Homemade Police Laser Speed Gun Jammers

[xJumper]

Ok so ever since I was in highschool and got my first car I was always interested in the electronic warfare and these radar detectors/jammers, to sum it all up I have tried/made everything for radar technologies, some have worked and some have not. Now see in the state of California they started using laser guns to clock speed and even if you build a detector for them it only takes like 0.1 seconds to read your speed so theirs no time to adjust and the only way to avoid them is with a laser gun jammer.


Now to start off these laser guns all operate in the infrared spectrum so to jam them you would have to use IR too. Now the concept seems pretty simple, just get a powerful IR laser and point it at their laser gun, sure that works but we don't all have sniper like accuracy and don't all have IR lasers, or do we?
So we would need a bigger laser spot and an IR laser.


Now my 50mW greenie using a plano convex lens in front of it makes a car sized green laser spot about 50 yards out, but still an IR police laser gun can read your speed very well up to 1000ft around 300yards (300m for you Canadians) so I would need more range and IR spectrum laser.

Now I heard that these lasers usually have high IR diode pumps so if I took out the KTP crystals and had only the powerful 400mW+ IR diode + plano convex lens infront I could make a car sized or even bigger spot in IR spectrum hundreds of yards away and just pointing it in the general direction of the police laser gun would jam it up.


Now thats my idea but I need a little feed back (keep the legal stuff aside I know what im getting into) before I scrap my laser and turn it into something else and if you know about police laser guns and this would not work please advise.

 

[diachi]

Re: Homemade Police Laser Gun Jammers

I don't know if that would work, it would need to operate on the exact same wavelength of the 'Laser gun', and even then, it may not work.

 

[RA_pierce]

Re: Homemade Police Laser Gun Jammers

Those laser gun things are probably pulsed, so only a beam from a laser with the same wavelength and frequency would have any effect.

But it's still possible, I mean we don't know if it will work or not until we try it. It would be nice if someone could get their hand on one of those things.

 

[pullbangdead]

Re: Homemade Police Laser Gun Jammers

Yeap, you'd need the wavelength being used by the police gun, and your light source would have to be close to the same wavelength. Remember that a laser doens't have a very wide "spectrum". It's pretty much 1 wavelength, the full width-half max for a laser is, by nature, very low.

 

[xJumper]

Re: Homemade Police Laser Gun Jammers

Laser speed guns probably wont cost that much more than a good radar gun, all we would need is a cheep one. A lot of them actually run on the 808nm spectrum and 1000 something nm spectrum. If their pulsed or not I don't know but what would be the advantage of them being pulsed lasers over constant wave?


I don't know the exact nm to what nm is the IR spectrum but theirs only so many wavelengths they could be on and they would probably stick to stock technologies where they could get the IR diodes for those guns easily.

 

[RA_pierce]

Re: Homemade Police Laser Gun Jammers

Laser speed guns probably wont cost that much more than a good radar gun, all we would need is a cheep one. A lot of them actually run on the 808nm spectrum and 1000 something nm spectrum. If their pulsed or not I don't know but what would be the advantage of them being pulsed lasers over constant wave?

IR TV remotes are pules at a specific frequency that the television can detect and respond to, that way your tv remote doesn't screw with your dvd player, computer, satellite reciever, etc.

 

[xJumper]

Re: Homemade Police Laser Gun Jammers

Well its not like two officers on opposite sides of the road would be shooting it at each other and since police laser guns are a new thing they probably don't count on people trying to use modified laser pointers and jam them.



What would be the max a lasers wavelength's could be off by before it could no longer jam, say police gun is at 1025nm and your at 1008nm?

 

[Benm]

Re: Homemade Police Laser Gun Jammers

What would be the max a lasers wavelength's could be off by before it could no longer jam, say police gun is at 1025nm and your at 1008nm?

This depends on the sensor used to collect the return signal, not on the laser in the units. I think the lasers most often used are 1064 nm, but the sensor is likely to be sensitive to a relatively broad range. Being off by 20 nm isn't likely to be that big a problem.

Now on the pulses: it's pulsed because the unit basically measures the time between a pulse being emitted and its reflection being recieved. Like radar, the time between them is the distance divided by the speed of light. Analyzing at least 2 of these pulses allows you to calculated the speed at which a car moves.

