Cell phone jammer with prescheduled time duration

Cell phone jammer with prescheduled time duration
Dept. of ECE, GECH. 2013 Page 1
VISVESVARAYA TECHNOLOGICAL UNIVERSITY
BELGAUM-590014
Dissertation Report on
“CELL PHONE JAMMER WITH PRESCHEDULED TIME
DURATION”
Submitted in partial fulfillment of the requirements for the award of degree
BACHELOR OF ENGINEERING
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
BY
CHETHAN KUMAR S.N. 4GH09EC010
GANESH M. 4GH10EC402
MANU M. 4GH09EC027
SRINIVAS H.V. 4GH09EC046
Under the guidance of
Mrs. BABY H.T. B.E., M.Tech,
Associate professor
Department of E&CE,
GEC, HASSAN-573201
Department of Electronics and Communication Engineering
GOVERNMENT ENGINEERING COLLEGE
DAIRY CIRCLE, HASSAN-573201
2012-2013

GOVERNMENT ENGINEERING COLLEGE
Dairy circle, Hassan-573 201
Department of Electronics & Communication Engineering
CERTIFICATE
Certified that the project work entitled “CELL PHONE JAMMER WITH
PRESCHEDULED TIME DURATION” is a bonafide work carried out by
Mr. CHETHAN KUMAR S.N (4GH09EC010)
Mr. GANESH M (4GH10EC402)
Mr. MANU M (4GH09EC027)
Mr. SRINIVAS H.V (4GH09EC046)
in partial fulfillment for the award of degree of Bachelor of Engineering in Electronics
and Communication Engineering of the Visvesvaraya Technological University, Jnana
Sangama, Belgaum-590014 during the year 2012-2013. It is certified that, all
corrections/suggestions indicated for internal assessment have been incorporated in the
report. The project report has been approved as it satisfies the academic requirements with
respect of Project work prescribed for the mentioned degree.
Internal guide: Head of dept.: Principal:
Mrs. Baby H.T Dr. Paramesha Dr. Karisiddappa
Associate Professor Professor GECH.
Dept. of ECE Dept. of ECE
GECH. GECH.

ABSTRACT
Mobile jammer is used to prevent mobile phones from receiving or transmitting signals
with the base stations. Mobile jammers effectively disable mobile phones within the
defined regulated zones without causing any interference to other communication means.
Mobile jammers can be used in practically any location, but are used in places where a
phone call would be particularly disruptive like temples, libraries, hospitals, cinema halls,
schools & colleges etc.
As with other radio jamming, mobile jammers block mobile phone use by sending out
radio waves along the same frequencies that mobile phones use. This causes enough
interference with the communication between mobile phones and communicating towers to
render the phones unusable. Upon activating mobile jammers, all mobile phones will
indicate "NO NETWORK‖. Incoming calls are blocked as if the mobile phone were off.
When the mobile jammers are turned off, all mobile phones will automatically re-establish
communications and provide full service.
Mobile Jammers were originally developed for law enforcement and the military to
interrupt communications by criminals and terrorists to foil the use of certain remotely
detonated explosives. The civilian applications were apparent with growing public
resentment over usage of mobile phones in public areas on the rise & reckless invasion of
privacy. Over time many companies originally contracted to design mobile jammers for
government switched over to sell these devices to private entities.

ACKNOWLEDGEMENTS
The satisfaction and euphoria that accompany the successful completion of any task would
be incomplete without mentioning the people who have made it possible, because “success
is the epitome of hard work and perseverance but stead-fast of all is encouraging
guidance”. So with deep gratitude we acknowledge all distinguished personalities whose
guidance and encouragement served as bacon light and crowned our efforts with success.
We wish to express our thanks to our beloved Principal, Dr. KARISIDDAPPA, for his
encouragement throughout our studies.
At the outset we express our most sincere grateful thanks to Dr. PARAMESHA, HOD
and Professor, department of Electronics and Communication Engineering, for his
continuous support and advice not only during the course of our project but also during our
stay in GECH.
We express our warm gratitude towards project co-ordinator and also being our seminar
guide, Mrs. BABY H.T Associate Professor, department of Electronics and
Communication Engineering, for her guidance, encouragement and support throughout our
project work.
We also gratefully thank holy sanctum “GOVERNMENT ENGINEERING COLLEGE,
HASSAN” the temple of learning, for giving us an opportunity to pursue the degree course
in Electronics and Communication Engineering thus help in shaping our career.
Finally, we express our thanks to all our teaching and non-teaching staff of the
department of Electronics and Communication Engineering, our fellow classmates
and our parents for their timely support and suggestions in completing our task well in
time. We thank once again to one and all who have been helped us in one or the other way
in completing our project in time.

CONTENTS
Abstract i
Acknowledgments ii
Table of Contents iii
List of figures v
List of table‘s vii
CHAPTER 1 PREAMBLE 1-3
1.1 Introduction 1
1.2 Objective of the project 2
1.3 Literature survey 2
1.4 Methodologies 5
CHAPTER 2 PROJECT OVERVIEW 6-11
2.1 Block diagram 6
2.2 Description of block diagram 7
CHAPTER 3 OPERATION OF CELL PHONE JAMMER 12-21
3.1 Mobile jamming techniques 14
3.2 Mobile jamming requirements 18
CHAPTER 4 HARDWARE IMPLEMENTATION 22-48
4.1 Circuit diagram 22
4.2 Regulated power supply 23
4.3 Microcontroller (PIC16F877A) 26

4.4 Relay 32
4.5 LCD display 34
4.6 Cell phone jammer schematic 37
CHAPTER 5 SOFTWARE IMPLEMENTATION 49-71
5.1 Flow chart 49
5.2 Source code 55
CHAPTER 6 TESTING AND RESULTS 72-76
CHAPTER 7 ADVANTAGES AND DISADVANTAGES 77
CHAPTER 8 APPLICATIONS 78
CONCLUSION 80
REFRENCES 81

LIST OF FIGURES
FIGURE NAME PAGE NO.
Figure 2.1 Block diagram of jammer with controller 6
Figure 2.2 Jammer block diagram 7
Figure 3.1 Signal handed from tower to tower 13
Figure 3.2 Denial of service attack 14
Figure 4.1 Circuit diagram of cell phone jammer 22
Figure 4.2 Regulated power supply IC 24
Figure 4.3 Bias connection of a three – terminal voltage
regulator IC to a load 25
Figure 4.4 Block diagram of power supply 26
Figure 4.5 Pin configuration of PIC16F877A 30
Figure 4.6 Basic relay switch and relay frames 32
Figure 4.7 Relay with its coil and switch contacts 33
Figure 4.8 2x16 line alphanumeric LCD display 34
Figure 4.9 Pin description of LCD display 35
Figure 4.10 LCD interface to microcontroller 36
Figure 4.11 Cell phone jammer schematic 37
Figure 4.12 Power supply unit 38
Figure 4.13 Block diagram of IF section 39
Figure 4.14 Simple function generator circuit 40
Figure 4.15 Op – amp summer circuit 41
Figure 4.16 Positive diode – clamper with bias 41
Figure 4.17 Block diagram of RF section 42
Figure 4.18 Pin diagram of MAXIM 44
Figure 4.19 MAXIM 2623 Pin connection 45

Figure 4.20 Typical biasing configuration for the MAR – 4SM 46
Figure 4.21 T – Network attenuator 47
Figure 4.22 Monopole antenna 48
Figure 4.23 Antenna patterns 48
Figure 6.1 Control toggle switches 72
Figure 6.2 Control switch to select network 73
Figure 6.3 Control switch to set time duration 73
Figure 6.4 Control switch to run the jammer 74
Figure 6.5 Jammer running stage on LCD display 74
Figure 6.6 Signal ON jammer OFF 75
Figure 6.7 Jammer ON signal OFF 76

LIST OF TABLES
TABLE NAME PAGE NO.
Table 3.1 Comparison between jammer/disablers
techniques 18
Table 3.2 GSM, DCS and 3G frequency band 20
Table 4.1 Input/output ports 29

CHAPTER 1
PREAMBLE
1.1 INTRODUCTION
Cell phones are everywhere these days. It‘s great to be able to call anyone at any time.
Unfortunately, restaurants, movie theaters, concerts, shopping malls and churches all suffer
from the spread of cell phones because not all cell-phone users know when to stop talking
while most of us just grumble and move on, some people are actually going to extremes to
retaliate.
Disrupting a cell phone is the same as jamming any other type of radio communication. A
cell phone works by communicating with its service network through a cell tower or base
station. Cell towers divide a city into small areas, or cells. As a cell-phone user drives
down the street, the signal is handed from tower to tower A jamming device
transmits on the same radio frequencies as the cell phone, disrupting the communication
between the phone and the cellphone base station in the tower Jamming devices overpower
the cell phone by transmitting a signal on the same frequency and at a high enough power
that the two signals collide and cancel each other out.
Cell phones are full-duplex devices, which mean they use two separate frequencies, one for
talking and one for listening simultaneously. Some jammers block only one of the
frequencies used by cell phones; some has the effect of blocking both. The phone is tricked
into thinking there is no service because it can receive only one of the frequencies. Less
complex devices block only one group of frequencies, while sophisticated jammers can
block several types of networks at once to head off dual-mode or tri-mode phones that
automatically switch among different network types to find an open signal.
To jam a cell phone, all you need is a device that broadcasts on the correct frequencies.
Although different cellular systems process signals differently, all cell-phone networks use
radio signals that can be interrupted. GSM, used in digital cellular and PCS-based systems,

Operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 1900-MHz
(sometimes referred to as 1.9-GHz) band in the United States. Jammers can broadcast on
any frequency and are effective against CDMA, GSM and DCS. Old-fashioned analog cell
phones and today's digital devices are equally susceptible to jamming.
The actual range of the jammer depends on its power and the local environment, which
may include hills or walls of a building that block the jamming signal. Low-powered
jammers block calls in a range of about 13 feet (~4 m). Higher-powered units create a cell-
free zone as large as a football field. Units used by law enforcement can shut down service
up to 1 mile (1.6 km) from the device.
1.2 OBJECTIVE OF THE PROJECT
Here our main intention is to block the signals of mobile phone using mobile phone signal
jammer for prescheduled time duration using real time clock controlled by microcontroller.
Switches are used to set the time for start and stop of jammer.
1.3 LITERATURE SURVEY
1.3.1 History of jammers
The technique used in most of the commercial jammers is based on noise attack. In the
previously designed cell-phone jammers, designers came up with an electronic device that
acts as a transmitter to transmit electromagnetic signals of respective frequency and higher
power as used by GSM/DCS systems. In this technique voltage controlled oscillator (VCO)
plays a major role in generating the jamming frequency. In our research we found that the
above technique is complex one as compared to our technique because our idea of jamming
through spectrum distortion proves to be simpler, easier to fabricate and cost effective [1].
The rapid proliferation of cell phones at the beginning of the 21st century to near
ubiquitous status eventually raised problems, such as their potential use to invade privacy
or contribute to academic cheating. In addition, public backlash was growing against the
disruption cell phones introduced in daily life. While older analog cell phones often
suffered from poor reception and could even be disconnected by simple interference such

as high frequency noise, increasingly sophisticated digital phones have led to more
elaborate counters.
Cell phone jamming devices are an alternative to more expensive measures against cell
phones, such as Faraday cages, which are mostly suitable as built in protection for
structures. They were originally developed for law enforcement and the military to
interrupt communications by criminals and terrorists. Some were also designed to foil the
use of certain remotely detonated explosives. The civilian applications were apparent, so
over time many companies originally contracted to design jammers for government use
switched over to sell these devices to private entities. Since then, there has been a slow but
steady increase in their purchase and use, especially in major metropolitan areas [2].
Disrupting a cell phone is the same as jamming any other type of radio communication.
A cell phone works by communicating with its service network through a cell tower or
base station. Cell towers divide a city into small areas, or cells. As a cell-phone user drives
down the street, the signal is handed from tower to tower A jamming device
transmits on the same radio frequencies as the cell phone, disrupting the communication
between the phone and the cellphone base station in the tower Jamming devices overpower
the cell phone by transmitting a signal on the same frequency and at a high enough power
that the two signals collide and cancel each other out [5].
In our research we found that the above technique is complex one as compared to our
technique because our idea of jamming through spectrum distortion proves to be simpler,
easier to fabricate and cost effective.
In our project we can jam the GSM, DCS and CDMA signals at a time. We can select
anyone system individually like GSM or DCS or CDMA which also includes a
prescheduled timer, by which we can set the duration of jamming of signals. The maximum
time duration will be half an hour [6] [7].

1.3.2 PIC16F877A Microcontroller
A PIC microcontroller is an application specific integrated circuit (ASIC) that
fetches and executes instructions based on input from some user program. These
devices do not have a fixed function, but rather are controlled by software [3].
PIC is a family of architecture microcontrollers made by Microchip Technology, derived
from the PIC1650 originally developed by General Instrument's Microelectronics Division.
The name PIC initially referred to "Peripheral Interface Controller". PICs are popular
with both industrial developers and hobbyists alike due to their low cost, wide availability,
large user base, extensive collection of application notes, availability of low cost or free
development tools, and serial programming (and re-programming with flash memory)
capability. The PIC16FXX series has more advanced and developed features when
compared to its previous series [8].
1.3.3 Embedded system
The C programming language is a general-purpose programming language that provides
code efficiency, elements of structured programming, and a rich set of operators. Its
generality combined with its absence of restrictions, makes C a convenient and effective
programming solution for a wide variety of software tasks. Many applications can be
solved more easily and efficiently with C than with other more specialized languages Cx51
is not a universal C compiler adapted for the target. It is a ground- up implementation
dedicated to generating extremely fast and compact code. Cx51 provides you with the
flexibility of programming in C and the code efficiency and speed of assembly language.
The C language on its own is not capable of performing operations (such as input and
output) that would normally require intervention from the operating system. Instead, these
capabilities are provided as the part of the standard library. Because these functions are
separate from the language itself, C is especially suited for producing code that is portable
across a wide number of platforms.
Since Cx51 is a cross compiler, some aspects of the C programming language and standard
libraries are altered or enhanced to address the peculiarities of an embedded target
processor [4] [9].

1.3.4 Mikro C compiler
The Mikro C PRO for PIC is a powerful, feature-rich development tool for PIC
microcontrollers. It is designed to provide the programmer with the easiest possible
solution to developing applications for embedded systems, without compromising
performance or control.
Mikro C PRO for PIC is a full-featured ANSI C compiler for PIC devices from Microchip.
It is the best solution for developing code for PIC devices. It features intuitive IDE,
powerful compiler with advanced optimizations, lots of hardware and software libraries,
and additional tools that will help to work. Compiler comes with comprehensive help file
and lots of ready-to-use examples designed to get started in no time. Compiler license
includes free upgrades and a product lifetime tech support.
Mikro C PRO for PIC provides plenty of examples to expand, develop, and use as building
bricks in your projects. Copy them entirely if you deem fit – that‘s why we included them
with the compiler [10].
1.4 METHODOLOGIES
Hardware used in the project:
i. Power supply board.
ii. Switches board.
iii. Microcontroller.
iv. RTC.
v. Relay circuit.
vi. Jammer.
Software used in the project:
i. Embedded ‗C‘ programming.
ii. Mikro C compiler.

CHAPTER 2
PROJECT OVERVIEW
In Cell phone jammer we can have various blocks like control switch set, LCD, RPS etc.,
each block has its own functions. Heart of the project is jammer block, which is explained
in subsequent chapters. The various blocks of cell phone jammer and controller is as
shown in Figure 2.1.
2.1 BLOCK DIAGRAM
R
Figure 2.1: Block diagram of jammer with controller
PIC16F877A
16×2 LCD
DISPLAY
CRYSTAL
OSCILLATOR
JAMMER
BLOCK
RELAYTRANSISTOR
DRIVER CIRCUIT
BACKUP
BATTERY
CRYSTAL
OSCILLATOR
CONTORL
SWITCH SET
RESET
CIRCUIT
ON
CHIP
RTC
REGULATED
POWER SUPPLY

The various blocks of cell phone jammer is shown in below Figure 2.2.
Figure 2.2 : Jammer block diagram
2.2 DESCRIPTION OF BLOCK DIAGRAM
The main parts of this schematic diagram are:
1) REGULATED POWER SUPPLY.
2) MICROCONTROLLER (PIC16F877A)
3) CRYSTAL OSCILLATOR
4) ON CHIP RTC
5) LCD DISPLAY
6) TRANSISTOR DRIVER CIRCUIT
7) RELAY
8) JAMMER BLOCK
9) CONTROL SWITCH SET
10) RESET CIRCUIT
2.2.1 Regulated power supply
A variable regulated power supply block shown in Figure 2.1, is also called a variable
bench power supply, is one where one can continuously adjust the output voltage as per
the requirements. Most digital logic circuits and processors need a 5 volt power supply.
POWER
SUPPLY
IF
SECTION
RF
SECTION
RF
JAMMIG
SIGNAL

To use these parts we need to build a regulated 5 volt source. To make a 5 volt power
supply, we use a LM7805 voltage regulator IC. The LM7805 is simple to use. Circuit
features are as follow:
i. 7805 is a 5V fixed three terminal positive voltage regulators IC.
ii. The IC has features such as safe operating area protection, thermal shut down,
internal current limiting which makes the IC very rugged.
iii.Output currents up to 1A can be drawn from the IC provided that there is a proper
heat sink.
2.2.2 Microcontroller (PIC16F877A)
Peripheral Interface Controllers (PIC) is one of the advanced microcontrollers developed
by microchip technologies. These microcontrollers are widely used in modern electronics
applications. A PIC controller integrates all type of advanced interfacing ports and
memory modules. The first PIC chip was announced in 1975 (PIC1650). As like normal
microcontroller, the PIC chip also combines a microcontroller unit called CPU and is
integrated with various types of memory modules (RAM, ROM, EEPROM, etc), I/O
ports, timers/counters, communication ports, etc.
All PIC microcontroller family uses Harvard architecture. This architecture has the
program and data accessed from separate memories so the device has a program memory
bus and a data memory bus (more than 8 lines in a normal bus). This improves the
bandwidth (data throughput) over traditional von Neumann architecture where program
and data are fetched from the same memory (accesses over the same bus). Separating
program and data memory further allows instructions to be sized differently than the 8-bit
wide data word.
PIC16F877A is one of the most advanced microcontrollers from Microchip. This
controller is widely used for experimental and modern applications because of its low
price, wide range of applications, high quality, and ease of availability.

2.2.3 Crystal oscillator
Crystal oscillator is made up of quartz crystal with the desired value of resonant
frequency forms part of the frequency-selective feedback network. Crystal oscillator is
the natural choice when the accuracy and stability of frequency. Crystal oscillator output
frequency is stable to temperature range of -400
C to +800
C.
2.2.4 On chip RTC
The real time clock (RTC) is a widely used device that provides accurate time and date
for many applications. The RTC chip present in the PC provides time components of
hour, minute and second. The RTC chip uses an internal battery that keeps the time and
date even when the power is off. One of the most widely used RTC chips is the DS1307
from Dallas semiconductor.
2.2.5 LCD screen
LCD screen consists of two lines with 16 characters each. Each character consists of
5x7dot matrix. Contrast on display depends on the power supply voltage and whether
messages are displayed in one or two lines. For that reason, variable voltage 0-Vdd is
applied on pin marked as Vee. Trimmer potentiometer is usually used for that purpose.
Some versions of displays have built in backlight (blue or green diodes). When used
during operating, a resistor for current limitation should be used (like with any LE diode).
2.2.6 Transistor driver circuit
An SPDT relay consists of five pins, two for the magnetic coil, one as the common
terminal and the last pins as normally connected pin and normally closed pin. When the
current flows through this coil, the coil gets energized. Initially when the coil is not
energized, there will be a connection between the common terminal and normally closed
pin. But when the coil is energized, this connection breaks and a new connection
between the common terminal and normally open pin will be established. Thus when
there is an input from the microcontroller to the relay, the relay will be switched on. Thus
when the relay is on, it can drive the loads connected between the common terminals and
normally open pin. Therefore, the relay takes 5V from the microcontroller and drives the

