TRACKING FILTER APPARATUS FOR WHEEL MONITORING SYSTEMS

摘要

A wheel monitoring system that includes a tracking filter apparatus for tracking a signal that has a varying main frequency. The tracking filter apparatus has an adjustable filter and a filter controller arranged to measure the amplitude of the filtered signal and to compare amplitude against a reference value. The filter controller adjusts the cut off frequency of the filter if the measured amplitude differs from the reference value by an amount that exceeds a threshold value. The filter controller adjusts the cut off frequency such that the main frequency lies within the roll off region of the filter's frequency response. The system may be used to track signals that are produced by shock sensors in a wheel mounted monitoring device.