Spatial noise reducing device for vehicle passenger compartment - generates and updates compensating noise to interfere with transmitted periodic spatial noise

摘要

The device includes compensating noise generators (7a-7d), remaining noise detectors (8a-8h) to determine remaining noise at predetermined positions in the vehicle, transfer function filters (C-1m) modelled according to the transfer functions between the generators (7a-7d) and detectors (8a-8h), and adaptive digital filters (Wm) with variable filter coefficients. A reference signal is generated (4,5) as a pulse train with the same period as the noise. The transfer function filters (C-1m) are combined with the ref. signal to provide processed reference signals. The adaptive filters (Wm) are combined with the ref. signal to provide drive signals to drive the compensating noise generators (7a-d). The filter coeffts. of the adaptive filters (Wm) are updated on the basis of the processed ref. signals and the remaining noise to reduce the noise in the passenger compartment. ADVANTAGE - Simple system which compensates for noise quickly.