How do highway police use radar guns?

trooper3316

Radar sends out a radio wave of a constant frequency. If this wave strikes a stationary object, it reflects unchanged. If the object is moving, the frequency changes in relation to the speed. The higher the speed, the more the change. The radar unit reads this change and calculates the speed. It is accurate to plus or minus one mile per hour.

Laser uses a beam of light, and the unit times how long it takes for the beam to return to the unit. The laser is capable of timing 80 pulses of light per second. It calculates your speed by the difference in time it takes for the pulses to return.

Both radar and laser are capable of locking your speed long before you see the officer.

On a multi-lane highway, laser is more popular. Radar only works in light traffic because the beam is 21 degrees, meaning it will take up all lanes of travel in just a few hundred feet, making it difficult to determine which car you are clocking. Laser is much more precise, the beam is less than three feet wide at 1,000 feet of distance.

Sparky

There are a couple of possible reasons. One may to keep the angle of the target low. The higher the angle from the direction of the source of the radar, the more inaccurate it will be. The inaccuracy is in favor of the motorist so I wouldn't be making that an argument. It is a measurable condition and can be accounted for.
Another reason is so that they could be getting you before you see them, just like you think.
Another reason may be because of the type of speed measuring device they are using. If it is radar, you will see them just holding the unit out in front of them or pointing it in the general direction of the traffic they are monitoring. The radar picks up all moving targets.
If it is lidar, the laser type, then you will see them aiming it like they are aiming through a rifle sight. Lidar uses a small area for targeting a vehicle and can single out vehicles in a busy location. Very specific.
So they can get you a long way down the road.
Is it any use to slow down? It can't hurt. It's better than acting like you don't care if they are there or not. I'd rather hear "I'm sorry, I just wasn't paying good enough attention and when I saw you, I realized I was over the limit" over "you darn pig, why aren't you out catching murderers?"

Brian O

If they don't hit you when you're far down the road, you'll have time to slow down right? Cuz you'll see them. They work by bouncing the beam off your car twice, then measuring the difference in time between the 2 beams that it takes to return to the gun.
If you're going fast, the diff. will be large, if slow, small.

Caleb C

alot of state police, dont even use them, in the sense that they just aim them, and wait...for someone to tap the breaks, those are the ones to get, the ones that try to slow down

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