Mobile Sniffer

VIVEKANAND EDUCATION SOCIETY’S
POLYTECHNIC
CHEMBUR, MUMBAI-400071
MOBILE SNIFFER
Submitted by
In partial fulfillment of the requirement of the degree
Of
DIPLOMA
IN
ELECTRONICS AND TELECOMMUNICATION
UNDER THE GUIDANCE OF
MRS. LINA PATIL
AFFILIATED TO
2012-2013
A PROJECT REPORT ON
MOHIT KHATRI

CERTIFICATE
This is to certify that the project entitled “MOBILE SNIFFER” is the bonafide work
Telecommunication, MSBTE, Mumbai, during the year 2012-2013, impartial fulfillment of the
requirements of the Degree of Diploma In Electronics and Telecommunication and that the
project has not formed the basis for the award previously of any degree, diploma, associate ship,
fellowship or any other similar title.
__________________
Signature of the Guide:
Place:
Date:
Department of Electronics & Telecommunication Engineering
V. E. S. Polytechnic, Mumbai-400071
carried out by MR. MOHIT KHATRI- student of Diploma in Electronics and

VIVEKANAND EDUCATION SOCIETY’S
POLYTECHNIC
CHEMBUR, MUMBAI-400071
CERTIFICATE OF APPROVAL
__________________ ___________________
Guide Examiner
Mrs. Lina Patil
________________ __________________
Head of the Department Principal
Mrs. Deena Shah Mr. Vikrant Joshi
Department of Electronics & Telecommunication Engineering
Project titled on “MOBILE SNIFFER”
Submitted by Mr. Mohit Khatri is approved for the diploma of Engineering.

ACKNOWLEDGEMENT
The completion of this project would not have been possible without the kind
support and help of many people. I would like to extend my sincere thanks to all of
them.
I am highly indebted to our project guide Mrs. Lina Patil for her guidance and
constant supervision as well as for providing necessary information regarding the
project and also for her support in completing the project.
I would like to express my gratitude towards our H.O.D Mrs. Deena Shah for her
kind co-operation and encouragement which help me in completion of this project.
I would like to tender my sincere thanks to our Principal Mr. Vikrant Joshi for
providing all the facilities required to complete the project successfully.
I would like to express my special gratitude and thanks to the Lab In-charge Mrs.
Sonali for giving me such attention and time.
I also owe a debt of gratitude to the college library for providing the necessary
information.

CONTENTS
List of Figures V
List of Tables VII
Abstract VIII
CHAPTER 1
INTRODUCTION 1
CHAPTER 2
BLOCK DIAGRAM
2.1 Block Diagram Description 3
CHAPTER 3
CIRCUIT DIAGRAM & EXPLANATION
3.1 Power Supply 5
3.2 Detector Stage 7
3.3 Controller Stage 9
CHAPTER 4
COMPONENTS DESCRIPTION
4.1 Detector Stage
4.1.1 Telescopic Antenna 12
4.1.2 Battery 13
4.1.3 BC 548 Transistor 15
I

II
4.1.4 CA 3130 16
4.1.5 Resistor 17
4.1.6 Capacitor 19
4.1.7 LM 555 Timer 23
4.1.8 Buzzer 24
4.1.9 LED 25
4.2 Controller Stage
4.2.1 Microcontroller 89S51 26
4.2.2 Voltage Regulator 36
4.2.3 MAX 232 37
4.2.4 LCD Display 40
4.2.5 GSM Modem 42
4.3 Components List 45
CHAPTER 5
PCB LAYOUT, PROTOTYPE AND
TROUBLESHOOTING
5.1 PCB Layout description 47
5.2 PCB Making Process 48
5.3 Drilling Process
5.4 Soldering
5.4.1 What Is Soldering
50
51
5.4.2 Steps In Soldering
5.5 Troubleshooting
5.5.1 Description
52
52
5.5.2 Need of troubleshooting 52
5.5.3 Device Required For Troubleshooting 53
5.5.4 Steps Prior To Troubleshooting 55

III
5.6 Troubleshooting steps
5.6.1 Identify The Symptom 56
5.6.2 Power Check 56
5.6.3 Perform SensoryCheck 56
5.6.4 Signal Tracing 56
5.6.5 Fault Analysis 57
CHAPTER 6
SOFTWARE DEVELOPMENT TOOLS AND
PROGRAMMING
6.1 Software Used For Making PCB Layout 58
6.2 Program 61
CHAPTER 7
ADVANTAGES AND LIMITATIONS
7.1 Advantages 63
7.2 Limitations 63
CHAPTER 8
CHAPTER 9
CONCLUSION 66
APPLICATIONS 64

IV
CHAPTER 10
BIBLIOGRAPHY
10.1 Reference Books 67
10.2 Reference Website 67

V
List of Figures
Figure No Name Page No
Figure 1.1 Jammer 1
Figure1.2 Mobile Sniffer 1
Figure 1.3 Blockers 1
Figure 1.4 Examination Hall 2
Figure 1.5 Auditorium 2
Figure 1.6 Conference Rooms 2
Figure 2.1 Block Diagram Of Mobile Sniffer 3
Figure 3.1 Circuit Diagram Of Power Supply 5
Figure 3.2 Circuit Of Detector Stage 7
Figure 3.3 Circuit Of Controller Stage 9
Figure 4.1 Telescopic Antenna 12
Figure 4.2 Battery 13
Figure 4.3 Piezoelectric Buzzer 24
Figure 4.4 LED 25
Figure 4.5 Pin Diagram of 89S51 27
Figure 4.6 Block Diagram of 89S51 28
Figure 4.7 Program Memory 32
Figure 4.8 Data Memory 33
Figure 4.9 Internal Data MemoryOrganization 33
Figure 4.10 Scratch Pad RAM Organization 34
Figure 4.11 128 Byte Memory Allocation 35
Figure 4.12 SFR 35
Figure 4.13 Voltage Regulator 36
Figure 4.14 Pin Out Of MAX232 37
Figure 4.15 LCD Display 40

VI
Figure 4.16 GSM Modem 42
Figure 4.17 GSM Network Structure 44
Figure 5.1 PCB Layout Of Controller Stage 47
Figure 5.2 PCB Layout Of Detector Stage 48
Figure 5.3 PCB Layout Of RS-232 48
Figure 5.4 Dipping The PCB In Coat 48
Figure 5.5 PCB After Dipping In Coat 48
Figure 5.6 Adjusting The PCB To Kept In Oven 49
Figure 5.7 PCB Oven 49
Figure 5.8 UV Exposure To PCB 49
Figure 5.9 Dipping PCB In Developer Liquid 49
Figure 5.10 PRITO-ETCH 50
Figure 5.11 Digital Multimeter 53
Figure 5.12 CRO, Frequency, Generator, Power Supply 54

VII
List of Tables
Table No Name Page No
Table 4.1 100K Specifications 17
Table 4.2 1K Specifications 18
Table 4.3 2.2M Specifications 19
Table 4.4 22pF Specifications 19
Table 4.5 4.7uF Specifications 20
Table 4.6 0.22uF Specifications 21
Table 4.7 47 pF Specifications 22
Table 4.8 RS-232 Pin functions 39
Table 4.9 LCD Pin Configuration 41
Table 4.10 Control codes for LCD 41
Table 4.11 Components List 43

VIII
ABSTRACT
Mobile phones today are causing disturbance in areas where use of mobile phones is
strictly prohibited. For eg:-When someone is watching a movie in a theatre and suddenly
a mobile phone in the crowd rings, the other people along with the person who is the
owner of the mobile get disturbed. If we see from the academic point of view, in college
libraries the use of cell phone disturbs the people around. This gives the need to build up
a device which can detect and stop the use ofcell phones in areas like class room, theatre,
college libraries etc.
This mobile transmission detector or sniffer can sense the presence of an activated mobile
cell phone from a distance of one and-a-half meters. So it can be used to prevent use of
mobile phones in examination hall, confidential rooms, etc. It is also useful for detecting
the use of mobile phone for Spying and unauthorized video transmission.
The circuit can detect the incoming and outgoing calls, SMS and video transmission even
if the mobile phone is kept in the silent mode. The moment the sniffer detects RF
transmission signal from an activated mobile phone it sends an SMS to a specific mobile
number

