Using microwaves to destroy speed cameras.

Using microwaves to destroy speed cameras.

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Discussion

dilbert

7,741 posts

230 months

Saturday 23rd December 2006
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I think X-rays are going to be a better bet if you actually want to damage the camera. For film cameras, you can use the X-Rays to over expose the film, and for electronic cameras you can use the X-Rays to damage the CCD permenantly.

Both solutions involve all of the same HT electronics, but I guess that if you're careful you can design the thing to generate either microwaves or X-Rays. Sadly however both solutions are more likely to cook the user than the camera.

The sad and sorry situation is that a tin of thermite is by far the cheapest, simplest and least dangerous way to achieve the end.

ATG

20,480 posts

271 months

Saturday 23rd December 2006
quotequote all
X-rays and microwaves are miles apart in the EM spectrum. X-rays have wavelengths of the order of 10^-10 metres, i.e. 100 million times shorter than microwaves. Microwaves can be generated by creating a resonating cavity ... i.e. a metal box about the size of the wavelength of the microwave you want to produce. It is very much like using an organ pipe to make a sound. Obviously you can't make a metal box with a resonating chamber the size of an X-ray, so they have to be produced in a completely different way. It's done by accelerating electrons in a synchrotron or by smashing electrons into metal sheets insode a vacuum tube.

dilbert

7,741 posts

230 months

Saturday 23rd December 2006
quotequote all
The basic elements for driving the X-Ray tube and the Magnetron are the same however. I'm not thinking super complicated here, I'm thinking the sort of thing that you could knock together in your shed......

When I posted before, I had a particular website in mind. Basically its a guy who wanted to do his own X-Ray photography.... Maybe I should have posted to the photography forum. Anyhow here goes!

X-Rays

I can probably come up with some stuff to help you build your own basic high power microwave solution if you want, but I think that the thermite solution to this problem is by far the best of all. Hope you find the link interesting!


Edited by dilbert on Saturday 23 December 02:07

ATG

20,480 posts

271 months

Saturday 23rd December 2006
quotequote all
Good link. Hope the bloke isn't planning on having children. Phew, what a loony.

dilbert

7,741 posts

230 months

Saturday 23rd December 2006
quotequote all
He's a bit of a nutter isn't he!!!

Dunk76

4,350 posts

213 months

Saturday 23rd December 2006
quotequote all
tank slapper said:
Dunk76 said:

How does Electronic Counter Measures on military aircraft work?

Remember the story about the copper pointing laser gun at the Harrier? RAF reservist I worked with at the time 'verified' the story and said that the Harrier fried the laser gun with the ECM.


That story is cobblers. See here


Well this is where it gets interesting - your link states Dutch Tornado playing around in the North Sea, yet my reservist colleague maintained it was a Harrier GR7 of the RAF doing the usual straffing of Telephone boxes somewhere in North Wales. It also only mentions Radar doesn't it? Police handhelds use laser - the only other laser device I can think of are repeater beacons for airport approach corridors.

There's another little gem, again according to my reservist colleague; the constabulary in question wrote to the MoD asking them to pay for a new laser gun. The MoD forwarded the letter onto the Squadron in question.

The squadron then wrote to the constabulary saying they were likely they weren't asking them to pay for a new patrol car and officer, and in future would they not point laser devices at aircraft.

As I said, I've only heard this third-hand through my colleague, so I make no claims for it's truth...

dilbert

7,741 posts

230 months

Saturday 23rd December 2006
quotequote all
Dunk76 said:
tank slapper said:
Dunk76 said:

How does Electronic Counter Measures on military aircraft work?

Remember the story about the copper pointing laser gun at the Harrier? RAF reservist I worked with at the time 'verified' the story and said that the Harrier fried the laser gun with the ECM.


That story is cobblers. See here


Well this is where it gets interesting - your link states Dutch Tornado playing around in the North Sea, yet my reservist colleague maintained it was a Harrier GR7 of the RAF doing the usual straffing of Telephone boxes somewhere in North Wales. It also only mentions Radar doesn't it? Police handhelds use laser - the only other laser device I can think of are repeater beacons for airport approach corridors.

There's another little gem, again according to my reservist colleague; the constabulary in question wrote to the MoD asking them to pay for a new laser gun. The MoD forwarded the letter onto the Squadron in question.

The squadron then wrote to the constabulary saying they were likely they weren't asking them to pay for a new patrol car and officer, and in future would they not point laser devices at aircraft.

As I said, I've only heard this third-hand through my colleague, so I make no claims for it's truth...


It's pretty unlikely. There are lots and lots of detection and jamming strategies. Added to that a small aircraft ESM/ECM is comparitively limited (lacking in smarts, sensitivity and power) when compared with that of airbourne surveillance or naval systems.

