Project report on signal jammer

VISVESVARAYA TECHNOLOGICAL UNIVERSITY

BELAGAVI, KARNATAKA- 590018

A PROJECT REPORT ON

“SIGNAL JAMMER”

Submitted in partial fulfillment of the requirement for the award of the degree

Bachelor of Engineering

in ELECTRONICS AND COMMUNICATION ENGINEERING

Prescribed by VISVESVARAYA TECHNOLOGICAL UNIVERSITY

by NAME

ARYAN KUMAR

KARTHIKEYAN R

M ADITYA

NIKHIL KUMAR

USN

1BY12EC006

1BY12EC021

1BY12EC028

1BY12EC036

Under the guidance of Prof. ASHA G. H.

Assistant Professor, Dept. of ECE, BMSIT & M

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT Avalahalli ,Yelahanka, Bengaluru-560064

2015-2016

BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT Department of Electronics and Communication Engineering

VISION

Provide Quality Education in Electronics, Communication and

Allied Engineering fields to serve as Valuable Resource for

Industry and Society.

MISSION

Impart Sound Theoretical Concepts and Practical Skills.

Promote Inter-disciplinary Research.

Inculcate Professional Ethics

BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT Avalahalli, Yelahanka, Bengaluru-560064

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

ENGINEERING

CERTIFICATE Certified that the project work entitled “Signal Jammer” carried out by Mr. ARYAN

KUMAR (1BY12EC006), Mr. KARTHIKEYAN R (1BY12EC021), Mr. M Aditya

(1BY12EC028) and Mr. NIKHIL KUMAR (1BY12EC036), bonafide students of BMS

Institute of Technology and Management in partial fulfillment for the award of Bachelor

of Engineering in Electronics and Communication Engineering prescribed by

Visvesvaraya Technological University, Belagavi during the academic year 2015-2016.

It is suggested that all corrections/suggestions indicated for internal assessment have been

indicated in the report deposited in the departmental library. The project report has been

approved as it satisfies the academic requirements in respect of project work prescribed for

the said degree.

Signature of HOD Signature of Guide Signature of Principal

Dr. M.C. Hanumantharaju Mrs.Asha G. H. Dr. Mohan Babu G.N.

Dept. of ECE Dept. of ECE BMSIT&M

External Viva

Name of the Examiners Signature with Date

1. 2.

i

ACKNOWLEDGEMENT

The satisfaction and euphoria that accompany the successful completion of any task

would be incomplete without the mention of the people who made it possible and whose

constant guidance and acknowledgement crowned our effort with success.

We express our profound gratitude to our Principal, Dr. Mohan Babu G.N, BMS

Institute of Technology and Management for providing all the facilities and encouragement.

We would like to thank our HOD, Dr. M.C.Hanumantharaju for the inspiration,

guidance and his valuable suggestions.

Our sincere gratitude to our guide, Mrs. Asha G. H. for her valuable time, patience,

suggestion and periodic evaluation that was conducive for the project.

We would also like to thank all the teaching and non-teaching staff of the Department

of Electronics and Communication Engineering for their co-operation and motivation.

Finally we express our cordial thanks to our parents and friends for their support and

guidance throughout the project preparation.

Names of the students

ARYAN KUMAR

KARTHIKEYAN R

M. ADITYA

NIKHIL KUMAR

ii

ABSTRACT

This report presents the design, implementation, and testing of a cell-phone jammer. This jammer

works at GSM 900 and thus jams the three well-known carriers in India (Airtel, Aircel, BSNL,

Vodafone, Tata Docomo and Reliance). The designed jammer was successful in jamming the

various carriers in India as will be shown at the end of this report. Nowadays, mobile (or cell)

phones are becoming essential tools in our daily life. Here in India, for example, with a rather low

population (around 1 billion), various cell phone carriers are available. Needless to say, the wide

use of mobile phones could create some problems as the sound of ringing becomes annoying or

disrupting. This could happen in some places like conference rooms, law courts, libraries, lecture

rooms and mosques. One way to stop these disrupting ringing is to install a device in such places

which will inhibit the use of mobiles, i.e., make them obsolete. Such a device is known as cell

phone jammer or “GSM jammer”, which is basically some kind of electronic countermeasure

device. The technology behind cell phone jamming is very simple. The jamming device

broadcasts an RF signal in the frequency range reserved for cell phones that interferes with the

cell phone signal, which results in a “no network available” display on the cell phone screen.

However, recently, there has been an increasing demand for portable cell phone jammers. In this

project, a device that will jam GSM 900 services is designed, built, and tested.

iii

Contents Page No.

CERTIFICATE i

ACKNOWLEDGEMENT ii

ABSTRACT iii

Chapter

1) INTRODUCTION_____________________________________________1-8

1.1 History………………………………………….………………….….....2

1.2 The main features of project ………..……………………………….......3

1.3 What is “Signal Jammer”? ........................................................................3

1.4 Various types of Jammers …....................................................................4

1.5 Scope of Signal Jammer ………………………………………….......... 4

1.6 Literature Survey………………………………………………….….....5

1.6.1GSM Architecture ………………………………………………………….......6

1.6.2 Base Station Centre (BSC) ……………………………………………….....…6

1.6.3 Main functions of Base station centre ……………………………....................7

1.6.4 Base Station Transceiver Architecture ………………………………….…..…7

1.7 Project Objective ………………………………………………..……………….…8

2) Concept of Signal Jammer ____________________________________9-12

2.1Jamming basics …………………………………………………..……9

2.2 Jamming Types ………………………………………….…………....11

2.3 Key Points to compare jamming Attacks ……………….…………... 11

2.4Proposed System Design …………………………….………………..11

2.5 Description ………………………………………….………………..12

3) Implications of Jammer _____________________________________13-19

3.1 Implications of using jammers ………………………………..........13

3.2 Coordinated and regulated implementation ……………………...…16

3.3 Alternatives to blockers ……………………………………….……..17

3.4 Detection of the use of Jammers ………………………………….….18

4) Working of Signal Jammer __________________________________20-22

4.1 How “Signal jammers” work? …………………………………… ..20

4.2 Jamming Techniques …………………………….…….……..……..21

4.3 Types of mobile jammer device ……………………………..….……21

4.4 Legal Issues of jammers ……………………………………….….… 22

5) Design Parameters of Signal Jammer _________________________24-27

5.1 The distance to be jammed (D) ……………………..……....…….24

5.2 The frequency bands …………………………………………….24

5.3 Noise Jammer Concept ……………………………………….…....25

5.4 Jamming to signal ratio ………………………………………….....26

5.5 Free space loss ……………………………………………………...27

6) System Design of Signal Jammer _____________________________28-39

6.1 Power calculations …………………………………………………. 28

6.1.1Parts of the jammer device ………………………………………...28

6.1.2The Power supply …………………………………………….……28

6.2 The IF-section ……………………………………………………….29

6.2.1 Triangle wave generator ………………………………………………….30

6.2.2 Noise generation ……………………………………………………….…32

6.2.3 Mixer ………………………………………………………………….….33

6.2.4 Clamper ……………………………………………………………….….33

6.2.5 Specification of IF Section …………………………………………...…..35

6.3 The RF-Section ……………………………………………..….…....35

6.3.1 Voltage Controlled Oscillator (VCO) …………………….……….….….36

6.3.2 The power amplifier ……………………………………….….…….……37

6.3.3 Antenna ……………………………………………………..……..….…38

7) Applications, Advantages, Disadvantages and Result ___________40- 49

7.1 Applications ……………………………..………..………….….. . 40

7.2 Advantages ………………………………..….…..……………… 41

7.3 Disadvantages …………………….……………….……………... 42

7.4 Design Limitations …………………………..………….………… 42

7.5 Results …...........................................................................................42

7.5.1Practical Results of Signal Jammer ……………………….….….. 43

8) Conclusion, Summary and References ________________________50-54

8.1 Conclusion …………………………………………………………50

8.2 Summary ……………………………………………………….......51

8.2.1 CIRCUIT COMPONENTS …………………………………………………..53

8.3 References ……………………………………………………..…..54

APPENDIX I ____________________________________________55-61

List of Figure

Figure Page No.

