Cell-phone users don't know they're being jammed. The phones just indicate that there's no service or no signal from the network. The jammer simply interrupts the phone's ability to establish a link with the nearest cell-phone tower.
Cell phones are designed to add power if they experience low-level interference, so the jammer must recognize and match the power increase from the phone. The actual range of the jammer depends on its power and the local environment, which may include hills or walls of a building that block the jamming signal
Jamming Devices are very basic devices.Power supply Smaller jamming devices are battery operated. Some look like cell phone and use cell-phone batteries. Stronger devices can be plugged into a standard outlet or wired into a vehicle's electrical system. Antenna Every jamming device has an antenna to send the signal. Some are contained rical cabinet. On stronger devices, antennas are external to provide longer range and may be tuned for individual frequencies.
Voltage-controlled oscillator - Generates the radio signal that will interfere with the cell phone signal Tuning circuit - Controls the frequency at which the jammer broadcasts its signal by sending a particular voltage to the oscillator Noise generator - Produces random electronic output in a specified frequency range to jam the cell-phone network signal (part of the tuning circuit) RF amplification (gain stage) - Boosts the power of the radio frequency output to high enough levels to jam a signal
The frequency blocked is somewhere between 800MHz and 1900MHz. Cell-phone users don't know they're being jammed. The phones just indicate that there's no service or no signal from the network. The jammer simply interrupts the phone's ability to establish a link with the nearest 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.
The bombs that blew upcommuter trains in Spain in March 2004, as well as blasts in Bali in October 2002 and Jakartain August 2003, all relied on cell phones to trigger explosives.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.
According to the U.S. the FCC (Federal Communications Commission) When an end-user pays to use that spectrum, jamming the signal is paramount to 'property theft.‘People can't tell the difference between being jammed and simply having poor signal strength.“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 franticallytrying to contact a parent or a someone trying to call for an ambulance.
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. 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.
1. Cell Phone Jammer
RONSON CALVIN FERNANDES
Mail To : email@example.com
MIT – MANIPAL
Cell Phone Jamming device
How Cell Phone Jamming Works
Types Of Jammer Device
Applications of Cell Phone Jamming
Legal Issues related to Cell Phone Jamming
Cell phone jammers are devices that create a temporary "dead zone" to all cell
phone traffic in their immediate proximity.
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.
It's a called a denial-of-service attack.
4. Introduction ( Continued . . )
Disrupting a cell phone is the same as jamming any other type of radio
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.
5. Cell Phone Jamming Device
Jamming devices overpower the cell phone by transmitting a signal on the
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.
6. Jamming Device ( Continued . . )
Less complex devices block only one group of frequencies, Some of the high-
end devices block all frequencies at once.
Low-powered jammers block calls in a range of about
30 feet (9 m).
Higher - powered units - as large as a football field.
Law enforcement jammer units - up to 1 mile
(1.6 km) from the device.
7. Components of Jamming Device
The simplest just have an on/off switch and a light that indicates it's on.
Complex devices have switches to activate jamming at different frequencies.
Main Components :
8. Components ( Continued . . )
The main electronic components of a jammer are:
9. How Cell Phone Jammers Work ?
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.
2 types of jammers. The first type are usually smaller devices that block the
signals coming from cell phone towers to individual cell phones.
10. How Jammers Work ? (
Continued . . )
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
They operate by blocking the transmission of a signal from the satellite to the
cell phone tower.
11. How Jammers Work ? (
Continued . . )
13. Applications of Cell Phone
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
14. Applications ( Continued . . )
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.
15. Cell Phone Jamming Legal Issues
Cell phone jammers are illegal in most countries — except to military, law
enforcement and certain governmental agencies.
It’s a “Property Theft”.
It also represents a “Safety Hazard”.
16. Legal Issues ( Continued . . )
In India - legal, Government, Religious Places, Prisons and Educational
Institutions use jammers
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.
We can say every device is acts as good aspects as well as bad aspects.
Operating or even owning a cell phone jammer is illegal in most municipalities
and specifically so in the United States.
Jamming is seen as Property Theft, Safety Hazard.
In many place cell phone jammer is useful but at many place it is a problem .
But it’s overall performance is very good and helpful in our life.
 "Zone of silence [cell phone jammer]," Spectrum, IEEE , vol.42, no.5, 18,
 Sami Azzam, Ahmad Hijazi, Ali Mahmoudy. ”Smart Jammer for mobile phone
 Mobile & Personal Communications Committee of the Radio Advisory Board of
Canada, “Use of jammer and disabler Devices for blocking PCS, Cellular & Related