16-10-2010, 10:43 AM
Prepared by:
Shashank
Kr. Rajeev Ranjan
Kiran Manandhar
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Abstract:
Cell phones and radio receivers are used everywhere these days. It's great to be able to call anyone anytime. But unfortunately, restaurants, movie theatres, concerts, shopping malls and churches all suffer from the spread of cell phones because not all cell-phone users know when to stop talking. While most of us just grumble and move on, some people are actually going to extremes to retaliate. FM Jammer can be one of the solutions to this problem.
A transmitter is a device from which signal is transmitted into free space, after insertion of suitable carrier, i.e. is superimposed on a high frequency-sine wave. In Frequency Modulation, frequency of carrier is varied according to the modulating signal.
The capture effect, or FM capture effect, is a phenomenon associated with FM reception in which only the stronger of two signals at, or near, the same frequency will be demodulated. It is defined as the complete suppression of the weaker signal at the receiver limiter (if it has one) where the weaker signal is not amplified, but attenuated. We are using this principle here to make a Jammer out of the FM transmitter.
Major application of Jammer includes in controlling a hostage situation in which 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. Moreover it can be used in places like Hospitals, restaurants, movie theatres, concerts, shopping malls and churches where silence is required