1. Fig1.1 : Jammer Devices ………………………………..…………4

2. Fig1.2 : Types of jammer ………………………………….…..…..4

3. Fig 1.3 Basic Network Architecture ……………………….………6

4. Fig 2.4: GSM Architecture ………………………………….……..7

5. Fig 1.5: TDMA Technology ……………………….……….……..7

6. Fig2.1: Jamming Basics …………………………………..……....9

7. Fig3.1: Increased noise levels using jammer …………………….14

8. Fig3.2: Jammer interference affects 2G / 3G ……………….......15

9. Fig3.3: Dropped calls increased by use of Jammer ……….……..16

10. Fig4.1: Working of Signal jammer ……………………….…...… 20

11. Fig 5.1: How J/S ratio works ………………………….………....27

12. Fig 6.1: Jammer main blocks …………………………….……...28

13. Fig 6.2 Parts of the power supply……………………………........29

14. Fig 6.3: IF Section block diagram …………………………….......30

15. Fig 6.4: A-stable 555time………………………………….…..….30

16. Fig 6.5. A-stable mode connection …………………………..…...31

17. Fig: a) Fig 6.6a Triangular wave generator ….………………........32

b) Fig 6.6b Generated triangular waveform ……….….…........32

18. Fig 6.7: Noise generation …………………………….…………...32

19. Fig 6.8: OP-AMP summer circuit ………………….……………..33

20. Fig 6.9: Diode clamper …………………………………….….….33

21. Fig 6.10: Schematic of the IF-section ………………………..….34

22. Fig 6.11: Modulated Circuit ……………………………….....…34

23. Fig 6.12: Modulated waveform …………………………………...35

24. Fig 6.13: RF section (The heart of the jammer) ………….............36

25. Fig 6.14: RF-section Schematic………………………………......39

26. Fig7.1 : Applications………………………………….………..... 41

27. Fig 7.2 to Fig 7.13 (Results of various Networks) ….………..….43

28. Fig 7.14: Complete circuit ………………….………..……….…49

SIGNAL JAMMER Page 1

Dept . o f ECE, BMS IT&M 2015-2016

Chapter 1

Introduction

Jamming devices were first put into use by the military and armed forces’ technical

department. This interest comes from the fundamental objective of denying the successful

transport of information from the sender (tactical commanders) to the receiver (the army

personnel), and vice-versa. That being said, nowadays, mobile phones have become an

essential tool in our daily life. Here in India, for example, with a rather High population

(around 1.25 billion), a large number of mobile network carriers are available such as

Airtel, Aircel, Vodafone, TATA DoCoMo, Reliance etc, which operate at Gsm 900

frequency bands. Needless to say, the wide use of mobile phones could create various

problems, but the sound of a ringing phone becomes annoying at certain times. This could

happen in some in some really important public places thereby putting you in the limelight.

Hence one simple way to stop this annoyance at some really important places is to install

a device in such places which will inhibit the use of mobiles, i.e., make them obsolete. Such

a device is known as cell phone signal jammer, which is basically some kind of electronic

countermeasure device. The technology behind cell phone jamming is very simple. The

jamming device broadcasts an RF signal in the frequency range reserved for cell phones

that interferes with the cell phone signal, which results in a "no network available" display

on the cell phone screen. All phones within the effective radius of the jammer are silenced.

It should be mentioned that cell phone jammers are illegal devices in most countries.

According to the Federal Communications Commission (FCC) in the USA: "The

manufacture, importation, sale, or offer for sale, of devices designed to block or jam

wireless transmissions is prohibited". However, recently, there has been an increasing

demand for portable cell phone jammers across the globe, with that being said one should

note that what we are presenting is totally with respect to gaining knowledge and mainly

for educational purposes only and that there is no intention for us to manufacture or sell

these devices in India, or elsewhere. In this project. Using the device causes extensive

disruption and involvement in mobile signal operation, by affecting coverage and a

degradation of service for customers. In some cases, mobile users may not be aware of the

blockade of its terminals as the above may not be evident until you make a call, case in

which receive a warning network is not available, seeing thus affected their rights to access

services, while not receive any communication on their mobile until they depart from the



affected area. Considering the serious damage generated in the network and the allocation

of user rights, it is understood critical control and restrict the supply of these teams, as well

as limiting its sole use and exceptionally for public security cases such as in prisons.

However, we believe that in this particular case, the real solution is that the controls should

be increased and that the prison authorities in each country take necessary measures to

prevent the introduction and use of cell phones in those precincts measures. On the other

hand, it has been an increasingly widespread of these teams by private use, generating

direct damage to mobile users and companies have acquired and paid millions of dollars

for the use, development and exploitation a valuable and finite well as radio spectrum and

network deployment. It will also be important to establish in a timely manner far the

responsibility of dealer’s telecommunication solution for the damages to the signal arrives.

1.1History

The rapid proliferation of cell dates back to the early twenty first century, close to a state

of ubiquity which finally raises problems, such as its potential use to invade privacy or

contribute to academic cheating. In addition, public reaction has been growing against that

communicator device for its irruption in daily life. While the analog cellular phone often

suffered from poor reception, and could even be disconnected by simple interference such

as high frequency noise, the digital phone increasingly sophisticated, has led such switches

also to develop into more elaborate devices. Cell phone interference, are the most

expensive alternative measure, such as the Faraday cage , most of which is suitable to

protect building structures. They were originally developed for law enforcement, and the

military could disrupt communications between criminals and terrorists. Some were also

designed for the use of certain explosives detonated remotely. Civilian applications were

evident, so that over time, many companies originally contracted to design inhibitors which

the government use, they chose to sell these devices to private entities. Since then, there

has been a slow but steady increase in purchase and use, especially in major metropolitan

areas. In most parts of the world using a blocker frequency (technically known as inhibitors

of frequency) is regulated by the central government, and its use is only allowed for public

forces and government agencies. 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

https://es.wikipedia.org/wiki/Jaula_de_Faraday



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. 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.

1.2 The main features of this project

1. User friendly operation.

2. Very easy to operate.

3. Switch ON-OFF.

4. Activities display on Phone display.

5. Jammer activation using relay switch

1.3 What is “Signal Jammer”?

A Jammer is a device that blocks transmissions by creating interference. The jammer emits

signals in the same frequency range that cell phones uses, and within the range of a jammer

a cell phone user may lose their signal. Jammers are usually undetectable, and users may

experience minimal effects such as poor signal reception.

The most common types of this form of signal jamming are random noise, random pulse,

and stepped tones, warbler, random keyed modulated CW, tone, rotary, pulse, spark,



recorded sounds, gulls, and sweep through. Signal Jammer 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.

Fig1.1: Jammer Devices

1.4 Various types of Jammers

Fig 1.2: Types of jammer

1.5 Scope of Signal Jammer

As in most Asian countries, signal blockers of various kinds, are not available. Thus,

restaurants, shops, theatres, cinemas, financial institutions and others, install blockers in

order that customers or employees do not use the terminal within its facilities. The issue of

mobile signal blocker has been treated at different times by the GSMA and have covered

different aspects of their use, from regulatory aspects to the security implications. An



important case, we see with great concern are questions about the limitations of mobile

services in prisons in Honduras, Guatemala and other countries in the region. Although use

in prisons is not a new practice, this approach has not yet been in the debates of the GSMA.

Operators of mobile networks made large investments to provide coverage and capacity by

installing radio base stations. Therefore, the indiscriminate use of blockers affect these

investments because customers cannot make use of mobile services in the ranges of these

blockers. To this end, this document has been agreed with industry, and other supranational

bodies GSMA to provide a common position including the implications for the end user,

which can be shared with telecommunications ministries and regulators. Cell phone

jamming devices can be used originally for law enforcement and the military to interrupt

communications by criminals and terrorists.

1.6 Literature Survey

In our technique voltage controlled oscillator (VCO) plays a major role in generating the

jamming frequency. In our research we found that this technique is a complex one

compared to our technique because our idea of jamming through spectrum distortion proves

to be simpler, easier to fabricate and cost effective. 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. 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. The techniques used in most of the commercial jammers is based on noise attack.

Cell phone jammer is a completely an analogue circuit. Designing of mobile phone jammer

is a step by step procedure.

1.6.1 GSM Architecture

GSM provide for data and voice communication throughout a wide geographic area. GSM

system divided large geographic area in Tanzania into small radio areas (cells) that are

interconnected each other (Microwave connection). Each cell coverage area has one or

several transmitter that communicates with mobile telephone within its coverage area. In

GSM system the mobile handset is approach to mobile phone jamming system that called

Mobile station (MS). A cell is formed by the coverage area of Base Transceiver Station



(BTS) which serves the MS in its coverage area. Several BTS together are controlled by

one Base Station Controller (BSC). The BTS and BSC together form Base Station

Subsystem (BSS).The combed traffic of the mobile station in their respectively cells is

routed through a switch called Mobile Switch Center (MSC). Connection originating or

terminating from external telephone (PSTN) are handle by a dedicated Gateway Mobile

Switching Center (GMSC).

