2. Mobile Jammer
Seminar
Submitted in partial fulfillment of the requirements
For the degree of
Bachelor of Technology in Information Technology
By
Ranavasiya Mehul
10BIT047
Department Of Computer Science and Engineering
Institute Of Technology
Nirma University
Ahmedabad-382481
April 2013
3. iii
Certificate
This is to certify that the Seminar entitled ”Mobile Jammer” submitted by Ranavasiya
Mehul(10BIT047), towards the partial fulfillment of the requirements for the degree of
Bachelor of Technology in Information Technology of Nirma University, Ahmedabad
is the record of work carried out by him under my supervision and guidance. In
my opinion, the submitted work has reached a level required for being accepted for
examination. The results embodied in this Seminar, to the best of my knowledge,
haven’t been submitted to any other university or institution for award of any degree
or diploma.
Prof. Jitali Patel Prof. Pimal Khanpara
Assistant Professor, Assistant Professor,
CSE Department , CSE Department,
Institute of Technology, Institute of Technology,
Nirma University, Ahmedabad Nirma University, Ahmedabad
Dr. Sanjay Garg
Head Of Department,
CSE Department,
Institute of Technology,
Nirma University, Ahmedabad
4. iv
Abstract
The last few years have witnessed a dramatic boom in the wireless communications
industry, hence increasing the number of users of mobile communication devices. This
magnified the need for a more efficient and reliable signal scrambler. This paper deals
with the Mobile Jamming Technology. A mobile Jammer is an instrument which is
used to prevent mobile phones from receiving signals from the base stations.Which
can be used in practically at any location, but are mostly found in places where a
phone call would be particularly disruptive because silence is expected.The concept of
jamming technology is studied in a step-by-step approach. Those steps include Intro-
duction to mobile jammer, Componets of mobile jammer, Mobile jamming techniques,
Design parameters for mobile jammer, Block diagram of mobile jammer and Legal
issues related with mobile jammer along with the Alternatives of mobile jammer.
5. v
Acknowledgements
I would like to express my special thanks of gratitude to my guide Prof. Pimal
Khanpara who gave me the golden opportunity to give her profound guidance in
this wonderful project on the Mobile jammer , which also helped me in doing a lot
of Research and i came to know about so many new things.I am really thankful to
them.
- Ranavasiya Mehul
10BIT047
8. Chapter 1
Introduction
1.1 Why mobile jammer is needed?
It’s great to be able to call anyone at anytime. 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. Who hasn’t
seethed through one side of a conversation about an incredibly personal situation
as the talker shares intimate details with his friend as well as everyone else in the
area?? While most of us just grumble and move on, some people are actually going
to extremes to retaliate. Cell phones are basically handheld two-way radios. And like
any radio, the signal can be disrupted, or jammed.
A mobile Jammer is an instrument which is used to prevent mobile phones from
receiving signals from the base stations.Which can be used in practically at any
location, but are mostly found in places where a phone call would be particularly
disruptive because silence is expected.
1.2 Cell Phone Jamming Basics
Disrupting a cell phone is the same as jamming any other type of radio commu-
2
9. CHAPTER 1. INTRODUCTION 3
nication. A cell phoneworks 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, dis-
rupting the communication between the phone and the cell-phone base station in the
tower. It’s a called a denial-of-service attack. The jammer denies service of the radio
spectrumto the cell-phone users within range of the jamming device.
10. Chapter 2
Components of Mobile Jammer
Components of a mobile jammer include:
• Voltage Controlled Oscillator(VCO)
• Tuning Circuit
• Noise Source
• RF Amplification Unit
• Transmitting Antenna
2.1 Voltage Controlled Oscillator(VCO)
VCO is the most important among other parts. It is like a heart of our jammer. VCO’s
can be built using op-amps, resistors and capacitors, but the low cost, availability
and reliability of prefabricated VCO’s make it optimum to just purchase it. VCO
produces RF signal which will interact with the blocked device. Firstly we must select
frequencies which will be used in our signal blocking device. It is also important to
think about its size because we might wish to create a desktop mobile phone jammer
or a portable handheld jamming device.
