terminal

Equipment and DCE stands for Data Communications

Equipment. As the full DTE name indicates this is a piece of

device that ends a communication line, whereas the DCE

provides a path for communication. Let's say I have a computer

on which wants to communicate with the Internet through a

modem and a dial-up connection. To get to the Internet I tell my

modem to dial the number of my provider. After my modem has

dialed the number, the modem of the provider will answer my

call and I will hear a lot of noise. Then it becomes quiet and I

see my login prompt or my dialing program tells me the

connection is established. Now I have a connection with the

server from my provider and I can surf the Internet [13].

MICROCONTROLLER – LCD INTERFACING

Above is the quite simple schematic. The LCD panel’s Enable

and Register Select is connected to the Control Port. The

Control Port is an open collector / open drain output. Therefore

by incorporating the two 10K external pull up resistors, the

circuit is more portable for a wider range of computers, some of

which may have no internal pull up resistors. I make no effort to

place the Data bus into reverse direction. Therefore I had wire

the R/W line of the LCD panel, into write mode. This will cause

no bus conflicts on the data lines. As a result I cannot read back

the LCD’s internal Busy Flag which tells us if the LCD has

accepted and finished processing the last instruction [20]. This

problem is overcome by inserting known delays into my

program. The 10k Potentiometer controls the contrast of the

LCD panel. Nothing fancy here.

I used a power supply of 5volt. The user may select whether the

LCD is to operate with a 4-bit data bus or an 8- bit data bus. If a

4-bit data bus is used, the LCD will require a total of 7 data

lines. If an 8-bit data bus is used, the LCD will require a total of

11 data lines [20]. LCD with 8-bit data bus is used for this

design. The three control lines are EN, RS, and RW. EN line

must be raised/lowered before/after each instruction sent to the

LCD regardless of whether that instruction is read or write text

or instruction. In short, I manipulate EN when communicating

with the LCD.

GPS MODEM

The Global Positioning System (GPS) is a space-based global navigation satellite system (GNSS) that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth when and where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely accessible by anyone with a GPS receiver. The GPS project was started in 1973 to overcome the limitations of previous navigation systems, integrating ideas from several predecessors, including a number of classified engineering design studies from the 1960s. GPS was created and realized by the U.S. Department of Defense (USDOD) and was originally run with 24 satellites. It became fully operational in 1994.

RS-232

In telecommunications, RS-232 is a standard for serial binary

data signals connecting between a DTE (Data terminal

equipment) and a DCE (Data Circuit-terminating Equipment)

[14]. It is commonly used in computer serial ports. In RS-232,

data is sent as a time-series of bits. Both synchronous and

asynchronous transmissions are supported by the standard. In

addition to the data circuits, the standard defines a number of

control circuits used to manage the connection between the DTE

and DCE [14]. Each data or control circuit only operates in one

direction that is, signaling from a DTE to the attached DCE or

the reverse. Since transmit data and receive data are separate

circuits, the interface can operate in a full duplex manner,

supporting concurrent data flow in both directions [15]. The

standard does not define character framing within the data

stream, or character encoding.

Female 9 pin plug

RTS/CTS Handshaking

The standard RS-232 use of the RTS and CTS lines is

asymmetrical. The DTE asserts RTS to indicate a desire to

transmit and the DCE asserts CTS in response to grant

permission. This allows for half-duplex modems that disable

their transmitters when not required, and must transmit a

synchronization preamble to the receiver when they are re

enabled [16]. There is no way for the DTE to indicate that it is

unable to accept data from the DCE. A non-standard

symmetrical alternative is widely used: CTS indicates

permission from the DCE for the DTE to transmit, and RTS

indicates permission from the DTE for the DCE to transmit [17].

The "request to transmit" is implicit and continuous. The

standard defines RTS/CTS as the signaling protocol for flow

control for data transmitted from DTE to DCE. The standard has

no provision for flow control in the other direction. In practice,

most hardware seems to have repurposed the RTS signal for this

function [18]. A minimal “3-wire” RS-232 connection

consisting only of transmits data, receives data and ground, and

is commonly used when the full facilities of RS-232 are not

required. When only flow control is required, the RTS and CTS

lines are added in a 5-wire version.