Fig 1.3: Basic Network Architecture

1.6.2 Base Station Center (BSC)

BSC is a high capacity switch with radio communication and mobility control

capabilities. The function of BSC is including radio channel allocation, location

update, and handover, timing advance, power control and paging. Figure 2 show

the architecture of the GSM network, the BSC is the center of different Base

Transceiver Station (BTS).



Fig 1.4: GSM Architecture

1.6.3 Main functions of Base station center

Control the handset between its BTS’s.

Switch traffic and signaling to/from the BTS’s and MSC.

Manage the interconnection between BTS’s MSC.

1.6.4 Base Station Transceiver Architecture

A BTS is radio transceivers stations that communicate with the mobile station. Its backend

to the BSC. More BTS is usually placed at the center of a cell. Its transmitting power

defines the size of a cell. Each BTS contains from TRX’s called radio, each radio has single

frequency. By using TDMA technology as shown in figure 3 bellow.

Fig 1.5: TDMA Technology



1.7 Project Objectives

The project involves the design and development of cell phone jammers to block all the

cell phones within the designated area, this device will disrupt cellular communication with

respect to the following:

Operate in the 900MHz band.

It has a two meter effective blocking radius.



Chapter 2

Concept of Signal Jammer

2.1 Jamming basics

Jamming is used to compromise nodes in wireless environment Its working goes in fake

way like jammer ensures authorized users as he is also an authorized one 2.4Ghz frequency

can easily be jammed by a good attacker. Signals are dropped by a good attacker to a level

where wireless network no longer works. 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. 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 cell-phone base station in the tower. Cell Phone

Jammer is an instrument to prevent cellular phone from receiving and transmitting the

mobile signals to the base station. Cell Phone Jammer can block all kinds of mobile signals

when installed at a particular location such as church, mosque, library, Movie Theatre and

conference rooms.

Fig 2.1: Jamming Basics



The rapid proliferation of cell phones at the beginning of the 21st century 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, now

interestingly 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. As with other radio

jamming, cell phone jammers block cell phone use by sending out radio waves along the

same frequencies that cellular phones use. This causes enough interference with the

communication between cell phones and towers to render the phones unusable. On most

retail phones, the network would simply appear out of range. Most cell phones use different

bands to send and receive communications from towers (called frequency division

duplexing, FDD). Jammers can work by either disrupting phone to tower frequencies or

tower to phone frequencies. Smaller handheld models block all bands from 800 MHz to

1900 MHz within a 30-foot range (9 meters). Small devices tend to use the former method,

while larger more expensive models may interfere directly with the tower. The radius of

cell phone jammers can range from a dozen feet for pocket models to kilometres for more

dedicated units. The TRJ-89 jammer can block cellular communications for a 5-mile (8

km) radius. Less energy is required to disrupt signal from tower to mobile phone than the

signal from mobile phone to the tower (also called base station), because the base station

is located at larger distance from the jammer than the mobile phone and that is why the

signal from the tower is not as strong. 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 (CDMA, iDEN,

GSM, et al.) 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. Some Cell Phone Jammers have been introduced to some



State Prisons in the United States. Cell phones that have been sneaked into prison pose a

security risk for guards and property owners living nearby.

2.2 Jamming Types:

Aim of jamming is to intentionally trying to interference with transmission and reception

of message across the wireless channel

Jammer can be divided into following types

1. Constant jammer: He continuously emits radio frequency signals transmits random bits

of data to channel

2. Reactive Jammer: He remains quite when channel is idle

3. Deceptive Jammer: He constantly injects series of packets to the channel without any

gap between subsequent transmissions. He also manages broadcasting of fabricated

messages and reply old ones.

4. Random Jammer: He changes periods of jamming randomly.

2.3 Key Points to compare jamming Attacks:

Following are some factors can be used to compare jamming attack

- Energy efficient

- Stealthy

- Strength against Phys. Layer techniques e.g. CDMA

- Strength against error correction module

- Management of behavior close to protocol standards

- Probability of detection

2.4 Proposed System Design

In most countries, it is illegal for private citizens to jam cell-phone transmission, but some

countries are allowing businesses and government organizations to install jammers in areas

where cell-phone use is seen as a public nuisance. In December 2004, France legalized

cell-phone jammers in movie theatres, concert halls and other places with performances.

France is finalizing technology that will let calls to emergency services go through. India

has installed jammers in parliament and some prisons. It has been reported that universities



in Italy have adopted the technology to prevent cheating. Students were taking photos of

tests with their camera phones and sending them to classmates.

2.5 Description

Signal Jammer: Devices that prevent mobile computers from communicating with radio

stations’ mobile operator, not allowing people to take calls or data transfer (SMS, Internet

access, etc.).These devices act by emitting a radio signal in different frequency bands (eg

850MHz and 1900MHz) covering all mobile telecommunications technologies (2G, 3G,

4G, Satellite, etc.) as well as any other radio communication as example television.



Chapter 3

Implications of Jammer

3.1 Implications of using jammers

Limited to a specific area of use: The nature of radio signals makes it virtually impossible

to ensure that the operation can be confined jammers, for example, within the confines of

a building. Studies from the beginning of use reflect cases of interference with base stations

located up to 670 meters away, blockers with ability of disrupting service to legitimate

users who might not be aware of the cause suffer from discontinuation of network.

Recently, there has been evidence indicating that operators are experiencing effects on their

mobile signal at even more than one (1) kilometer of distance away from the jammer. This

causes harm or damage to customers outside the area to block with consequent claims, and

operators experience a degradation of service and considerable economic losses.

Decrease of Mobile Coverage: Operators are making efforts to increase and maintain the

coverage and scope of their access networks as a pillar of their strategies in both directions,

vertically and horizontally especially in buildings. The use of these blockers go against this

trend in increasing coverage and create areas without it, affecting service quality indicators

demanded by governments and the rights of many other users. Sometimes it is the law of

telecommunications in each country which requires the deployment of the network and the

consequent coverage as possible expanded to all corners of the territory in question, and

the installation and operation of blockers just defies this.

Increased insecurity: These devices cause a variety of problems of interference, affecting

both civil society as to the same law enforcement, which reduces the security that is

provided to citizens and can directly increase delinquency. It could be limiting user access

to emergency services such as "911" or similar services that exist in different countries.

Moreover, some applications such as alarms connected to mobile devices, or devices

mobile personal health, could see interrupted by the use of inhibitors, even outside the

target area thereof with the consequent implications of liability when a legitimate service

disabled without the knowledge or consent of the user, or reasons of general interest that

seek to justify it. The characteristic and so prominent and important functionality of mobile

communications, as is the ubiquity with the respective terminals, is threatened and

decreased with the operation of blockers.



Health and Non-ionizing radiation: Unlike mobile devices go through rigorous

certification processes in accordance with international standards for human exposure to

radio frequencies or non-ionizing radiation has been reported that there may be problems

in the use of high power for legal blocking transmissions that may affect human health.

Several affected services: In interference studies carried out by operators, is that there are

flaws in some inhibitors equipment not only affect mobile phone signals but even affect

the signal of other telecommunications services. Findings have been made where some

blockers by faulty workmanship reach inhibit telecommunications systems in frequencies

near the bands operating mobile phone.

In actual case studies on the use of inhibitors is checked how:

The noise floor interfering gang is well above usual as shown in Figure

Fig 3.1: Increased noise levels using jammer

Since blockers signal emitted at different frequencies affect any mobile

telecommunications technology (2G, 3G, 4G, etc.) and any other in radio

communication frequencies interfered. It can be seen in Figure how spectrum

analyzers detect a noise level on GSM but especially important in UMTS:



Fig 3.2: Jammer interference affects 2G / 3G

Disconnecting blockers: Operators are facing cases of use of inhibitors more complex to

analyze and detect signal. Even if their location is known, they face not only the reluctance

of the entities that install these devices to turn them off but regulations also contain

mechanisms or streamlined procedures for quick disconnect.

Decrease Quality Network: Since the signal blockers cannot physically be limited to a

specific area, a deterioration in service delivery around the place where they are installed

is detected, a fact that goes against service initiatives that are promoting regulators, the

right of users to access services and operators to make efficient use of spectrum, the case

is especially critical in the buildings where they are installed inhibitors within the city limits

of big cities.

In addition, in some markets, operators are sanctioned if the established indicators meeting

the service is not provided. It must take into account that in some countries in the region

has even begun to make measurements of service provided by operators using applications

that measure accessibility and the number of dropped calls. In these cases, look for

alternative solutions to signal inhibitors or exempt the affected areas of compliance with

the technical conditions prescribed by the regulator.