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11. CHAPTER 2. COMPONENTS OF MOBILE JAMMER 5
Figure 2.1: Voltage Controlled Oscillator
2.2 Tuning Circuit
Tuning Circuit can be of two types:
• open-loop
• feedback
Open-loop is quite simple and requires just a few op-amps with additional passive
components.It is a sawtooth-wave generator which makes VCO to go from lowest
to highest frequency. The feedback is using PLL to adjust the VCOs frequency
constantly. For this purpose we need to use microcontroller. It is programmed once
and then connected to the VCO, thus it is not adjustable.
2.3 Noise generator
Produces random electronic output in a specified frequency range to jam the cell-
phone network signal (part of the tuning circuit).
2.4 RF Amplification Unit
RF Amplification Unit is what we need when we wish to increase the area covered
by our jammer along with its signal blocking power. The more power has our signal
blocker, the bigger radius it jams. The cost is, as we may guess, battery working
time. More power equals less time for battery to live.
12. CHAPTER 2. COMPONENTS OF MOBILE JAMMER 6
Figure 2.2: Transmitting Antenna
2.5 Transmitting Antenna
Transmitting Antenna is a tool which transmits signals produced by your jammer.
The main characteristic of antenna is VSWR (Voltage Standing Wave Ratio). If your
antenna has VSWR of 3 or lower, then this is what you need, because the return loss
of this antenna is minimal.
VSWR: For example, the VSWR value 2:1 denotes a maximum standing wave
amplitude that is 2 times greater than the minimum standing wave value.
Generally we use SMA antennas due to their ability of being removed or replaced
easily. It is worth to mention that omnidirectional antennas are preferable, unless..
we like to use our cell phone jammer in a TV remote style!!
SMA (SubMiniature version A) connectors are coaxial RF connectors developed in
the 1960s as a minimal connector interface for coaxial cable with a screw type cou-
pling mechanism.
2.6 Power Source
Power Source makes our creation to become alive. Generally mobile phone jammers
use 5VDC to operate. Thus you may use Lithium-ion battery to supply our creation.
In the case of using common power source we will need power adapter. The power
13. CHAPTER 2. COMPONENTS OF MOBILE JAMMER 7
adapter may be of one of two types: switched-capacitor voltage doubler or inductor-
based boost regulator. The first one is simple and efficient yet not regulated solution,
so we will need LDO regulator to fix the voltage. The second one is regulated but it
has bigger cost, more complex and requires precise specification of all components to
work properly
14. Chapter 3
Mobile Jamming Techniques
There are various types of jamming devices available which are using different jam-
ming techniques.
• Type ”A” Device
• Type ”B” Device
• Type ”C” Device
• Type ”D” Device
• Type ”E” Device
3.1 Type ”A” Device
Type ”A” Devices are simple Jammer.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 systems control channels for
call establishment.
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15. CHAPTER 3. MOBILE JAMMING TECHNIQUES 9
3.2 Type ”B” Device
Type ”B” Devices are also known as 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 quite area, functions as a detector.
It has a unique identification number for communicating with the cellular base station
3.3 Type ”C” Device
Type ”C” Devices are also known as 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 com-
patible terminal is instructed to disable its ringer or disable its operation, while within
the coverage area of beacon.
3.4 Type ”D” Device
Type ”D” Devices are Direct Receive Transmit Jammers. This jammer behaves like
a small, independent and portable base station, which can directly interact intelli-
gently or unintelligently with the operation of the local mobile phone. The jammer
is predominantly in receive mode and will intelligently choose to interact and block
the cell Phone directly if it is within close proximity of the jammer.
3.5 Type ”E” Device
Type ”E” Devices are used for EMI Shield - Passive Jamming. This technique is
using EMI suppression techniques to make a room into what is called 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.
