Patent ID: 8635906

Claim:
A wheel monitoring system, comprising: a wheel monitoring device that is mountable on a wheel and configured to generate a first signal that is indicative of a characteristic of said wheel, said first signal having a main frequency that varies corresponding to a variation of a rotational speed of said wheel; and a tracking filter apparatus, comprising: an input configured to receive said first signal from said wheel monitoring device; an adjustable filter having an adjustable cut off frequency and configured to filter said first signal to produce a filtered first signal; and a filter controller being co-operable with said adjustable filter and being configured to: measure a characteristic of said filtered first signal; and compare said characteristic of said filtered first signal against a reference value; adjust said adjustable cut off frequency corresponding to a variation of said main frequency when said characteristic of said filtered first signal differs from said reference value by an amount that exceeds a threshold value, wherein said filtered first signal has a main signal component at said main frequency, said main signal component having an amplitude, wherein said characteristic of said filtered first signal comprises a peak said amplitude of said main signal component, wherein said filter controller comprises a peak detector configured to: detect the peak amplitude of said filtered first signal, and generate a direct current signal comprising an amplitude that is indicative of said detected amplitude of said filtered first signal.