| 摘要 |
<p>An improved traffic monitoring system is disclosed in which a microprocessor (24) is connected to an analog to digital converter (18) providing a series of digital samples of the pressure within a road tube (10) for analysis of the signals. If a pulse is detected exceeding a threshold level, corresponding to passage of a tire over the road tube at a relatively high rate, the microprocessor (24) then determines whether pressure in the tube subsequently drops below a repetitively-updated baseline value. If the pulse in the pressure does not exceed a predetermined threshold, the microprocessor (24) determines whether the pressure continues to rise for a stated period of time and to exceed a set minimum value, whereupon the conclusion is reached that a relatively slowly moving tire has passed over the road tube. The microprocessor (24) is disabled from detecting a second tire within varying intervals after detection of a pulse. The disabled interval is longer for pulses due to passage of fast vehicles than for pulses due to slow vehicles, as increased internal pressure fluctuations are caused by passage of fast moving vehicles over the road tube.</p> |