The number of disconnections or falls, both voice and data, increases significantly with the

presence of external noise. This level is recovered when detected and shutdown inhibitor

is requested; which involves the recovery to normal and stable rate of dropped calls as

shown in Figure.



Fig 3.3: Dropped calls increased by use of Jammer

3.2 Coordinated and regulated implementation

Currently, the installation of signal jammers does not have a clear policy about it. The

impact of the use of these is substantially minimized if the coordination of its

implementation with mobile operators are favoured if their operation is checked and if their

use was only in cases of general interest of public safety, being specifically authorized by

the authority in each country, for which it would be appropriate to contemplate:

Block transmission frequencies.

Technical equipment used in blocking signal specifications.

Guidance should have blockers to streamline locking in the desired areas and not

affect neighbouring customers entitled to have the service.

Establish mechanisms and / or procedures to resolve potential interference to mobile

systems user’s affectations.

Registration location and configuration of blockers, and notification to operators.

Requiring Approval Certificate blocker equipment to be used.

Regulatory guidelines for the use and marketing of blockers is not made arbitrarily,

and must have a specific authorization, in accordance with local regulation, limiting

its scope to the area that meets the legitimate security needs.

Installation is appropriate in accordance with good engineering practices.

Signaling installation blockers for the purpose of informing users.



3.3 Alternatives to blockers

Given the need to restrict access to cellular networks it means appropriate to access other

alternative or complementary solutions whether technological or non-technological nature.

Regarding current technological solutions such different alternatives or complementary

measures to using signal jammers to consider, as appropriate:

Passive sensing technology active mobile devices followed by a request for

restriction of external (or integrated) use network operators: intelligent selective

Interceptors or pseudo-antennas.

Redesign the access network to provide no coverage in the sensitive area taking into

account the peculiarities of the area to be covered, provided that technically

appropriate, and implement "indoor" coverage with access restrictions.

Monitoring Network: The mobile platforms legal interception that may allow the

security forces to detect its activity, identify its location, and monitor traffic in those

terminals to detect illegal activities, perhaps under technical schemes geo-location.

And thus discourage theft by criminal gang’s terminals.

Possible use of other nodes to intercept unwanted or illegal from communications

terminals.

Analyse the traffic to locate the IMEI being used in prisons and lock through

systems that allow it, using some IMEIs database, such as the GSMA

Establish a phrase indicating the receiver of the call is originating a call from an

area of "risk".

Inspection communications via SMS, as detecting keywords, footprint spam, spam

filters, etc. Also being the GSMA offers a spam reporting service to its members.

This service enables consumers to easily report spam using a universal short code

("7726" (SPAM)) to its operator.

Among non-technological solutions, we emphasize prevention and education of the

population, although it should be noted the following:

The broadcast media of the modus operandi of the fraudsters, as well as actions to be

performed by the population in case of being involved in one of these cases.

The creation of telephone numbers managed and monitored by the authorities to

receive the complaint of the numbers involved in extortions.

Coordination between operators and authorities to the cancellation of the lines

involved in cases of extortion.



Plan of action for a longer-term improvement in the management of prisons, with

even major changes in the situation of different aspects in prisons (infrastructure of

them, the laws governing its operation on the behaviour, codes of conduct of

officials, etc.).

Share information on ways of detecting fraud through activation patterns, prone to

massive purchases to commit fraud, recharge patterns and transfer of refills

distributors.

Control the use of mobile services in certain places, request put phones in silent

mode, issue codes of conduct, etc. This may be the case of the financial sector and

banks in which the use of inhibitors is increasing citing security reasons and

libraries where looking for quiet, or at various workplaces as a way to control the

use of cell by their users

Individuals and authorities have different ways to control the use of services without being

required installation blockers, for example, control the use of mobile services on the

premises, request put phones in silent mode, issue codes behaviour, among others.

3.4 Detection of the use of Jammers

Detection using signal jammers, is not simple. Different methods involving the combined

use of different mechanisms, among which are:

Study of the different databases of information on the access network of a mobile

operator to analyze the noise level of a cell (Average RSSI ~ measurement noise)

in the event that there has been a recent change of level in a given area that is

unusual level. Detected an abnormality can proceed to a detailed study of the

affected area to the location by triangulating the source of noise.

Claims of users who are affected by lack of access to services in certain places.

Operators can find spectrum analyzers on the market with directional antennas that

facilitate more precise location of the problem frequencies inhibitor. These analysers check

the status of emissions over a wide frequency range including a large bandwidth.

In the event that mobile network operators undertake measures in the affected area and use

of these devices is verified, it is advisable that the situation be reported to the competent

authorities and that governments order their immediate removal. It would be important that

countries expressly regulate this prohibition, preventing the marketing and use by



individuals, limiting the use specifically for cases of general interest, for reasons of public

safety, in the absence of other alternatives.



Chapter 4

Working of Signal Jammer

4.1 How “Signal jammers” work?

Jammers block cell use by sending out radio waves along the same frequencies that cellular

phones use at a high enough power that the two signals collide and cancel each other out.

This causes interference with the communication of cell phones and the towers to render

the phones unusable. Signal jammers work in a similar way to radio jammers by sending

out the same radio frequencies that cell phones operate on. Doing so creates enough

interference so that a call cannot connect with a cell phone. There are two types of cell

phone jammers currently available. The first type are usually smaller devices that block the

signals coming from cell phone towers to individual cell phones. The frequency blocked is

somewhere between 800MHz and 1900MHz. Most devices that use this type of technology

can block signals within about a 30-foot radius. Cell phones within this range simply show

no signal.

The second type of cell phone jammer is usually much larger in size and more powerful.

They operate by blocking the transmission of a signal from the satellite to the cell phone

tower. Some powerful models can block cell phone transmissions within a 5 mile radius. It

should be noted that these cell phone jammers were conceived for military use.

Fig 4.1: Working of Signal jammer



Once again, it should be noted that operating or even owning a cell phone jammer is illegal

in most municipalities and specifically so in the United States. Many businesses such as

theatres and restaurants are trying to change the laws in order to give their patrons better

experience instead of being consistently interrupted by cell phone ring tones.

4.2 Jamming Techniques

There are several ways to jam an RF device. The three most common techniques can be

categorized as follows:

1. Spoofing: In this kind of jamming, the device forces the mobile to turn off itself.

This type is very difficult to be implemented since the jamming device first detects

any mobile phone in a specific area, then the device sends the signal to disable the

mobile phone. Some types of this technique can detect if a nearby mobile phone is

there and sends a message to tell the user to switch the phone to the silent mode

(Intelligent Beacon Disablers).

2. Shielding Attacks: This is known as TEMPEST or EMF shielding. This kind

requires closing an area in a faraday cage so that any device inside this cage can not

transmit or receive RF signal from outside of the cage. This area can be as large as

buildings, for example.

3. Denial of Service: This technique is referred to DOS. In this technique, the device

transmits a noise signal at the same operating frequency of the mobile phone in

order to decrease the signal-to-noise ratio (SNR) of the mobile under its minimum

value. This kind of jamming technique is the simplest one since the device is always

on. Our device is of this type.

4.3 Types of mobile jammer device

There are many types of cell phone jammer device which is used in our daily life .as we

take an example of class room ,where we does not want to use of cell phone than there we

can use cell phone jammer device .by this we can produce the interface between the cell

phone station and jamming device. Resulting it disconnect the cell from base station and

we can not receive the any calls from base station.

For this there are many types of cell phone jammer devices which is given as below:



cell phone jammer

Portable cell phone jammer

Remote control cell phone jammer

Adjustable cell phone jammer

School &prison phone jammer

Explosion-proof cell phone jammer

Police &military phone jammer

One of the cell phone jammer device is “single knight brand ultra-thin cell phone

jammer”

4.4 Legal Issues of jammers

In the United States, United Kingdom, Australia and many other countries, blocking cell-

phone services (as well as any other electronic transmissions) is against the law. In the

United States, cell-phone jamming is covered under the Communications Act of 1934,

which prohibits people from "wilfully or maliciously interfering with the radio

communications of any station licensed or authorized" to operate. In fact, the "manufacture,

importation, sale or offer for sale, including advertising, of devices designed to block or

jam wireless transmissions is prohibited" as well.

Table 4.1

http://www.fcc.gov/Reports/1934new.pdf



Jamming is seen as property theft, because a private company has purchased the rights to

the radio spectrum, and jamming the spectrum is akin to stealing the property the company

has purchased. It also represents a safety hazard because jamming blocks all calls in the

area, not just the annoying ones. Jamming a signal could block the call of a babysitter

frantically trying to contact a parent or a someone trying to call for an ambulance.

