Devices Enforce Cellular Silence, Sweet but Illegal

There are better ways than jamming to deal with rude people on public transportation. There are plenty of people who are able to use their mobile devices, including cell phones, in a way that does not disrupt others.

As most of us technical people know, there is no need to talk loudly into a cell phone. The level of volume of your voice in no way alters the strength of the transmission. Thus, it is perfectly possible to use a cell phone without disturbing others.

When some cretin uses a jammer, he disrupts everybody who uses a mobile device. Sooner or later, this is going to interfere with emergency communications and people will die as a result.

As for the cretins who have long, loud, and non-critical cell phone calls on public transportation, the way to deal with it is public humiliation. Around here, the biggest offenders are lawyers, executives, and trophy wives -- all of whom are quite vulnerable to well-placed barbs.

-- Mark --

is two wolves and a sheep deciding what to eat for lunch. Liberty is a well-armed sheep contesting the vote.

***** Moderator's Note *****

I doubt that jamming cell phones on the commuter rail or underground is going to endanger anyone's life: in the first place, the railway workers have two-way radios that work on separate frequencies well away from the cellular bands, and in the second, I doubt anyone in a train wreck thinks of dialing 911.

"Public humiliation" is not, IMO, a way to deal with cell phone users on public transportation. If I tried to do that, I would know going in that the _best_ result I could hope for would be a temporary silence, and only from _that_ particular cretin I took the risk of offending.

Telling another passenger to be civil is a risk that most office workers aren't willing to take. It's all very nice to imaging that we're all super-heroes with a cape under our business suit, but the ordinary world isn't like that, and ordinary people aren't like that.

This isn't the wild west, after all: men do not go around armed and are not usually prepared or inclinded to start fights with strangers. It's no good to say "Change your seat" - seats are precious on the commuter rail at rush hour, and so is the chance to tune out (pun intended) and have a few minutes of quiet time to oneself.

What we're seeing here is just another wave of resentment against an ever-more-intrusive world. It seems that, overnight, everybody else put us in charge of listening to their voice mail messages and suffering the inconvenience of preparing a response. Overnight, we were all expected to become like the Oracle at Delphi, as fax machines and emails demanded that we reply instantly and competently to anyone demanding information, or a decision, or anything else. Overnight, our weekends vanished and were replaced by home offices that have become just another place to joust with the world. Overnight, so it seems, the very idea that people need, deserve, and are entitled to peace and quiet while among strangers has vanished. It's a shame.

Bill Horne Temporary Moderator

(Please put "[Telecom]" (without the quotes, but _with _ the brackets) in your subject line, or I may never see your post.)

[moderator snip]

Some upscale restaurants and sensitive offices have installed mesh screening in the walls and special glass in the windows that blocks wireless. That is perfectly legal.

Jammers are legal in Mexico and are installed in many churches. ;-)

***** Moderator's Note *****

Passive screening can only be done to fixed locations, and it's expensive: you have to build a Faraday cage around the whole restaurant, including the kitchen and restroom vents and the doors. That means that only expensive restaurants can afford it, and it's paradoxical that they're the least likely to need it: upscale restaurants attract upscale customers, who are, I would hope, more mindful of the rules of etiquette.

Jamming is a lot cheaper, so I expect it to become a bigger problem as time goes by. The original issue of cell phone use on public transportation, which is the one that raises my hackles, will almost certainly create more demand for portable jammers.

If jammers are legal in Mexico, that begs the question of whether Mexico uses the same system(s) as the U.S. Sorry to be ignorant, but I'm not familiar with the cell system in Mexico. If it's the same (CDMA, TDMA, AMPS, ??), then someone in Mexico must be doing a land-office business in portable jammers.

Bill Horne Temporary Moderator

Mexico uses the same mobile bands as the US and Canada, CDMA and GSM at

850 and 1900, and iDen at 800. They recently changed the numbering and billing to caller pays, but that didn't change the technology.

If you jam the GSM 900 and 1800 bands, the AMPS 850 and PCS 1900 bands (used for GSM and CDMA in North America) and iDen 800, you'll get most mobile usage in the world except for Japan and a few old 450 networks. I gather that's what the portable jammers do.

Also, how good of a Faraday cage would you really need to block phone usage in a restaurant? Seems to me that the bands are high enough frequency that the transission is straight line, so if you could figure out where the towers were, you could put strategic areas of grounded screen to block the paths without enclosing the whole place.

Regards, John Levine, snipped-for-privacy@iecc.com, Primary Perpetrator of "The Internet for Dummies", Information Superhighwayman wanna-be,

ex-Mayor "More Wiener schnitzel, please", said Tom, revealingly.

***** Moderator's Note *****

The only experience I had with Faraday cages was when NYNEX built one around the microwave ovens in their cafeteria, due to concerns about possible interference with pacemakers.

IIRC, the theory was that any opening greateer than 1/4 wavelength was unacceptable, but it's been a few years. We used copper screen, which looks exactly like window screen, and soldered it together at the edges. It must have worked: the guy who measured the radiation gave us high marks, although we didn't do anything with the entry/exitways.

Bill Horne Temporary Moderator

The few offices that have done it in NYC don't have an entry/exit problem. ;-)

There was a "Criminal Minds" episode where the killers used a pocket jammer to disable the victims' cell phones - modern version of cutting the phone wires.

Law and Order did the flip side last season. A NYC office suite with their competitors in the next skyscraper. They had the whole thing done, windows and all.

Speaking of Faraday cages, I watched them build the room for an MRI. It had a full Farady cage around it because the room has to be RF quiet since the magnets just get everything aligned while the RF signal from the atoms spinning down is very faint.