1
CHAPTER-1
INTRODUCTION
The field of mobile communication has grown very fast in the few last decades. Mobile
phones have become a need for human being. It has made the life of a man very easy
and comfortable. One can easily communicate with other person situated in any part of
the world through this device called mobile phone. Everything has its own advantages
as well as disadvantages. There are certain areas like examination halls, temple, theatre,
conference rooms etc. where the use of mobile phones is strictly prohibited. But since
this need is not met, there has to be a device which could prevent people from using
their mobile phones in such areas.
Devices which can be used to solve this problem are:-
1. Jammer 2. Mobile Sniffer
Figure 1.1 Jammer Figure 1.2 Mobile Sniffer
3. Blockers
Figure 1.3 Blockers

2
Our project “Mobile Sniffer” is made to solve this problem. This mobile transmission
detector or sniffer can sense the presence of an activated mobile cell phone from a
distance of one and-a-half meters. So it can be used to prevent use of mobile phones in
examination hall, confidential rooms, etc. It is also useful for detecting the use of
mobile phone for Spying and unauthorized video transmission.
Places where our project can be implemented:-
1. Examination Hall 2. Auditorium
Figure 1.4 Examination Hall Figure 1.5 Auditorium
3. Conference Rooms
Figure 1.5 Conference Rooms

3
CHAPTER-2
BLOCK DIAGRAM
Figure 2.1 Block Diagram of Mobile Sniffer
2.1 Block Diagram Description
1. Antenna
There are two antennas which are used out of which one is the transmitter antenna
and the other is the receiver antenna. The first antenna is the receiver antenna which
catches the RF signals from the sample mobile. The antenna then converts the
electromagnetic signal to electrical signal and sends it to the detector circuit. The
other antenna which is connected to the GSM modem is the transmitter antenna
which is used for sending SMS to a particular mobile number.
2. LC Tank Circuit
This is the mobile detector stage which detects the signals from the sample mobile.
It consists of various resistors, capacitors, a NPN transistor, LED and a current to
voltage convertor IC.

4
3. Microcontroller
The microcontroller is the brain of this project. IC 89S51 is used which has 4KB of
EPROM (Erasable Programmable Read Only Memory). It works on +5V power
supply. It sends signals to the LCD display and the buzzer on detecting a cell phone.
4. MAX 232
MAX 232 is standard protocol which is used for serial communication. It is a dual
driver/receiver that includes a capacitive voltage generator to supply TIA/EIA-232-
F voltage levels from a single 5-V supply. Each receiver converts TIA/EIA-232-F
inputs to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3 V,
a typical hysteresis of 0.5 V, and can accept ±30-V inputs. Each driver converts
TTL/CMOS input levels into TIA/EIA-232-F levels
5. GSM Modem
A GSM modem is a specialized type of modem which accepts a SIM card, and
operates over a subscription to a mobile operator, just like a mobile phone. From the
mobile operator perspective, a GSM modem looks just like a mobile phone. When a
GSM modem is connected to a computer, this allows the computer to use the GSM
modem to communicate over the mobile network.

5
CHAPTER-3
CIRCUIT DIAGRAM AND EXPLANATION
Our project has been divided into three stages:-
1. Power supply
2. Detector Stage
3. Controller Stage
The study of these stages will help us to know the complete working of this project. The
power supply stage provides 12V and 5V power supply to the detector stage and
controller stage respectively.
3.1 Power Supply
Power supply is the first and the most important part of our project. For our project we
require +5V regulated power supply with maximum current rating 500 MA.
Following basic building blocks are required to generate regulated power supply.
Figure 3.1 Circuit Diagram of power supply

6
I. Step down Transformer:-
Step down transformer is the first part of regulated power supply. To step down the
mains 230V A.C. we require step down transformer. Following are the main
characteristic of electronic transformer.
1) Power transformers are usually designed to operate from source of low impedance at
a single freq.
2) It is required to construct with sufficient insulation of necessary dielectric strength.
3) Transformer ratings are expressed in volt–amp. The volt-amp of each secondary
winding or windings are added for the total secondary VA. To this are added the
load losses.
4) Temperature rise of a transformer is decided on two well-known factors i.e. losses on
transformer and heat dissipating or cooling facility provided unit.
II. Rectifier Unit:-
Rectifier unit is a circuit which converts A.C. into pulsating D.C. Generally semi-
conducting diode is used as rectifying element due to its property of conducting current
in one direction only. Generally there are two types of rectifier.
1) Half wave rectifier
2) Full wave rectifier.
In half wave rectifier only half cycle of mains A.C. is rectified so its efficiency is very
poor. So we use full wave bridge type rectifier, in which four diodes are used. In each
half cycle, two diodes conduct at a time and we get maximum efficiency at o/p.
III. …Filter Circuit:-
Generally a rectifier is required to produce pure D.C. supply for using at various places
in the electronic circuit. However, the o/p of rectifier has pulsating character i.e. if such
a D.C. is applied to electronic circuit it will produce a hum i.e. it will contain A.C. and
D.C. components. The A.C. components are undesirable and must be kept away from

7
the load. To do so a filter circuit is used which removes (or filters out) the A.C.
components reaching the load. Obviously a filter circuit is installed between rectifier
and voltage regulator. In our project we use capacitor filter because of its low cost,
small size and little weight and good characteristic. Capacitors are connected in parallel
to the rectifier o/p because it passes A.C. but does not pass D.C. at all
3.2 Detector Stage
Figure 3.2 Circuit of detector stage
Circuit Explanation
An ordinary RF detector using tuned LC circuits is not suitable for detecting signals in
the GHz frequency band used in mobile phones. The transmission frequency of mobile
phones ranges from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm. So a circuit
detecting gigahertz signals is required for a mobile bug. Here the circuit uses a 0.22μF
disk capacitor (C3) to capture the RF signals from the mobile phone. The lead length of
the capacitor is fixed as 18 mm with a spacing of 8 mm between the leads to get the
desired frequency. The disk capacitor along with the leads acts as a small gigahertz loop
antenna to collect the RF signals from the mobile phone.

8
Op-amp IC CA3130 (IC1) is used in the circuit as a current-to-voltage converter with
capacitor C3 connected between its inverting and non-inverting inputs. It is a CMOS
version using gate-protected p-channel MOSFET transistors in the input to provide very
high input impedance, very low input current and very high speed of performance. The
output CMOS transistor is capable of swinging the output voltage to within 10 mV of
either supply voltage terminal.
Capacitor C3 in conjunction with the lead inductance acts as a transmission line that
intercepts the signals from the mobile phone. This capacitor creates a field, stores
energy and transfers the stored energy in the form of minute current to the inputs of IC1.
This will upset the balanced input of IC1 and convert the current into the corresponding
output voltage. Capacitor C4 along with high-value resistor R1 keeps the non-inverting
input stable for easy swing of the output to high state. Resistor R2 provides the
discharge path for capacitor C4.
Feedback resistor R3 makes the inverting input high when the output becomes high.
Capacitor C5 (47pF) is connected across ‘strobe’ (pin 8) and ‘null’ inputs (pin 1) of IC1
for phase compensation and gain control to optimize the frequency response. When the
cell phone detector signal is detected by C3, the output of IC1 becomes high and low
alternately according to the frequency of the signal as indicated by LED1.This triggers
monostable timer IC2 through capacitor C7. Capacitor C6 maintains the base bias of
transistor T1 for fast switching action. The low-value timing components R6 and C9
produce very short time delay to avoid audio nuisance.