The Federal Communications Commission is charged with enforcing jamming laws.

However, the agency has not yet prosecuted anyone for cell-phone jamming. Under the

U.S. rules, fines for a first offense can range as high as $11,000 for each violation or

imprisonment for up to one year, and the device used may also be seized and forfeited to

the government.

In most countries, it is illegal for private citizens to jam cell-phone transmission, but some

countries are allowing businesses and government organizations to install jammers in areas

where cell-phone use is seen as a public nuisance. In December 2004, France legalized

cell-phone jammers in movie theaters, concert halls and other places with performances.

France is finalizing technology that will let calls to emergency services go through. India

has installed jammers in parliament and some prisons. It has been reported that universities

in Italy have adopted the technology to prevent cheating. Students were taking photos of

tests with their camera phones and sending them to classmates.



Chapter 5

Design Parameters of Signal Jammer

Based on the above, our device which is related to the DOS technique is transmitting noise

on the same frequencies of the two bands GSM 900 MHz, and GSM 1.8 GHz (known also

as DCS 1800 band). We focused on some design parameters to establish the device

specifications. These parameters are as follows:

5.1 The distance to be jammed (D)

This parameter is very important in our design, since the amount of the output power of the

jammer depends on the area that we need to jam. Later on we will see the relationship

between the output power and the distance D. Our design is established upon D=0 to 8

meters for GSM 900 band.

5.2 The frequency bands

GSM SIM 900

GSM/GPRS RS232 Modem is built with SIMCOM Make SIM900 Quad-band GSM/GPRS

engine, works on frequencies 850 MHz, 900 MHz, 1800 MHz and 1900 MHz. It is very

compact in size and easy to use as plug in GSM Modem. The Modem is designed with

RS232 Level converter circuitry, which allows you to directly interface

PC Serial port .The baud rate can be configurable from 9600-115200 through AT

command. Initially Modem is in Auto baud mode. This GSM/GPRS RS232 Modem is

having internal TCP/IP stack to enable you to connect with internet via GPRS. It is suitable

for SMS as well as DATA transfer application in M2M interface. The modem needed only

3 wires (Tx, Rx, GND) except Power supply to interface with Microcontroller/Host PC.

The built in Low Dropout Linear voltage regulator allows you to connect wide range of

unregulated power supply (4.2V -13V). Yes, 5 V is in between

Using this modem, you will be able to send & Read SMS, connect to internet via GPRS

through simple AT commands. 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 as1.9-GHz) band in the United States. Jammers can broadcast on

any frequency and are effective against AMPS, CDMA, TDMA, GSM, PCS, DCS systems.



Table 5.1: Operating frequency bands

UPLINK

(Handset transmit)

DOWNLINK

(Handset receive)

USED IN India

BY:

GSM 900 890-915MHz

935-960 MHz MTNL , BSNL,

IDEA, etc.

DCS 1800 1710-1785 MHz 1805-1880 MHz

Airtel, Vodafone,

etc.

In our design, the jamming frequency must be the same as the downlink, because it needs

lower power to do jamming than the uplink range and there is no need to jam the base

station itself. So, our frequency design will be as follows :

GSM 900: 935-960 MHz

GSM 1800: 1805-1880 MHz

The CDMA frequency range will be 860-894 MHZ (Asia & Europe) and 850-894 MHZ (United States).

5.3 Noise Jammer Concept

With little effort the developing of radio signal technologies has permitted challengers to

Construct purposeful jammers to interrupt network communication between the network

nodes. Regardless of unintentional interference or malicious jamming. Radio jamming

technique is an electromagnetic waves transmitted to the purpose of interrupting the

transmission of communication by reducing the SNR (signal to noise ratio). Sometimes

jamming take a place when the sender node sends on a full of activity channel without

testing that the frequency is in use or not, or when the network nodes unintentionally release

a signal, this called unintentional jamming. Therefore, to interrupt the transmission in the

wireless network, purposeful wireless jammers is used, where the wireless sender is tuned

to the same frequency and the same type of modulation as the opponents' receiving device,

and with enough amount of power it can override any signal at the receiver across the

targeted network. Wireless jammers has many types, such as recorded sounds, spark,

random keyed modulated CW, warbler, tone, random pulse, random noise, stepped tones,

pulse, rotary, sweep through and gulls, all the mentioned types can be categorized into two

main groups, obvious and subtle.



Noise jammer system depend on a noise signal which is generated by noise source, and

that signal will be limited by certain bandwidth by a filter, and convert to desired radio

frequency RF, then amplified to desire power by an amplifier, then the signal will be

transmitted by an antenna. Demonstrate the elements that connected together to generate

noise jammer.

Where the Fc is the frequency of the carrier and BW is the bandwidth.

5.4 Jamming–to-signal ratio J/S

Jamming is successful when the jamming signal denies the usability of the communication

transmission. In digital communications, the usability is denied when the error rate of the

transmission can not be compensated by error correction. Usually, a successful jamming

attack requires that the jammer power is roughly equal to signal power at the receiver

(mobile device).

The general equation of the jamming-to-signal ratio is given as follows:

… (5.1)

where: Pj=jammer power,

Gjr= antenna gain from jammer to receiver,

Grj= antenna gain from receiver to jammer,

Rtr= range between communication transmitter and receiver,

Br= communication receiver bandwidth,

Lr = communication signal loss,

Pt= transmitter power,

Gtr= antenna gain from transmitter to receiver,

Grt= antenna gain from receiver to transmitter,

Rjr= range between jammer and communication receiver,

Bj= jammer bandwidth, and

Lj= jamming signal loss.

For GSM, the specified system SNRmin is 9 dB which will be used as the worst case

scenario for the jammer. The maximum power at the mobile device Pr is -15 dBm.



Fig 5.1: How J/S ratio works

5.5 Free space loss F

The free-space loss (or path loss) is given by:

Path loss (dB) = 32.44 + 20 log d (km) + 20 log f (MHz) … (5.2)

The maximum free space loss (worst case F) happens when the maximum frequency is

used in the above equation. Using 1880 MHz gives: F (dB) =32.44+20 log 0.01 + 20 log

1880 which gives F =58 db.



Chapter 6

System Design of Signal Jammer

6.1 Power calculations

Here, we need to find the power that is needed to be transmitted to jam any cell phone

within a distance of around 10 meters for DCS. From the above considerations, we can find

the required output power from the device, as follows: Using SNR=9 dB and the maximum

power signal for mobile receiver=-15 dBm, gives J=-24 dBm. But, our goal is to find the

output power from the device, so when we add the free space loss to the amount of power

at the mobile receiver we get our target:

Output power=-24dBm+58dB = 34 dBm … (6.1)

6.1.1Parts of the jammer device

Figure shows the block diagram for the jammer to be designed

Fig 6.1. Jammer main blocks.

6.1.2The Power supply

This is used to supply the other sections with the needed voltages. Any power supply

consists of the following main parts:

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:

A] Half wave-rectification: the output voltage appears only during positive cycles of the

input signal.



B] 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.

Figure shows the general parts of the power supply.

Fig 6.2: Parts of the power supply.

In our project we need 12, -12, 5 and 3.5 volts. We found that the PC power supply can

provide all the voltages that we need in the jammer, so we bought one.

6.2 The IF-section

The tuning section of the jammer sweeps the VCO through the desired range of

frequencies.

Basically, it is just a triangle or saw tooth-wave generator; offset at a proper amount so as

to sweep the VCO from the minimum desired frequency to a maximum. The tuning signal

is generated by a triangular wave mixed with noise. The IF section consists of three main

parts:

1. Triangle wave generator. (To tune the VCO in the RF section).

2. Noise generator (provides the output noise).

3. Mixer “summer” (to mix the triangle and noise waves).



Fig 6.3: IF Section block diagram

6.2.1 Triangle wave generator

The main use of the triangle wave is to sweep the VCO through the desired

frequency range. We want to cover the downlink through our VCO, i.e., 935-960

MHz, and 1805-1880 MHz.

In our design, we will use 555 timer IC operating in the a-stable mode to generate

the sweeping signal. The output frequency depends on the charging and discharging

of the capacitor, resistors values and the power supply for the IC. Figure 3 shows

how we can use the 555timer in the general A-stable mode.

Fig 6.4: A-stable 555timer.



