The radar speedometer is based on the received frequency shift of reflected waves to calculate the moving speed of the object. Radar beam irradiation is large, so the radar speed is easy to capture target, no precise aim. Radar equipment not only can be fixed on the pavement, but also can be installed on patrol vehicles, the implementation of the movement detection speed, is the "mobile electronic police" very important component; second, the radar speed error is about: Speed V or 0.1031%V, can meet the requirements of traffic violation, and the international use of radar speed is also more than 20 years of history, and technology mature, low cost. From the present situation to see, Beijing city on the road surface or with the main backward speed, but also has a small number of positive speed radar gun appearance. The expressway is mostly on the forward speed measuring device. The back is the Lei Dabo and the camera direction and the car in the direction of the vehicle, the car when the camera shooting the vehicle after the license plate. Forward is the Lei Dabo and camera direction and vehicle direction in the contrary, vehicle speed camera shooting vehicles in the front card.
Radar detector principle is very simple, is to receive the radar signal, immediately alarm, prompting the car owner to slow down. Its price is generally at 800 yuan to 5000 yuan, the performance is also very different. The biggest difference is that the frequency bands of radar waves can be sensed. Because our country's City Road radar velocimetry equipment from different countries imports, the use of radar frequency is mostly not the same, the same city has some of the three or four countries with different frequency bands of radar gun. Low-end radar detectors, often only induction of a band of radar waves, and high-end radar detectors, can be sensitive to multiple frequency bands of radar waves. In addition, the sensing distance also reflects the performance of radar detectors. If the induction distance is too close, the car owner too late to Decelerate, has been photographed, such as slow down too fierce, but also prone to cause rear-end accidents. High-end radar detectors can perceive radar waves around a kilometer, while the difference is only about 200 meters.