9
Figure 3.3 Circuit of Controller Stage

10
Circuit Explanation
In order to send an SMS (Short Message Service) on detecting a cell phone, here we
require a controller. The controller which is used is 89S51. 89S51 has 4KB of flash
memory due to which it is preferred over 8051 microcontroller. For any microcontroller
to start 3 things are mandatory:
1. Power supply
2. Clock
3. Reset Circuit
The microcontroller has 4 ports: - Port0, Port 1, Port2 and Port 3. All these ports are 8
bit bidirectional ports. Pin 40 is connected to +5v power supply and Pin 20 is connected
to ground (0V). A crystal of frequency 11.0592 MHZ is connected between Pin 18 and
19 along with two 22PF capacitors.
A reset circuit is connected to Pin 9 of the controller which consists of a resistor and a
capacitor. This reset is a power on reset i.e. as the microcontroller turns on a pulse is
provided which resets the microcontroller and the execution starts from 0000H memory
location. This reset is an automatic reset but it can be made a manual reset by
connecting a switch.
Port 0 is used to connect a 16x2 LCD display which displays the various modes of the
project. A variable resistor is connected between the VCC and GND pin of the LCD and
the variable pin of the resistor is connected to the contrast pin of LCD for varying the
brightness of the LCD. The three control pins of LCD are Data/Command, Read/Write
and Enable pins which tell the microcontroller that whether the operation to be
performed is a command or data, read or write and to enable the LCD.
To send SMS on detection of a mobile phone, a GSM modem is connected to the
microcontroller. Since GSM modem works on a serial protocol, the serial port of
microcontroller i.e. Port 3 is used.

11
The output from the detector stage is fed as input at port 1 of the microcontroller. Port 3
pins are connected to a GSM modem through RS 232 interface IC. As soon as a cell
phone is detected the output from the detector stage will make P1.0 pin of the
microcontroller high and a program written and stored in the microcontroller starts
executing. The program provides functions like sending signal to the LCD display,
signal to the GSM modem through RS 232. The GSM modem sends SMS to a particular
mobile number thus informing that a cell phone has been detected. When P1.0 is not
high the LCD displays Scanning which means that the controller is in search of a mobile
phone. When a mobile phone is detected the LCD displays a message “Mobile Phone
Alert” and after a few seconds it will display “Sending SMS”.
In this way the project works with the help of the two stages. The detector stage is
responsible for sensing the RF signal within a particular range. The controller stage
functions as the brain of the project since all the important functions apart from sensing
is carried out by the controller stage.

12
CHAPTER-4
COMPONENT DESCRIPTION
4.1 Detector Stage
4.1.1 Telescopic Antenna
Figure 4.1 Telescopic Antennas
An antenna whose receiving or radiating elements, such as the arms of a dipole, are
made in the form of an extensible system of metal tubes or rods of approximately equal
length. Such a design facilitates changing the length of the antenna elements during
tuning and permits the size of the antenna to be reduced when it is not in operation—for
example, during transport or storage.
For each pair of telescoping tubes, the interior diameter of the outer tube is
approximately equal to the exterior diameter of the inner tube. The tubes fit into one
another with some friction, which is needed to provide electrical contact and to maintain
the required length of each element of the telescopic antenna under operating
conditions—that is, under the action of gravity or exposure to shaking or vibration. In
some cases the required position of the tubes may be fixed by additional means. For
example, collet chucks or springs may be employed.
Telescopic antennas are used principally in conjunction with radio receivers, radio
transmitter-receivers, portable television receivers, and television receivers installed in

13
moving objects, such as automotive vehicles; such antennas are also used as indoor
television antennas.
Specifications:-
Packing: By boxes
Model no: tcs –jg-3-150-j
Trademark: HYS
Electrical specifications:
Frequency range: 900 MHz-1800 MHz
Impedance: 50Ω
VSWR <2
Gain: 3db
Radiation: Omni
Polarization: Vertical
Max power input-watts: 50w
4.1.2 Battery
Figure 4.2 Battery

14
1. Sealed Maintenance Free
The valve regulated, spill-proof construction of this battery allows trouble-free, safe
operation in any position. There is no need to add electrolyte, as gases generated during
charging are recombined in a unique "oxygen cycle".
2. Long Service Life
A dependable service life can be expected under normal operating conditions.
3. Long Shelf Life
Low self-discharge rate allows for storage of fully charged batteries for longer periods
of time before charging is required. Lower storage temperatures will further extend
shelf life.
4. Wide Operating Temperature Range
May be discharged over a temperature range of -40°C to +60°C (-40°F to +140°F), and
charged at temperatures ranging from -20°C to +50°C (4°F to +122°F).

17
Description:
CA3130A and CA3130 are op amps that combine the advantage of both CMOS and
bipolar
transistors. Gate-protected P-Channel MOSFET (PMOS) transistors are used in the
input circuit to provide very-high-input impedance, very-low-input current, and
exceptional speed performance. The use of PMOS transistors in the input stage results
in common-mode input-voltage capability down to 0.5V below the negative-supply
terminal, an important attribute in single-supply applications.
The CA3130 Series circuits operate at supply voltages ranging from 5V to 16V, (±2.5V
to ±8V). They can be phase compensated with a single external capacitor, and have
terminals for adjustment of offset voltage for applications requiring offset-null
capability. Terminal provisions are also made to permit strobing of the output stage. The
CA3130A offers superior input characteristics over those of the CA3130.
4.1.5 Resistors
1. 100kΩ
Table 4.1. 100K Specifications
Resistance (Ohms) 100K
Power (Watts) 0.5W, 1/2W
Tolerance ±5%
Packaging Bulk

18
Composition Carbon Composition
Temperature Coefficient ±10ppm/°C
Lead Free Status Lead Free
2. 1k
Table 4.2. 1K Specifications
Resistance (Ohms) 1K
Power (Watts) 1W
Tolerance ±10%
Packaging Bulk
Temperature Coefficient -
3. 2.2M

19
Table 4.3. 2.2M Specifications
Resistance (Ohms) 2.2M
Power (Watts) 8W
Tolerance ±10%
Packaging Bulk
Temperature Coefficient -
4.1.6 Capacitors
1. 22pf
Table 4.4. 22pF Specifications
Category Capacitors
Capacitance 22pF
Voltage – Rated 16V
Tolerance ±5%
Package / Case 01005 (0402 Metric)
Temperature Coefficient C0G, NP0
Packaging Cut Tape (CT)
Features -

20
Lead Spacing -
Operating Temperature -55°C ~ 125°C
Mounting Type Surface Mount, MLCC
2. 4.7uf
Table 4.5. 4.7uF Specifications
Category Capacitors
Capacitance 4.7µF
Voltage - Rated 6.3V
Tolerance ±20%
Temperature Coefficient X5R
Features -
Lead Spacing -

21
3. 0.22uf
Table 4.6. 0.22uF Specifications
Category Capacitors
Capacitance 0.22µF
Voltage - Rated 50V
Tolerance ±10%
Package / Case Radial
Temperature
Coefficient
X8L
Packaging Bulk
Features -
Lead Spacing 0.197" (5.00mm)
Operating
Temperature
-55°C ~ 150°C
Mounting Type Through Hole
4. 47pf

22
Table 4.7. 47 pF Specifications
Category Capacitors
Capacitance
47pF
Voltage - Rated 50V
Tolerance ±5%
Temperature Coefficient C0G, NP0
Features -
Lead Spacing -
Mounting Type Surface Mount, MLCC

24
4.1.8 BUZZER
Figure 4.3 Piezoelectric Buzzer
Electrical Specifications:
1. SoundPressureLevel:80dBmin./30cm./9VDC
2. OscillatingFrequency:2.5±0.5 KHz
3. Current Consumption: 8 mA max. /9VDC
4. Operating Voltage: 3to30VDC
Mechanical Specifications:
1. Operating Temperature:-30°Cto+70°C
2. Storage Temperature:-40°Cto+85°C
Materials:
1. Tone: Continuous
2. Case: PBT
3. Lead Wire:28AWG
4. Weight:7grams

25
4.1.9 LED (Light Emitting Diode)
Figure 4.4 LED
LED means Light Emitting Diode. It is an electronic device that lights up when
electricity is passed through it. LEDs are usually red. They are good for displaying
images because they can be relatively small. The moment the bug detects RF
transmission signal from an activated mobile phone, it starts sounding a beep alarm
and the LED blinks. LED‟s contain an integrated multivibrator circuit inside which
causes the LED to flash with a typical time period.