In practice these units rely on many more than 2 peaks for a good reading, and getting a signal in between them is likely to result in the lasergun displaying an error.

Unfortutanly, laser jammers have been outlawed here in holland. They have been on the market for a while, and did work, though results were variable.

 

[pullbangdead]

Re: Homemade Police Laser Gun Jammers

Umm, these laser guns aren't THAT new.  I got a ticket in Virgina from LIDAR in 2003.  

And reading the Wikipedia entry on LIDAR, it does use pulses, and the systems use an algorythm to pick which pulses to measure/use in the speed calculation.  If your pulse is the wrong length, the gun isn't going to believe it and be fooled, I would imagine.

Also, since you don't know when the cop is going to "pull the trigger", your jammer would have to be in constant-on mode, or sending out a constant stream of pulses. I don't know if they do this, but it wouldn't be hard to account for that in the gun's measurement by taking a background sample before and after the gun's actual send-receive routine.

 

[Murudai]

Re: Homemade Police Laser Gun Jammers

Just drive under the damn limit, lol

People have been trying to beat speed detecting devices since forever. Don't you think the police realize that and make their devices so they are virtually impossible to counter?


Here's a better idea. Mod your engine so you can driver faster than the speed of light. Then you can outrun the laser, problem solved.

 

[xJumper]

Re: Homemade Police Laser Gun Jammers

The way I would use this, is just tape it to my side view mirrors and have it modified it so it accepts power from the electrical cigarette lighter and stay on the whole time.

Next thing is it would be plain stupid to use this or any other jammer for that matter when your alone, jammers are for use when you ride in packs of cars like at 6:30 pm rush hour.


I honestly am not to much of an expert when it comes to lasers ( I know what I need to know) but my theory is simple, here is how it goes.

Say your trying to use your laser to pop your friends balloon, your friend does not want you to pop his balloon so he turns on his flashlight and aims it in the direction of your laser beam, now the laser is not as clear/bright/ect and wont transfer as much heat energy and will not pop the balloon.


Basically if you fire enough IR at the police gun (witch contains the sensor) you man disrupt the signal and make it give errors or false readings.

 

[Murudai]

Re: Homemade Police Laser Gun Jammers

Say your trying to use your laser to pop your friends balloon, your friend does not want you to pop his balloon so he turns on his flashlight and aims it in the direction of your laser beam, now the laser is not as clear/bright/ect and wont transfer as much heat energy and will not pop the balloon.

That analogy just convinced me that it WON'T work Firing a 2 Watt laser at someone using a 100mW to pop a balloon still wouldn't stop the balloon from being popped (unless you burn their hand).

How does a laser speed detection system work anyway?

Wait wait, nevermind. HowStuffWorks to the rescue! http://auto.howstuffworks.com/question396.htm

 

[moond0ggie]

Wouldn't discharging powerful IR laser light toward a police officer be grounds for some serious trouble?

 

[freshert]

Exactly what I was thinking... :-?

 

[mikeeey]

so wait... you would need to stick your laser at the window and point it into the police car at their radar gun. You need to keep pointing your laser at them until you are out of the measuring distance, also keep in mind it's a green laser,
so shine a green laser at the cop's gun while going over the speed limit. This will keep you from getting a ticket... ;D

 

[Cyparagon]

Wikipedia states an average operating parameter is 100 1-microjoule pulses over 300 milliseconds. That's a .33mw average pulsed laser at 330Hz. peak power or pulse width is not mentioned, but it stated to be eye safe.

Also, one situation where lidar is more prevalent is in high traffic situations because it can pick out a single car in a group, unlike radar.

My most pressing question is even IF this was feasible, how would you know where you're pointing an IR laser and would your accuracy be high enough to even hit a lidar gun while driving?

...he turns on his flashlight and aims it in the direction of your laser beam, now the laser is not as clear/bright/ect

How in gods name did you come to this conclusion?

Wouldn't discharging powerful IR laser light toward a police officer be grounds for some serious trouble?

Invisible radiation is... kinda hard to see. I somehow doubt he would ever know.

so wait... you would need to stick your laser at the window and point it into the police car at their radar gun.

lasers do not emit radio waves and would thus have no effect on a radio device.

shine a green laser at the cop's gun while going over the speed limit. This will keep you from getting a ticket... ;D

And 194 hobbits die every tuesday from accidental burns on their armpits from tomatoes. ;D