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For many people, speeding is a normal part of everyday life. This seemingly superficial law-bending is so prevalent and widely accepted that there is even the availability of specialized electronic equipment to assist drivers in getting away with it. Ever since their introduction in the 1970s, radar detectors have become an integral accessory for would-be "F1 hopefuls" everywhere. The Radar Basics Radio Transmitter Radio Receiver Radar is the act of using radio waves to monitor and detect various objects. The most basic function of radar is to tell the distance of an object. To make this possible, the radar device emits a highly concentrated radio wave and listens for echoes. If there is an object along the radio wave's path, some of the electromagnetic energy will be reflected, and the radio signal will bounce back into the radar device. Since radio waves move through the air at a constant speed, which is the speed of light, the radar device can then calculate the distance of the object based on the time it takes for the radio signal to return. Radar can also be used as well in measuring the speed of objects; this is due to a phenomenon referred to as "Doppler shift". Similar to sound waves, radio waves have distinct frequency, or the number of oscillations per unit of time. When the car and the radar gun are both standing still, the resulting echo will have the wave frequency similar to the original signal. Each part of the signal is reflected as it reaches the car, duplicating exactly the original signal. Though, if the car is in motion, each part of the radio signal is reflected back to the radar gun from a different point in space, which results in a change in the wave pattern. When the car is moving further away from the radar gun, the second segment of the signal travels a greater distance in order to reach the car than the signal's first segment. The change in distance has the effect of "stretching out" the wave, or lowering its wave frequency. If the car however, is moving toward the radar gun, the second segment of the signal would travel a shorter distance than the first segment prior to being reflected. This results in the peaks and valleys of the wave getting squeezed together, at this, the frequency increases. Basing on how much the frequency changes, a radar gun can then calculate the speed of the car moving toward it or away from it. If the radar gun is activated while inside a moving police car, its own movement must also be used, or factored in the calculation of the target's speed. In example, if the police car is moving at 50 miles per hour and the radar gun detects that the targeted object is moving away at 20 miles per hour, using physics formulas, the target must be driving at a speed of 70 miles per hour. Police officers have used radar guns in catching speeders for more than 50 years. Recent technology has developed a new sort of speed detector, which makes use of light instead of radio waves.
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