FM Transmitter as a JAMMER
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Joined: Sep 2010
16-10-2010, 10:43 AM
Kr. Rajeev Ranjan
23290898-FM-Jammer.pdf (Size: 1.85 MB / Downloads: 382)
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
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Joined: Feb 2012
10-02-2012, 09:41 AM
to get information about the topic Simple FM transmitter full report ,ppt and related topic refer the link bellow
topicideashow-to-a-mini-project and implimentation-on-simple-fm-transmitter
Joined: Apr 2012
30-07-2012, 01:31 PM
FM JAMMER.pptx (Size: 625.31 KB / Downloads: 29)
History of Jamming
During World War II ground radio operators would attempt to mislead pilots by false instructions in their own language.
Jamming of foreign radio broadcast stations has often been used in wartime to prevent or deter citizens from listening to broadcasts from enemy countries.
Jamming has also occasionally been used by the Governments of Germany (during WW2), Cuba, Iraq, Iran (Iraq and Iran war, 1980-1988), China, North and South Korea and several Latin American countries.
Why do we need FM Jammer?
To make it difficult or impossible to receive desired signals.
Jamming is accomplished by transmitting a strong signal on the same frequency as that used for communications.
A jamming signal may be intended to block a single frequency --- called spot jamming, or, to block a band of frequencies --- called barrage jamming.
Jammers work by outputting a RF signal at the same frequency expected by the device that’s being jammed, but at a higher power compared to the normal signal.
The jamming signal itself is usually random noise or a pure signal. The device being jammed will then receive the higher power signal which is from the jammer, and then the device can no longer function correctly.
ADVANTAGES AND APPLICATION
Such device can be used to jam detonation of remote controlled explosive devices.
In case of earthquakes, floods or other such circumstances, we can jam the desired frequency band and deliver the message needed to be delivered.
It can be used in military installations like in military headquarters, checkpoints, base camps etc.
We can use it in institutions to jam FM so that no one can use radio while studying.
The device is low cost, and can be used by untrained personnel.