26
4.2.1 Microcontroller 89S51
Features:-
1. Compatible with MCS-51™ Products
2. 4K Bytes of In-System Reprogrammable Flash Memory Endurance: 1,000
Write/Erase Cycles
3. Fully Static Operation: 0 Hz to 24 MHz
4. Three-level Program Memory Lock
5. 128 x 8-bit Internal RAM
6. 32 Programmable I/O Lines
7. Two 16-bit Timer/Counters
8. Six Interrupt Sources
9. Programmable Serial Channel
10. Low-power Idle and Power-down Modes
11. Compatible with MCS51 products
12. Eight interrupt sources
13. Dual data pointer
14. Power off flag
15. Three 16 bit timer/ counters
16. Watch dog timer

27
Description:-
The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 8K
bytes of in-system programmable Flash memory. The device is manufactured using
Atmel’s high-density non-volatile memory technology and is compatible with the
industry-standard 80C51 instruction set and pin out. The on-chip Flash allows the
program memory to be reprogrammed in-system or by a conventional non-volatile
memory programmer. By combining a versatile 8-bit CPU with in-system
programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful
microcontroller which provides a highly-flexible and cost-effective solution to many
embedded control applications.
Pin Diagram:
Figure 4.5 Pin Diagram of 89S51

28
Block Diagram:
Figure 4.6 Block Diagram of 89S51

29
Pin Description:
1. VCC
Supply voltage.
2. GND
Ground.
3. Port 0
Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink
eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high
impedance inputs. Port 0 may also be configured to be the multiplexed low order
address/data bus during accesses to external program and data memory. In this mode P0
has internal pull-ups. Port 0 also receives the code bytes during Flash programming, and
outputs the code bytes during program verification. External pull-ups are required
during program verification.
4. Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers
can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled
high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are
externally being pulled low will source current (II L) because of the internal pull-ups.
In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count
input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as
shown in the following table. Port 1 also receives the low-order address bytes during
Flash programming and verification.
5. Port 2
Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers
can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are
externally being pulled low will source current (IIL) because of the internal pull-ups.
Port 2 emits the high-order address byte during fetches from external program memory

30
and during accesses to external data memory that uses 16-bit addresses (MOVX @
DPTR). In this application, it uses strong internal pull-ups when emitting 1s. During
accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits
the contents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some control signals during Flash
programming and verification.
6. Port 3
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers
can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are
externally being pulled low will source Current (IIL) because of the pull-ups. Port 3 also
serves the functions of various special features of the AT89S51 as listed below:
Port Pin Alternate Functions – Port Pin Alternate Functions –
P3.0 RXD (serial input port)
P3.1 TXD (serial output port)
P3.2 INT0 (external interrupt 0)
P3.3 INT1 (external interrupt 1)
P3.4 T0 (timer 0 external input)
P3.5 T1 (timer 1 external input)
P3.6 WR (external data memory write strobe)
P3.7 RD (external data memory read strobe)

31
7. RST
Reset input. A high on this pin for two machine cycles while the oscillator is running
resets the device. This pin drives High for 96 oscillator periods after the Watchdog
times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this
feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.
8. ALE/PROG
Address Latch Enable output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse input (PROG) during
Flash programming. In normal operation ALE is emitted at a constant rate of 1/6 the
oscillator frequency, and may be used for external timing or clocking purposes. Note,
however, that one ALE pulse is skipped during each access to external Data Memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With
the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the
pin is weakly pulled high. Setting the ALE-disable bit has no effect if the
microcontroller is in external execution mode.
9. PSEN
Program Store Enable (PSEN) is the read strobe to external program memory. When
the AT89S51 is executing code from external program memory, PSEN is activated
twice each machine cycle, except that two PSEN activations are skipped during each
access to external data memory.
10. EA/VPP
External Access Enable. EA must be strapped to GND in order to enable the device to
fetch code from external program memory locations starting at 0000H up to FFFFH.
11. XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating
circuit.

32
12. XTAL2
Output from the inverting oscillator amplifier
Memory Organisation:
Program Memory-
The TEMIC S51 Microcontroller Family has separate address spaces for program
Memory and Data Memory. The program memory can be up to 64 K bytes long. The
lower 4 K for the 80S51 may reside on chip.
Figure 4.7 Program Memory
Data Memory
The S51 Microcontroller Family can address up to 64 K bytes of Data Memory to the
chip. The “MOVX” instruction is used to access the external data memory. The 80S51
has 128 bytes of on-chip-RAM plus a number of Special Function Registers (SFR). The
lower 128 bytes of RAM can be accessed either by direct addressing (MOV data addr)
or by indirect addressing (MOV @Ri).

33
Figure 4.8 Data Memory
Internal Data Memory Organization
Internal data memory is shown in Figure. The memory space is divided into three
blocks, which are generally referred to as the Lower 128, the Upper 128, and SFR
space.
Figure 4.9 Internal Data Memory Organisation
Internal data memory addresses are always 1 byte wide, which implies an address space
of only 256 bytes. However, the addressing modes for internal RAM can in fact
accommodate 384 bytes. Direct addresses higher than 7FH access one memory space,
and indirect addresses higher than 7FH access a different memory space. Thus, Figure 7

34
shows the Upper 128 and SFR space occupying the same block of addresses, 80H
through FFH, although they are physically separate entities.
Scratch Pad RAM Organization
Figure shows how the lower 128 bytes of RAM are mapped. The lowest 32 bytes are
grouped into 4 banks of 8 registers. Program instructions call out these registers as R0
through R7. Two bits in the Program Status Word (PSW) select which register bank is
in use. This architecture allows more efficient use of code space, since register
instructions are shorter than instructions that use direct addressing
Figure 4.10 Scratch Pad Ram Organisation
The 128 Byte Memory
The next 16 bytes above the register banks form a block of bit-addressable memory
space. The microcontroller instruction set includes a wide selection of single-bit
instructions, and these instructions can directly address the 128 bits in this area. These
bit addresses are 00H through 7FH. All of the bytes in the Lower 128 can be accessed

35
by either direct or indirect addressing. The Upper 128 (Figure 9) can only be accessed
by indirect addressing. The Upper 128 bytes of RAM are only in the devices with 256
bytes of RAM.
The SFR (Special Function Register)
Figure gives a brief look at the Special Function Register (SFR) space. SFRs include
Port latches, timers, peripheral controls, etc. These registers can only be accessed by
direct addressing. In general, all Phillips microcontrollers have the same SFRs at the
same addresses in SFR space as the AT89S51 and other compatible microcontrollers.
However, upgrades to the AT89S51 have additional SFRs. Sixteen addresses in SFR
space are both byte- and bit addressable. The bit-addressable SFRs are those whose
address ends in 000B. The bit addresses in this area are 80H through FFH.
Figure 4.11 128 byte memory allocation Figure 4.12 SFR

36
MCS-51 devices have a separate address space for Program and Data Memory. Up to 64k
bytes each of external. Program and Data Memory can be addressed.
4.2.2 Voltage Regulator
Figure 4.13 Voltage Regulator
Features:
1. O u t p u t Current upto1A
2. O u t p u t Voltages of 5,6,8,9, 10,12,15, 18,24V
3. T h e r ma l Overload Protection
4. S h o r t Circuit Protection
5. O u t p u t Transistor Safe Operating Area Protection
Description:
The MC78XX/LM78XX/MC78XXA SERIES OF THREE TERMINAL positive
regulators are available in the TO-220/D-PAK package and with several fixed output
voltages, making them useful in a wide range of applications. Each type employs
internal current limiting, thermal shut down and safe operating area protection, making
it essentially indestructible. If adequate heat sinking is provided, they can deliver over
1A output current. Although designed primarily as fixed voltage regulators, these
devices can be used with external components to obtain adjustable voltage and currents.