loads which consume high currents. Thus the relay acts as an isolation device. Digital
systems and microcontroller pins lack sufficient current to drive the relay. While the
relay‘s coil needs around 10milli amps to be energized, the microcontroller‘s pin can
provide a maximum of 1-2milli amps current. For this reason, a driver such as a power
transistor is placed in between the microcontroller and the relay.
The operation of this circuit is as follows:
i. The input to the base of the transistor is applied from the microcontroller port pin
P1.0.
ii. The transistor will be switched on when the base to emitter voltage is greater than
0.7V (cut-in voltage). Thus when the voltage applied to the pin P1.0 is high i.e.,
P1.0=1 (>0.7V), the transistor will be switched on and thus the relay will be ON and
the load will be operated.
iii. When the voltage at the pin P1.0 is low i.e., P1.0=0 (<0.7V) the transistor will be in
off state and the relay will be OFF. Thus the transistor acts like a current driver to
operate the relay accordingly.
2.2.5 Relay
A relay is an electrically operated switch. Current flowing through the coil of the relay
creates a magnetic field which attracts a lever and changes the switch contacts. The coil
current can be on or off so relays have two switch positions and they are double throw
(changeover) switches.
Relays allow one circuit to switch and second circuit which can be completely separate
from the first. For example a low voltage battery circuit can use a relay to switch a 230V
AC mains circuit. There is no electrical connection inside the relay between the two
circuits; the link is magnetic and mechanical.
The coil of a relay passes a relatively large current, typically 30mA for a 12Vrelay, but it
can be as much as 100mA for relays designed to operate from lower voltages. Most ICs
(chips) cannot provide this current and transistors usually used to amplify the small IC
current to the larger value required for the relay coil. Relays are usually SPDT (single
pole double throw) or DPDT (double pole double throw) but they can have many more
sets of switch contacts, for example relays with 4 sets of changeover contacts are readily

available. Relays used in our project have got a Coil rating of 12V, and Contact rating of
10 Amps.
2.2.7 Jammer blocks
Jammer block mainly consists of three parts, they are
i. Power supply.
ii. IF section.
iii.RF section.
2.2.8 Control switch set
Here the control switch is used to set the timer of Jammer block and it is also used for to
select different jamming frequency i.e. GSM, CDMA, 3G. The Microcontroller scans
these switches continuously to detect and identify the jamming frequency and jamming
duration.
2.2.9 Reset circuit
Reset button is used to initialize the operation of microprocessor and resets input and
output ports of microprocessor and program counter.

CHAPTER 3
OPERATION OF CELL PHONE JAMMER
Jamming devices overpower the cell phone by transmitting a signal on the same frequency
as the cell phone and at a high enough power that the two signals collide and
cancel each other out. Cell phones are designed to add power if they experience low-level
interference, so the jammer must recognize and match the power increase from
the phone. Cell phones are full-duplex devices, which mean they use two separate
frequencies, one for talking and one for listening simultaneously . Some jammers
block only one of the frequencies used by cell phones, which has the effect of
blocking both. The phone is tricked into thinking there is no service because
it can receive only one of the frequencies. Less complex devices block only one group
of frequencies, while sophisticated jammers can block several types of networks at once to
head off dual-mode or tri-mode phones that automatically switch among
different network types to find an open signal. Some of the high-end devices block all
frequencies at once and others can be tuned to specific frequencies.
To jam a cell phone, all you need is a device that broadcasts on the correct frequencies.
Although different cellular systems process signals differently, all cell-phone networks use
radio signals that can be interrupted. GSM, used in digital cellular and PCS-based systems,
operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the
1900-MHz (sometimes referred to as 1.9-GHz) band in the United States. Jammers can
broadcast on any frequency and are effective against AMPS, CDMA, TDMA, GSM, PCS,
DCS, iDEN and Nextel systems. Old fashioned analog cell phones and today's
digital devices are equally susceptible to jamming. Disrupting a cell phone is the
same as jamming any other type of radio communication. A cell phone works by
communicating with its service network through a cell tower or base station.
Cell towers divide a city into small areas, or cells. As a cell phone user drives down
the street, the signal is handed from tower to tower as shown in Figure 3.1.

Figure 3.1 : Signal handed from tower to tower
A jamming device transmits on the same radiofrequencies as the cell phone, disrupting the
communication between the phone and the cell-phone base station in the town as shown in
Figure 3.2. It's a called a denial-of-service attack. The jammer denies service of the radio
spectrum to the cell-phone users within range of the jamming device. Older jammers
sometimes were limited to working on phones using only analog or older digital
mobile phone standards. Newer models such as the double and triple band jammers
can block all widely used systems (AMPS, iDEN, GSM, etc.) and are even very
effective against newer phones which hop to different frequencies and systems
when interfered with. As the dominant network technology and frequencies used
for mobile phones vary worldwide, some work only in specific regions such as Europe or
North America.

Figure 3.2 : Denial of service attack
The power of the jammer's effect can vary widely based on factors such as
proximity to towers, indoor and outdoor settings, presence of buildings and landscape,
even temperature and humidity play a role. There are concerns that crudely
designed jammers may disrupt the functioning of medical devices such as
pacemakers. However, like cell phones, most of the devices in common use
operate at low enough power output (<1W) to avoid causing any problems.
3.1 MOBILE JAMMING TECHNIQUES
3.1.1 Type "A" Device: JAMMERS
In this device we overpower cell phone's signal with a stronger signal, This type
of device comes equipped with several independent oscillators transmitting
‗jamming signals‘ capable of blocking frequencies used by paging devices as well
as those used by cellular/PCS systems‘ control channels for call establishment. When
active in a designated area, such devices will (by means of RF interference) prevent

all pagers and mobile phones located in that area from receiving and
transmitting calls. This type of device transmits only a jamming signal and has
very poor frequency selectivity, which leads to interference with a larger
amount of communication spectrum than it was originally intended to target. Technologist
Jim Mahan said, ―There are two types. One is called brute force jamming,
which just blocks everything. The problem is, it‘s like power-washing the airwaves
and it bleeds over into the public broadcast area. The other puts out a small amount of
interference, and you could potentially confine it within a single cell block. You
could use lots of little pockets of small jamming to keep a facility under control.‖
3.1.2 Type “B” Device: INTELLIGENT CELLULAR DISABLERS
Unlike jammers type ―B‖ devices do not transmit an interfering signal on the control
channels. The device, when located in a designated ‗quiet‘ area, functions as a ‗detector ‘.
It has a unique identification number for communicating with the cellular base station.
When a Type ―B‖ device detects the presence of a mobile phone in the quiet
room; the ‗filtering‘ (i.e. The prevention of authorization of call establishment) is done
by the software at the base station.
When the base station sends the signaling transmission to a target user , the device after
detecting simultaneously the presence of that signal and the presence of the
target user, signals the base station that the target user is in a ‗quiet‘ room;
therefore, do not establish the communication. Messages can be routed to the user‘s
voice- mail box, if the user subscribes to a voice-mail service. This process of
detection and interruption of call establishment is done during the interval
normally reserved for signaling and handshaking. For ‗emergency users‘, the intelligent
detector device makes provisions for designated users who have emergency
status. These users‘ must pre-register their phone numbers with the service providers.
When an incoming call arrives, the detector recognizes that number and the call
are established for a specified maximum duration, say two minutes. The emergency
users are also allowed to make outgoing calls. Similarly, the system is capable of
recognizing and allowing all emergency calls routed to ―911‖.

It should be noted that the Type ―B‖ detector device being an integral part
of the cellular/PCS systems, would need to be provisioned by the cellular/PCS
service providers or provisioned by a third-party working cooperatively with full
support of the cellular/PCS service providers.
3.1.3 Type “C” Device: INTELLIGENT BEACON DISABLERS
Unlike jammers, Type ―C‖ devices do not transmit an interfering signal on the control
channels. The device, when located in a designated ‗quiet‘ area, functions as a ‗beacon‘
and any compatible terminal is instructed to disable its ringer or disable its
operation, while within the coverage area of the beacon. Only terminals which have a
compatible receiver would respond and this would typically be built on a separate
technology from cellular/PCS, e.g., cordless wireless, paging, ISM, Bluetooth. On leaving
the coverage area of the beacon, the handset must re-enable its normal function.
This technology does not cause interference and does not require any changes
to existing PCS/cellular operators. The technology does require intelligent handsets with a
separate receiver for the beacon system from the cellular/PCS receiver. It will
not prevent normal operation for incompatible legacy terminals within a ―quiet‖
coverage area, thus effective deployment will be problematic for man-years.
While general uninformed users would lose functionality, pre-designated
―emergency‖ users could be informed of a ―bypass terminal key sequence‖ to inhibit
response to the beacon. Assuming the beacon system uses a technology with its own
license (or in the license exempt band), no change to the regulations are needed
to deploy such a system. With this system, it would be extremely difficult to police
misuse of the ―bypass key sequence by users.
3.1.4 Type “D” Device: DIRECTRECEIVE & TRANSMIT JAMMERS
This jammer behaves like a small, independent and portable base station,
which can directly interact intelligently or unintelligently with the operation of the local
mobile phone. The jammer is predominantly in receiving mode and will
intelligently choose to interact and block the cell phone directly if it is within close

proximity of the jammer. This selective jamming technique uses a discriminating
receiver to target the jamming transmitter. The benefit of such targeting
selectivity is much less electromagnetic pollution in terms of raw power
transmitted and frequency spectrum from the jammer , and therefore much less
disruptive to passing traffic. The jam signal would only stay on as long as the
mobile continues to make a link with the base station, otherwise there would be no
jamming transmission – the technique forces the link to break or unhook and
then it retreats to a passive receive mode again.
This technique could be implemented without cooperation from PCS/cellular providers, but
could negatively impact PCS/cellular system operation. This technique has an added
advantage over Type B in that no added overhead time or effort is spent
negotiating with the cellular network. As well as Type B, this device could
discriminate 911 calls and allow for breakthrough‖ during emergencies.
3.1.5 Type “E” Device: EMI SHIELD - PASSIVE JAMMING
This technique is using EMI suppression techniques to make a room into what is
called a Faraday cage. Although labor intensive to construct, the Faraday cage essentially
blocks, or greatly attenuates, virtually all electromagnetic radiation from entering or
leaving the cage – or in this case a target room. With current advances in EMI shielding
techniques and commercially available products one could conceivably implement this
into the architecture of newly designed buildings for so-called ―quiet-conference‖
rooms. Emergency calls would be blocked unless there was a way to receive and decode
the 91 1 transmissions, pass by coax outside the room and re-transmitted. This passive
configuration is currently legal in most worlds‘ countries for any commercial or residential
location in so far as DOC Industry Canada is concerned, however municipal or provincial
building code by-laws mayor may not allow this type of construction. Table 3.1 shows a
comparison between the different jammer/disablers techniques.

