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Mobile Phone Squelchers – - Register readers weigh in

Jammit Dammit

Thanks to all the readers who filled in the gaps on my recent piece on phone jamming(Mobile Squelcher jams cellphone calls). Now here are some answers. The Israeli company which makes mobile phone jammers is called Netline Communications and its squelcher is called C-Guard. And there's an article about C-Guard in New Scientist But as reader dunking Ben Rose points out, C-Guard makes quite a large device to be used in "restaurants, cinemas, theatres etc. It was also apparently "smart" and so might let calls through to certain phones eg. those of doctors. " SESP, A British security company with a vaguely sinister Web site also flogs jammers for commercial and private use, says technical consultant Fraser Smith. South Africans love squelching mobile phone calls, according to Craig Blanckenberg, who sends us the following links: In South Africa we use on people who use their cellphones while driving the Rooikat-76 or for those with less of a budget or who don't like demolishing buildings to get to illegal cell users (which the Rooikat does very well) you can try the C-Guard. Register Factoid 63: The Rooikat76 is an armoured personnel vehicle. It has also happened in Africa as a "competitive business practice", as this link sent by Ken Hendrickson shows. There could be a bit of an Oriental theme to squelching phones, according to Mark Vanstone, a Brit who has lived in Hong Kong "for 10 years. One of the things that needs to be put in context here (lest the guy (Mobile Phone Squelcher inventor Anil Vora) look like a complete asshole) is that Hong Kong people do not have the same value set as most Brits, and frequently answer, or sometimes even make cell phone calls (loudly as you would know from eating Dim Sum in China Town) whilst watching a movie in a cinema, and at the very least one can expect to hear many pagers go off. You would think that cinemas would forego the 'asking' to turn off phones, and actually install a Faraday cage in the brickwork". Looks like there's huge demand for mobile phone jammers in Japan where a company called s Medic Inc. peddles the Wave Wall.. Check out this link sent by afficionado Jim Mitchell. Even better, he says, try out the following search: Ken Hendrickson suggests you try searching for Japanese Movie Theatres. Search for "Kengai-kun" or "Nikko-do" in the following links: and Sometimes mobile phone jamming happens by accident. But from the several dozen emails we've received from readers wanting to buy the Mobile Squelcher, an awful lot of you out there want to jam mobile phones on purpose. Broadcasting and satellite communications engineer Paul Stimpson confirms my suspicion that the legality of this device is "questionable. Provided its transmissions can't be detected outside your premises you may be able to use it (but you would still almost certainly need an official licence - which is about as likely as pigs achieving unaided sub-orbital flight) but if it causes trouble for someone standing 6 six inches outside your door then the DTI/RA would be most interested in "having a little chat" with you. Allan Stokes disagrees with my contention that fights will break out between phone jammers and phone jammees. "The point of having such a device is NOT to be ostentatious (if that was your goal a cell phone would do just fine). Hide it in your briefcase and disable commuter train calls. Not every day. Just on days when the market is topsy. That's the best way to use it. Very hard to catch." Dave Preston takes issue with my comments about the inventor "having a problem, I probably get out less than he does and boy do inconsiderate jackoffs with cell phones irritate me, primarily in restaurants and movie theaters. I'm not overly concerned with people walking down the street jabbering away into thin air...hell, Tesla'd be proud...but there are more than enough people with those phone who have no consideration of others." Register Factoid No.64 Nikolai Tesla was the 19th Century pioneer in the study of electromagnetism. All right then, why don't you just go ahead and make your own Squelcher, just like Ken Shimmin. "Just out of interest," he writes,"I made a crude mobile phone jamming device once - it consisted of using my computer to generate white-noice signal at a multiple of the frequency of the mobile phone, then running the output from my soundcard through a powerful audio amplifier, to which was attached, instead of speakers, a radiator (yeah, I know it sounds odd...) "This crude system broadcast a very strong signal around the radiator, disrupting a mobile phone (it probably simply swamped the phone's noise control circuits). The range extended for about 20 meters from the radiator, and people outside could be seen shaking their phones and looking puzzled. The range was actually better than I expected, but I suppose that comes from using an amp that is much more powerful than the mobile phones. "Needless to say I only tried it out a couple of times... the things we do as students! I must have been very bored that day." This seems an appropriate time to resurrect one of our more popular stories Build your own Klingon Disruptor Register Bulletin Board stalwart and retired phone jammer Bill Jackson weighs in with some useful pointers. " The older analog phones are far easier to jam. All that is needed is a multifrequency oscillator that puts out a small signal on each channel. This will make the users system see a busy network and knock him off the air. Spread spectrum CDMA is far harder to jam and I suspect that squelcher does not do that mode. To jam spread spectrum you need to make a frequency agile unit that will fill the available frequencies with fake signals that resemble genuine signals at a high enough level that the system finds it hard to establish a frequency spread pattern. This may take 100 times more power than an actual cell phone will put out since you have to make all the possible frequencies unuseable. This is very hard to do, even the military has a hard time jamming CDMA signals. Years ago I used to make a jammer for Satellite broadcasts of champion fights to jam the small bars that had bootleg decoders. This was easy since the space signal is micro micro volts and then needed a 12 foot dish. So I made a small 1/4 watt voltage controlled oscillator that went from 3.8 to 4.2 gigahertz driven by a voltage ramp from a 555 timer at a 200 sweeps per second rate. The whole thing cost about $20 and I sold them for $200 would buy 20-30 pieces and then find out what bars were offering to show the fight and who had not paid his fee ($2000, up, depending on seating). And then he would send a person to place one of these about 200 feet SW of the satellite dish and turn it on after the preliminary warm up bouts, just as the main event was starting up. Talk about riots and anger. The bar owner was charging $20-50 per head as well as selling drinks and all these angry drunks wanted their money back. Of course Bill Ballard (the license holder who bought the units) said that it was advanced scrambling technology in the transmitted signal, etc etc. He and I had many a chuckle over the stories of the fights that broke out when the video went west. The only problem was the fact that I should have made sealed units that would break after one use so I could sell him more next time, or better yet rent them. Hey I was young and foolish, but it paid the rent and then some. They soon went to an encrypted digital method that made it impossible to crack the signal and they still cannot crack the expensive pay per view direct satellites stuff. Each decoder box costs about $10,000. Domestic DBS satellite stuff can be cracked as the box has to be so cheap they can sell it for $200 and that will not permit the fast CPUs and other parts to decrypt video in real time. " But what kind of guy would invent such a mobile phone squelcher? Alan Stokes, a self-confessed trainspotter, wonders if Anil Vora, is the same guy as the " Anil Vora who went to school in the early eighties at the University of Waterloo in Ontario, Canada. He was tallish, thin Indian pursuing a degree in stock speculation. He's the kind of guy who could be found living just about anywhere. Hong Kong: no problem." How common is this name, he asks? Could c-guard have anything to do with the "guy at Hertfordshire University", asks Kemal Bayram, "who designed exactly that product for a course project about two years ago.. I heard he ended up selling it to some security company in Israel after no one in the UK was interested in buying the design (go figure)". Or can we pinpoint the birth of the phone jammer on Marc Abrahams, who claims it was all a joke. "You might be interested to see the original idea for this: my humor column in the late, lamented Byte Magazine. The column is still up on the web here. Sincerely and improbably, Marc Abrahams Editor Annals of Improbable Research (AIR) PO Box 380853 Cambridge MA 02238 USA" AIR runs the annual Ig Nobel awards. Find out more at ®

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