30-03-2012, 12:12 PM
Mobile phone jammer
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Introduction:
A mobile phone jammer is an instrument used to prevent cellular
phones from receiving signals from base stations. When used, the jammer
effectively disables cellular phones. These devices can be used in practically any
location, but are found primarily in places where a phone call would be particularly
disruptive because silence is expected
Operation
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).
Antenna
Every jamming device has an antenna to send the signal. Some
are contained within an electrical cabinet. On stronger devices,
antennas are external to provide longer range and may be tuned
for individual frequencies.
Circuitry
The main electronic components of a jammer are:
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
Application
Cell Mobile Phone Jammer provides the ultimate solution in any area where
cellular communications frequently cause nuisance either by loud incoming call
rings or loud telephone conversations. cell mobile Phone Jammer is suitable in
executive offices, board meetings, conferences, seminars, libraries, cinemas,
religious places, public transport, concert halls, restaurants and educational
institutions etc.
Conclusion
This project is mainly intended to prevent the usage of mobile phones in
places inside its coverage without interfering with the communication channels outside its range, thus providing a cheap and reliable method for blocking mobile
communication in the required restricted areas only.