Table 3.1 : Comparison between jammer/disablers techniques
3.2 MOBILE JAMMING REQUIREMENTS
Jamming objective is to inject an interference signal into the communications frequency
so that the actual signal is completely submerged by the interference. It is important to
notice that transmission can never be totally jammed - jamming hinders the reception at
the other end. The problem here for the jammer is that only transmitters can be found
using direction finding and the location of the target must be a specific location, usually
where the jammer is located and this is because the jamming power is never infinite.
Jamming is successful when the jamming signal denies the usability of the
communications transmission. In digital communications, the usability is denied when the
error rate of the transmission cannot be compensated by error correction. Usually a

successful jamming attack requires that the jammer power is roughly equal to signal
power at the receiver. The effects of jamming depend on the jamming-to-signal ratio
(J/S), modulation scheme, channel coding and interleaving of the target system. Generally
Jamming-to-Signal ratio can be measured according to the following Equation.
Pj= jammer power.
Pt= transmitter power.
Gjr= antenna gain from jammer to receiver.
Grj= antenna gain from receiver to Jammer.
Gtr= antenna gain from transmitter to receiver.
Grt= antenna gain from receiver to transmitter.
Br= communications receiver bandwidth.
Bj= jamming transmitter bandwidth.
Rtr= range between communications transmitter and receiver.
Rjt= range between jammer and communications receiver.
Lj= jammer signal loss (including polarization mismatch).
Lr= communication signal loss.
The above Equation indicates that the jammer Effective Radiated Power, which is the
product of antenna gain and output power, should be high if jamming efficiency is
required. On the other hand, in order to pr event jamming, the antenna gain toward the
communication partner should be as high as possible while the gain towards the jammer

should be as small as possible. As the equation shows, the antenna pattern, the relation
between the azimuth and the gain, is a very important aspect in jamming.
Also as we know from Microwave and shown in the equation distance has a strong
influence on the signal loss. If the distance between jammer and receiver is doubled, the
jammer has to quadruple its output in order for the jamming to have the same effect. It
must also be noted here the jammer path loss is often different from the communications
path loss; hence gives jammer an advantage over communication transmitters. In the
GSM network, the Base Station Subsystem (BSS) takes care of the radio resources. In
addition to Base Transceiver Station (BTS), the actual RF transceiver, BSS consists of
three parts. These are the Base Station Controller (BSC), which is in charge of mobility
management and signaling on the Air-interface between Mobile Station (MS), the BTS,
and the Air-interface between BSS and Mobile Services Switching Center (MSC).
UPLINK DOWNLINK
GSM 900 890 – 950 MHz 935 – 960 MHz
DCS 1800 1710 – 1785 MHz 1805 – 1880 MHz
3G 1850 – 1910MHz 2110 – 2170MHz
Table 3.2 : GSM, DCS and 3G frequency band
The comparison between the frequency bands is as shown in Table 3.2.
Frequency Hopping in GSM is intended for the reduction of fast fading caused by
movement of subscribers. The hopping sequence may use up to 64 different frequencies,
which is a small number compared to military FH systems designed for avoiding
jamming. Also, the speed of GSM hopping is approximately 200 hops /s; So GSM
Frequency Hopping does not provide real protection against jamming attacks.
Although FH doesn‘t help in protection against jamming, interleaving and forward error
correction scheme GSM Systems can protect GSM against pulsed jamming. For GSM it

was shown that as the specified system SNR is 9 dB, a jammer min requires a 5 dB S/J in
order to successfully jam a GSM channel. The optimum GSM SNR is 12 dB, after this
point the system starts to degrade.
GSM system is capable to withstand abrupt cuts in Traffic Channel (TCH) connections.
These cuts are normally caused by propagation losses due to obstacles such as bridges.
Usually another cell could be used to hold communication when the original BTS has
disconnected. The GSM architecture provides two solutions for this: first handover when
the connection is still available, second call reestablishment when the original connection
is totally lost. Handover decisions are made based on transmission quality and
reception level measurements carried out by the MS and the BTS. In jamming situations
call re-establishment is probably the procedure the network will take in order to re-
connect the jammed TCH.
It is obvious that downlink jamming (i.e. jamming the mobile station 'handset'(receiver) is
easier than uplink, as the base station antenna is usually located far away from the MS on
a tower or a high building. In the above table 3.2 we shown that the uplink and downlink
frequency range of different network. This makes it efficient for the jammer to overpower
the signal from BS. But the Random Access Channel (RACH) control channels of all
BTSs in the area need to be jammed in order to cut off transmission. To cut an existing
connections, the jamming has to last at least until the call re-establishment timer at the
MSC expires and the connection is released, which means that an existing call can be cut
after a few seconds of effective jamming.
The GSM RACH random access scheme is very simple: when a request is not answered,
the mobile station will repeat it after a random interval. The maximum number of
repetitions and the time between them is broadcast regularly. After a MS has tried to
request service on RACH and has been rejected, it may try to request service from
another cell. Therefore, the cells in the area should be jammed. In most cases, the
efficiency of a cellular jamming is very difficult to determine, since it depends on many
factors, which leaves the jammer confused.

CHAPTER 4
HARDWARE IMPLEMENTATION
4.1 CIRCUIT DIAGRAM
Circuit diagram involves rectifier, PIC microcontroller, LCD, relay and jammer. The
circuit diagram of cell phone jammer is as shown in Figure 4.1.
Figure 4.1 : Circuit diagram of Cell Phone Jammer

The system basically consists of
i. Regulated power supply.
ii. Microcontroller.
iii. Relay.
iv. LCD display.
v. Cell phone jammer schematic.
4.2 REGULATED POWER SUPPLY
4.2.1 DESCRIPTION
A variable regulated power supply, also called a variable bench power supply, is one
where you can continuously adjust the output voltage to your requirements. Varying the
output of the power supply is the recommended way to test a project after having double
checked parts placement against circuit drawings and the parts placement guide. This type
of regulation is ideal for having a simple variable bench power supply. Actually this is
quite important because one of the first projects a hobbyist should undertake is the
construction of a variable regulated power supply. While a dedicated supply is quite
handy e.g. 5V or 12V, it's much handier to have a variable supply on hand, especially for
testing. Most digital logic circuits and processors need a 5 volt power supply. To use
these parts we need to build a regulated 5 volt source. Usually you start with an
unregulated power supply ranging from 9 volts to 24 volts DC (A 12 volt power supply is
included with the Beginner Kit and the Microcontroller Beginner Kit.). To make a 5 volt
power supply, we use a LM7805 voltage regulator IC shown in Figure 4.2.
The LM7805 is simple to use. You simply connect the positive lead of your unregulated
DC power supply (anything from 9VDC to 24VDC) to the Input pin, connect the negative
lead to the Common pin and then when you turn on the power, you get a 5volt supply
from the Output pin.

Figure 4.2 : Regulated power supply IC
Circuit features
 Brief description of operation: Gives out well regulated +5V output, output
current capability of 100 mA.
 Circuit protection: Built-in overheating protection shuts down output when
regulator IC gets too hot
 Circuit complexity: Very simple and easy to build.
 Circuit performance: Very stable +5V output voltage, reliable operation.
 Availability of components: Easy to get, uses only very common basic
components.
 Design testing: Based on datasheet example circuit, we have used this circuit
successfully as part of many electronics projects.
 Applications: Part of electronics devices, small laboratory power supply.
 Power supply voltage: Unregulated DC 5V-18V power supply.
 Power supply current: Needed output current + 5 Ma.
 Component costs: Few dollars for the electronics components + the input
transformer cost.

4.2.2 IC VOLTAGE REGULATORS
Voltage regulators comprise a class of widely used ICs. Regulator IC units contain the
circuitry for reference source, comparator amplifier, control device, and overload
protection all in a single IC. Although the internal construction of the IC is somewhat
different from that described for discrete voltage regulator circuits, the external operation
is much the same. IC units provide regulation of either a fixed positive voltage, a fixed
negative voltage, or an adjustable set voltage.
A power supply can be built using a transformer connected to the ac supply line to step
the ac voltage to desired amplitude, then rectifying that through an ac voltage, filtering
with a capacitor and RC filter, if desired, and finally regulating the dc voltage using an IC
regulator. The regulators can be selected for operation with load currents from hundreds
of mA to tens of amperes, corresponding to power ratings from mill watts to tens of watts.
4.2.3 THREE – TERMINAL VOLTAGE REGULATOR
Figure 4.3 : Basic connection of a three – terminal voltage regulator IC to a load
Figure 4.3 shows the basic connection of a three - terminal voltage regulator IC to a load.
The fixed voltage regulator has an unregulated dc input voltage, VIN, applied to one input
terminal, a regulated output dc voltage, VOUT, from a second terminal, with the third
terminal connected to ground. While the input voltage may vary over some permissible
voltage range, and the output load may vary over some acceptable range, the output
voltage remains constant within specified voltage variation limits. The IC LM7805 takes
a maximum voltage of +35 volts and gives an output of +5 volts.

4.2.4 BLOCK DIAGRAM OF POWER SUPPLY
Figure 4.4 shows the block diagram of power supply. A 230V, 50Hz AC input signal is
applied to bridge rectifier circuit. After rectification, the output of the rectifier is filtered
by using Low Pass Filter (LPF) which removes unwanted high frequency ripple
components, and then it is regulated to produce a constant DC output.
Figure 4.4 : Block diagram of power supply
4.3 MICROCONTROLLER (PIC16F877A)
4.3.1 BRIEF HISTORY OF PIC16F877A
The original PIC was built to be used with General Instrument's new 16-bit CPU, the
CP1600. While generally a good CPU, the CP1600 had poor I/O performance, and the 8-
bit PIC was developed in 1975 to improve performance of the overall system by
offloading I/O tasks from the CPU. The PIC used simple microcode stored in ROM to
perform its tasks, and although the term was not used at the time, it shares some common
features with RISC designs. In 1985, General Instrument spun off their microelectronics
division and the new ownership cancelled almost everything — which by this time was
mostly out-of-date. The PIC, however, was upgraded with internal EPROM to produce a

programmable channel controller and today a huge variety of PICs are available with
various on-board peripherals (serial communication modules, UARTs, motor control
kernels, etc.) and program memory from 256 words to 64k words and more (a "word" is
one assembly language instruction, varying from 12, 14 or 16 bits depending on the
specific PIC micro family).
PIC and PIC micro are registered trademarks of Microchip Technology. It is generally
thought that PIC stands for Peripheral Interface Controller, although General
Instruments' original acronym for the initial PIC1640 and PIC1650 devices was
"Programmable Interface Controller". The acronym was quickly replaced with
"Programmable Intelligent Computer". The Microchip 16C84 (PIC16x84), introduced
in 1993, was the first Microchip CPU with on-chip EEPROM memory. This electrically
erasable memory made it cost less than CPUs that required quartz "erase window" for erasing
EPROM.
PIC is a family of architecture microcontrollers made by Microchip Technology, derived
from the PIC1650 originally developed by General Instrument's Microelectronics
Division. The name PIC initially referred to "Peripheral Interface Controller". PICs are
popular with both industrial developers and hobbyists alike due to their low cost, wide
availability, large user base, extensive collection of application notes, availability of low
cost or free development tools, and serial programming (and re-programming with flash
memory) capability. Microchip announced on September 2011 the shipment of its ten
billionth PIC processor.
4.3.2 FEATURES OF MICROCONTROLLER (PIC16F877A)
The PIC16FXX series has more advanced and developed features when compared to its
previous series. The important features of PIC16F877 series is given below.
General Features
 High performance RISC CPU.
 ONLY 35 simple word instructions.
 All single cycle instructions except for program branches which are two Cycles.