16. Chapter 4
Design Parameters/ Specification
of mobile jammer
There are various types of jamming devices available which are using different jam-
ming techniques.
• The frequency bands
• Distance to be jammed (D)
• Jamming-to-signal ratio J/S
• Power calculations
• Free space loss
The Jamming Coverage Area for a particular model jammer should be consid-
ered a General or typical area of coverage. The situation may vary and is specific
to the site. Every JAMMING DEVICE outputs a JAMMING SIGNAL on one or
more frequencies at a particular OUTPUT POWER. The OUTPUT POWER of the
JAMMER will typically be stated in WATTS or in some Cases DBM, (decibels per
meter), or both. The OUTPUT POWER correlates generally to the COVERAGE
AREA that the JAMMER will provide an Effective blocking or JAMMING signal.
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17. CHAPTER 4. DESIGN PARAMETERS/ SPECIFICATION OF MOBILE JAMMER11
However, because many factors affect both cellular phone Reception and jamming
efficiency the advertised or sated AREA of COVERAGE may be more or less than
What a manufacture states.
In most cases a JAMMER will be easier to implement and more effective indoors.
In urban settings and In high-rise buildings, a jammer will typically be more effective
on lower floors. This is because the Building and surrounding structures diminish
the cellular signal. In some cases a JAMMER will be more Effective when placed
on the side of a room or building which is closest to a cellular tower. And in other
Cases a JAMMER may be more effective when placed by a window or door. The
design of a jammer design begins with a desired area of coverage as it correlates to
a particular Frequency. Jammers like all radio devices operate according to certain
laws of physics and energy. The 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 commu-
nications 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 Equa-
tion.
Where:
Pj = jammer power
Pt = transmitter power
18. CHAPTER 4. DESIGN PARAMETERS/ SPECIFICATION OF MOBILE JAMMER12
Figure 4.1: J/S Ratio
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 prevent 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 that jammer path Loss is often
different from the communications path loss; hence giving the jammer an advantage
over Communication transmitters.
19. Chapter 5
Block Diagram of Mobile Jammer
There are main 4 sections in the block diagram of mobile jammer.
5.1 Power Supply
The mobile jammer was designed for fixed use, and to take its power from the regular
220V AC wall outlets. The IF RF sections of the jammer require +5, +9, and -9 DC
Voltages. So a dc-dual polarity power supply should be designed. The basic parts for
a power supply are rectifier, filter, and regulator. The rectifier coverts the ac input
voltage to a pulsating dc voltage and can be either half wave rectifier and full wave
rectifier, the one we use is the full wave rectifier which has the advantage that it allows
unidirectional current to the load during the entire cycle of the input voltage and the
Figure 5.1: Block diagram
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20. CHAPTER 5. BLOCK DIAGRAM OF MOBILE JAMMER 14
Figure 5.2: Power Suppy
Figure 5.3: IF Section
result of the full wave rectification is an output voltage with a frequency twice the
input frequency that pulsated every half-cycle of the input. The second part of the
power supply is the filter which eliminate the fluctuations in the output of the full
wave rectifier so as to produce a constant dc voltage, the filter is simply a capacitor
and its chosen to be as large as possible to minimize voltage ripple in the output. The
final part of the power supply is the regulator and it is used to provide the desired
constant dc output that is basically independent of the input voltage. Single chip
regulators were used to give +5, +9, and -9 dc voltages
21. CHAPTER 5. BLOCK DIAGRAM OF MOBILE JAMMER 15
Figure 5.4: RF Section
5.2 IF Section
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 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. The triangle wave and
noise signals are mixed using Op-Amp configured as summer. Then a DC voltage is
added to the resulted signal to obtain the required tuning voltage.
5.3 RF Section
The RF-section is the most important part of the mobile jammer it consist of the
Voltage Controlled Oscillator (VCO), RF Power amplifiers, and the antenna. These
components were selected according to the desired specification of the jammer such
as the frequency range and the coverage range.
