what is concept of cellphone jammer?
142202
it basicly just jamms the freq. field by buting a content signal on it, exactly like a rido jamed used by us here in the US ARMY signal corps. by putting a constent "keyying" of the net it over rides any incomeing or outgoing signal with in its effective area (both freq spectrim and distance range) but if one is is use it is highly traceable (i know that dont make anyting easier for u but it does here in iraq.) hope i helped some, i dont know a ton on this subject just i was trained, any one with coreections to my answer i would love to know.
695807
To buffer and reduce the noise of people talking, moving, dropping popcorn and using cell phones.
403843
Dangerous.\n\nIt'd be WAY too big of a target for electronic sabotage. Sooner, rather than later, people are going to find ways to bypass any and all security mechanisms that can be placed on the devices and their data stores.
873537
When a person speaks into a telephone, the sound waves created by his voice enter the mouthpiece. An electric current carries the sound to the telephone of the person he is talking to. A telephone has two main parts: (1) the transmitter and (2) the receiver.\nThe Transmitter of a telephone serves as a sensitive "electric ear." It lies behind the mouthpiece of the phone. Like the human ear, the transmitter has an 14 eardrum." The eardrum of the telephone is a thin, round metal disk called a diaphragm. When a person talks into the telephone, the sound waves strike the diaphragm and make it vibrate. The diaphragm vibrates at various speeds, depending on the variations in air pressure caused by the varying tones of the speaker's voice.\n\n\nBehind the diaphragm lies a small cup filled with tiny grains of carbon. The diaphragm presses against these carbon grains. Low voltage electric current travels through the grains. This current comes from batteries at the telephone company. The pressure on the carbon grains varies as sound waves make the diaphragm vibrate. A loud sound causes the sound waves to push hard on the diaphragm. In turn, the diaphragm presses the grains tightly together. This action makes it easier for the electric current to travel through, and a large amount of electricity flows through the grains. When the sound is soft, the sound waves push lightly on the diaphragm. In turn, the diaphragm puts only a light pressure on the carbon grains. The grains are pressed together loosely. This makes it harder for the electric current to pass through them, and less current flows through the grains.\n\n\nThus, the pattern of the sound waves determines the pressure on the diaphragm. This pressure, in turn, regulates the pressure on the carbon grains. The crowded or loose grains cause the electric current to become stronger or weaker. The current copies the pattern of the sound waves and travels over a telephone wire to the receiver of another telephone.\n\n\nThe Receiver serves as an "electric mouth." Like a human voice, it has "vocal cords." The vocal cords of the receiver are a diaphragm. Two magnets located at the edge of the diaphragm cause it to vibrate. One of the magnets is a permanent magnet that constantly holds the diaphragm close to it. The other magnet is an electromagnet. It consists of a piece of iron with a coil of wire wound around it. When an electric current passes through the coil, the iron core becomes magnetized. The diaphragm is pulled toward the iron core and away from the permanent magnet. The pull of the electromagnet varies between strong and weak, depending on the variations in the current. Thus, the electromagnet controls the vibrations of the diaphragm in the receiver.\nThe electric current passing through the electromagnet becomes stronger or weaker according to the loud or soft sounds. This action causes the diaphragm to vibrate according to the speaker's speech pattern. As the diaphragm moves in and out, it pulls and pushes the air in front of it. The pressure on the air sets up sound waves that are the same as the ones sent into the transmitter. The sound waves strike the ear of the listener and he hears the words of the speaker.
883744
Yes I do agree.  I've seen people running stop signs and nearly causing accidents, and seemingly not even realize what they almost did!  All states should have a law against cell phone use while driving.