The charging time for the capacitor can be found as follows:

Tc=0.693(Ra+Rb)C … (6.2)

For discharging time, the following equation can be used:

Td=0.693RbC … (6.3)

The output frequency can be calculated as follows:

f = 1.44/ (Ra+2Rb) c … (6.4)

In our project, we need to get the duty cycle (D.C.) equal to 50% which means the

time needed for charging equals the discharging time. This can be done by using

Ra=Rb and placing a diode across Rb. The following equation shows the output

frequency:

f = 1.44/(Ra+Rb)c …(6.5)

Fig 6.5. A-stable mode connection [D.C. = 50%].

In our project, we used Ra=Rb=750 Ω with C=0.1 µF, then the output frequency is 10 KHz

Since we use +12 V (Vcc), the output signal will be bounded from 4 V (Vcc/3) to 8 V

(2Vcc/3). Figure 6 shows all the components used to generate the triangular wave. The

output is shown in figure.



This capacitor is used to Remove

the DC signal With C=0.1µF

Fig 6.6a Triangular wave generator Fig 6.6b Generated triangular waveform.

6.2.2 Noise generation

Without noise, the output of the VCO is just an un-modulated sweeping RF carrier. So, we

need to mix the triangular signal with noise (FM modulating the RF carrier with noise). To

generate noise signal, we used the Zener Diode operated in reverse mode. Operating in the

reverse mode causes what is called avalanche effect, which causes wide band noise. This

noise is then amplified and used in our system. We use two amplification stages: in the first

stage, we use NPN transistor as common emitter, and in the second stage, we use the

LM386 IC Audio amplifier.

Fig 6.7: Noise generation



6.2.3 Mixer

The mixer here is just an amplifier that operates as a summer. So, the noise and triangular

wave will add together before entering the VCO. The LM741 IC was used to achieve this.

Fig 6.8: OP-AMP summer circuit

Using Rnoise =1 KΩ, we amplify the noise signal by 2. In this case, the ratio of the noise

to the sweep signal is 2:1.

The triangle wave and noise signals are mixed using OP-Amp configured as summer shown

in Figure 6.8, 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 6.8 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.

6.2.4 Clamper

The input of the VCO must be bounded from 0 to 3.5 V to get the needed frequency range.

So, we need to add a clamper to get our goal. The clamper consists of a capacitor connected

in series with a resistor and diode.

Positive Diode-Clamper

Fig 6.9: Diode clamper



NO ISE GENERATO R

Fig 6.10: Schematic of the IF-section.

Fig 6.11: Modulated Circuit



Fig 6.12 Modulated waveform

6.2.5 Specification of IF Section

6.3 The RF-Section

This is the most important part of the jammer, since the output of this section will be

interfacing with the mobile. The RF-section consists of three main parts: voltage controlled

oscillator VCO, power amplifier and antenna.



Fig 6.13: RF section (The heart of the jammer)

6.3.1 Voltage Controlled Oscillator (VCO)

The voltage controlled oscillator (VCO) is the heart of the RF-section. It is the device that

generates the RF signal which will interfere with the cell phone. The output of the VCO

has a frequency which is proportional to the input voltage, thus, we can control the output

frequency by changing the input voltage. When the input voltage is DC, the output is a

specific frequency, while if the input is a triangular waveform, the output will span a

specific frequency range. In our design, we need to find a VCO for GSM 900 and GSM

1800. There are three selection criteria for selecting a VCO for this application. Most

importantly, it should cover the bands that we need, secondly, it should be readily available

at low cost, and finally, it should run at low power consumption. Moreover, we need to

minimize the size of GSM-jammer. So, we started to search through the internet for VCO's

that work for GSM 900 & GSM 1800 bands.

Finally, we will use the following VCO IC’s:-

CVCO55CL: this is for GSM 900. The output frequency is 925-970 MHz and the output

power is up to 8 dBm.

We chose these IC’s for the following reasons:-

[A] Surface mount, which reduces the size of product.



[B] Having large output power that reduces the number of amplification stages that we

need.

[C] Having same value of power supply which is typically equal to 5 volt.

[D] Having same noise properties. Figure 14 shows these two IC’s.

6.3.2 The power amplifier

Since 5 dBm output power from the VCO does not achieve the desired output power of the

GSM jammer, we are adding an amplifier with a suitable gain to increase the VCO output

to 34 dBm. We are firstly designing and built our circuit using only one power amplifier

IC. We firstly designed and built our circuit using only one power amplifier IC. Upon

testing, the jammer didn’t work properly. It was concluded that amplifier IC does not work

at the two bands simultaneously. Such a fact was not indicated in the datasheets. This result

was really a big shock, but easily solved by changing the whole RF design. The new design

uses two power amplifier IC’s instead of one amplifier. Figure 16 shows the two designs

for the RF-Section.

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 … (6.6)

Since SNRmin = S/J … (6.7)

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 … (6.8)

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 an 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

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.

6.3.3 Antenna

A proper antenna is necessary to transmit the jamming signal. In order to have optimal

power transfer, the antenna system must be matched to the transmission system. In this

project, we are using two 1/4 wavelength monopole antennas, with 50 Ω input impedance

so that the antennas are matched to the system. We are using monopole antenna since the

radiation pattern is Omni-directional.

Specifications of DCS Antenna:

Frequency: 1700-1900MHz

Input impedance 50Ω

VSWR<2

Specifications of GSM 90 Antenna:

Frequency: 850MHz-1GHz

Input impedance 50Ω

VSWR<2



Fig 6.14: RF-section Schematic.



Chapter 7

Applications, Advantages, Disadvantages, Limitations

and Result

7.1 Applications

1. 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.

2. 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.

3. 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.

4. 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.

5. Courts: May avoid the handset ting the disturbance, maintains the court conference

site the dignity and the sacredness.

6. Libraries, New Bookstore: May avoid the handset ting and answer the telephone

the noise, builds to study the study peaceful environment.

7. Theatres: As the upscale recreation area, eliminates the handset ting noise to be

possible to maintain the audience to appreciate the program the interest.

8. Tests places, examination centre: May cease the examinee, monitor an exam the

personnel to cheat using the modern communication facilities.



9. Schools classrooms and training organization classroom: May avoid the hand

setting and answers when the handset telephone to attending class student's

disturbance.

10. Instead fears the unit: Locking goal of tendency by handset telecontrolled bomb.

11. Coast defences unit: May prevent the seacoast smuggling member discloses secret

information using the handset, effectively attacks smuggling criminal offender's

smuggling.

12. 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.

13. Temples, Mosques and Churches: May eliminate the handset signal noise, by

maintains the religious place solemn and respectful.

Fig7.1: Applications

7.2 Advantages

We can provide security to V.I.P's from the anti-social elements.

Using cell phone jammers we can maintain law and order for maintaining peace.

By cell phone jammers we can't disturb other people in the public places like

restaurants, shopping places.

It is very necessary to use cell phone jammers in naxal feared places. This helps

the authorities to work their duty softly.



By using cell phone jammers in the vehicles, we can overcome accidents

problems which is very helpful to the people.

Work for both GSM and CDMA networks.

No loss of data due to backup battery.

7.3 Disadvantages

Cost oriented.

Required special hardware.

People feel inconvenience.

V.I.P's may lose some important calls.

7.4 Design Limitations

While the GSM recognizes and is sympathetic to the difficulties facing Corrective Services

in relation to use of mobile phones in prisons, the JAMMER considers that the

disadvantages of allowing the use of mobile phone jammers appear to outweigh the

advantages. The legal issues surrounding the use of mobile phone jammers are complex.

There is significant doubt as to whether mobile phone jammers could be used without a

change to existing legislation. The does not support the introduction of mobile phone

jammers because they:

Interfere with licensed radio communications;

Disrupt telecommunications networks; and

Raise serious safety of life issues.

Therefore, the ACA recommends that the available alternatives to mobile phone

Jammers described above to be further explored by Corrective Services in consultation.

7.5 Results

As we tested our jamming device, the result was a full success. The device was able to jam the

three cell phone carriers: Airtel, Aircel, Vodafone, Tata Docomo, and Reliance. The effective

jamming range was around 0-5 meters. This is more than what it was designed for. The reason

is that in our calculations, we considered the worst case of having the cell phone close to the

base station. It is expected that as the distance between the cell phone and the base station

increases, the effective jamming distance will 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. The Figure in the next page 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".

7.5.1 Practical Results of Signal Jammer

1) Airtel Network

Fig 7.2 Before Signal jammer turned ON

Fig 7.3 After Signal jammer turned ON



2) Aircel Network





3) Vodafone Network for Old phone





4) Vodafone for Smart Phone





5) Tata Docomo Network





6) Reliance Network





Fig 7.14: Complete circuit



Chapter 8

Conclusion and Summary

8.1 Conclusion

Every technology has good aspect as well as bad aspect the important thing is, how we are

using it. Cell phone jammers are very useful to the society from the anti-social elements.