37
4.2.3 MAX 232
The MAX232 was the first IC which in one package contains the necessary drivers
(two) and receivers (also two), to adapt the RS-232 signal voltage levels to TTL logic. It
became popular, because it just needs one voltage (+5V) and generates the necessary
RS-232 voltage levels (approx. -10V and +10V) internally. This greatly simplified the
design of circuitry. The MAX232 has a successor, the MAX232A. It should be noted
that the MAX232 (A) is just a driver/receiver. It does not generate the necessary RS-232
sequence of marks and spaces with the right timing, it does not decode the RS-232
signal, and it does not provide a serial/parallel conversion. All it does is to convert
signal voltage levels. Generating serial data with the right timing and decoding serial
data has to be done by additional circuitry.
The original manufacturer offers a large series of similar ICs, with different numbers of
receivers and drivers, voltages, built-in or external capacitors, etc. E.g. The MAX232
and MAX232A need external capacitors for the internal voltage pump, while the
MAX233 has these capacitors built-in.
Figure 4.14 Pin out of MAX 232

38
Features:
1. Meets or Exceeds TIA/EIA-232-F and ITU Recommendation V.28
2. Operates From a Single 5-V Power Supply With 1.0-uF Charge-Pump Capacitors
3. Operates Up To 120 Kbit/s
4. Two Drivers and Two Receivers
5. 30-V Input Levels
6. Low Supply Current 8 mA Typical
7. ESD Protection Exceeds JESD 222000-V Human-Body Model (A114-A)
8. Upgrade With Improved ESD (15-kV HBM) and 0.1-uF Charge-Pump Capacitors is
9. Available With the MAX202
Transmission with 89S51
89S51 has a serial data communication circuit that uses register SBUF to hold data.
Register SCON controls data communication. Register PCON controls data rates. Pins
RxD (3.0) and TxD (3.1) connect to serial data network. SBUF is physically two
registers, one is writing only i.e. to hold data to be transmitted out of microcontroller via
TxD. The other is read only and holds received data from an external transmitting
source via RxD. Whenever a data byte is transmitted T1 flag is set and so program is
interrupted to transmit another byte of data. The main program is interrupted only serial
port interrupt is 1E SFR is enable.
The data transmission steps are:
1. Initially the t1 flag is reset.
2. Data to be transmitted must be written into SBUF.
3. As soon as data is transmitted the T1 flag is set and main program is interrupted to
execute ISR. In the ISR T1 flag is reset another data is written in SBUF register.

39
RS-232 Level Converters
Almost all digital devices which we use require either TTL or CMOS logic levels.
Therefore the first step to connecting a device to the RS-232 port is to transform the RS-
232 levels back into 0 and 5 Volts. As we have already covered, this is done by RS-232
Level Converters. Two common RS-232 Level Converters are the 1488 RS-232 Driver
and the 1489 RS-232 Receiver. Each package contains 4 inverters of the one type, either
Drivers or Receivers. The driver requires two supply rails, +7.5 to +15v and -7.5 to -
15v. As you could imagine this may pose a problem in many instances where only a
single supply of +5V is present. However the advantages of these I.C's are they are
cheap.
Pin Functions:
Table 4.8 RS-232 Pin Functions

40
4.2.4 LCD Display
Figure 4.15 LCD Display
Liquid crystal Display (LCD) displays temperature of the measured element, which is
calculated by the microcontroller. CMOS technology makes the device ideal for
application in hand held, portable and other battery instruction with low power
consumption.
General Specifications:
1. Drive method: 1/16 duty cycle
2. Display size: 16 character * 2 lines
3. Character structure: 5*8 dots.
4. Display data RAM: 80 characters (80*8 bits)
5. Character generate ROM: 192 characters
6. Character generate RAM: 8 characters (64*8 bits)
7. Both display data and character generator RAMs can be read from MPU.
8. Internal automatic reset circuit at power ON.
9. Built in oscillator circuit.

41
Pin Configuration:
Table 4.9 LCD Pin Configuration
JP1/JP14
Pins 1 – 8
Description JP1/JP14
Pins 9 -16
Description
Pin1 Ground Pin9 D2 (Not Used)
Pin2 VCC (+5) Pin10 D3 (Not Used)
Pin3 Contrast Pin11 D4
Pin4 Data/Command (R/S) Pin12 D5
Pin5 Read/Write (W) Pin13 D6
Pin6 Enable (E1) Pin14 D7
Pin7 D0 (Not Used) Pin15 VCC (LEDSV+)
Pin8 D1 (Not Used) Pin16 Ground
LCD Control Codes:
Table 4.10 Control Codes for LCD
Description Keyboard Code ASCII or Decimal
value
Display custom
character 0-7
Ctrl-@ -Through- Ctrl-G 0 - 7
Backspace Ctrl-H 8
Horizontal Tab Ctrl-I 9
New Line Ctrl-J 10
Vertical Tab Ctrl-K 11
Form Feed (Clear
Screen)
Ctrl-L 12
Carriage Return Ctrl-M 13
Reset Controller Ctrl-N 14
Set Geometry Ctrl-O 15
Set Tab Size Ctrl-P 16
Set Cursor Position Ctrl-Q 17
*Not Used ***** **
Set Contrast Ctrl-S 19
Set Backlight Ctrl-T 20
Command Escape Ctrl-U 21
Data Escape Ctrl-V 22
Raw Data Escape Ctrl-W 23

42
*Not Used ***** **
Display an ASCII
Character
None 22 – 255
4.2.5 GSM Modem
Figure 4.16 GSM Modem
What is a GSM Modem?
A GSM modem is a specialized type of modem which accepts a SIM card, and operates
over a subscription to a mobile operator, just like a mobile phone. From the mobile
operator perspective, a GSM modem looks just like a mobile phone.
When a GSM modem is connected to a computer, this allows the computer to use the
GSM modem to communicate over the mobile network. While these GSM modems are
most frequently used to provide mobile internet connectivity, many of them can also be
used for sending and receiving SMS and MMS messages.

43
A GSM modem can be a dedicated modem device with a serial, USB or Bluetooth
connection, or it can be a mobile phone that provides GSM modem capabilities.
For the purpose of this document, the term GSM modem is used as a generic term to
refer to any modem that supports one or more of the protocols in the GSM evolutionary
family, including the 2.5G technologies GPRS and EDGE, as well as the 3G
technologies WCDMA, UMTS, HSDPA and HSUPA.
TECHNICAL DETAILS
GSM is a cellular network, which means that mobile phones connect to it by searching
for cells in the immediate vicinity. There are five different cell sizes in a GSM
network—macro, micro, Pico, femto and umbrella cells. The coverage area of each cell
varies according to the implementation environment. Macro cells can be regarded as
cells where the base station antenna is installed on a mast or a building above average
roof top level. Micro cells are cells whose antenna height is under average roof top
level; they are typically used in urban areas. Pico cells are small cells whose coverage
diameter is a few dozen meters; they are mainly used indoors. Femto cells are cells
designed for use in residential or small business environments and connect to the
service provider’s network via a broadband internet connection. Umbrella cells are used
to cover shadowed regions of smaller cells and fill in gaps in coverage between those
cells.
GSM CARRIER FREQUENCIES
GSM networks operate in a number of different carrier frequency ranges
(separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G), with
most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Where these
bands were already allocated, the 850 MHz and 1900 MHz bands were used instead (for
example in Canada and the United States). In rare cases the 400 and 450 MHz
frequency bands are assigned in some countries because they were previously used for
first-generation systems.

