System for determining vehicle speed and presence
First Claim
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1. A system for monitoring traffic comprising:
- a magnetic probe to produce an electrical signal in response to changes in magnetic flux in a sensing area caused by a vehicle in the sensing area, the electrical signal having a beginning and an end;
means for digitizing the electrical signal;
means for analyzing the digitized signal to determine the duration of the electrical signal by measuring an elapsed time from said beginning of the electrical signal to said end of the electrical signal; and
means for determining the speed of the vehicle from said duration of the electrical signal wherein the means for determining the speed of the vehicle includes a digital processor having a memory with calibration information, the calibration information including a duration of an electrical signal caused by a vehicle having a known speed for comparison with said determined duration of the electrical signal.
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Abstract
A system for monitoring ferromagnetic materials in proximity to a sensing region, which is particularly applicable to traffic monitoring and controlling. A magnetic probe generates a signal in response to magnetic flux changes caused by a vehicle moving through a sensing area. A processor analyzes the signal to determine the duration of the signal and correlates that duration to a vehicle velocity. A checking system periodically sends a checking signal to the magnetic probe and monitors the return signal to verify that the probe is operative and also analyzes the return signal to determine whether a stationary vehicles is in the sensing area.
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Citations
10 Claims
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1. A system for monitoring traffic comprising:
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a magnetic probe to produce an electrical signal in response to changes in magnetic flux in a sensing area caused by a vehicle in the sensing area, the electrical signal having a beginning and an end; means for digitizing the electrical signal; means for analyzing the digitized signal to determine the duration of the electrical signal by measuring an elapsed time from said beginning of the electrical signal to said end of the electrical signal; and means for determining the speed of the vehicle from said duration of the electrical signal wherein the means for determining the speed of the vehicle includes a digital processor having a memory with calibration information, the calibration information including a duration of an electrical signal caused by a vehicle having a known speed for comparison with said determined duration of the electrical signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining the speed of a ferromagnetic material having a known estimated speed, in relation to a speed detector containing a magnetic probe, which changes a magnetic flux passing through the detector, comprising the steps of:
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producing an electrical signal by a change in the magnetic flux passing through the detector, the electrical signal having a beginning and an end and a leading edge having a leading edge duration and a trailing edge having a trailing edge duration; digitizing the electrical signal, measuring an elapsed time from said beginning of the electrical signal to said end of the electrical signal to determine the duration of the change in the magnetic flux; and determining the speed of the ferroelectric material in relation to the speed detector utilizing a first formula if the estimated speed is within a first speed range, wherein said first formula includes a sum of the duration of the leading edge and the duration of the trailing edge. - View Dependent Claims (9, 10)
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Specification