567030
A cacophony of ringing cell phones is annoying anywhere, but in the classroom it's an unacceptable distraction. A decade ago, it would have been an unheard-of distraction, as well. Few adults owned or used cellular phones then, and even fewer children. \n\nBut times have changed. As the prices of cell phones fall, their use is growing, especially among teenagers. Increasingly, school boards are having to decide how to deal with students who bring these ubiquitous communication devices to school. \n\nIt might seem like a no-brainer to ban student use of cell phones in schools, but few policy decisions are that clear-cut. The necessity for banning another electronic communication device -- the pager -- has been widely understood and accepted. Cell phone bans, however, present a conundrum: During the Columbine shootings, students were able to call for help on their cell phones, drawing dramatic attention to the safety aspects of cell phones. \n\nInexpensive equipment and low-cost family service plans have made cell phones "affordable to just about anyone," says Lisa Ihde, manager of wireless education programs at the Cellular Telecommunications Industry Association in Washington, D.C. Parents want the phones, says Ihde, to communicate with their children throughout the day. The association doesn't know how many of the phones that parents buy go to their children, but anecdotally, cell phone use by teens seems to be on the rise. \n\nSchool boards can find themselves at odds with parents or their communities when forming policies about student cell phones, despite the conviction held by many educators that student cell phones do not belong in school. "Cell phones ringing during a class would be very distracting to the learning environment," says Mary Beth King, vice president of the Plano, Texas, school board. "We are committed to maintaining the sanctity of the classroom." \n\nEven among those who endorse cell phone restrictions, there is disagreement. Some educators believe only a total ban will prevent disruptions. Others argue that bans don't teach children to use technology like cell phones responsibly.\n\n\nCommunity support: \n\nSome school boards have faced dissenting parents over the ban, while others have earned community support. The Plano Independent School District has banned electronic communication devices since 1995. Board vice president King says the board put the policy in place before many students had access to cell phones or pagers. \n\n"Parents have been very understanding about the policy and supportive of [there being] no disruptions in student learning," says King. "We are also very good about facilitating communication, should a parent need to reach the child during the school day." \n\nIn Franklin, Wis., the school board first banned pagers, then broadened the policy to include two-way electronic communication devices. Dave Szychlinski, president of the Franklin School Board, says the broad language was necessary because it could include up-and-coming technology, such as handheld computers like Palm Pilots. "Students functioned well before cell phones," says Szychlinski. "They're not necessary for students in their daily activities." \n\nBefore the Cobb County (Ga.) School Board banned pagers and cell phones in 1997, teachers complained that students interrupted class when they forgot to turn off their beepers or ringers. Also, students talked on the phones between classes. \n\nBoard member Curt Johnston says parents were unhappy at first, but became used to the rule. On the other hand, students complained that they were being punished for the misbehavior of only a few students, a point he sees as valid. "I would prefer to confiscate devices and charge in-school suspensions for in-school users or disrupters on a case-by-case basis," says Johnston, "but not ban possession by students who use them responsibl
920038
with our scanner, we have a frequency that allows you to pick up both sides of your nearby neighbors phone conversation as long as one is talking on a cordless phone.\nwhen we lived near the college, I heard people talking about cooking drugs, cheating on their wife, drunk people,etc.\ni stopped listening when we moved into a neighborhood of mostly retired people. I swear they talk about being constipated and not getting enough fiber, and arthritis... I haven't listened in since\n\nohhh did you know we can pick up baby monitors too? And guess where most parents put one of the radios- in their bedroom!\nat first I thought it was porn or something i was hearing(those kind of sounds ) then I heard a baby!!  It took me a little bit to figure out because they were mexican and didn't speak english, but i could hear what went on in their house 24/7 \nI'm sure most people are unaware of this juicy little fact :-)
176427
A pair of handcuffs attached to something too heavy to move.\n\nDon't let him near a phone.\n\nSeriously, you can't do it.
485501
There are various towers placed to receive the signal from the phone and pass it into a "land line." These towers are placed to divide a city into various "cells" that are served by each tower, and as you move your phone looks for and communicates with the nearest tower.
19694
A missle defense system
470962
either smash your cell or get protection if they dont have that just blosk em its pretty easy.\nDO NOT PANIC!
106067
Cell phones, no matter what technology, use a paging channel with which they detect nearby cellsites and establish communication through control channels, which deliver synchronisation info. The control channel also establishes calls and manages the phone handovers to other cellsites.
379889
It appears to be a device to flash your phone. That is, to re-write your phones memory. To what end, I'm not sure. Maybe to unlock it so it can be used on a different network that it was originally made to. When you buy a cell phone from a service provider it's "locked" by that company so that it can only be used with their network. Which is a crappy practice, since they all use the same frequencies, they could be used on any network if this wasn't done. One could consider it mal-wear, really.
774967
I can't speak to cell phone bans, but I do know that there are laws on the books in many states that specifically exempt on-duty police officers from two-way radio and communicator bans.  Maybe there are similar ones in "hands free" areas that exempt them as well.\n\nKeep in mind, that they _usually_ are communicating with other officers (though that surely isn't always the case).