44
Most 3G networks in Europe operate in the 2100 MHz frequency band.
Regardless of the frequency selected by an operator, it is divided into timeslots for
individual phones to use. This allows eight full-rate or sixteen half-rate speech channels
per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into
a TDMA frame. Half rate channels use alternate frames in the same timeslot. The
channel data rate for all 8 channels is 270.833 Kbit/s, and the frame duration is
4.615 ms. The transmission power in the handset is limited to a maximum of 2 watts in
GSM850/900 and 1 watt in GSM1800/1900.
NETWORK STRUCTURE
Figure 4.17 GSM Network Structure
The network is structured into a number of discrete sections:
1. The Base Station Subsystem (the base stations and their controllers).
2. 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.

45
3. The GPRS Core Network (the optional part which allows packet based Internet
connections).
4. The Operations support system (OSS) for maintenance of the network.
SUBSCRIBER IDENTITY MODULE
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. 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.
4.3 COMPONENT LIST
Table 4.11 Component List
COMPONENTS TYPE QTY APPROX
PRICE (RS)
RESISTORS 2.2K 1 3
2.2M 2 3
100K 2 2
1K 1 1
12K 1 1
CAPACITORS 1000uF 2 8
4.7μF 3 4
22pF 2 4
0.22μF 1 1
47pF 1 1

46
0.1μF 2 2
0.01μF 1 2
0.47uF 1 22
MICROCONTROLLER 89S51 1 55
IC'S LM555N 1
CA3130 1 25
TRANSISTOR BC548 1 20
BATTERY 12V 1 40
SWITCH SLIDER SWITCH 1 15
BUZZER 3-24V 1 22
RESISTOR PACK 1K 1 9
POTENTIOMETER 10K 1 20
DIODES IN4007 8 16
VOLTAGE REGULATOR 7812 1 15
LEDS 5mm 4 8
LCD DISPLAY 16X2 1 240
CRYSTAL 12MHZ 1 20
IC BASE 8PIN 2 16
16PIN 1 8
40PIN 1 20
GSM MODEM 900MHZ 1 2150
PCB COPPER CLADED 3 105
TRANSFORMER 230V(AC)-12V(DC) 1 120
POWER CORD 230V 1 20
CONNECTOR 10PIN 1 18
DC PLUG 1 5

47
CHAPTER-5
PCB LAYOUT, PROTOTYPE AND TROUBLESHOOTING
5.1 PCB Layout Description
1. PCB is printed circuit board which is of insulating base with layer of thin copper-
foil .
2. First the PCB is dipped in the solution of ferric chloride so that unwanted
copper is removed from the PCB thus leaving component interconnection on the
board .
3. The specification of the base material is not important to know in most of the
application but it is important to know something about copper foil which is drawn
through a thin slip .
4. The resistance of copper foil will have an effect on the circuit operation .
5. Base material is made of lamination layer of suitable insulating material such as
treated paper , fabric or glass fibres and binding them with resin.
6. It is possible to obtain a range thickness between 0.5 mm to 3mm.
Figure 5.1 PCB Layout of Controller Stage

48
Figure 5.2 PCB Layout of Detector Stage Figure 5.3 PCB Layout of RS-232
5.2 PCB Making Process:
STEP-1: After cutting the copper clad PCB sheet to required size, the PCB is cleaned
with thinner, to remove dust on the PCB is removed and we get a shiny copper clad
surface. Then we insert the PCB in Dip coat, that is negative photo resistive material.
Figure 5.4 Dipping the PCB in coat Figure 5.5 PCB after Dipping in the coat
STEP-2: The photo resistive material (liquid) should be made hard on the PCB for
which the PCB is kept in the oven (protocure) for 5 minutes.

49
Figure 5.6 Adjusting the PCB to be kept in oven Figure 5.7 PCB oven (Protocure)
STEP-3: After the liquid is made hard, it is kept in the UV exposure for two minutes. In
the UV exposure, the circuit is kept with its layout. The ultraviolet rays are passed
through the white part of butter paper while getting blocked by black lines on PCB.
Figure 5.8 UV exposure to PCB
STEP-4: Then we have to expose our PCB to nail polish remover solution which is also
called as developer liquid. As a result of this an impression of tracks is formed on the
PCB. Repeat the STEP-2, in which the PCB is kept in the oven for four minutes.
Figure 5.9 Dipping the PCB in developer liquid

50
STEP-5: After removing the PCB from the oven, the tracks on the PCB will be
developed. After this the PCB is dipped into the PRITO-ETCH for five minutes. The
solution used in the PROTO-ETCH is ferric chloride. Due to this the tracks are fully
developed on the PCB.
Figure 5.10 PRITO-ETCH
STEP-6: Then the PCB is washed in water and cleaned by the soft cloth.
Thus, the etching process was completed. Following this, we tested the track continuity,
whether there is any copper intersecting the two tracks. If present it was removed by the
knife. After this the PCB was completely ready for further process. Next, we needed to
drill the PCB according to layout so that the components could be mounted and
soldered.
5.3 Drilling Process:
1. First the PCB is placed on the drilling machine and drill bit is inserted. We used the
drill bit of 0.8mm.
2. The PCB is placed in such a way that the drill bit is exactly on the top of the place
where we need to drill.
3. Then, the machine is turned on and the handle is to pressed down to drill on the
PCB.

51
4. Care should be taken while drilling that PCB is firmly held or else it will come up
into the drill bit.
5. After drilling first hole we checked whether the component is getting inserted in the
hole or not.
6. For this we changed the drill bit to 1mm and drilled those holes again so that
components were properly inserted.
Thus our copper clad PCB was etched, drilled and was ready for mounting and
soldering of the components on the PCB.
5.4 Soldering
5.4.1 What is soldering?
Soldering is a process in which two or more metal items are joined together by melting
flowing a filler metal (solder) into the joint, the filler metal having a lower melting point
than the work piece. Soldering differs from welding in that soldering does not involve
melting the work pieces.
Cleanliness is essential for efficient, effective soldering. Solder will not adhere to dirty,
greasy, or oxidized surfaces. Heated metals tend to oxidize rapidly. This is the reason
the oxides, scale, and dirt must be removed by chemical or mechanical means. Grease
or oil films can be removed with a suitable solvent. Connections to be soldered should
be cleaned just prior to the actual soldering operation. Items to be soldered should
normally be "tinned" before making a mechanical connection.
Tinning is the coating of the material to be soldered with a light coat of solder. When
the surface has been properly cleaned, a thin, even coating of flux should be placed over
the surface to be tinned. This will prevent oxidation while the part is being heated to
soldering temperature. Rosin-core solder is usually preferred in electrical work.
However, a separate rosin flux may be used instead. Separate rosin flux is frequently
used when wires in cable fabrication are tinned.

52
5.4.2 Steps in soldering:-
1. For soldering of any joints first the terminal to be soldered are cleaned to remove
oxide film or dirt on it. If required flux is applied on the points to be soldered.
2. Now the joint to be soldered is heated with the help of soldering iron. Heat applied
should be such that when solder wire is touched to joint, it must melt quickly.
3. The joint and the soldering iron is held such that molten solder should flow
smoothly over the joint.
4. When joint is completely covered with molten solder, the soldering iron is removed.
5. The joint is allowed to cool, without any movement.
6. The bright shining solder indicates good soldering.
7. In case of dry solder joint, an air gap remains in between the solder. It means that
soldering is improper. This is removed and again soldering is done.
8. Thus is this way all the components are soldered on P. C. B.
5.5 Troubleshooting:-
5.5.1 Description:
Troubleshooting is a form of problem solving, often applied to repair failed circuits. It is
a logical, systematic search for the source of a problem so that it can be solved, and
circuit can be made operational again. Troubleshooting is needed to develop and
maintain complex systems where the symptoms of a problem can have many possible
causes. Troubleshooting requires identification of the malfunction(s) or symptoms
within a system and confirms the solution so that can work again.
5.5.2 Need Of Troubleshooting:
1. Every product, circuit and instruments are designed to give desired output, but there
are many problems associated with the design which tend to produce unexpected
output. Therefore, for satisfactory performance, it needs to be troubleshooted so that
the circuit can be made operational again.

