Patent ID: 7859327

Claim:
A device for filtering a signal representative of a phenomenon of determined instantaneous period, delivered as output by at least one sensor installed in a motor vehicle, characterized in that it comprises: a comparator (A) offering as output a first logic signal (S A ) representative of the positive and negative transitions of the output signal (S M ) from the sensor, a clock (G) delivering a signal (S G ) serving as time base for the whole device, means (E, D, F) making it possible to fix a filtering time (T Filt ) of said output signal (S M ) from the sensor and comprising: a counter (F) whose counting is triggered by said control block (C) when said second logic signal (S B ) changes state, said counting not exceeding a maximum value (t dmax ), said counter (F) being reinitialized by said control block (C) when said maximum value (t dmax ) is reached or when said second logic signal (S B ) changes state, a register (E) storing a fraction of the value contained in the counter (F) on receipt of a storage command signal (Str) emanating from the control block (C), said storage command signal (Str) being dispatched when at least one change of state is detected on said first logic signal (S A ) during said filtering time (T Filt ), and a down counter (D) containing the value stored in said register (E) and of which a first countdown is triggered by said control block (C) when at least one change of state is detected on said second logic signal (S b ), a suppression block (B) receiving as input said first logic signal (S A ) and delivering as output a second logic signal (S B ) whose duration of holding (tn) in a logic state depends at least on said filtering time (T Filt ), and a control block (C) managing at least the set of the signals of the device, and having as input signals at least said first and second logic signals (S A , S B ).