I think it's unlikely that the systems would be remotely compatible, let alone verging on the possibility of killing a police officer with a wayward hairdryer.

madleee

720 posts

210 months

Saturday 23rd December 2006
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Just slap a meat pie over the lens.
Are scamera lenses resistant to ballistics?
ie airgun pellets.

nel

4,763 posts

240 months

Saturday 23rd December 2006
quotequote all
madleee said:
Are scamera lenses resistant to ballistics?
ie airgun pellets.


I'm sure that the lenses will be proof against low power projectiles like air gun pellets - what you need is a proper hunting rifle. I know that back home in France plenty of fixed radar installations have been taken out with gun shots, but they are keen hunters and still well tooled up. Will see if I can find photos of the results - have seen some in the past.

simonrockman

6,843 posts

254 months

Saturday 23rd December 2006
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If you are prepared to do something illegal wouldn't you be better off with a transmitter which caused the cars in front to give a reading of 200mph.

love machine

Original Poster:

7,609 posts

234 months

Saturday 23rd December 2006
quotequote all

I do like the idea of building the device out of things I can get my hands on without breaking the bank or travelling across the continent. The home microwave idea struck me as they are easy to get hold of and produce about 700W of energy which is a good starting point. The device would be something which could be aimed out of the back of a suzuki jeep and in an Ali G drive by stylee BOOKAAAAAAH!!!!blow the thing up. (in theory, remember)

The X-ray idea is not a snag as I have access to an old x-ray tube and power source, however would rather use high explosives in a home made gun

What we need to do is find out more about the nature of the beam from a 700W microwave. How much of a beam is it? What would a reflector be made out of, how would you construct a waveguide?

I suppose if you could construct a tube for the waves to travel down, you would be pretty safe from stray waves, unless you fired it at a suitable parabolic reflector with the focus on your head!

I'm also wondering about the power source, I would be tempted to use a simple inverter and run 240ac as per microwave.

As for creating a specific R/F frequency, how would you do that from things lying around? Would it be possible to modify the magnetron to produce a different frequency?

S

wizzpig

2,039 posts

227 months

Saturday 23rd December 2006
quotequote all
I've been thinking about this and I think it could really work. What you do is get your mate in the passenger seat to launch the microwave out the window as you fly past. Jobs a carrot.

For top results, however, I would recomend an Arga...

mr phish

55 posts

223 months

Saturday 23rd December 2006
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I think you're going to find it difficult to focus and direct a microwave beam with enough power to knock out a Gatso.

I reckon you should forget microwaves and think about using a laser instead. Much less dangerous for the operator and innocent bystanders too.

A CO2 laser would be a good bet. Nice beam profile, good power and available on ebay: http://cgi.ebay.com/LMI-CNC-1000w-CO2

Or you could have a go at making your own. This guy used some copper pipe and a pump from his central heating system.... www.imajeenyus.com/v5/main_framset.htm (look under 'projects')

A couple of thousand watts should be enough to take out the camera or just slice off Gatso's head. You would need a tow bar on your car though as you'd need to bring along a 3 phase generator to power the laser.

What do you think?

Witchfinder

6,250 posts

251 months

Saturday 23rd December 2006
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Would clamping a couple of those really strong rare earth magnets onto a scam-cam casing work?

Pigeon

18,535 posts

245 months

Saturday 23rd December 2006
quotequote all
The microwave output from an oven magnetron, as you will see when you take the magnetron out of the oven, is emitted from a projection on the side that looks like a small dog's penis with a brass bell end. This is coupled into a small waveguide section made from oddments of pressed steel which leads the microwaves into the main oven cavity... the magnetron is bolted to the side of the waveguide section in such a way that the bell end is in the centre of the empty space inside.

Knowing the operating frequency (2.45GHz) it is straightforward to google up wads of stuff on waveguide design and how to couple sources into it, from which the necessary dimensions could be worked out. This is left as an exercise for the reader.

Antennas... problem is the wavelength; at something over 10cm you need a pretty big one to get any sort of beam. A parabolic dish is probably the most awkward, being large and more-or-less flat and with the need to be fed from in front; you'd end up with a flying saucer a metre across stuck vertically on the front of your car, which would not be very practical. A horn would be a lot easier... wouldn't need to be quite so big and with rear feed the apparatus ends up a more manageable shape.

Personally I'd start experimenting with a poly rod antenna, which is basically a long plastic cone stuck in the end of the waveguide, point outwards. You trade width for length, in a way - the antenna is no wider than the waveguide but it is pretty long. This makes for a much more wieldy device... long thin things being easier to handle than wide flat ones or big boxes. Trouble is that while design equations for parabolic and horn antennas are easy to come by, poly rods are more obscure and Google is of less help.

