Guys, let’s leave Carl the Criminal alone. We don’t want this rethread relocked :smack:
It seems to be. Here’s the point: sure, when I change a CD I look away from traffic and am distracted. As distracted as using a cell phone, I concur. But, there’s two things- the act of changing a CD takes a minute, while some dudes talk for hours - start to end- on their cell. So, over an hour drive, the cell phone is 60 times more distracting. Then again, when I know I am about to do something weird while driving, I can up my vigilence and concentration for a few minutes. You can’t do that for an hour conversation.
So sure- there are many things which are just as distracting as using a cell phone is. But I can’t think of any which are done for hours and hours, the entire length of a trip. So, sure dudes, if you need to make that 30sec call home to tell wifey that you’re stuck in traffic and you’re going to be late- fine. But the ceaseless yap yap yaping is dangerous to you-* and *to me, and you have no right to endanger me.
Cell phone driving is as dangerous as driving mildly drunk. Even Mythbusters agrees.
If Carl got pulled over and felt an alteration was inevitable, it seems like a pretty smart plan to disable the police officer’s only means of calling for help. He could then, ‘deal with the cop’ (i.e. tie him up or what have you) and go on his merry way. There would be no need to have the jammer on constantly so he couldn’t be tracked.
Lets say Carl just robbed a bank within the last few days, and has the option of either driving around without a jammer, or bringing one along. It seems incredibly prudent to have one available so that in the event that a single patrol car pulls him over, he can ‘deal with the situation’ before it gets out of hand.
Now there must be some military technique to overcome my little scenario here, because I imagine its probably a reality in the theatre of war.
Several people have mentioned copper screening used as shielding. Would aluminum screening be that much less effective? How about the aluminum screening used on many house windows to keep the bugs out when the windows are open? Is it the aluminum content that would make it less effective or that the screening is not heavy enough?
It’s not so much the material, as long as it’s electrically conductive, as it is the dimensions of the openings. The interior cavity of a microwave oven, for example, is an effective Faraday cage for microwave radiation at 2.45 GHz, even though the material is generally some sort of steel. Steel is much less conductive than either copper or aluminum, but it works just fine to contain the microwave radiation. The important thing is that the longest dimension of any single opening is much smaller than the wavelength of the EM emissions to be blocked, and the cage is electrically continuous and completely surrounds the area to be shielded.
I thought the most dangerous thing about cell phones was the dialing and the answering. And the whole frantically trying to get to it when it starts ringing in your pocket or something.
How is talking on the phone more distracting than talking to a person sitting next to you? They only thing I’ve seen cell phone drivers to while talking is drive really slow. The swerving into other lanes and other really dangerous stuff comes from dialing or text messaging.
What’s so bad about talking? Isn’t that why states that outlaw cell phones in the care make exceptions for handsfree devices? On military bases, you can’t have a phone up to your ear, but you can talk on the phone via hands free all you want. (While driving, I mean)
How is the act of carrying on a conversation as dangerous as being drunk?
in every test/study I have come across the act of talking on the phone while driving is very very distracting and yes its much more distracting than talking to a person in the car.
one reason is even with a strong signal its hard to hear the person on the phone so you shift your attention from your eyes on the road to your ears on the phone as your primary focus, another is that the person on the other end will keep talking no matter whats going on because they cant see that huge truck about to crush you to death since they are miles away.
hell the DoT did a study that confirms this.
Cite?
We use several different police radios at work and none of them frequency hop. I think you may be confusing frequency hopping with trunking
There are web sites with build your own plans.
There are some individuals who would argue that the reason cell phone jammers are illegal in the US is because of Congressional sell-out to business.
What’s the difference between the two? I just read the trunking cite and it sounds similar to frequency hopping.
My understanding is that frequency hopping changes the frequency during the broadcast, while with trunking, the entire broadcast is done on the same frequency.
Will Repair- what about the concers I mentioned? Not much of a sell-out to business there.
Anyone?
It would be very leaky. A Faraday cage is only effective of the longest dimension of any opening is a small fraction of a wavelength long, but windows and doors are typically several wavelengths long at cell phone frequencies in all dimensions. There might be some attenuation of the received signal, depending upon the orientation of the transmitting cell towers in relation to where the user is standing in the building, but chances are there will be enough signal coming in through the relatively huge gaps provided by your unshielded windows and doors, and reflecting off the interior of the walls to allow a decent connection. Even in an elevator, which is pretty well enclosed by metal walls and doors, there are sufficient gaps to allow decent reception in many cases. I’ve been able to make and receive calls in some elevators many times.
Then how come I lose all reception whenever I go inside a Wal-Mart? Whatever they are made of, it is damn near cell-proof.
I guess a church is out of the question, then. Would it be possible to shield a theatre? All the space is surrounded by solid walls and doors so it could all be “meshed”. How hard is it to seal doors and ventilation openings? Is it a NASA/Intel level of endeavour or is it something that could be done under a reasonable budget?
Because Walmart is evil.
More seriously, it’s likely because Walmarts tend to be in very large buildings with few, if any, windows and only a few doors. The construction is usually steel-framed with a corrugated steel roof, so if your local tower isn’t close by and is not in a line of sight with one of the few openings, you won’t get much signal when you’re well inside the building. Plus, there’s likely to be a large amount of electrical noise due to all the lighting and equipment in operation, which can interfere with good reception, as well. IME, reception in large, windowless buildings like that is a crap shoot that I usually lose.
Any large holes, in comparison to the wavelength, severely compromise a faraday cage. That includes things like doors, windows, and ventilation ducts.
A jammer can be as small or large as you like, depending on money available, functional and power requirements. They can be primitive or very sophisticated. Electronic warfare has been a very active area of research and development for many decades.
So, what would it take (power-wise and equipment-wise) to jam ALL frequencies in the given area? Is this something that could be fit in a briefcase? A car? A semi trailer? Would it take an entire building?
-Joe
That is because the Cell Phone companies are a HUGE lobby. They fight tooth and nail over any “driving while dialing” law. “Hands-free only” laws will not put a large nasty dent in their profits, so they don’t fight quites as hard against them.
It’s entirely political, :rolleyes: it has been shown that talking on the phone while driving is as dangerous as being just “under the influence”. Not stinking drunk, but “0.8” type DUI.
Next, you’ll claim that “hand-free drinking” while driving isn’t any safer either!
-Joe, 