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Would it disable an annoying car alarm?
by greenhatman 10y ago
Would it disable an annoying car alarm?
- nickpsecurity 10y agoOr stereo or subwoofer? I find that an interesting concept.
- Steeeve 10y agoFor stereos, use an AM transmitter and send your neighbor dora-the-explorer theme music on repeat.
- dotancohen 10y agoCan am AM transmitter be made directional though? Otherwise the power would be forbidding, and the collateral damage would be worse than the cause.
- kec 10y agoSure it can. Phased shifted arrays of monopole antennas are often used to steer broadcast signals in a particular direction (If you've ever seen a group of 2-3 radio towers sitting close together in the country side, that's what they're doing). That said: if you're in the US and transmit outside of the ISM bands or at anything above about a few hundred milliwatts of power, you risk the FCC coming down on you with some hefty fines or jail time.
- jacquesm 10y agoAM is used to describe a frequency range here (the 'AM Band'), but it is actually referring to 'Amplitude Modulation', a way to superimpose the signal on the carrier wave. You can do 'AM' at any frequency and your ability to direct the radio waves goes up as the frequency goes up. AM transmitters at the frequencies associated with the AM band (550-1600 KHz) can be directional, in fact, every antenna is more or less directional. What makes it tricky is that at those low frequencies the antenna elements are very large, and this is what will play havoc with any attempts to make a directional antenna for the AM Band that is still practical to use for the purpose described here. So in all likelihood you'll end up upsetting all your neighbors instead of just the one you're targeting.
- nickpsecurity 10y agoGood idea. Too many are using MP3 or streaming now, though. We need something for that.
- Steeeve 10y agoA focused AM transmitter will send it directly to the speakers. When you're close enough to the towers, you can hear the transmissions on leaves.
- nickpsecurity 10y agoLeaves? Hows that work? Ive seen a person do it with jumper cables but do you have a video of that? Note: I also have a new theory behind schizophrenia diagnoses about trees talking to people.
- Steeeve 10y agoBest I could do put on the spot: http://www.dailymail.co.uk/sciencetech/article-3276974/Incredible-video-shows-foolhardy-Ukrainians-listening-radio-just-touching-WEEDS-against-50-000-watt-transmitter-station.html http://www.dailymail.co.uk/sciencetech/article-3276974/Incre... It's actually touching the tower though. (and I have no idea how it works)
- nickpsecurity 10y agoI thought you meant plants nearby. Ive seen that trick. Same as jumper cables. What the latter appeared to do what (a) get conductor close enought to it for spark to jump, (b) spark superheats/vibrates the air in way corresponding to waves its carrying, and (c) those sound waves reach your ear. This is what I gathered as someone without RF training but knowing how sound usually forms.
- deleted 10y ago[deleted]
- sargun 10y agoYes, or the entire car: https://www.youtube.com/watch?v=cuus8OtPY0w https://www.youtube.com/watch?v=cuus8OtPY0w Vehicle disabling EMPs are of great interest to the likes of CHP, and such.
- userbinator 10y agoThat would probably be completely ineffective on something like an old-school fully-mechanical diesel, which will run as long as there's fuel and air. I suspect a lot of military vehicles use those for the same EMP-proofing reason.