How do you explain laser jammers when you get pulled over by police?

[khabel]

Wouldn't the cop pull you over anyway if he knows you're speeding even if he can't get a reading on you and then also ticket you for having a jammer?

[pritch]

Eh? Who has got a laser jammer?

Or, who has even seen one?

[slofox]

Eh? Who has got a laser jammer?

Or, who has even seen one?

"Not I" said the cat...

[Latte]

Mate had one on his car, 2 little black boxes either side of his number plate. Obvious once he showed you, but if you weren't looking you'd not notice them.

Got to see them in action too, he told me the trick was to turn them off once you got down to 110-120 under braking so the cop would get a lock at around 110-100, if you left it on you might get pulled over.

[pzkpfw]

... he told me the trick was to turn them off once you got down to 110-120 under braking so the cop would get a lock at around 110-100, if you left it on you might get pulled over.

I'd have throught there was a way to wire them into the car so they'd do that automatically.

[Latte]

I'd have throught there was a way to wire them into the car so they'd do that automatically.

Maybe on later model ones, this was about 6-7 years ago and he bought it 2nd hand from overseas (for about $1500 from memory). He had that and a high end radar detector for similar money. Reckons they paid for themselves in about 2 years.

[Road kill]

A mate that has one turns it off as soon as he's reacted to his detector going off.
I don't think there's anything illegal about them,but bragging about it to a cop might not be the done thing.

Riding a 1973 twin means I don't need none of that shit

[Damantis]

[QUOTE=Road kill;1130150184]A mate that has one turns it off as soon as he's reacted to his detector going off.
I don't think there's anything illegal about them,but bragging about it to a cop might not be the done thing.

Anything that interferes or impedes the operation of speed detection equipment is actually illegal. So yes, you can be fined for operating a jammer. Detectors don't emit anything to interfere with detection equipment so are fine.

[red mermaid]

How is it possible to jam a Laser, a beam of light, when you have no idea on what part of the vehicle the officer is going to point it at?

[Gman71]

Laser jammers are not illegal. Radar jammers are.

Lasers are just the hand held units they point at you, and jammers work by returning an extra 'character' if you like in what the laser is expecting back, so they can't get a reading.

Radar jammers fuck with radio/radar transmissions and are a illegal.

Laser jammers dont help you for the in car hawk units. Only the hand held units the really lazy cops use.

At least that's how I understand it.

[davereid]

There are passive ways of defeating laser. It operates on a different principle to traffic radar and has a few vulnerabilities.

It sends a pulse of light, which hopefully reflects from your vehicle and the reflection is detected by the laser. The time taken allows calculation of the distance to the target.

A short time later it sends another pulse which is also timed, allowing a second distance reading to be taken.

If (for example) the time between the two pulses was 1/100th of a second, and the distance had decreased by 278mm you are travelling at 27.8m a second or 100 km/hr.

But thats where the vulnerability of the laser occurs. It ASSUMES that BOTH reflections come from the same place on the car.

But thats not always true. If your car was stationary, and the first reflection came from the back of the headlight reflector, and the second reflection came from the front, an apparent speed towards the laser would be measured even though you are not moving.

Laser manufacturers are aware of this, and they use special techniques to try and overcome it.

The first is a highly reflective numberplate, so a good flat target is available.

The second is to take multiple readings really quickly, and ensure several of them give the same distance to target.

So repainting your numberplate so it is no longer reflective reduces laser effectiveness, as does putting it on a slope, so the top and bottom of the plate are at different distances to the laser.

And putting cat eye reflectors on your vehicle, close together but at different distances from the front of your vehicle also helps.

This is because the operator is unlikely to be able to hold the laser on any one cateye. (Actually he wont be trying to !, but as the cat eye is a far far better reflector than the vehicles paint, the laser will "grab" any reading that occurs as the laser paints a cateye).

So the laser wont get the same distance to target twice in a row, and will restart target acquirement.

As you get closer to the operator, especially if the operator is using a tripod or side of vehicle as a "steady" you will eventually get pinged.

But if the MK1 eyeball is in service, this ping should be irrelevant.

[Blackbird]

It's a bit academic about radar jammers (microwave band) being illegal as you couldn't build one sufficiently compact for a bike anyway - they take a huge amount of energy and are pretty much limited to military applications. With respect to laser jammers, there are technically some avenues for a prosecution according to a police riding partner of mine but he has never heard of one being brought.

When I last looked at some independent tests, the Blinder and the Cheetah were the only ones which worked well, the rest were "snake oil". Not only are they bloody expensive, they need to be hooked up to a top quality detector too.

I've got a good detector but my right wrist and choosing time and place is a much cheaper alternative than a jammer

[Scuba_Steve]

How is it possible to jam a Laser, a beam of light, when you have no idea on what part of the vehicle the officer is going to point it at?

Prob just based on the assumption the cops are gonna do what they're told & point it at the plate, as is procedure.

[tigertim20]

Wouldn't the cop pull you over anyway if he knows you're speeding even if he can't get a reading on you and then also ticket you for having a jammer?

well that would be interesting wouldnt it?
you use a jammer, doing 115km/hr, and he gives you a ticket for 123km/hr.

what are you going to say?

Decide which is the lesser of the two evils and go from there i guess.

[davereid]

It's a bit academic about radar jammers (microwave band) being illegal as you couldn't build one sufficiently compact for a bike anyway - they take a huge amount of energy and are pretty much limited to military applications.

I have never researched jamming modern radar, but the old 10.7 GHz stuff was very easy to jam.

You used to be able to buy 10.7 GHz gunn diode oscillators, they only produced a few u-watts but they easily stuffed the radar of the day and were match box sized.

From memory we used to amplitude modulate them - actually we used to turn the power supply on and off.

Seem to remember 19hz per km/hr was the rule of thumb. So 1900 hz am modulation gave the cop a reliable 100 km/hr regardless of actual speed. Must look in the shack, may still have one somewhere.