Microwave size/speed vehicle detector.

摘要

A vehicle sensing apparatus and method for detecting the size and speed of a vehicle traveling on a roadway. The apparatus comprises a directional microwave non-emitting antenna (9) for collecting reflected microwave signals from above a roadway (8). An electronic vehicle sensing circuit (10) is connected to the antenna (9) for processing detected signals to identify a vehicle's (7) physical parameter. The sensing circuit has an ambient temperature detector and a peak detector, the latter detecting a reflected temperature signal at said antenna (9) and generating a detected temperature signal. A physical parameter calculating circuit is provided for determining the true amplitude of the detected signal and interpreted by the maximum ratio of the solid angles of the antenna beam filled by the vehicle (7) to be detected and a roadway (8) in the beam of the antenna. A processing circuit (ROM) is provided to identify the vehicle's physical parameter. A vehicle speed calculating circuit (ROM) is also connected to the peak detector for providing a value of the antenna effective footing length to a divider circuit which is also fed a half pulse time whereby to provide a speed output