We all know that radar detectors are supposed to tell us if we’re about to pass near a police radar and help us avoid being pulled over for speeding. But how do they work? Nothing reinforces the confidence in a machine that to know a little bit about how it functions.
To understand how this device detects radars, we must first get to know how radars work themselves. These pieces of apparatus create and broadcast electromagnetic waves, which, in their path, encounter different objects and bounce back off them. It is the same principle that bats use when they’re flying. The time that the wave needs to return to the radar is used in calculating the distance of that particular object. As to the speed of a moving object, the radar reads the different frequencies of the returning wave and is able to calculate the speed of the object the wave hit. So basically, a radar consists of a transmitter and a receiver. The more expensive it is, the better results you will experience.
So a radar detector actually detects the electromagnetic waves that are emitted by the police radar – in theory. In practice, radar detectors detect all the waves on the frequencies it’s capable of reading, so if a garage or supermarket door functions on the same frequency, the radar detector will go off.
However, radar detectors manufacturers have thought of ways to eliminate the number of false alarms, by giving the driver the possibility to turn off some of the frequency bands, for example the x-band, which is the oldest and is now slowly becoming obsolete. Another addition to the modern radar detectors is the integrated GPS that shows you where the immobile red light cameras and speed cameras are, and let you see is you have other type of emitters nearby.
Lidar or laser guns are much more difficult to avoid, since their beams are shorter and quicker. However, some radar detectors can be accompanied by a light-sensitive panel that will catch the laser beams from a lidar gun.
POP radar was invented to take drivers who use radar detectors by surprise, by emitting a radar transmission with a very small duration and it was a very effective method for a while, but now most radar detectors are prepared to seize these types of beams as well.