Specifying Baud Rate, Parity & Stop bits

Serial communication using RS-232 requires four parameters:

the baud rate of the transmission, the number of data bits

encoding a character, the sense of the optional parity bit, and the

number of stop bits. Each transmitted character is packaged in a

character frame that consists of a single start bit followed by the

data bits, the optional parity bit, and the stop bit or bits. A

typical character frame encoding the letter "m" is shown here.

I specified the parameters as baud rate – 9600 bps, 8 data bits,

no parity, and 1 stop bit (9600-8 N-1). This was set in pre-

operational phase while setting up the modem through the hyper

terminal, as per the serial transmission standards in 8051

microcontroller [19].

DCE Baud Rates

110,300,1200,2400

,4800,9600,19200,38400,57600,115200,230400,460800,921600

(Possible Baud Rates) Baud Rate Used Power on default rate

Testing a DB-9 RS-232 serial port in HyperTerminal

This procedure explains how to troubleshoot a COM card using

HyperTerminal. Before testing my serial ports, I first hook up a

loopback. A loopback connects the output signal (TXD) to the

input signal (RXD) in a single serial port connector to make it

seem like there are two ports connected together.

Making a loopback

Steps

Turn off the computer.

Connect RXD (pin 2) and TXD (pin 3) of the serial port.

Use a loop-back connector if available, or any kind of

conductive wire, even a paper clip .

Turn on the computer. I am now ready to test the port.

DB9 interface

Running HyperTerminal

Step Procedure Description

Launch HyperTerminal. In Windows, select Programs/

Accessories/ Communications/HyperTerminal.

Create a new session. When prompted, give the session

any name I wish.

Select the COM # associated with the computer, I am

now set up to test the port.

With the session open, type any text. If the text I type is

echoed on the screen, the port is functioning properly.

Close the session.

Repeat all above steps to test additional you will first

need to connect the Loopback Ports [22]. On the other

ports using the steps above.

Initializations

The baud rate of the modem was set to be 9600 bps using the

HyperTerminal, The ECHO from the modem was turned off

using the command ATE0 at the HyperTerminal. For serial

transmission and reception to be possible both the DTE and

DCE should have same operational baud rates. Hence to set the

microcontroller at a baud rate of 9600bps, I set terminal count of

Timer 1 at 0FFh (clock frequency = 1.8432). The TCON and

SCON registers were set accordingly.

Serial transfer using TI and RI flags

After setting the baud rates of the two devices both the devices

are now ready to transmit and receive data in form of characters.

Transmission is done when TI flag is set and similarly data is

known to be received when the Rx flag is set. The

microcontroller then sends an AT command to the modem in

form of string of characters serially just when the TI flag is set.

After reception of a character in the SBUF register of the

microcontroller (response of MODEM with the read message in

its default format or ERROR message or OK message), the RI

flag is set and the received character is moved into the physical

memory of the microcontroller.

SOFTWARE USED

AVR Studio –

An integrated development environment for AVR applications.

AVR Studio is an Integrated Development Environment for writing and debugging AVR applications in Windows 98/XP/ME/2000 and Windows NT environments.

AVR Studio provides a project management tool, source file editor and chip simulator.

An example of what AVR Studio may look like during

execution of a program is shown below in Figure. (3). In

addition to the Source window, AVR Studio defines a number of

other windows which can be used for inspecting the different

resources on the microcontroller.

AVR Studio

Simulation for LED blinking using AVR Studio

CONCLUSION AND FUTURE SCOPE

This project deals with the design & development of a theft

control system for an automobile, which is being used to prevent

or control the theft of a vehicle. The simulation of the circuit

design and its implementation is done using PROTEUS

software. This system is designed to improve vehicle security

and accessibility. With the use of wireless technology vehicle

owners are able to enter as well as protect their automobiles with

more passive involvement.

Ideally, this project could be made more convenient and secure

with the use of satellite modems instead of cell phones as

tracking device as the system may fail when there is no network

coverage. This design can be made more enhanced in future to

support camera, handset phone / hands free, mobile data LCD

display, web based tracking software, also PC based stand alone

software. In our project the security system is based on

embedded control which provides security against theft. The

GSM modem provides information to the user on his request.

The owner can access the position of the vehicle at any instant.

He sends a message in order to lock the vehicle. The GPS

receiver on the kit will locate the latitude and longitude of the

vehicle using the satellite service. This is reliable and efficient

system for providing security to the vehicles through GSM, GPS

and serial communication. The maximum speed according to the

standard is 20kbits/sec.