Digital filter modeling for active noise cancellation
AssigneeSiemens VDO Automotive Corporation
InventorManish Vaishya
Life of this patent
Estimating the term…
Abstract
An active noise cancellation system (20) includes digital modeling of the physical path that is compensated for using a digital filter (34). An initial estimate of the time domain response of the system (20) is achieved using inverse time domain convolution to determine the signal values of a speaker (24) and a microphone (26) in the system. The estimated time domain response of the system is used to determine the initial estimate of the modeled digital filter. In one example, the initial estimate is then used as part of a convergence technique, such as a least mean squares algorithm. In another example, a plurality of initial estimates are determined and then averaged to arrive at the filter value used during noise cancellation.
Claims16
A method of determining a digital filter value for use in an active noise cancellation system, comprising the steps of:
- (A) applying a noise signal to the system;
- (B) estimating an initial filter value using the system response to the noise signal;
- and
- (C) determining the filter value using the estimated initial filter value.
A method of determining an initial estimate of a digital filter for use in an active noise cancellation system, comprising the steps of:
- applying a test signal to the system;
- determining a time domain response of the system to the test signal;
- and
- estimating the initial filter value based upon the time domain response.
A noise cancellation system, comprising:
- a speaker;
- a microphone that detects a combination of a sound from the speaker and noise in the system;
- and
- a controller that determines a digital filter used during noise cancellation by initially estimating a filter based upon a time domain response of the system to a test noise signal.
Dependencies are inferred from the claim text.