We can save our national leaders. We can restrict the communication network between the

anti-social elements by using the Mobile jammers. Cell phone jammers prevent the students

from carrying cell phones to the colleges. Jammers and / or interference caused by these

devices affects citizens, public safety and services. Not only limited network coverage, but

also degrade service delivery, generate harmful interference additional services using radio

communications, increases the problems for public health officials and security, but also

limit access to services primary aid and can even be used to offense blocking security

services. At the same time, blocking the signal does not attack the root of the problem -

that wireless devices end up illegally in the hands of inmates, who then use them for

illegitimate purposes, or that services are not used in areas or places where there It

corresponds. There are many and various alternative ways that allow meet this end without

affecting the rights of other users.

The GSMA and its members are committed to cooperate with governments in the region,

using technology as an aid to keep cell phones out of sensitive areas, as well as efforts to

detect smuggling devices, track and prevent their use. It is imperative that a viable solution

that does not negatively impact legitimate users, or affecting the significant investments

that Mobile operators have made to improve coverage and provide quality service in the

region. It would be advisable that any measure involving the use of exceptional blockers,

as a last resort, and is carried out in coordination with operators throughout their life cycle

(from its installation to its low) to minimize interference in the adjacencies areas sensitive,

where users who make legitimate use of cell there. At the same time, to safeguard the public

interest and the correct provision of the service, regulatory authorities should prohibit use

blockers are private entities and marketing, and promote both the regulation and the

various regional regulations regarding the use of these blockers devices, take into account

their effect on normal service provision processes and quality control. Additionally, the

regulator in each country should assess conformity blockers, manage and keep track of the

number of blockers will attest, they are installed and operated in sensitive areas, and



establish penalties for those individuals that use and / or commercialization without

permission from the competent authorities.

We reiterate that the use of inhibitors should be exceptional, last resort, seeking take

alternative measures with the same purpose while not affect the rights of other users.

The illegitimate use of cell phones in sensitive areas is a growing public safety; therefore,

the Mobile operators are committed to working with governments in Latin America to find

a solution. As described earlier in the document, although the use of signal inhibitors has

proliferated in recent years in various countries of the region, unfortunately this technology

also interferes with legitimate wireless telephone and other radio communications in

adjacent areas.

Notwithstanding the foregoing, an important consideration is that attribute responsibility

to block signals to mobile operators, contrasts with the obligation to provide the service

by themselves, so that the obligation to install such blockers and fix the damages that they

can cause to remain as an obligation as per of the completeness authorities.

Thus, although we share the concern of the countries of the region on the urgent need to

eliminate the illegal use of mobile services in sensitive areas, we believe that the most

efficient and effective way to do this is not necessarily through the installation of devices

and equipment that may prejudice the provision of services to third parties, or through a

complex and costly regulation monitoring, detection, blocking suspension equipment and

mobile lines. They are the State which must lead actions needed to prevent the entry of

terminals or mobile devices for use by inmates of prisons.

Strengthen security to prevent the entry of these illegal equipment, prevent the

communication of internal through them and therefore it is the most effective measure to

eliminate the illegal use of mobile services from within prisons, without affecting the rights

other users who live, work or are simply passing through the establishment environments.

8.2 Summary

The project was implemented according to the following plan:

We started by studying the jamming techniques, and GSM system to find the best

jamming method. The system block diagram was also specified in this stage.

We searched for components that are needed for building this device, and specified

the main components which were :

For RF section, we needed one VCO’s that operate at the needed bands, one power

amplifier, and one antenna.



For the IF section, we used 555timer, Zener diode, mixer, PC power supply and

some discrete components (resistors and capacitors).

The schematic was drawn and some simulations for the IF-Section were performed.

Then, we started to designing on a pcb chip using soldering.

All the IF-components were bought from local companies. Then, the IF-section was

built and tested.

After that, we began to search for the RF-components (VCO and the board) in the

local market. Since we failed to collect these IC’s from the local market, we had to

order them from "Digi-key" US company.

Finally, we assembled and tested the jammer. Fortunately, we got positive results.

The bands were fully jammed.

We hope that this project will be useful for the community where such jamming

devices are needed.



8.2.1 CIRCUIT COMPONENTS

Table 8.1

CIRCUIT COMPONENTS RELATED COMPONENTS

USED

C7=1pf 10pf

C4=5uf 4.7uf

C3=50p 47pf

C2=1pf 10pf

C1=30pf trimmer 150pf

L2=2.2nH 15nH

L1=1nH 15nH

Relay 1

R4=6.8k 6.8k

R5=82k 82k

R2=6k 5.8k

R3=10k 10k

R1=220 220

Lm555 timer



8.3 References

[1]. N. R. Krishniah, “Dual Band”, International Journal of Modern Engineering Research

(IJMER) Vol. 3, Issue. 4, Jul - Aug. 2013.

[2]. P. Raveendra Babu, International Journal of Science, Engineering and Technology

Research (IJSETR) Volume 2, Issue 9, September 2013.

[3]. Hongbo Liu∗ and Wenyuan Xu , Localizing Jammers in Wireless Networks vol. 1,

Issue 6 May 2013 .

[4]. Rick Hartley, RF / Microwave PC Board Design and Layout, Avionics Systems.

[5]. John Scourias, Overview of the Global System for Mobile Communications,

University of Waterloo.

[6]. Pozar, D., Microwave Engineering, John Wiley and Sons, 2005.

[7]. Tony Van Roon, 555 timer tutorial.

[8] Mobile & Personal Communications Committee of the Radio Advisory Board of

Canada. Use of jammer and disabler. Devices for blocking PCS, Cellular & Related

Services.

[9] Prasad, Sudarshan, and David J. Thuente. "Jamming attacks in 802.11 g—a cognitive

radio based approach." MILITARY communications conference, 2011-MILCOM 2011.

IEEE, 2011.

[10] John Scourias Overview of the global system for Mobile communications,

http://ccnga.uwaterloo.ca/~jscouria/GSM/gsmreport.

Cell phone antenna GSM Antenna

http://ccnga.uwaterloo.ca/~jscouria/GSM/gsmreport



APPENDIX I

LM 555 Timer

The 555 timer IC was first introduced around 1971 by the Signe tics Corporation as the

SE555/NE555 and was called "The IC Time Machine" and was also the very first and only

commercial timer IC available. It provided circuit designers with a relatively cheap, stable,

and user-friendly integrated circuit for both constable and actable applications. Since this

device was first made commercially available, a myriad of novel and unique circuits have

been developed and presented in several trade, professional, and hobby publications. The

past ten years some manufacturers stopped making these timers because of competition or

other reasons. Yet other companies, like NTE (a subdivision of Philips) picked up where

some left off.

Although these days the CMOS version of this IC, like the Motorola MC1455, is mostly

used, the regular type is still available, however there have been many improvements and

variations in the circuitry. But all types are pin-for-pin plug compatible.

In this tutorial the 555 timer is examined in detail along with its uses, either by itself or

in combination with other solid state devices. This timer uses a maze of transistors, diodes

and resistors and for this complex reason a more simplified (but accurate) block diagram

is used to explain the internal organizations of the 555.

All IC timers rely upon an external capacitor to determine the off-on time intervals of the

output pulses. It takes a finite period of time for a capacitor (C) to charge or discharge

through a resistor (R). Those times are clearly defined and can be calculated given the

values of resistance and capacitance.

The basic RC charging circuit is shown in fig. 4. Assume that the capacitor is initially

discharged. When the switch is closed, the capacitor begins to charge through the resistor.

The voltage across the capacitor rises from zero up to the value of the applied DC voltage.

The charge curve for the circuit is shown in fig. 6. The time that it takes for the capacitor



to charge to 63.7% of the applied voltage is known as the time constant (t). That time can

be calculated with the simple expression: t = R X C

Definition of Pin Functions:

Refer to the internal 555 schematic of Figure

Pin 1 (Ground): The ground (or common) pin is the most-negative supply potential of the

device, which is normally connected to circuit common (ground) when operated from

positive supply voltages.

