PLA Forums
Other Stuff That Has Little To Do With PLA => General Discussions => Topic started by: judasiscariot on November 04, 2007, 05:41:37 AM
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I saw this link on Digg today. It's about a man that uses a device to emit a strong radio signal to block any cell phones within a desired radius in order to silence the conversation of one annoying valley girl. It also segways into a nice piece about how this is a FCC no-no.
http://www.nytimes.com/2007/11/04/technology/04jammer.html?_r=2&ex=1351828800&en=e80e8e8d2c6a9275&ei=5088&partner=rssnyt&emc=rss&oref=slogin&oref=slogin
(I posted this here instead of 'Phone News' because this is General Discussion god damn it. More activity as well. Ban me!)
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Clients, he said, include owners of cafes and hair salons, and a New York school bus driver named Dan. “The kids think they are sneaky by hiding low in the seats and using their phones,†Dan wrote in an e-mail message to Mr. Thakkar thanking him for selling the jammer.
What's the point in that? He should be happy that some kids are quietly talking or texting instead of talking out loud to their friends all around them. What a waste of his money.
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Can you hear me now? NO! Good,†the purchaser of a jammer wrote last month in a review on a Web site called DealExtreme.
That's right near the thread about how the pla is a bunch of elitist jerks for removing the jammer thread.
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Can you hear me now? NO! Good,” the purchaser of a jammer wrote last month in a review on a Web site called DealExtreme.
That's right near the thread about how the pla is a bunch of elitist jerks for removing the jammer thread.
You reminded me of that and it made me giggle.
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It would be a good thing to have when you're behind those people on the road that can't drive and talk at the same time.
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I wonder if something similar could be used to block radar. Like if you were transmitting a very powerful signal on the same frequency as the radar gun would it affect it so that you'd be invisible to it?
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I wonder if something similar could be used to block radar. Like if you were transmitting a very powerful signal on the same frequency as the radar gun would it affect it so that you'd be invisible to it?
In order to do this you'd need two line of sight transmitters mounted inside the car windshield at 40 and 320 degrees with some sort of power source hooked up to it. I'm not sure on the technical details of the wavelength and frequency but I'm sure you could accomplish some jamming this way.
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I wonder if something similar could be used to block radar. Like if you were transmitting a very powerful signal on the same frequency as the radar gun would it affect it so that you'd be invisible to it?
That's a good question. I'm sure it's possible.
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I wonder if something similar could be used to block radar. Like if you were transmitting a very powerful signal on the same frequency as the radar gun would it affect it so that you'd be invisible to it?
From this site (http://www.laserveil.com/radar/jammers/): "Active radar jammers work on the principle of interfering with or overwhelming the doppler shift that occurs from the reflected radar beam that police RADAR guns require to obtain a vehicles speed."
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"While active radar jammers are most certainly illegal (unlike laser jammers), they are mostly ineffective, especially against the latest digital RADAR guns."
So even if you had one it probably wouldn't work these days.
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My uncle has one in his super fancy porche, it works. Maybe its fancier than what that article is talking about.
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I guess I'll have to hold off on my plans for a warp engine go-cart.
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I have a 4 cylinder that I pulled out of an old car that a friend wants to put in his go cart. Keep an eye on the Darwin Awards folks.
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I have a 4 cylinder that I pulled out of an old car that a friend wants to put in his go cart. Keep an eye on the Darwin Awards folks.
It can be done. I don't know what kind of go cart he's planning on using but I would suggest reinforcing it everywhere so that it's basically a roll cage on wheels. The engine is going to make a lot of tourque (At least in proportion to the size of what it's pushing.) too so make sure that axle and everything is strong enough to withstand it. Is the engine from a FWD car? If it was front wheel drive that will actually make it a lot easier to do since he won't have to cut a drive shaft down to fit the shorter distance. It would be a lot of work and take some careful planning but if done right could be the sickest go cart EVAR.
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I just keep a gun in my car. If a cop around here tries to write me a ticket, BLAM! In the face. The cops around here know to leave me the hell alone.
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http://www.brad-carter.com/archives/2006/03/hes-got-a-gun/
It's true!
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...uses a device to emit a strong radio signal to block any cell phones within a desired radius in order to silence the conversation of one annoying valley girl...
You used to be able to do this with a ham radio using some quick math. Find the transmit frequency of the desired cell phone with optimally a frequency counter, a nearfield receiver or the ham radio itself (discussed below). Take that frequency, add 45 MHz and divide by 2. 45MHz because the tower transmits 45MHz above what the portables do. When you divide by 2, you should have a frequency that most dual band (or 70cm monoband) radios can transmit on with a mod. When transmitting, the first harmonic will be on the same frequency the cell phone is receiving on and if you're close enough you could easily overcome the cell tower and cause the phone to drop call. Of course, that's not so easy now with most phones digital and many in the PCS block at that. A first order harmonic is weak enough as it is and each multiple beyond this gets increasingly weaker thus much more difficult to overcome a transmission on a primary frequency.
You might ask how can you listen to an analog cell phone on a ham radio when the frequencies are blocked. A lot of ham radios, although the cell frequencies are blocked, you could still receive cell phone signals imaging onto another frequency. For example, let's say the ham radio had an IF of 41.85MHz and the cell phone was transmitting on 833.1, the ham radio's LO is at 791.25 mixed with the IF to make 833.1, but the radio's CPU blocks 833.1 from being entered on the keypad. But a superhet receiver "receives" at the IF frequency above and below [abs(f − fLO)] so if you could tune to 833.1 you'd actually be listening to 833.1 AND 749.4 and the 749.4 would be filtered out with some filters. With that in mind, you can tune your radio to 916.8 (which isn't blocked) making the LO tune to 874.95 and you'll receive both 916.8 and 833.1. Now 833.1 would be filtered out with some bandpass filters but usually a person within an earshot with a cell phone will give a plenty strong enough signal to overcome those filters. On top of this, many ham radios have poor filtering outside of the ham bands anyway.
As for interfering with radar, a strong signal could very well overload a radar gun's receiver, especially if it was very powerful and broadbanded but many radar guns have an audio out where they can hear when something is interfering. Plus, if you are watching a bunch of cars and see what their speeds are, it wouldn't be hard to visually determine that someone is driving over the speed limit, especially if they were going 15+ over. Also, you would lose your ability to detect radar. You would have to transmit like this on every radar band used. You would also set off every other persons radar detector around you which could slow down the flow of traffic. It's also probably not too safe to sit around higher powered microwave transmitters for extended periods of time unless you plan on growing a third testicle.
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That post just gave me a woody
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...uses a device to emit a strong radio signal to block any cell phones within a desired radius in order to silence the conversation of one annoying valley girl...
It's also probably not too safe to sit around higher powered microwave transmitters for extended periods of time unless you plan on growing a third testicle.
I always wanted a third testicle.
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Then we could call you E.T.
I remember in Batman Begins they use a giant microwave generator to make all the water vaporize and spread weaponized hallucinogens across all of Gotham City.
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Then we could call you E.T.
MEEP MEEP MEEP!
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I just keep a gun in my car. If a cop around here tries to write me a ticket, BLAM! In the face. The cops around here know to leave me the hell alone.
All this time I thought you just hack the Gibson and connect into the cop's TNI box and intercept any incoming phone calls. *police*
MIB