 Operating speed: clock input (200MHz), instruction cycle (200nS).
 Up to 368×8bit of RAM (data memory), 256×8 of EEPROM (data memory), and
8k×14 of flash memory.
 Pin out compatible to PIC 16C74B, PIC 16C76, PIC 16C77.
 Eight level deep hardware stack.
 Interrupt capability (up to 14 sources).
 Different types of addressing modes (direct, Indirect, relative addressing modes).
 Power on Reset (POR).
 Power-Up Timer (PWRT) and oscillator start-up timer.
 Low power- high speed CMOS flash/EEPROM.
 Fully static design.
 Wide operating voltage range (2.0 – 5.56) volts.
 High sink/source current (25mA).
 Commercial, industrial and extended temperature ranges.
 Low power consumption (<0.6mA typical @3V-4MHz, 20µA typical @3V-
32MHz and <1 A typical standby).
Key Features
 Maximum operating frequency is 20MHz.
 Flash program memory (14 bit words), 8KB.
 Data memory (bytes) is 368.
 EEPROM data memory (bytes) is 256.
 5 input/output ports.
 3 timers.
 2 CCP modules.
 2 serial communication ports (MSSP, USART).
 PSP parallel communication port.
 10bit A/D module (8 channels).

4.3.3 PIN CONFIGURATIONS of PIC16F877A
INPUT/OUTPUT PORTS
PIC16F877 has 5 basic input/output ports with its bit wide shown below Table 4.1. They
are usually denoted by PORT A (RA), PORT B (RB), PORT C (RC), PORT D (RD), and
PORT E (RE). These ports are used for input/ output interfacing. In this controller,
―PORT A‖ is only 6 bits wide (RA-0 to RA-5), ‖PORT B‖,―PORT C‖,‖PORT D‖ are
only 8 bits wide (RB-0 to RB-7,RC-0 to RC-7,RD-0 to RD-7),‖PORT E‖ has only 3 bit
wide (RE-0 to RE-2), All these ports are bi-directional.
Table 4.1 : Input/output ports
PORT-A RA-0 to RA-5 6 bit wide
PORT-B RB-0 to RB-7 8 bit wide
PORT-C RC-0 to RC-7 8 bit wide
PORT-D RD-0 to RD-7 8 bit wide
PORT-E RE-0 to RE-2 3 bit wide

Figure: 4.5 : Pin configuration of PIC16F877A
Figure 4.5 shows the pin configuration of PIC16F877A. The direction of the port is
controlled by using TRIS(X) registers (TRIS A used to set the direction of PORT-A,
TRIS B used to set the direction for PORT-B, etc.). Setting a TRIS(X) bit ‗1‘ will set the
corresponding PORT(X) bit as input. Clearing a TRIS(X) bit ‗0‘ will set the
corresponding PORT(X) bit as output.(If we want to set PORT A as an input, just set
TRIS(A) bit to logical ‗1‘ and want to set PORT B as an output, just set the PORT B bits
to logical ‗0‘).
i. Analog input port (AN0 TO AN7) : these ports are used for interfacing analog
inputs.
 TX and RX: These are the USART transmission and reception ports.
 SCK: these pins are used for giving synchronous serial clock input.

 SCL: these pins act as an output for both SPI and I2C modes.
 DT: these are synchronous data terminals.
 CK: synchronous clock input.
 SD0: SPI data output (SPI Mode).
 SD1: SPI Data input (SPI mode).
 SDA: data input/output in I2C Mode.
 CCP1 and CCP2: these are capture/compare/PWM modules.
 OSC1: oscillator input/external clock.
 OSC2: oscillator output/clock out.
 MCLR: master clear pin (Active low reset).
 Vpp: programming voltage input.
 THV: High voltage test mode controlling.
 Vref (+/-): reference voltage.
 SS: Slave select for the synchronous serial port.
 T0CK1: clock input to TIMER 0.
 T1OSO: Timer 1 oscillator output.
 T1OS1: Timer 1 oscillator input.
 T1CK1: clock input to Timer 1.
 PGD: Serial programming data.
 PGC: serial programming clock.
 PGM: Low Voltage Programming input.
 INT: external interrupt.
 RD: Read control for parallel slave port.
 CS: Select control for parallel slave.
 PSP0 to PSP7: Parallel slave port.
 VDD: positive supply for logic and input pins.
 VSS: Ground reference for logic and input/output pins.

4.4 RELAY
A relay is an electrically operated switch. Current flowing through the coil of the relay
creates a magnetic field which attracts a lever and changes the switch contacts. The coil
current can be on or off so relays have two switch positions and they are double throw
(changeover) switches.
Inductor
Figure: 4.6 : Basic relay switch and relay frames
Basic relay switch and relay frames are shown in above Figure 4.6. Relays allow one
circuit to switch a second circuit which can be completely separate from the first. For
example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit.
There is no electrical connection inside the relay between the two circuits; the link is
magnetic and mechanical.
The coil of a relay passes a relatively large current, typically 30mA for a 12V relay, but it
can be as much as 100mA for relays designed to operate from lower voltages. Most ICs
(chips) cannot provide this current and a transistor is usually used to amplify the small IC
current to the larger value required for the relay coil. The maximum output current for the
popular 555 timer IC is 200mA so these devices can supply relay coils directly without
amplification.
Relays are usually SPDT or DPDT but they can have many more sets of switch contacts,
for example relays with 4 sets of changeover contacts are readily available. For further
information about switch contacts and the terms used to describe them please see the page
on switches. Most relays are designed for PCB mounting but you can solder wires
directly to the pins providing you take care to avoid melting the plastic case of the relay.
The supplier‘s catalogue should show you the relay's connections. The coil will be
ON
COM
NC

obvious and it may be connected either way round. Relay coils produce brief high voltage
'spikes ‗when they are switched off and this can destroy transistors and ICs in the circuit.
To prevent damage you must connect a protection diode across the relay coil.
The Figure 4.7 shows a working relay with its coil and switch contacts. You can see a
lever on the left being attracted by magnetism when the coil is switched-on. This lever
moves the switch contacts. There is one set of contacts (SPDT) in the foreground and
another behind them, making the relay DPDT.
Figure: 4.7 : Relay with its coil and switch contacts
The relay's switch connections are usually labeled COM, NC and NO.
 COM = Common, always connect to this; it is the moving part of the switch.
 NC = Normally Closed, COM is connected to this when the relay coil is OFF.
 NO = Normally Open, COM is connected to this when the relay coil is ON.
 Connect to COM and NO if you want the switched circuit to be on when the
relay coil is on.
 Connect to COM and NC if you want the switched circuit to be on when the
relay coil is off.
Advantages of relays
i. Relays can switch AC and DC, transistors can only switch DC.
ii. Relays can switch high voltages, transistors cannot.
iii.Relays are a better choice for switching large currents (> 5A).
iv. Relays can switch many contacts at once.

Disadvantages of relays
i. Relays are bulkier than transistors for switching small currents.
ii. Relays cannot switch rapidly (except reed relays), transistors can switch many
iii.Times per second.
iv. Relays use more power due to the current flowing through their coil.
4.5 LCD DISPLAY
LCD stands for Liquid Crystal Display. To display interactive messages we are using
LCD Module. We examine an intelligent LCD display of two lines, 16 characters per line
that is interfaced to the controllers. The protocol (handshaking) for the display is as
shown. Whereas D0 to D7th bit is the Data lines, RS, RW and EN pins are the control
pins and remaining pins are +5V, -5V and GND to provide supply. Where RS is the
Register Select, RW is the Read Write and EN is the Enable pin.
The display contains two internal byte-wide registers, one for commands (RS=0) and the
second for characters to be displayed (RS=1). It also contains a user-programmed RAM
area (the character RAM) that can be programmed to generate any desired character that
can be formed using a dot matrix.
.
Figure 4.8 : 2x16 line alphanumeric LCD display
Most commonly used ALPHANUMERIC displays are 1x16 (Single Line & 16
characters), or 2x16 (Double Line & 16 character per line). Figure 4.8 shows 2x16 line
alphanumeric LCD display. The LCD requires 3 control lines (RS, R/W & EN) & 8 (or 4)
data lines. The number on data lines depends on the mode of operation.

