USA As Represented by Secretary of the Navy

Adam C Feaga

John F Scarzello

Daniel S Lenko

An improved detector is provided for installation in a roadway surface. The detector finds utility in a highway vehicle detection system for determining vehicle presence, vehicle speed and vehicle length. First and second matched induction coil magnetic sensors are maintained at or near the roadway surface. Each of the sensors has a longitudinal axis aligned normal to the roadway surface. The first and second sensors are separated from one another by a known distance in a direction substantially aligned with a direction of traffic flow. Each of the sensors generate a differential magnetic field signature with respect to time to indicate a passing vehicle's leading and trailing edge magnetic signatures. Vehicle speed is determined by a time-distance relationship using the leading and trailing edge magnetic signatures and the known distance. Vehicle length is determined by a time-speed relationship using the leading and trailing edge magnetic signatures and the determined vehicle speed. A triaxial magnetometer maintained at a location in close proximity to the first and second sensors measures a DC magnetic field. The DC magnetic field has vertical and horizontal magnetic field components with the horizontal components including a component substantially aligned with the direction of traffic flow and a component substantially perpendicular to the direction of traffic flow. The vertical and horizontal components caused by the passing vehicle are used to determine vehicle presence. An ELF communications system may be incorporated with the detector to link roadside and vehicle transmitted/received information.

Vehicle presence, speed and length detecting system and roadway installed detector therefor

A portable electromagnetic field exposure dosimeter includes a triaxial fite-loaded coil sensor, a group of amplifiers and bandpass filters, a data control board, and a computer. The triaxial sensor receives electromagnetic radiation along three orthogonal axes for measurement which is channelled through a group of amplifiers and then bandpass filtered into three frequency signal ranges. One frequency range corresponds to exposure at 60 Hz and two of its harmonics. The second frequency range corresponds to high frequency pulsed energy. The third frequency range reflects body motion of a tested individual. The data control board converts such filtered signals into digital code and controls the flow of the converted data to random access memory and to the computer. The computer performs a Fast Fourier Transform on the converted data from the 60 Hz frequency range and then stores or displays the analyzed data as a function of frequency and time. The computer also stores or displays the data from the other two frequency ranges.

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Clarksville, MD, United States of America

Adam C Feaga