Cell phone jammers are devices that create a temporary 'dead zone' for cell phone signals. They work by transmitting radio signals on the same frequencies as cell phones, disrupting communication between phones and cell towers. Jammers were originally developed for law enforcement and military use but can also be used in places where silence is needed, like hospitals, schools, and theaters. They block cell signals within a range of 30 feet to 5 miles depending on the model. While jammers have valid applications, their use may be illegal or cause problems in emergencies if all signals are blocked in an area.

2. Introduction
 Cell phone jammers are devices that create a temporary "dead
zone" to all cell phone traffic in their immediate proximity.
 A mobile jammer is an instrument which is used to prevent mobile
phones from receiving signals from the base stations.
 A jamming device transmits - same radio frequencies of greater
power as the cell phone, disrupting the communication between the
phone and the cellphone base station in the tower.

3. Introduction
( Continued . . . )
 Practically it can be used at any location but used mostly in places
where silence is expected.
 A cell phone works by communicating with the service network
through a cell tower as base station.
 Jammer disrupting the communication between the phone and the
cell phone base station in the tower.
 Originally developed for law enforcement and the military to
interrupt communications by criminals and terrorists.

4. History
 Mobile 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.

5. Cell Phone
Jamming
Device
 Jamming devices overpower the cell phone by transmitting a signal
on the same frequency
 Power of the signal should be high enough so that the two signals
collide and cancel each other out.
 The phone is tricked into thinking there is no service because it can
receive only one of the frequencies.
 Mobile phone jammer block cell phone use by sending out radio
waves along the same frequencies that Mobile phones use.so
mobile phone would simply appear out of range.

6. Cell Phone
Jamming
Device
 Most Mobile phones use different bands to send and receive
communications from towers. Jammers can work by either disrupting
phone to tower frequencies or tower to phone frequencies.
 Mobile jammer operates in the 900 MHz and 1800 MHz bands in
Europe and Asia and in the 1900 MHz in the US.
 It is a device that transmit signal on the same frequency at which the
GSM system operates, the jamming success when the mobile phones
in the area where the jammer is located are disabled.
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7. Cell Phone
Jamming
Device
 The radius of cell phone jammers can range from a dozen feet for
pocket models to kilometers for more dedicated units.
 Older jammers sometimes were limited to working on phones using
only analog or older digital mobile phone standards.
 Smaller handheld Mobile jammer block all bands within a 30-foot
range (9 meters). The TRJ-89 jammer can block cellular
communications for a 5-mile (8 km) radius.
(Continued . . . )

8.  Cell phone jammers work in a similar way to radio jammers by
sending out the same radio frequencies that cell phones operate on.
 This creates enough interference so that a call cannot connect with a
cellphone.
 It causes enough interference with the communication between cell
phone and base stations in the tower .
Principle of
Operation

9. Principle of
Operation
 2 types of jammers. The first type are usually smaller devices that
block the signals coming from cell phone towers to individual cell
phones.
 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.
(Continued . . . )

10. Principle of
Operation
 A cell phone works by communicating with its service network
through a cell tower or base station.
 Cell towers divide a city into small areas, or cells. As a cell-phone
user drives down the street, the signal is handed from tower to
tower.
(Continued . . . )

11.  Portable Mobile Jammer
Types of cell
phone jammer
device
 Remote Control Cell Phone Jammer
 Adjustable Cell Phone Jammer
 School & Prison Phone Jammer
 Explosion - Proof Cell Phone Jammer
 Police & Military Phone Jammer

12.  Noise Strategy: The main idea here is to insert additional noise in
receivers which prevent them from getting the correct information
from the receiving signal. Almost all the techniques which will be
discussed later depend on these strategies
 Phase Strategy: The main idea is to change the phase of signals to
prevent the receivers which uses this phase to receive signal in
correct phase
Jamming
Strategies

13.  Spoofing- in this method the mobile phone is been detected and the
jamming device sends as signal to disable the mobile phone or sends
a message to the user of that phone to switch it to the silent mode.
 Shielding attacks- this is EMF shielding of the mobile phone signal
in which phone cannot transmit or receive any RF signal from
outside.
Jamming
techniques
 Daniel of service-in this DOS technique the device transmits a noise
signal at the same operating frequency of mobile phone in order to
decrease the SNR of the mobile. This is the simplest technique and
is very common.

14.  Cell phone jamming devices were originally developed for law
enforcement and the military to interrupt communications by
criminals and terrorists.
 During a hostage situation or drug raid police can control when and
where a captor can make a phone call.
 Cell-phone jammers can be used in areas where radio transmissions
are dangerous.
Application

15.  Corporations use jammers to stop corporate espionage by blocking
voice transmissions and photo transmissions from camera phones.
 Can be used in the areas like Schools or Academic areas , Exam
centers , Medical facilities , Public libraries.
 Can be used in Govt. offices and High security areas like Prisons ,
Courts , Scientific research labs and Military facilities
Application
(Continued . . . )

16.  To maintain the complete silence in library and lecture hall
Application
 To avoid fraud in examination hall
 To avoid disturbance in class room
 For providing calm and peaceful atmosphere in Hospitals
 Church/Mosques/Cathedral/Temple/Religious establishment
 For providing security in business conference, board of directors
rooms, seminars, etc.,
(Continued . . . )

17.  Police can block phone calls during a drug raid so suspects can't
communicate outside the area.
 Restricts explosion of cell phone triggered bombs .
 Provides security in business conference, board of director’s rooms,
seminars, etc.
Advantages
 Avoids fraud in examination hall.
 Provides calm and peaceful atmosphere in Hospitals , churches ,
temples etc.

18.  Cost oriented.
Disadvantages
 Requires special hardware.
 People feel inconvenience.
 V.I.P.’s may loose some important calls.
 As cell phone jammer blocks all the signals within its working
range, there may be grave consequences in an emergency.

19.  While the law clearly prohibits using a device to actively disrupt a
cell-phone signal, there are no rules against passive cell-phone
blocking.
 Companies are working on devices that control a cell phone but do
not "jam the signal.
Future scope

20.  We can say every device is acts as good aspects as well as bad
aspects.
 In many situations cell phone jammer is useful but at many places
it creates problems.
 Cell phone jammers are very useful to the society for protecting
from anti-social elements.
Conclusion
 It’s overall performance is very good and helpful in our lives.