gyan priyadarshi

8/9/2019 gyan priyadarshi

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CELL-PHONE JAMMERS

Presented by:

GYAN PRIYADARSHI


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Contents

Introduction

Cellphone basics

Cell-phone JammingJammer Circuitry

Range

The Legal Issues

Where jammers can be used?

Presently in Use

Alternatives to Jamming


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Introduction:

Cell phones are used everywhere these days.

It's great to be able to call anyone atanytime.

Unfortunately, movie theaters,class rooms,

concerts, libraries, temples etc all suffer from the

use of cell phones.


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Cellphone basics:

Cell phones are basically handheld

two-way radios.

A cell phone is a full-duplex device.

.


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Half duplex

Communication


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Full Duplex

Communication


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A cell phone works by communicating with

its service network through a cell tower orbase station.

Cell towers divide a city into small

areas,called cells.

Each cell is typically sized at about 26square kilometers (10 square miles).

Cells are normally thought of as hexagons ona big hexagonal grid.


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8Cell network


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Jammer Network


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Cell network


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Radio Transmitter & Receiver

Each cell has a base station that consists ofa tower and radio equipment .


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Tower


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Cell phones have low-power

transmitters in them.

Cell phones have two signal strengths:

0.6 watts & 3 watts.


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What is a Jammer? A jammer is an instrument used to prevent

the cellular phones from receiving and

transmitting the mobile signal to a base

station.


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Cell-phone Jamming:

Like any radio, the cell phone signal can be

disrupted, or jammed.

Disrupting a cell phone is the same as

jamming any type of radio communication.

It's a called a denial-of-service attack.


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A jamming device transmits on the sameradio frequencies as the cell phone,

disrupting the communication between thephone and the cell-phone base station in thetower.

Jamming devices overpower the cell phoneby transmitting a signal on the samefrequency and at a high enough power thatthe two signals collide and cancel each otherout.

The jammer denies service of the radiospectrum to the cell-phone users withinrange of the jamming device.


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Jammer activated region


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Comparison


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Although different cellular systems processsignals differently, all cell-phone networks

use radio signals that can be interrupted.

Jammers can broadcast on any frequencyand are effective against AMPS, CDMA,

TDMA, GSM, PCS, DCS, iDEN and Nextelsystems.

Sophisticated jammers can block several

types of networks.

To jam a cell phone, all you need is a devicethat broadcasts on the correct frequencies.


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Jammer Circuitry:

Voltage-controlled oscillator - Generatesthe radio signal that will interfere with thecell phone signal .

Tuning circuit - Controls the frequency atwhich the jammer broadcasts its signal bysending a particular voltage to the oscillator

Noise generator - Produces randomelectronic output in a specified frequencyrange to jam the cell-phone network signal(part of the tuning circuit)


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RF amplification (gain stage) - Boosts thepower of the radio frequency output to highenough levels to jam a signal .

Power supply-Smaller jamming devices arebattery operated whereas larger devicesuses standard outlet or vehicles electricalsystem.

Antenna-Every jamming device has anantenna to send the signal.


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Jammer circuit


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Range:

The actual range of the jammer depends onits power and the local environment.

Low-powered jammers block calls in a range

of about 30 feet (9 m).

Higher-powered units can shut down serviceup to 1 mile (1.6 km) from the device.

The TRJ-89 jammer from Antenna System &Supplies Inc.block cellular communicationsin a 5-mile (8-km) radius.


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Portable Jammer


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Outdoor Jammer


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SOME USUAL CELL PHONE

JAMMER:1. Y050 HAND HELD

2. SH066

3. MGB1

4. YK300(3G)


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The Legal Issues:

Jamming is seen as property theft.

It also represents a safety hazard.

In most countries, it is illegal for privatecitizens to jam cell-phone transmission.

Some countries are allowing businesses andgovernment organizations to install jammersin areas where cell-phone use is seen as apublic nuisance


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Where jammers can be used?

Cell phone jamming devices were originallydeveloped for the military to interruptcommunications by criminals and terrorists.

Police can block phone calls during a raidand in hostage situation so suspects can'tcommunicate outside the area.

Cell-phone jammers can be used in areassuch as chemical storage facilities or grainelevators.


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This is a remote-controlled, fully digitized jamming

device designed for outdoor use, covering a radius

ranging from 30 feet to 0.6 miles (10 meters to 1

kilometer).


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Presently in Use:

In India jammers are installed in parliamentand some prisons.

Universities in Italy have adopted thejammers to prevent cheating.

France legalized cell-phone jammers in

movie theaters, concert halls and otherplaces with performances.


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Alternatives to Jamming:

Using things like wallpaper or buildingmaterials embedded with metal fragmentsto prevent cell-phone signals from reachinginside or outside the room.

Some buildings have designs that block radiosignals by accident due to thick concretewalls or a steel skeleton.

Cell-phone alerters and Mobile sniffers areavailable that indicate the presence of acell-phone signal


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Thank U

gyan priyadarshi

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