Limitations
Traffic radar comes in many models. Hand-held units are mostly battery powered, and for the most part are used as stationary speed enforcement tools. Stationary radar can be mounted in police vehicles and may have one or two antennae. Moving radar is employed, as the name implies, when a police vehicle is in motion and can be very sophisticated, able to track vehicles approaching and receding, both in front of and behind the patrol vehicle. It can also track the fastest vehicle in the selected radar beam, front or rear.
However, there are a number of limitations to the use of radar speed guns. For example, user training and certification are required so that a radar operator can use the equipment effectively. Stationary traffic enforcement radar must occupy a location above or to the side of the road, so the user must understand trigonometry to "guess" vehicle speed as the direction changes while a single vehicle moves within the field of view. Vehicle speed and radar measurement are rarely the same for this reason. Radar speed guns do not work reliably in traffic, and significant vehicle separation is essential for proper operation when used for speed monitoring.
Mobile or hand-held radar is only reliable when one moving object is in the field of view and there are no other moving objects nearby.
Read more about this topic: Radar Gun
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