Importance

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Abstract

A vehicle sensing apparatus and method for detecting the size and speed of a vehicle travelling on a roadway. The apparatus comprises a directional microwave non-emitting antenna for collecting reflected microwave signals from above a roadway. An electronic vehicle sensing circuit is connected to the antenna for processing detected signals to identify a vehicle's physical parameter. The sensing circuit has an ambient temperature detector and a peak detector, the latter detecting a reflected temperature signal at said antenna 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 to be detected and a roadway 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 corrected velocity output signal.

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First Claim