Method of and apparatus for cancelling vibrations from a source of repetitive vibrations
Active sound attenuation system with on-line adaptive feedback cancellation
Selective active cancellation system for repetitive phenomena Patent #: 4878188
ApplicationNo. 477432 filed on 02/09/1990
US Classes:708/300, Filtering381/71.11, Adaptive filter topology708/322Adaptive
ExaminersPrimary: Malzahn, David H.
Attorney, Agent or Firm
International ClassG06F 015/31
AbstractA digital virtual earth active cancellation system which receives a phenomena input signal representing residual phenomena to be cancelled and has an adaptive filter which generates a cancellation signal. A system impulse response is convolved with the cancellation signal and is subtracted from the input signal to produce an estimate of noise. This substantially eliminates the problems associated with destructive feedback due to phase shifts. The residual signal is used to control an adaptive filter that receives the estimated noise as an input. The adaptive filter produces the cancellation signal by filtering the estimated noise with filter weights that are adapted using the residual signal and the estimated noise convolved with the system impulse response.