Pin description of LCD:-
Pin Symbol Function
1 Vss Ground
2 Vdd
Supply
Voltage
3 Vo
Contrast
Setting
4 RS
Register
Select
5 R/W
Read/Write
Select
6 En
Chip
Enable Signal
7-14
DB0-
DB7
Data Lines
15 A/Vee
Ground for
the backlight
16 K
Vcc for
the backlight
Figure 4.9 : Pin description of LCD display

Figure 4.9 shows the pin description of LCD display. When RS is low (0), the data is to
be treated as a command. When RS is high (1), the data being sent is considered as text
data which should be displayed on the screen. When R/W is low (0), the information on
the data bus is being written to the LCD.
When R/W is high (1), the program is effectively reading from the LCD. Most of the
times there is no need to read from the LCD so this line can directly be connected to
Ground thus saving one controller line.
The ENABLE pin is used to latch the data present on the data pins. A HIGH - LOW
signal is required to latch the data. The LCD interprets and executes our command at the
instant the EN line is brought low. If you never bring EN low, your instruction will never
be executed. Below Figure 4.10 shows how LCD interfaced to microcontroller.
Figure 4.10 : LCD interface to microcontroller

4.6 CELL PHONE JAMMER SCHEMATIC
Figure 4.11 shows the schematic representation of cell phone jammer.
Figure 4.11 : Cell phone jammer schematic

The schematic consists of mainly
1 Power supply.
2 IF section.
3 RF section.
4.6.1 POWER SUPPLY
The power supply consists of the following main parts as shown in the Figure 4.12.
Figure 4.12 : Power supply unit
Transformer: Is used to transform the 220VAC to other levels of voltages.
Rectification: This part is to convert the AC voltage to a DC one. We have two methods
for rectification: Half wave-rectification: the output voltage appears only during positive
cycles of the input signal. Full wave –rectification: a rectified output voltage occurs during
both the positive and negative cycles of the input signal.
The Filter: Used to eliminate the fluctuations in the output of the full wave rectifier
―eliminate the noise‖ so that a constant DC voltage is produced. This filter is just a large
capacitor used to minimize the ripple in the output.
Regulator: This is used to provide a desired DC-voltage.
4.6.2 IF SECTION
The block diagram of IF section is as shown in Figure 4.13. The function of the IF-section
of the Mobile jammer is to generate the tuning signal for the VCO in the RF-
Section, which will sweep the VCO through the desired range of frequencies.
This tuning signal is generated by a triangular wave generator (1 10 KHz) along with noise

generator, and then offset by proper amount so as to sweep the VCO
output from the minimum desired frequency to a maximum.
Figure 4.13 : Block diagram of IF section
The IF section consists of three main parts
i. Triangle wave generator. (To tune the VCO in the RF section).
ii. Noise generator (provides the output noise).
iii. Signal mixer and DC offset circuits (to mix the triangle and the noise waves).
Triangle wave generator
The triangle wave generator consists of op-amp LM1458. Its block diagram and description
is as shown in Figure 4.14. The next op amp IC 1b is wired as an integrator.R5 is the
feedback resistor and C2 is the integrating capacitor. Non inverting input of IC 1b (pin6) is
tied to ground using resistor R7. The output of IC 1a which is a square wave is applied to
the inverting input of IC 1b (pin 5) through R4 which is the input resistance of IC 1b.The
output of IC 1b will be a triangular wave form, because integrating a square wave will
result in a triangular waveform. IC 2a forms another integrator, where R11 is its feedback
resistor and C3 is the integrating capacitor.R6 is the input resistance of IC 2a. Non
inverting input of IC 2a (pin 3) is tied to ground using the 10K resistor R8. IC 2b forms an
inverting amplifier where R9 is its input resistor and R10 the feedback resistor. With the
values of R10 & R9, the gain of the inverting amplifier stage will be 27, (AV = -Rf/Rin).

The triangular output waveform from the IC 1b is further integrated using IC 2a inverter
using IC 2b circuit diagram.
Figure 4.14 : Simple function generator circuit
Noise generator
To achieve jamming a noise signal is mixed with the triangle wave signal to produce
the tuning voltage for the VCO. The noise will help in masking the jamming transmission,
making it look like random "noise‖ to an outside observer .Without the noise generator, the
jamming signal is just a sweeping, unmodulated Continuous Wave RF carrier.
The noise generator used in this design is based on the avalanche noise generated
by a Zener breakdown phenomenon. It is created when a PN junction is
operated in the reverse breakdown mode. The avalanche noise is very similar to
shot noise, but much more intense and has a flat frequency spectrum (white).
The magnitude of the noise is difficult to predict due to its dependence on the materials.
Basically the noise generator circuit consists of a standard 6.8 volt zener
diode with a small reverse current, a transistor buffer, and The National
LM386 audio amplifier which acts as a natural band-pass filter and mall-signal
amplifier.

Signal mixer and DC offset circuits
Figure 4.15 : Op – amp summer circuit
The triangle wave and noise signals are mixed using OP-Amp configured as summer
shown in Figure 4.15, then a dc voltage is added to the resulted signal to obtain the
required tuning voltage using diode-clamper circuit that is shown in Figure 4.16. To gain
good clamping the RC time constant selected so that it‘s more than ten times the period of
the input frequency, also a potentiometer was added to control the biasing voltage so as to
get the desired tuning voltage.
Figure 4.16 : Positive diode – clamper with bias

4.6.3 RF SECTION
The block diagram of RF section is as shown in Figure 4.17.
Figure 4.17 : Block diagram of RF section
The RF-section is the most important part of the mobile jammer it consists of
i. Voltage Controlled Oscillator (VCO).
ii. RF Power amplifier.
iii. Antenna.
These components were selected according to the desired specification of the
jammer such as the frequency range and the coverage range. It‘s important to note that all
the components used has 50 ohm input/output impedance, so 50 ohm micro
strip was needed for matching between the components.
Power requirements
To successfully jam a particular region, we need to consider a very important parameter
the signal to noise ratio, referred to as the SNR. Every device working on radio
communication principles can only tolerate noise in a signal up to a particular level. This

is called the SNR handling capability of the device. Most cellular devices have a SNR
handling capability of around 12dB. A very good device might have a value of 9dB,
although it is highly unlikely. To ensure jamming of these devices, we need to reduce the
SNR of the carrier signal to below the 9dB level.
For this, we consider the worst-case scenario from a jammers point of view. This would
mean maximum transmitted power Smax from the tower, along with the lowest value of
the SNR handling capability of a mobile device. So, mathematically,
J = -24dBm
Since SNRmin = S/J
Where J is the power of the jamming signal.
So we need to have jamming signal strength of -24dBm at the mobile device‘s reception
to effectively jam it. However, our radiated signal will undergo some attenuation in being
transmitted from the antenna of the jammer to the antenna of the mobile device. This path
loss can be calculated using the simple free space path loss approximation:
Here f is the frequency in MHz, and D the distance traveled in kilometers. Using the
GSM downlink center frequency (947.5MHz) and a jamming radius of 20m, we get the
value of path loss to be 58dBm. This ideal path loss is for free space only, and the path
losses in air will me much greater. This means that the jamming radius will be less than
the 20m used to calculate this value. So, including the power lost in path loss, we need to
transmit a signal with strength of:
JT = 58 - 24 = 34dBm
Now, the power output of our VCO is -3dBm, which needs to be amplified by 37dBm to
meet our requirements. For this, we used a two-stage amplification mechanism. The first
stage is the MAR-4SM pre-amplifier, which provides a 8dBm power gain. This takes the
power level to 5dBm. To match the power to the input recommendation of the second

amplification stage (the PF08103B), we need to attenuate this by 4dB, for which a pi-
attenuator is used. Now the power level is 1dB, which is amplified by a gain of 33dB by
the PF08103B to an output power level of 34dBm.
Voltage controlled oscillator
The VCO is responsible for generating the RF signal which will over power the mobile
downlink signal. The selection of the VCO was influenced by two main factors, the
frequency of the GSM system, which will be jammed and the availability of the chip. For
the first factor which implies that the VCO should cover the frequencies from 935 MHz
to 960 MHz, The MAX2623 VCO from MAXIM IC was found to be a good choice, and
fortunately the second factor was met sequentially since MAXIM IC was willing to send
two of the MAX2623 for free. The pin diagram of MAXIM is as shown in Figure 4.18.
Figure 4.18 : Pin diagram of MAXIM
The MAX2623 VCO is implemented as an LS oscillator configuration, integrating
all tank circuit of the tank circuit on-chip, this makes the VCO extremely easy-to use ,
and the tuning input is internally connected to the varactor as shown in Figure 4.16 .The
typical output power is -3dBm, and the output was best swept over the desired range
when the input tuning voltage was around 120 KHz.

Figure 4.19 : MAXIM 2623 Pin connection
Figure 4.19 shows voltage controlled osillator MAXIM 2623 pin connections.
About VCO:
i. Fully Monolithic.
ii. Guaranteed Performance.
iii.On-Chip 50Ω Output Match.
iv. 885MHz to 950MHz (MAX2623).
v. +2.7V to +3.3V Single-Supply Operation.
vi. Low Current Shutdown Mode.
vii. Smaller than Modules (8-pin µMAX package).
Pin description of VCO:
1) NC- No Connection. Not internally connected.
2) TUNE- Oscillator Frequency Tuning Voltage Input. High-impedance input with a
voltage input range of 0.4V (low frequency) to 2.4V (high frequency) adjustment.

3) GND- Ground Connection for Oscillator and Biasing requires a low-inductance
connection to the circuit board ground plane.
4) SHDN- Shutdown Logic Input. A high-impedance input logic level low disables the
device and reduces supply current to 0.1μA. A logic level high enables the device.
5) VCC- Output Buffer DC Supply Voltage Connection, bypass with a 220pF capacitor to
GND for best high frequency performance.
6) VCC- Bias and Oscillator DC Supply Voltage Connection. Bypass with a 220pF
capacitor to GND for low noise and low spurious content performance from the oscillator.
7) GND-Ground Connection for Output Buffer. Requires a low-inductance connection to
the circuit board ground plane.
RF Power amplifier
To achieve the desired output power a gain stage was needed, about searching for a
suitable power amplifier it is cheaper to use power amplifier from an old Mobile phones.
The PF08103b Hitachi power amplifier module from Nokia mobile phone is sufficient to
amplify an input signal in the range 800MHz to 1 GHz by 34 db. But in the data sheet
input should be 1dBm.To meet this requirement we use another power amplifier stage
after VCO and before Hitachi power amplifier .For this stage we use MAR-4SM power
amplifier, so the output at this stage is around 5dBm.A typical biasing configuration for
MAR-4SM is shown in the Figure 4.20.
Figure 4.20 : Typical biasing configuration for the MAR – 4SM

Now the power before the Hitachi RF power amplifier is 5dBm and since 1dBm is
required; so here we used 4dBm T-Network attenuator is as shown in the Figure 4.21.
Figure 4.21 : T- Network attenuator
For a 4-dB attenuation and symmetric Network S12=S21=0.631 And for 50 ohms
characteristic impedance we found the values of the resistor using the following
equations.
Where X= (R2+50))/R3.
Antenna
The most important part of any transmitter is the antenna. So a suitable antenna should be
selected .The antenna used in the project is λ/4 wave monopole antenna and it has 50
Ohm impedance so that the antenna is matched to the transmission system .Also this
antenna has low VSWR less than 1.7, and a bandwidth of 150MHz around 916MHz
center frequency which cover the mobile jammer frequency range .The antenna gain is
2dBi. Figure 4.22 shows the monopole antenna.

