| 摘要 |
The apparatus is a vehicle motion detection apparatus for short driveways which uses passive ferromagnetic detecting coils reacting to the fluctuation in the earth's magnetic field caused by moving vehicles. The preferred embodiment of the invention uses two sensor coils located on a line that is approximately perpendicular to the adjacent road and parallel to the driveway. The sensor coils are designed and connected so that they generate signals of opposite polarity so that together they cancel out the signals generated by vehicles on the road, but the signals generated by a vehicle moving on the driveway do not cancel each other and are electronically processed.
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