Guide on Why Police Use Radar Detector & How it works

Here you can clear your doubt on Why Do Police Use Radar Detector. Police use radar guns or camera guns to detect the speed of oncoming vehicles in roads. Police radar guns are custom-made devices combining the features of a radar transmitter and receiver into a single unit.

Why Do Police Use Radar Detector?

The normal radar sends out a radio pulse and waits for the reflecting pulse. Then by measuring the Doppler shift in the signal, the speed of the object is determined. Let’s see how police radars work.

Why Do Police Use Radar Detector image
Why Do Police Use Radar Detector image

How do police radars work?

The concept of measuring the speed of a vehicle using a radar gun is very simple. At the heart of the device, it is just transmission of electromagnetic waves through space.

The function of radar is to determine how far an object is. Radar waves move through at a constant speed. When they encounter an object, it is reflected back. This reflected wave is measured to determine the speed of the object.

Radar can measure the speed of an object through a phenomenon known as Doppler shift. Radio waves also have a certain frequency range just like sound waves. When the car and radar gun are both in idle state, the reflected radio wave will have the same frequency as the emitted wave.

When the car moves, each part of the radio signal reflected at a higher frequency when it’s moving towards the police car and at a lower frequency if it’s moving away from the car.

Based on the frequency, the radar gun can quickly arrive at a speed value at which the car is moving. If the radar gun is in a moving police car, then the speed of the police car also needs to be factored in.

For instance, if the police car is moving at a speed of 60mph and the gun detects that the target vehicle is moving away at a speed of 20mph, then the vehicle must be traveling at a speed of 80mph.

If the radar gun determines that the target vehicle is moving away from the police car, then the target is driving exactly at 60mph. Police officers have been catching speedsters this way for years.

How Do Cops Know Which Car Is Speeding?

How Do Cops Know Which Car Is Speeding image
How Do Cops Know Which Car Is Speeding image

In recent times, police have started using laser guns or LIDAR. The basic element in a LIDAR gun is a laser beam. The gun tracks the time for a laser beam to reach the target vehicle and bounce off of it.

Instead of sending out a single radar wave like the traditional radar gun, the LIDAR guns sends multiple bursts of laser beams and measures multiple distances in a short time using the reflected beams. Based on this collection, the laser gun can determine the speed at which the target vehicle is moving.

These guns can take several hundred samples in a minute and they are very accurate. The system can detect multiple speeding incidents in different lanes even when the target vehicle in changing lanes or tailgating.

The advantage of a laser gun is that the size of the “cone” of light it emits is very small and hence it can easily target a specific vehicle.

Unlike radar-based systems, the LIDAR guns can be used along with road work areas, curved roads or even tunnels. The modern laser guns have a dual camera system that can capture all the speeding vehicles in the measuring system’s tracking zone.

Violations are automatically attributed to specific vehicles and documented in a digital case file.

Myths around police radar guns

The myths and misconceptions around speed guns are aplenty. Let us try to bust them in this article.

Myths around police radar guns image
Myths around police radar guns image

Speed guns don’t work well in the rain

Poor weather can affect the accuracy of the radar and laser speed guns. However, it is not so inaccurate that the gun won’t work at all. Officers taught on how to use speed guns in adverse weather to get accurate results.

Speed guns don’t work in the night

Radar or laser guns emit bursts of radio waves or infrared beams and there is no way that they might not work well during the night. Although the officers might have some difficulty in finding the right car if it’s very dark, they can still pinpoint the right car if they aim the target vehicle for a longer time.


Final thoughts

We have seen how police use radar and laser guns to identify speedsters. While the conventional radar guns are easy to detect using a radar detector, the laser or LIDAR gun cannot be detected easily. It is also illegal to use a laser gun detector. While it might be easy to use a radar detector to identify police guns, it is safe always keep a check on the speedometer of your car while driving. For more info, stay tuned to our Radar Detector Guide portal.

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