Figure 4.22 : Monopole antenna
The patterns of antenna are as shown in Figure 4.23.
a) Monopole principle E – Plane pattern
b) Monopole principle H – Plane pattern
Figure 4.23 : Antenna patterns

CHAPTER 5
SOFTWARE IMPLEMENTATION
5.1 FLOW CHART
Yes
No
Yes
No
BEGIN
A
Initialize LCD,
Clear LCD
Output string on LCD
(Select Network
DCS CDMA 3G)
Is
sw0 =1
1
Input from either of
the switches
sw0, sw1, sw2, sw3
reset sw
Selected network
―DCS‖
Is
Reset sw=1
A
B C
D

No
Yes
Yes
NO
Yes
No
Yes
CA B
Is
sw1 =1
Selected network
―CDMA‖
Is
Reset sw=1
Is
sw2 =1
Selected network
―3G‖
Is
Reset sw=1
No
Yes
Yes
Is
sw3 =1
Selected All
network
Is
Reset sw=1
D
No
No
2

2
Wait for
500ms
Output string on LCD
(Set on time)
1
Is
Reset sw=1
Place cursor of
LCD to next row
Print the number
(time) on LCD
Print string ―mins‖
on LCD
1
Is
Reset sw=1
Input from
sw0 or sw1
Yes
No
Yes
No
E

Is
Sw0=1
time=time+1
E
Yes
No
Is
Sw1=1
time=time-1
Yes
No
Is reset
Sw=1 1
3
Yes
No

3
Is selected
network is
DCS
Print string
(DCS network
is on for)
Print time
Yes
No
Print string
(CDMA network
is on for)
Print time
No
Is selected
network is
CDMA
Yes
Print string
(3G network is
on for)
Print time
Is selected
network is
3G
F HG
Yes
No

Print string (All
network is on
for)
Print time
Is All
network is
selected
F HG
No
Yes
Is
Reset sw=1 1
No
Yes
Is
Sw2=1
Yes Run jammer for selected
network and time duration
No
Reset
Sw=1
while
running
Abort jammer
End
Yes
No
1
1

5.2 SOURCE CODE
#define PIC
//Defines for microcontroller
#define P16F877a
//LCDDisplay(0): //Macro function declarations
void LCDDisplay0_RawSend(UINT8 in, UINT8 mask);
void LCDDisplay0_Start();
void LCDDisplay0_Clear();
void LCDDisplay0_PrintASCII(UINT8 Character);
void LCDDisplay0_Command(UINT8 in);
void LCDDisplay0_Cursor(UINT8 x, UINT8 y);
void LCDDisplay0_PrintNumber(SINT16 Number);
void LCDDisplay0_PrintString(STRING String, UINT8 MSZ_String);
void LCDDisplay0_ScrollDisplay(UINT8 Direction, UINT8 Num_Positions);
void LCDDisplay0_ClearLine(UINT8 Line);
void LCDDisplay0_RAM_Write(UINT8 nIdx, UINT8 d0, UINT8 d1, UINT8 d2, UINT8
d3, UINT8 d4, UINT8 d5, UINT8 d6, UINT8 d7);
//LCDDisplay(0): //Macro implementations
void LCDDisplay0_RawSend(UINT8 in, UINT8 mask)
{
UINT8 pt;
CAL_Bit_Low(LCD_5__PORT0, LCD_5__BIT0);
CAL_Bit_Low(LCD_5__PORT4, LCD_5__RS);
CAL_Bit_Low(LCD_5__PORT5, LCD_5__E);
pt = ((in >> 4) & 0x0f);
if (pt & 0x01)
CAL_Bit_High(LCD_5__PORT0, LCD_5__BIT0);
if (pt & 0x02)
if (pt & 0x04)
if (pt & 0x08)
if (mask)
CAL_Bit_High(LCD_5__PORT4, LCD_5__RS);
LCD_5__DELAY;

CAL_Bit_High (LCD_5__PORT5, LCD_5__E);
LCD_5__DELAY;
CAL_Bit_Low (LCD_5__PORT5, LCD_5__E);
pt = (in & 0x0f);
LCD_5__DELAY;
CAL_Bit_Low(LCD_5__PORT4, LCD_5__RS);
CAL_Bit_Low(LCD_5__PORT5, LCD_5__E);
if (pt & 0x01)
if (pt & 0x02)
if (pt & 0x04)
if (pt & 0x08)
if (mask)
CAL_Bit_High(LCD_5__PORT4, LCD_5__RS);
LCD_5__DELAY;
CAL_Bit_High (LCD_5__PORT5, LCD_5__E);
LCD_5__DELAY;
CAL_Bit_Low (LCD_5__PORT5, LCD_5__E);
LCD_5__DELAY;
}
void LCDDisplay0_Clear()
{
LCDDisplay0_RawSend(0x01, 0);
Wdt_Delay_Ms(2);
Wdt_Delay_Ms(2);
}
void LCDDisplay0_PrintASCII(UINT8 Character)
{
LCDDisplay0_RawSend(Character, 0x10);
}

void LCDDisplay0_Command(UINT8 in)
{
LCDDisplay0_RawSend(in, 0);
Wdt_Delay_Ms(2);
}
void LCDDisplay0_Cursor(UINT8 x, UINT8 y)
{
#if (LCD_5__ROWCNT == 1)
y=0x80;
#endif
if (y==0)
y=0x80;
else
y=0xc0;
#endif
if (y==0)
y=0x80;
else if (y==1)
y=0xc0;
#if (LCD_5__COLCNT == 16)
else if (y==2)
y=0x90;
else
y=0xd0;
#endif
else if (y==2)
y=0x94;
else
y=0xd4;
#endif
#endif
LCDDisplay0_RawSend(y+x, 0);
Wdt_Delay_Ms(2);

}
void LCDDisplay0_PrintNumber(SINT16 Number)
{
SINT16 tmp_int;
UINT8 tmp_byte;
if (Number < 0)
{
LCDDisplay0_RawSend('-', 0x10);
Number = 0 - Number;
}
tmp_int = Number;
if (Number >= 10000)
{
tmp_byte = tmp_int / 10000;
LCDDisplay0_RawSend('0' + tmp_byte, 0x10);
while (tmp_byte > 0)
{
tmp_int = tmp_int - 10000;
tmp_byte--;
}
}
if (Number >= 1000)
{
{
tmp_byte--;
}
}
if (Number >= 100)
{
{
tmp_byte--;

}
}
if (Number >= 10)
{
{
tmp_byte--;
}
}
LCDDisplay0_RawSend('0' + tmp_int, 0x10);
}
void LCDDisplay0_PrintString(STRING String, UINT8 MSZ_String)
{
UINT8 idx = 0;
for (idx=0; idx<MSZ_String; idx++)
{
if (String[idx] == 0)
{
break;
}
LCDDisplay0_RawSend(String[idx], 0x10);
}
}
void LCDDisplay0_ScrollDisplay(UINT8 Direction, UINT8 Num_Positions)
{
UINT8 cmd = 0;
UINT8 count;
//Choose the direction
switch (Direction)

{
case 0:
case 'l':
case 'L':
cmd = 0x18;
break;
case 1:
case 'r':
case 'R':
cmd = 0x1C;
break;
default:
break;
}
//If direction accepted then scroll the specified amount
if (cmd)
{
for (count = 0; count < Num_Positions; count++)
LCDDisplay0_Command(cmd);
}
}
void LCDDisplay0_ClearLine(UINT8 Line)
{
UINT8 count;
UINT8 rowcount;
//Define number of columns per line
rowcount=80;
#endif
rowcount=40;
#endif
rowcount=16;
#endif

rowcount=20;
#endif
#endif
//Start at beginning of the line
LCDDisplay0_Cursor (0, Line);
//Send out spaces to clear line
for (count = 0; count < rowcount; count++)
LCDDisplay0_RawSend(' ', 0x10);
// Move back to the beginning of the line.
LCDDisplay0_Cursor (0, Line);
}
void LCDDisplay0_RAM_Write (UINT8 nIdx, UINT8 d0, UINT8 d1, UINT8 d2, UINT8
d3, UINT8 d4, UINT8 d5, UINT8 d6, UINT8 d7)
{
//set CGRAM address
LCDDisplay0_RawSend(64 + (nIdx << 3), 0);
delay_ms(2);
//write CGRAM data
LCDDisplay0_RawSend (d0, 0x10);
//Clear the display
delay_ms(2);
delay_ms(2);
}
void time()
{
//Delay

//Delay: 500 ms
delay_ms(255);
delay_ms(245);
//Loop
//Loop: While 1
while (1)
{
//Call Component Macro
//Call Component Macro: Clear ()
LCDDisplay0_Clear ();
//Call Component Macro: PrintString ("Set On Time")
LCDDisplay0_PrintString ("Set On Time", 11);
//Call Component Macro: Cursor (0, 1)
LCDDisplay0_Cursor (0, 1);
//Call Component Macro: PrintNumber (time)
LCDDisplay0_PrintNumber (TIME);
//Call Component Macro: PrintString(" mins")
LCDDisplay0_PrintString(" mins", 5);
//Input
//Input: B0 -> sw1
trisb = trisb | 0x01;
SW1 = ((portb & 0x01) == 0x01);
//Decision
//Decision: sw1 = 0?
if (SW1 == 0)
{
//Calculation
//Calculation:
// time = time + 1
TIME = TIME + 1;
// } else
{

}
//Input
//Input: B1 -> sw2
SW2 = ((portb & 0x02) == 0x02);
//Decision
if (SW2 == 0)
{
//Calculation
//Calculation:
// time = time - 1
TIME = TIME - 1;
// } else
{
}
//Input
//Input: B2 -> sw3
SW3 = ((portb & 0x04) == 0x04);
//Decision
if (SW3 == 0)
{
//Call Macro
//Call Macro: start()
start();
//Goto Connection Point
//Goto Connection Point: [A]: A
goto time_A;
// } else
{
}
//Input
//Input: B3 -> sw4

