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Shut down the dopey chatter box
2008-08-18

We've all wanted to strangle them before. There's nothing worse than some jerk blabbing away on their cell phone while you're trying to enjoy a movie, meal at a restaurant, or a nice quiet nap on the bus/train ride to work. Actually, only hearing only one side of a stupid conversation makes us pay more attention than normal. Our brain expects information from both sides of a conversation, and it will try to fill in the blanks. You can try to send the offending mobile blabbermouth a few evil looks or the old "courtesy cough" but those passive aggressive gestures rarely work. If you really want to shut down a dopey chatter box, then you'll need to acquire a cell phone jammer.  WHAT IS A "JAMMER"? A cell phone jammer is an instrument used to prevent cellular phones from receiving signals from or transmitting signals to 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. Some cell-phone jammers are made to look like actual phones. Others are briefcase-sized or larger. USING A JAMMER Because jammers now come in much smaller sizes, they are very easy to carry around. Portable personal jammers will fit into the palm of your hand or easily slip into your coat pocket. So the next time someone on your commuter bus refuses to shut up, you can just reach into your backpack and turn on a temporary "dead zone" with your jammer. Then get back to some nice peace and quiet. How It Works Jamming devices overpower the cell phone by transmitting a signal on the same frequency and at a high enough power that the two signals collide and cancel each other out. 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 physics of jamming a cell phone are actually quite simple. To jam a cell phone, all you need is a device that broadcasts on the correct frequencies. Although different cellular systems process signals differently, all cell-phone networks use radio signals that can be interrupted. GSM, used in digital cellular and PCS-based systems, operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 1900-MHz (sometimes referred to as 1.9-GHz) band in the United States. Jammers can broadcast on any frequency and are effective against AMPS, CDMA, TDMA, GSM, PCS, DCS, iDEN and Nextel systems. Old-fashioned analog cell phones and today's digital devices are equally susceptible to jamming. 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. Low-powered jammers block calls in a range of about 30 feet (9 m). Higher-powered units create a cell-free zone as large as a football field. Units used by law enforcement can shut down service up to 1 mile (1.6 km) from the device. MILITARY APPLICATIONS FOR JAMMERS The US military routinely uses jammers to protect secure military areas from electronic surveillance. Jammers can also be used to protect traveling convoys from cell phone triggered roadside bombs in places like Iraq.  THE LEGALITY OF JAMMING In the United States, actively jamming a cell-phone signal is illegal. According to the FCC, cell-phone jammers should remain illegal. Since commercial enterprises have purchased the rights to the spectrum, the argument goes, jamming their signals is a kind of property theft. But there are countries with less draconian rules. France, for instance, seems to turn a blind eye to the active use of cell-phone jammers in movie theaters, and countries such as China, Russia, and Israel either permit use of these technologies, or are very lax when it comes to enforcing restrictions. FINAL THOUGHTS Banning the sale and civilian use of cell phone jammers in the US and UK certainly has its reasons. You certainly wouldn't want someone's jammer blocking a 911 phone call you're trying to make. For example, a jammer hypothetically could be used by criminals who break into homes and want to prevent any calls for help. However, jammers can also be used for good. Spanish terrorists used cell phone triggered bombs in the 2004 Madrid train bombings. Just think someone using a cell phone jammer who was only trying to protect themselves from a mobile blabbermouth could have prevented the bombing and saved hundreds of lives. Maybe someday governments will relax their restrictions on jammers and they will become standard in places like churches, movie theaters and courthouses. Until then, only government personnel, and outlaw jammers will be able to enjoy some peace and quiet at the movie theater or the ride via public transportation to work.

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