It is not feasible to change the operating frequency of a magnetron; once its components have been machined to a particular set of dimensions that's it, fixed. And to get a 10:1 change in the frequency would involve a serious redesign of the thing. It doesn't matter, though. The receiver element is a waveguide section with a diode in it designed to receive microwatts of power. It's not massively selective. It's certainly not selective enough to reject 700W (or a significant fraction thereof) of radiation being squirted at it from a magnetron.

The metal Gatso case does not provide any shielding against microwaves because it's got three bloody great holes in the front. It might, however, provide a useful resonating cavity in which the microwave flux could build up to high levels, rather like the oven cavity itself does. So either way, you stand a good chance of frying either the diode or the digital stuff or both.

The biggest problem is getting a tight enough beam to get a significant fraction of the 700W into the Gatso from any kind of reasonable range - and if you do get a tight enough beam, there's then the problem of aiming it, though that's not too hard to solve with a laser pointer aligned along the beam axis. It would be a whole lot easier to make a short-range device, so you stop the car by the Gatso, hold up the device on a pole, press the button, and drive off again. Doesn't have the stealth of the long-range option but it's still massively quicker and more straightforward than trying to climb up the post of the thing carrying a tyre and a bottle of petrol, or even a tin of thermite.

WRT safety and not frying yourself, there are quite a few pages on the net by people who have built crude directed energy weapons from microwave ovens without frying themselves, despite in some cases a somewhat cavalier attitude. Said pages could also provide useful background information and ideas. There are stories of GIs in Britain during WW2 standing in front of H2S sets to cook their nuts as a form of contraception... no idea if it worked but it sounds much more pleasant than having some medic cut your sack open and snip the tubes; I've got a couple of magnetrons and also a microscope with which to examine the product before and after, might give it a shot.

Boosted LS1

21,165 posts

259 months

Saturday 23rd December 2006
quotequote all
I love the idea of a drive by shooting but it's looking really impractical unless you have the right skills.

Best I heard to date was fire lighters placed inside the small grey post located near all truvelos. The cover uses the type of key used by the gas board and meter people in general. Think this takes out all the wiring and makes a sticky mess of the insides.

Boosted.

brakedust300

1,059 posts

208 months

Saturday 23rd December 2006
quotequote all
Dunk76 said:

How does Electronic Counter Measures on military aircraft work?

Remember the story about the copper pointing laser gun at the Harrier? RAF reservist I worked with at the time 'verified' the story and said that the Harrier fried the laser gun with the ECM.



Edited by Dunk76 on Friday 22 December 23:39


Military aircraft have a number of different Electronic Counter Measures, radar jamers are mostly blanket types that cover the area the aircraft is flying in, or some use a powerful infra-red emitter that confuses electronic equipment, a focused powerful infra-red beam would be more affective and easier to build with less complications and should fry a gatso!

sadako

7,080 posts

237 months

Saturday 23rd December 2006
quotequote all
I would mount the device in a remote controlled vehicle. The problem is if someone finds a way to take out these devices that efficiently then the SCP will be out for blood.

Perhaps designing a remote controlled helicopter or robot to drop thermite packages would be better.

cyberface

12,214 posts

256 months

Saturday 23rd December 2006
quotequote all
Pigeon - I'm no expert but the poly-rod antenna you're talking about sounds a bit like a Yagi antenna - if this is what you're getting at, then there's plenty of antenna design detail available on the internet.

Remember that 802.11b/g wireless networking uses the ISM band which is basically a wedge of the microwave spectrum floating around the hydroxyl bond resonant frequency (2.45 GHz?)... yes microwave oven leakage plays havoc with home wireless networking systems.

Now if the Gatso radar uses 24.1 GHz then there's a factor of 10 in there which, if you can use the same generator, would make the required antenna shorter (Yagi and 'cantenna' Wi-Fi hacker stuff can be up to a metre long). Equally if you're just going to stick to 2.45 GHz and pump up the power to heat up everything you can inside the Gatso, then you'll need an antenna that can take that sort of power and focus it all into a tight beam rather than re-radiating back at the operator yikes

That young guy who messes about with energy weapons for fun did something with microwaves IIRC - not sure what he ended up with, nor whether it'd be appropriate for Gatso-cooking, but may be worth a starting point - his website is Sam Barros Powerlabs

A4_Family_Man

420 posts

208 months

Saturday 23rd December 2006
quotequote all

Wow, what an interesting post. Even if some of the techno stuff goes over my head a little!

All this sounds something like a smaller version of the Tesla death-ray for scameras!!

All you would need is a tight fitting superhero costume, armed with your camera killing raygun!