SW4 = ((portb & 0x08) == 0x08);
//Decision
if (SW4 == 0)
{
//Goto Connection Point
//Goto Connection Point: [A]: A
goto time_A;
// } else
{
}
//Delay
//Delay: 300 ms
delay_ms(255);
delay_ms(45);
}
//Connection Point
//Connection Point: [A]: A
time_A;
}
void start()
{
//Switch
//Switch: network?
switch (NETWORK)
{
case 1:
{
//Call Component Macro: Clear()
LCDDisplay0_Clear();
//Call Component Macro: PrintString("DCS Network is ")
LCDDisplay0_PrintString("DCS Network is ", 15);

//Call Component Macro: Cursor(0, 1)
LCDDisplay0_Cursor(0, 1);
//Call Component Macro: PrintString("on for")
LCDDisplay0_PrintString("on for", 6);
//Call Component Macro: PrintNumber(time)
LCDDisplay0_PrintNumber(TIME);
//Call Component Macro: PrintString("mins")
LCDDisplay0_PrintString("mins", 4);
break;
}
case 2:
{
//Call Component Macro: Print String("CDMA Network is ")
LCDDisplay0_PrintString("CDMA Network is ", 16);
//Call Component Macro: Print String("on for")
//Call Component Macro: Print Number(time)
//Call Component Macro: Print String("mins")

break;
}
case 3:
{
//Call Component Macro: PrintString("GSM Network is ")
LCDDisplay0_PrintString("GSM Network is ", 15);
break;
}
case 4:
{
//Call Component Macro: PrintString("All Network are")
LCDDisplay0_PrintString("All Network are", 15);

break;
}
// default:
}
//Output
//Output: 1 -> A0
trisa = trisa & 0xFE;
if ((1))
porta = (porta & 0xFE) | 0x01;
else
porta = porta & 0xFE;
//Calculation
//Calculation:
// delay = time * 60
DELAY = TIME * 60;
//Loop
//Loop: While delay = 0
while (!(DELAY == 0))
{
//Calculation
//Calculation:
// delay = delay - 1
DELAY = DELAY - 1;
//Delay
//Delay: 1 s
delay_s(1);

}
//Output
//Output: 0 -> A0
if ((0))
else
}
void main()
{
//Initialization
adcon1 = 0x07;
//Interrupt initialization code
option_reg = 0xC0;
//Output
//Output: 0 -> A0
if ((0))
else
//Call Component Macro: Start()
LCDDisplay0_Start();
//Loop
//Loop: While 1
while (1)
{
//Call Component Macro: PrintString("Select Network")
LCDDisplay0_PrintString("Select Network", 14);

//Call Component Macro: PrintString("DCS CDMA 3G")
LCDDisplay0_PrintString("DCS CDMA 3G", 15);
//Input
//Input: B0 -> sw1
SW1 = ((portb & 0x01) == 0x01);
//Decision
if (SW1 == 0)
{
//Calculation
//Calculation:
// network = 1
NETWORK = 1;
//Call Macro
//Call Macro: time()
time();
// } else {
}
//Input
//Input: B1 -> sw2
SW2 = ((portb & 0x02) == 0x02);
//Decision
if (SW2 == 0)
{
//Calculation
//Calculation:
// network = 2
NETWORK = 2;
//Call Macro
time();
// } else

{
}
//Input
//Input: B2 -> sw3
SW3 = ((portb & 0x04) == 0x04);
//Decision
if (SW3 == 0)
{
//Calculation
//Calculation:
// network = 3
NETWORK = 3;
//Call Macro
time();
// } else
{
}
//Input
//Input: B3 -> sw4
SW4 = ((portb & 0x08) == 0x08);
//Decision
if (SW4 == 0)
{
//Calculation
//Calculation:
// network = 4
NETWORK = 4;
//Call Macro
time();
// } else
{

}
//Delay
//Delay: 300 ms
delay_ms(255);
delay_ms(45);
}
mainendloop: goto mainendloop;
}
void INTERRUPT_MACRO(void)
{
}

CHAPTER 6
TESTING AND RESULTS
Testing
To test the project, it has to be set to specific mode of operation, i.e. we have to select the
toggle switch according to our specification. The toggle switch has been shown in the
Figure 6.1. It has three toggle switches, to run the jammer toggle switches are set to
specific operation mode:
First toggle switch is used to charge the battery (when it is in the up side) and run the
jammer (when it is in the down side).
Second toggle switch is used to run the jammer with battery (when it is in the up side)
and run the jammer with main power supply (when it is in the down side).
Third toggle switch is used to turn on and off the control from PIC, but jammer runs
continuously.
Figure 6.1 : Control toggle switches

After the selection of toggle switch, next we have to select which network has to be
blocked, so to select network kit consist of control switches. First switch selects the DCS
(Digital Cellular System) network, second switch selects the CDMA network, and third
switch selects the 3G network and finally fourth switch selects all the networks.
After selection of which network has to be blocked, next step is to set the time duration to
block the selected network. Time duration is set by the switch one and switch two by
incrementing and decrementing the timer respectively.
If time duration is selected, jammer is run to selected time duration and selected network,
when we press the third switch .These are all the steps involved to run the jammer step by
step respectively are as shown in Figures 6.2, 6.3, 6.4 and 6.5.
Figure 6.2 : Control switch to select network
Figure 6.3 : Control switch to set time duration

Figure 6.4 : Control switch to run the jammer
Figure 6.5 : Jammer running stage on LCD display

Results
As we tested our jamming device, the result was a successful one. The device was able to
jam the cell phones. Here we considered the worst case of having the cell phone close to
the base station where the effective jamming range was around 3-4 meters. It is expected
that as the distance between the cell phone and the base station increases, the effective
jamming distance will also increase. This is due to the fact that the amount of power
reaching the cell phone from the base station decreases as the cell phone moves farther
from the base station. If jammer placed where the region covered by more towers and
distance between the cell phone and the base station is less, then blocking range will be
less. The Figures 6.6 and 6.7 shows the results, it can be clearly seen that the signal is
"ON" when the jammer is "OFF", while the signal disappears when the jammer is "ON"
respectively.
Figure 6.6 : Signal ON jammer OFF

Figure 6.7 : Jammer ON signal OFF

CHAPTER 7
ADVANTAGES AND DISADVANTAGES
Advantages
i. We can provide security to V.I.P‘s from the anti-social elements.
ii. By using cell phone jammers we can maintain law and order for maintaining
peace.
iii. By cell phone jammers we can‘t disturb other people in the public places like
restaurants, shopping places.
iv. It is very necessary to use cell phone jammers in naxal feared places. This
helps the authorities to work their duty softly.
v. By using cell phone jammers in the vehicles, we can overcome accidents problem
which is very helpful to the people.
vi. Works for both GSM and CDMA networks.
vii. No loss of data due to backup battery.
Disadvantages
i. Cost oriented.
ii. Requires special hardware.
iii. People feel inconvenience.
iv. V.I.P.‘s may lose some important calls.

CHAPTER 7
APPLICATIONS
 Gas stations, the air entrainment station, the fuel depot and the flammable
explosive chemical warehouse, the refinery, the petrified factory and so on
need safely to protect place: May avoid changing suddenly the detonation which
the signal radiative generation static electricity spark but causes, the fire. Posts the
prohibition to dial the handset sign, does not have the initiative, this kind of
accident all has the appearance in national many gas stations, in order to safeguard
these important situations the security to be supposed to take the precautionary
measure.
 Governments, enterprise's each kind of conference room: May avoid the
handset ting disturbs and answers when the telephone breaking the leader to speak
but interrupts its person to hold a meeting.
 Armies, public security department's important conference rooms: Might avoid
the attending personnel divulging the military and the government using the handset
is secret, at present the new spy science and technology, already used the handset
interception, the monitor environment sound, therefore to important conference
place, it is necessary to take effective also of security the initiative.
 Hospitals: Might avoid the goon machine-hour but causing doctor to the hospital
precision instrument equipment disturbance to misdiagnose, has delayed the rescue
patient, as well as was surgery doctor to answer the handset telephone disturbance
attention, underwent the surgery to doctor to the patient to be extremely
disadvantageous.
 Courts: May avoid the handset ting the disturbance, maintains the court conference
site the dignity and the sacredness.
 Libraries, New Bookstore: May avoid the handset ting and answer the telephone
the noise, builds to study the study peaceful environment.

 Theaters: As the upscale recreation area, eliminates the handset ting noise to be
possible to maintain the audience to appreciate the program the interest.
 Tests places, examination center: May cease the examinee, monitor an exam the
personnel to cheat using the modern communication facilities.
 Schools classrooms and training organization classroom: May avoid the handset
ting and answers when the handset telephone to attending class student's
disturbance.
 Instead fears the unit: Locking goal of tendency by handset telecontrolled bomb.
 Coast defense unit: May prevent the seacoast smuggling member discloses secret
information using the handset, effectively attacks smuggling criminal offender's
smuggling.
 The jail, detains the place: Prevented the criminal, the news media, the visit
personnel, the prison tube does not collude with according to the stipulation inside
and outside, forms conspires to get the story straight.
 Temples, Mosques and Churches: May eliminate the handset signal noise, by
maintains the religious place solemn and respectful.

CONCLUSION
In this project a GSM, CDMA, 3G Mobile jammer was designed and built. The project was
tested against the networks and has proven success with average range of 4m. This project
is mainly intended to prevent the usage of mobile phones in places inside its coverage
without interfering with the communication channels outside its range, thus providing a
cheap and reliable method for blocking mobile communication in the required restricted
areas only.
Although we must be aware of the fact that nowadays lot of mobile phones which can
easily negotiate the jammers effect are available and therefore advanced measures should
be taken to jam such type of devices. These jammers includes the intelligent jammers
which directly communicates with the GSM provider to block the services to the
clients in the restricted areas, but we need the support from the providers for this purpose.
Testing in different locations shows the dependent of the jamming range on the signal
strength, for instance in low network coverage area of the base station the jamming range
exceed 7m.In general the jamming attack was protected by network signal power, and
having large power jamming device the Network will be jammed for sure, from this
observation it can be concluded that the protection against jamming attack in the low
coverage area was very weak and couldn‘t withstand the simplest jamming techniques.

Cell phone jammer with prescheduled time duration

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Cell phone jammer with prescheduled time duration

Similar to Cell phone jammer with prescheduled time duration (20)

Recently uploaded

Recently uploaded (20)

Cell phone jammer with prescheduled time duration