53
2. Troubleshooting is needed to develop and maintain complex systems where the
symptoms of the problem can have many possible causes.
3. It is needed for identifying the symptoms and rectifying the problem so that it gives
the desired output.
4. Troubleshooting is used in many fields such as engineering, system administration,
electronics, automotive repair and diagnostic medicine.
5.5.3 Device Required For Troubleshooting
Multimeter - To be able to do even the most basic fault finding, you will need at the
very least a multimeter, and preferably two. Most people prefer digital meters, but if
you know how to use an analogue meter you may find things that a digital will miss.
Figure 5.11 Digital Multimeter
You need to be able to measure.
1. Volts, both AC and DC, from a few millivolts to 100V (or more)
2. Amps, DC only is sufficient, but preferably up to at least 2A
3. Ohms, from less than 1 ohm up to 10 Mega ohms
4. Other functions (transistor tests, capacitance, frequency) are useful, but not essential

54
Signal Source - You also need a signal source. While a walk person (for example) is
useful, it is not a good source of proper test signals, and is therefore limited. There are
several PC based audio oscillators available on the Web, and these are fine (if a little
inconvenient). Ideally, an audio oscillator should be used, see the Projects Pages for
details of test gear you can make quite cheaply.
Figure 5.12 CRO, Frequency Generator, Power Supply
Oscilloscope - For some tests, an oscilloscope is almost essential. While few hobbyists
can justify the purchase of such an expensive piece of test gear, for many professionals
the CRO (Cathode Ray Oscilloscope) or 'scope, is the first thing that is attached to
anything that does not work. Again, there are many PC programs that allow you to use
your computer as a basic oscilloscope. By nature, most soundcards are limited to 20kHz
upper frequency, so such PC based tools will not find all problems.
Load - A "dummy load", usually a high powered resistor or bank of resistors, and
ideally switch able to 4 or 8 ohms. This enables you to perform full power tests without
the noise, and if a fault develops, the load just gets hot, but your speakers do not get
fried. If desired, you can have a 47 ohm 10W resistor from each terminal of your load to
an external speaker, so you can monitor the output signal.

55
Power Supply - A bench power supply is immensely useful, but possibly even more
useful is a variable voltage transformer ("Variac™"). This allows you to make any
power supply variable, and the amplifier voltage can be slowly increased while
monitoring the amplifier's output voltage (and supply current with your second
multimeter). Another useful test tool for those who cannot justify the expense (again,
Variacs are not cheap) is a "lamp lead" - a standard light bulb (100W is usually about
right), carefully wired in series with a mains lead (and properly insulated!). An amp
with a short circuit fault will cause the lamp to glow at full brightness, but a normal load
will cause the lamp to flash brightly for a moment, then settle down to a steady dull
glow. One of the most essential power supply tools is a pair of 10 Watt resistors,
between 10 and 22 ohms (or as suggested in the project article). These must be used in
series with the supply leads before applying power, and limit the current to a (hopefully)
safe value, especially when used in conjunction with a variac or lamp lead.
5.5.4 Steps Prior To Troubleshooting:
1. Before applying power, read the instructions carefully to check we haven’t missed
anything, and whether there are any specific instructions for switching on and
testing.
2. Check again that we have all polarity sensitive components the right way around,
and that all components are in the correct places. Then check whether the off –
board components are connected correctly.
3. Check the underside of the board carefully for short circuit between tracks which is
a common reason for circuits failing to work.
4. When we are sure that everything is correct, apply power and see if the circuit
behaves as expected, again following the kit manufactures instructions.

56
5.6 Troubleshooting Steps
5.6.1 Identify The Symptom:
Determine what the voltage levels in the circuit should be so that you know what to look
for.
5.6.2 Power Check:
The first thing to do while checking a defective circuit is to make sure the power cord is
plugged in and the fuse is not burnt. In case of battery powered system, make sure the
battery is good.
5.6.3 Perform Sensory Check:
After power check, observe for the obvious defects. Example burnt resistor is often
visible as are broken wires, poor solder connection and burnt out fuses. Also when
certain types of components fail, may be able to detect a smell of smoke if you happen
to be there.
Since some failures are temperature dependant, you can sometimes unplug the circuit
and immediately use your sense of touch to detect an overheated component. Always
perform sensory check before proceeding with more sophisticated troubleshooting
methods. Never touch operating circuit because there may be a risk of burn or electrical
shock.
5.6.4 Signal Tracing:
In this you look for a point in a circuit or system where you first lose signal or an
incorrect signal first occurs. There are three ways of signal tracing as given below:
1. Method 1: It starts at the input of a circuit where there is a known input signal and
work towards the output. Check the signal at successive test points until you get
incorrect measurement, when it is found, the problem is isolated from the last test
point to the present test point.

57
2. Method 2: It starts at the output of a circuit and works towards the input. Check for
voltage at each test point until you get a correct measurement. At this point you have
isolated the problem between the last point and the current test point.
3. Method 3: This method is called as half splitting. It starts in the middle of the test
circuit. If a beginning test point has a correct signal, you know that the circuit is
working properly from input to that test point. This means the fault is somewhere
between the test point and output. Therefore begin signal tracing from test point
towards output and get the point at fault.
5.6.5 Fault Analysis:
1. Voltages Analysis: After performing the visible testing, if the problem still persists,
then go for voltage analysis. In this method the voltage at different test points is
checked.
2. Resistance Analysis: In this analysis power supply connected to the circuit must be
switched off when resistance is measured. Resistor analysis is generally used for
continuity testing. For example, check the continuity of PCB track from one test
point to other or in case of double- sided PCB it helps for checking the connectivity
between the holes from both the sides. Similarly this can be used for testing the
component such as diode, capacitor and transistor (e.g. open or short). This method
requires the instrument such as ohmmeter.
3. Signal Analysis: Sometimes it is important to observe the nature of signal at test
point (e.g. in case of rectifier). Whereas it is not possible in voltage analysis. By
observing the waveform at test point we can estimate the waveform distortion. For
testing the circuit such as rectifier, multivibrator, amplifier it is important to know
the nature. Therefore signal analysis is done. For carrying signal analysis, we
require a CRO.
5. Replace Or Repair: With the power turned off, replace the defective component or
repair defective connection. Turn on the power, and check the proper operation of
the circuit

58
CHAPTER-6
SOFTWARE DEVELOPMENT TOOLS AND PROGRAMMING
6.1 Software used for making PCB Layout
Cadsoft Eagle
The award winning EAGLE is a powerful and flexible PCB design software offering
high level functionality of expensive commercial circuit board design software at a
fraction of the cost for over 20 years. EAGLE is easy to learn, easy to use and easy to
buy. It runs on Linux, Mac and Windows and allows feature enhancement, such
as simulation, data import and export and self-defined commands, through User
Language Programs (ULP’s) which are partly integrated in EAGLE and available at
the download area. EAGLE offers Design Link, an automated connection to the
database from Premier Farnell to search and find parts from within the EAGLE design
environment without ever having to leave it. The innovative PCB services interface
integrated in EAGLE enables users to receive quotes and order their prototypes from
high quality manufacturers on mouse click.
EAGLE includes the following modules:
1. Schematic Editor
2. Layout Editor
3. Auto router
NEW CADSOFT EAGLE VERSION 6
What’s new in Version 6?
XML database structure redesign
Read, edit and parse the data outside of the EAGLE tool
The new XML database structure provides the ability to write scripts that manipulate
designs in the EAGLE format which will give users huge productivity benefits. You can
make design changes, import information from other designs, and even translate from