Pin 2 (Trigger): This pin is the input to the lower comparator and is used to set the latch,

which in turn causes the output to go high. This is the beginning of the timing sequence in

monostable operation. Triggering is accomplished by taking the pin from above to below

a voltage level of 1/3 V+ (or, in general, one-half the voltage appearing at pin 5). The action

of the trigger input is level-sensitive, allowing slow rate-of-change waveforms, as well as

pulses, to be used as trigger sources. The trigger pulse must be of shorter duration than the

time interval determined by the external R and C. If this pin is held low longer than that,

the output will remain high until the trigger input is driven high again.



One precaution that should be observed with the trigger input signal is that it must not

remain lower than 1/3 V+ for a period of time longer than the timing cycle. If this is allowed

to happen, the timer will retrigger itself upon termination of the first output pulse. Thus,

when the timer is driven in the monostable mode with input pulses longer than the desired

output pulse width, the input trigger should effectively be shortened by differentiation.

The minimum-allowable pulse width for triggering is somewhat dependent upon pulse

level, but in general if it is greater than the 1uS (micro-Second), triggering will be reliable.

A second precaution with respect to the trigger input concerns storage time in the lower

comparator. This portion of the circuit can exhibit normal turn-off delays of several

microseconds after triggering; that is, the latch can still have a trigger input for this period

of time after the trigger pulse. In practice, this means the minimum monostable output pulse

width should be in the order of 10uS to prevent possible double triggering due to this effect.

The voltage range that can safely be applied to the trigger pin is between V+ and ground.

A dc current, termed the trigger current, must also flow from this terminal into the external

circuit. This current is typically 500nA (nano-amp) and will define the upper limit of

resistance allowable from pin 2 to ground. For an astable configuration operating at V+ =

5 volts, this resistance is 3 Mega-ohm; it can be greater for higher V+ levels.

Pin 3 (Output): The output of the 555 comes from a high-current totem-pole stage made

up of transistors Q20 - Q24. Transistors Q21 and Q22 provide drive for source-type loads,

and their Darlington connection provides a high-state output voltage about 1.7 volts less

than the V+ supply level used. Transistor Q24 provides current-sinking capability for low-

state loads referred to V+ (such as typical TTL inputs). Transistor Q24 has a low saturation

voltage, which allows it to interface directly, with good noise margin, when driving current-

sinking logic. Exact output saturation levels vary markedly with supply voltage, however,

for both high and low states. At a V+ of 5 volts, for instance, the low state Vce(sat) is

typically 0.25 volts at 5 mA. Operating at 15 volts, however, it can sink 200mA if an output-

low voltage level of 2 volts is allowable (power dissipation should be considered in such a

case, of course). High-state level is typically 3.3 volts at V+ = 5 volts; 13.3 volts at V+ =

15 volts. Both the rise and fall times of the output waveform are quite fast, typical switching

times being 100nS.

The state of the output pin will always reflect the inverse of the logic state of the latch, and

this fact may be seen by examining Fig. 3. Since the latch itself is not directly accessible,

this relationship may be best explained in terms of latch-input trigger conditions. To trigger



the output to a high condition, the trigger input is momentarily taken from a higher to a

lower level. [see "Pin 2 - Trigger"]. This causes the latch to be set and the output to go high.

Actuation of the lower comparator is the only manner in which the output can be placed in

the high state. The output can be returned to a low state by causing the threshold to go from

a lower to a higher level [see "Pin 6 - Threshold"], which resets the latch. The output can

also be made to go low by taking the reset to a low state near ground [see "Pin 4 - Reset"].

The output voltage available at this pin is approximately equal to the Vcc applied to pin 8

minus 1.7V.

Pin 4 (Reset): This pin is also used to reset the latch and return the output to a low state.

The reset voltage threshold level is 0.7 volt, and a sink current of 0.1mA from this pin is

required to reset the device. These levels are relatively independent of operating V+ level;

thus the reset input is TTL compatible for any supply voltage.

The reset input is an overriding function; that is, it will force the output to a low state

regardless of the state of either of the other inputs. It may thus be used to terminate an

output pulse prematurely, to gate oscillations from "on" to "off", etc. Delay time from reset

to output is typically on the order of 0.5 µS, and the minimum reset pulse width is 0.5 µS.

Neither of these figures is guaranteed, however, and may vary from one manufacturer to

another. In short, the reset pin is used to reset the flip-flop that controls the state of output

pin 3. The pin is activated when a voltage level anywhere between 0 and 0.4 volt is applied

to the pin. The reset pin will force the output to go low no matter what state the other inputs

to the flip-flop are in. When not used, it is recommended that the reset input be tied to V+

to avoid any possibility of false resetting.

Pin 5 (Control Voltage): This pin allows direct access to the 2/3 V+ voltage-divider point,

the reference level for the upper comparator. It also allows indirect access to the lower

comparator, as there is a 2:1 divider (R8 - R9) from this point to the lower-comparator

reference input, Q13. Use of this terminal is the option of the user, but it does allow extreme

flexibility by permitting modification of the timing period, resetting of the comparator, etc.

When the 555 timer is used in a voltage-controlled mode, its voltage-controlled operation

ranges from about 1 volt less than V+ down to within 2 volts of ground (although this is

not guaranteed). Voltages can be safely applied outside these limits, but they should be

confined within the limits of V+ and ground for reliability.



By applying a voltage to this pin, it is possible to vary the timing of the device

independently of the RC network. The control voltage may be varied from 45 to 90% of

the Vcc in the monostable mode, making it possible to control the width of the output pulse

independently of RC. When it is used in the astable mode, the control voltage can be varied

from 1.7V to the full Vcc. Varying the voltage in the astable mode will produce a frequency

modulated (FM) output.

In the event the control-voltage pin is not used, it is recommended that it be bypassed, to

ground, with a capacitor of about 0.01uF (10nF) for immunity to noise, since it is a

comparator input. This fact is not obvious in many 555 circuits since I have seen many

circuits with 'no-pin-5' connected to anything, but this is the proper procedure. The small

ceramic cap may eliminate false triggering.

Pin 6 (Threshold): Pin 6 is one input to the upper comparator (the other being pin 5) and

is used to reset the latch, which causes the output to go low.

Resetting via this terminal is accomplished by taking the terminal from below to above a

voltage level of 2/3 V+ (the normal voltage on pin 5). The action of the threshold pin is

level sensitive, allowing slow rate-of-change waveforms.

The voltage range that can safely be applied to the threshold pin is between V+ and ground.

A dc current, termed the threshold current, must also flow into this terminal from the

external circuit. This current is typically 0.1µA, and will define the upper limit of total

resistance allowable from pin 6 to V+. For either timing configuration operating at V+ = 5

volts, this resistance is 16 MW For 15 volt operation, the maximum value of resistance is

20 MW.

Pin 7 (Discharge): This pin is connected to the open collector of a NPN transistor (Q14),

the emitter of which goes to ground, so that when the transistor is turned "on", pin 7 is

effectively shorted to ground. Usually the timing capacitor is connected between pin 7 and

ground and is discharged when the transistor turns "on". The conduction state of this

transistor is identical in timing to that of the output stage. It is "on" (low resistance to

ground) when the output is low and "off" (high resistance to ground) when the output is

high.

In both the monostable and astable time modes, this transistor switch is used to clamp the

appropriate nodes of the timing network to ground. Saturation voltage is typically below

100mV (milli-Volt) for currents of 5 mA or less, and off-state leakage is about 20nA (these

parameters are not specified by all manufacturers, however).



Maximum collector current is internally limited by design, thereby removing restrictions

on capacitor size due to peak pulse-current discharge. In certain applications, this open

collector output can be used as an auxiliary output terminal, with current-sinking capability

similar to the output (pin 3).

Pin 8 (V +): The V+ pin (also referred to as Vcc) is the positive supply voltage terminal

of the 555 timer IC. Supply-voltage operating range for the 555 is +4.5 volts (minimum)

to +16 volts (maximum), and it is specified for operation between +5 volts and + 15 volts.

The device will operate essentially the same over this range of voltages without change in

timing period. Actually, the most significant operational difference is the output drive

capability, which increases for both current and voltage range as the supply voltage is

increased. Sensitivity of time interval to supply voltage change is low, typically 0.1% per

volt. There are special and military devices available that operate at voltages as high as 18

V.



Check the listing in Table. It shows some variations in the 555 manufacturing process by

two different manufacturers, National Semiconductor and Signetics Corporation.

STUDENTS’ PROFILE

1. ARYAN KUMAR

2. KARTHIKEYAN R

3. M ADITYA

4. NIKHIL KUMAR

USN- 1BY12EC006

EMAIL ID- [email protected]

CONTACT NUMBER- 7204045295

USN- 1BY12EC021



USN- 1BY12EC028



USN- 1BY12EC036



Documents

Project report on signal jammer