| 摘要 |
<p>For sensing a moving body, including vehicles and personnel, a fibre- optic cable 1 is laid across the path of the moving body and light transmitted through the cable. Pressure of the body on the cable causes variations in the light transmission which can be detected. Different bodies or vehicles may be distinguished by their characteristic transmission loss patterns, axle weights may be measured, or speeds measured if the cable comprises a loop to produce two signals. In the latter case the light is not reflected back down the fibre by a mirror 9, as shown, but the detector is placed at the end of the fibre opposite the end by the source 7. The light may be chopped or modulated sinusoidally. <IMAGE></p> |