763866
This probably is of little practical value, since I haven't seen the product I speak of for years.  But it is an idea that might prompt something useful.\n\nThere used to be a product called Call Manager I.  You installed this between the line to the phone company and the phones in your home.  Phones would operate normally.  To call someone on the intercom, you'd pick up a phone and "flash" it.  (quickly press-release a button in the cradle or push the flash button or turn the phone on, then off then on.)  The phone would then emit a noise.   You would then dial 1 -- 1, 2, 3, 4 or 5 times and hang up.  All phones would then start ringing a ring code -- short, short short, short short short, short long or long short.  The person who recognized his ring would pick up.  You, upon hearing the ringing stop, would pick up.  Talk to each other and hang up.\n\nIt also acted as a call forwarding device.  While on a call to an outsider, you could "flash" the phone, enter the code of the person to transfer to and hang up.\n\nFantastic device.  I have one and love it.
362051
Not certain as to what the regulations are in India, but in the U.S., operating such a device is not legal.\n\nJust build an oscillator that works roughly in the same frequency band as the frequencies assigned to cell phones in India.
861697
Hi there:\n\nThe cell phone keyboard with the typical ABC\nis, as one answerer stated, a clone of the Alexander Graham Bell    configuration put out by Bell Laboratories, many years ago.\nAs someone stated, this crude way of using the numbers to\nget " words" was a memonic aid, so that "ASH 277" would be easier to remember, than all numbers. Since there were only a few phones, by grouping 3 or 4 numbers into a word, meant you only had to remember the last few digits, so " ROCK " would be the first area code for 999 phone numbers, and you just had to remember the last three digits.\n ( more Bell Labs trivia - did you know that the # sign is an octothorpe? This is out of a 1967 RED BOOK handbook for Bell Linemen... since then the name has been lost, and no one knows what it is called anymore, not even computer reference guides....   -- and, Alexander Bell wanted a word to sign in on a phone call CLEARLY, and searched around the world for a sound that was easy to recognize - the best he could find was the call for fishermen in foggy weather, who yelled AH - Looo, which reverberated like a fog horn and helped to prevent two sailing ships from hitting each other - He modified it a bit and invented the word " hello ", which never existed in the English language until he had all his operators use it... )\n  \n As for the QWERTY layout of the keyboard, here is a previous answer that I gave... your question is asked repeatedly on the ANSWER forum...\n\n__________________________________\n\nEarly typewriters were mechanically crude and the swing arms that\nhad the letters on the end moved 6 inches or more from a circle around\nthe center of the page. If two arms reached the same strike slot,\nthey jammed together, often bending the thin swing arms.\n\nA group of Engineers was given a typewriter by Remmington in New York, to design a jam- proof machine. Instead, the Engineers looked at a data base of the most used and least used\nletters of the English alphabet.\nThey put the most used letters on the LEFT hand, since most people are right  handed, and the most used letters on the weakest, least used fingers - note that  the letter "A" is on the baby finger on the left hand. The baby finger on the left hand was designated the weakest, most difficult to use finger, while the letter A is always abound across almost all amounts of actual typing.\nThe ploy worked, and typists who were using the common keyboard of the day, with all the letters in alphabetical order, slowed to an absoute crawl.\nRepairs of jammed keys stopped immediately.\nDVORAK was designed to improve typing, and " reportedly " quadruples the words per minute.\nRAND in England designed a keyboard with two bowls shaped to\nfit the human hand natural swing movements, so that the typist\ndoes not "reach" for top row keys and left and right keys, but\nmoves only the fingers, and unlike the old typewriters, which had\nkeys that would have to be pressed down against huge springs,\nabout one to two INCHES, the RAND keyboard had touch-screen like keys, that have no visible movement at all. The words per minute reach 2000, easily, by anyone with a bit of practice.\nToday, on a typical computer, programmers and general public are considered " good " if they can do 30 or 60 words per minute.\nSecretaries start at 120 words per minute.\nMost of the computer people I know still use two fingers, including\nsome of the fastest and best programmers, following the GIGO rule.\n(( Computers use a stack of memory, which programmers fill and recall with numbers, using either FIFO or FILO, First In, First OUT, or First in, Last Out. All early calculators like the HP65 I use, with RPN ( Reverse Polish Notiation) use FILO ). GIGO is a parody of this terminology, with Garbage In = Garbage Out. ie. Typing in huge amounts of poorly written and poorly tested program code, is not as fast as typing in well written, well tested