22. Chapter 6
Applications
There are various types of jamming devices available which are using different jam-
ming techniques.
• To maintain the complete silence in library and lecture hall.
• To avoid fraud in examination hall.
• To avoid disturbance in class room.
• For providing security in business conference, board of directors rooms, semi-
nars, etc.
• For providing calm and peaceful atmosphere in Hospitals.
• Church/Mosques/Cathedral/Temple/Religious establishment
Cell phone jamming devices were originally developed for law enforcement and the
military to interrupt communications by criminals and terrorists. The bombs that
blew up commuter trains in Spain in March 2004, as well as blasts in Bali in October
2002 and Jakarta in August 2003, all relied on cell phones to trigger explosives. It has
been widely reported that a cell-phone jammer thwarted an assassination attempt on
Pakistani President Musharraf in December 2003. When President Bush visited Lon-
don in November 2004, it was reported that British police considered using jammers
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23. CHAPTER 6. APPLICATIONS 17
to protect the president’s motorcade through London. During a hostage situation,
police can control when and where a captor can make a phone call. Police can block
phone calls during a drug raid so suspects can’t communicate outside the area. Cell-
phone jammers can be used in areas where radio transmissions are dangerous, (areas
with a potentially explosive atmosphere), such as chemical storage facilities or grain
elevators. The TRJ-89 jammer from Antenna System Supplies Inc. carries its own
electrical generator and can block cellular communications in a 5-mile (8-km) radius.
Corporations use jammers to stop corporate espionage by blocking voice transmis-
sions and photo transmissions from camera phones. On the more questionable end of
the legitimacy spectrum, there are rumors that hotel chains install jammers to block
guests’ cell-phone usage and force them to use in-room phones at high rates.
24. Chapter 7
Legal Issues and Alternatives of
Cell Phone Jamming
7.1 Cell Phone Jamming Legal Issues
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 ”willfully 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. 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
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25. CHAPTER 7. LEGAL ISSUES AND ALTERNATIVES OF CELL PHONE JAMMING19
jamming.
7.2 Alternatives to Cell Phone Jamming
While the law clearly prohibits using a device to actively disrupt a cell-phone signal,
there are no rules against passive cell-phone blocking. That means using things
like wallpaper or building materials embedded with metal fragments to prevent cell-
phone signals from reaching inside or outside the room. Some buildings have designs
that block radio signals by accident due to thick concrete walls or a steel skeleton.
Companies are working on devices that control a cell phone but do not ”jam the
signal.” One device sends incoming calls to voicemail and blocks outgoing calls. The
argument is that the phone still works, so it is technically not being jammed. It is a
legal gray area that has not been ruled on by the FCC as of Apr-+il 2005. Cell-phone
alerters are available that indicate the presence of a cell-phone signal. These have
been used in hospitals where cell-phone signals could interfere with sensitive medical
equipment. When a signal is detected, users are asked to turn off their phones. For a
less technical solution, Coudal Partners, a design firm in Chicago, has launched the
SHHH, the Society for HandHeld Hushing. At its Web site, you can download a note
to hand to people conducting annoying cell-phone conversations, expressing your lack
of interest in what they’re talking about.
26. Chapter 8
Conclusion
8.1 Conclusion
At last we can say every device is acts as good aspects as well as bad aspects. In
many place cell phone jammer is useful but at many place it is a problem .for this we
can take a example that if at any place cell phone jammer is on than anybody wants
to use than there creates some problems. But its overall performance is very good
and helpful in our life.
8.2 References
• www.HowStuffWork.com
• wikipedia.org/wiki/Mobilephonejammer
• Mobile Personal Communications Committee of the Radio Advisory Board of
Canada, Use of jammer and disabler Devices for blocking PCS, Cellular Related
Services
• http://whatisacellphonejammer.com
• http://blog.jammer-store.com/2009/11/how-mobile-jammers-work
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