59
other formats. EAGLE is one of the first Commercial CAD Programs that adopts a
ASCII XML data structure as their native file. This makes EAGLE the most flexible,
user friendly and productive PCB tool on the market.
Design Reuse (available for EAGLE Professional and EAGLE Standard)
Merge board/schematic pairs using the PASTE function with full consistency
You can copy an already finished design consisting of a consistent pair of Schematic
and Layout into another project. Enumeration of components and signals will be exactly
the same in board and schematic, so that consistency between schematic and board will
be maintained. This supports easy design, for example, of multi-channel devices. You
only have to design schematic and layout for one channel and can copy it easily.
Routing capability enhancement
1. Optimize your work-flow with Undo/Redo log
The UNDO/REDO log shows the history of each step you have made. You have full
control of the steps going back or forward.
2. Work with flawless conversions between mm and inches through increased internal
resolution (allows grids of 1/4, 1/8, 1/16,1/32 and 1/64 mil)
If you have to work with both systems, metric and imperial, you know about
problems that can arise in converting the usual imperial grid values (always divided
by 2) and the resulting mm values. Increasing the internal resolution up to 1/64 mil
will allow a proper conversion in all situations.
3. Benefit from differential pair routing and automatic meanders
Special signals can be routed with exactly the same length. Differential pair routing
is used for pairs of differential (equal and opposite) signals across the board to
create a balanced transmission system. Creating meanders helps users automatically
give a signal a certain length in the PCB. Meanders in traces are used to increase
delay times in high speed digital circuits.
4. Improve your efficiency through BGA escape routing (ULP)
BGA devices can have a 1000 connections or more. Packages are getting smaller
and smaller. It is a hard and tedious work to connect all the pins, set vias, decide

60
about the layers to use, and come out from the BGA area. This ULP helps you in
escaping from the BGA in a proper way.
Library editor optimization
1. Connect a pin to multiple pads
You can now connect one pin in the schematic symbol to any number of pads of the
package. With this function EAGLE can handle components internal connected
pins. Compared to previous versions schematic symbols look nicer and you save
time in defining them.
2. Draw arbitrary pad shapes easily
Take a pad or an SMD as basis and draw the final contour with the help of the
WIRE or POLYGON command. These objects will be considered as part of the
pad/smd. No more problems with Design Rules Check for such objects.
3. Benefit from unlimited number of technologies and package variants
Until now the maximum number of technologies and package variants was limited.
In some cases one could reach the limits and had to split a library into two parts. No
more limitation in EAGLE 6.
Layout editor add-ons
1. Dimension your layout automatically-
A dimensioning tool where you decide by a few mouse clicks the objects to be
dimensioned.
2. Create restricted areas with Cutout polygons-
Outer and inner layers can now have individual restricted areas that will be avoided
by signal polygons. Simply draw a polygon and define it as cutout.
3. Be flexible with assembly variants-
One schematic but a number of different assembly variants can be handled now.
4. Justify your text to left, top, right, bottom, middle or center with one mouse click
This allows you to adjust texts as you know it from text editors. Gives a neat look
and makes writing, for example, comments more comfortable.

61
File description functionality
Individualize your schematics, sheets, boards and symbols with descriptions.
The file description can inform you about the content of a board or schematic. It is
shown in the Control Panel without loading the file in the editor windows. This makes
your project management clearer. See what this file contains without loading it in an
editor window. This also works with sheets of multi-sheet schematics.
GUI improvement
Define your own context menu
Speed up your work-flow with self-defined content in the context menu. Frequently
used commands or combinations of commands can be integrated into the context menu.
This minimizes mouse-clicks and increases working speed.
6.2 Program
P1 = 255
Cls
Lcd“ V.E.S.P”
Wait 2
Do
Cls
Lcd“Scanning…..”
If P1.0 = 1 Then
Cls
Lcd“ Mobile Sniffer”
Lowerline
Lcd“ Alert!”

62
Wait 2
Call Sms
End If
Waitms 250
Loop
Sub Sms
Cls
Lcd“Sending sms….”
Print “AT+CMGF=1”
Wait 1
Print “AT+CMGS=” ;Chr(34) ; “08097544508” ; Chr(34)
Wait 1
Print “ Mobile sniffer alert. “ ; Chr(26)
Wait 7
End Sub

63
CHAPTER-7
ADVANTAGES AND LIMITATIONS
7.1 Advantages
1. Use of cell phones can be prohibited in restricted areas.
2. Misuse of cell phones can be controlled.
3. Silence in a particular place can be achieved when required.
4. It can detect the mobile up to range of 7 ft.
5. Circuit has high sensitivity
6. Low power consumption
7. High reliability
7.2 Limitations
1. Circuit is complex
2. Accuracy in selecting the circuit components is very high
3. Even a single component defect can affect the output of the circuit

64
CHAPTER-8
1. Military Basis:
In government buildings and military bases the unit should be installed in all sensitive
areas. In addition to potential RAT phones, the Cell phone Detector can detect bugs
emitting RF within the specified band range. In addition, it can be rigged to trigger a
digital camera to capture an image of a person using a phone in a restricted area by
sending a signal to an external trigger mechanism from the remote alarm terminal.
2. Prisons:
Cell phone Detector may be placed outside cell doors during lockup hours within prison
wings to reduce ill legal cellular phone activity. In addition, Cell phone Detector may be
installed in entrance ways, corridors, waiting and meeting areas wherein mates visits are
conducted.
3. Hospitals:
Cell phone Detector units are installed in general locations in corridors and waiting
rooms to deter nuisance public cellular phone usage .Sensitive electronic equipment
within intensive care wards and operating theatres that are vulnerable to RF interference
will have units installed near them.
4. Schools and Colleges:
Cell phone Detector units are installed in general locations in corridors, assembly
points, classrooms and lecture theatres to promote conformity and establishment order.
Cell phone detector units are deployed in examination rooms to deter examination fraud
via text messaging.
APPLICATIONS

65
5. Places of Worship:
Cell phone Detector units are installed as a deterrent at the main entrance where cellular
phone misuse is a severe or persistent problem then units can be installed in the main
prayer area with audio alert set to low volume.
6. Museums and Libraries:
Cell phone Detector units are installed in all areas in museums and libraries with audio
warning on low volume.
7. Courtrooms:
Cell phone Detector units are installed directly outside courtrooms with range set to
near. Inside the courtroom itself a wall-mounted unit silently flashing in the public
gallery may alert security staff.
8. General Application:
Cellular phone detection and deterrence is an additional layer of security for your
organization. How effective this layer of security will be will be is dependent on the
environment, the number of devices installed and how the detectors are integrated.

66
CHAPTER-9
CONCLUSION
As all we know from last 8-10 years there is a boost in mobile communication. There
are many uses of this communication but at the same time some people misuse it by
hacking someone’s account or tracking someone with help of the GPRS, or use mobile
in examination hall for copying etc.
Our project is very useful for this condition as it detects the cell phone in restricted area
by catching the RF (radio frequency) signals which are used in a mobile phone.
Our project can be kept anywhere in order to prevent the use of mobile phones in the
restricted areas like temple, theatre, auditorium, examination halls etc.

67
CHAPTER-10
BIBLIOGRAPHY
10.1 REFERNCE BOOKS
1. Electronics for you magazine
2. 8051 microcontroller and embedded systems- Muhammad Ali Mazdi
3. 8051 microcontroller and embedded systems- Kenneth Ayla
4. Applied Electronics- R.S.Sedha
10.2 REFERNCE WEBSITE
1. www.google.co.in
2. www.electronicextreme.com
3. www.codeproject.com
4. www.scribd.com
5. www.allaboutcircuits.com
6. www.engineersgarage.com
7. www.alldatasheet.com
8. www.electronicsforu.com

Mobile Sniffer

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Mobile Sniffer

Similar to Mobile Sniffer (20)

Recently uploaded

Recently uploaded (20)

Mobile Sniffer