A delayless adaptive IFIR filterbank structure for wideband and narrowband active noise control

  • Authors:

  • K. Rajgopal;S. Venkataraman

  • Affiliations:

  • Department of Electrical Engineering, Indian Institute of Science, Bangalore, India;Department of Electrical Engineering, Indian Institute of Science, Bangalore, India and Research Engineer, Centre for Development of Telematics (C-DOT), Phase I Electronic City, Bangalore, India

  • Venue:
  • Signal Processing - Special section: Distributed source coding
  • Year:
  • 2006

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Abstract

Active noise control (ANC) applications involve adaptive filters with hundreds of taps. These filters are associated with high computational burden depending on the number of taps in the filter and may suffer from slow convergence if the reference signal spectrum has a large dynamic range. Subband and filterbank techniques have been proposed to address these problems. It is known that linear systems can be modeled exactly using a set of filter bank basis functions. Filter bank adaptive filter (FBAF) is one such model in adaptive filterbank techniques. The FBAF model is a parallel bank of filters with each bank (channel) comprising of cascade of a set of short length filter called interpolator followed by adaptive sparse filter also called the model filter. The interpolator-sparse model filter cascade in each channel is identical to the classical interpolated finite impulse response (IFIR) filter. Hence, the structure is called IFIR filterbank structure. The filterbank basis functions are orthonormal, which introduces delay in the signal path, thereby, degrading the performance of the adaptive filter. In this paper, we propose a delayless adaptive IFIR filterbank structure for wideband and narrowband active noise control. The proposed delayless adaptive filter has improved mean square error (MSE) convergence rate and shows marginally better noise cancellation in the wideband and narrowband ANC domain when compared with the conventional fullband adaptive structure. The computational complexity of the proposed structure is compared with the fullband structure.