New Delay Less Sub Band Adaptive Filtering Algorithm for Active Noise Control Systems
The delay less SAF scheme in an ANC system involves the decomposition of input noise (i.e., the reference signal) and error signals into sub bands using analysis filter banks, and combining the sub band weights into a full-band noise canceling filter by a synthesis filter bank called weight stacking. Typically, a linear-phase finite-impulse response (FIR) low-pass filter (i.e., prototype filter) is designed and modulated for the design of such filter banks. The filter must be designed so that the side-lobe effect and spectral leakage are minimized. The delay in filter bank is reduced by prototype filter design and the side-lobe distortion is compensated for by oversampling and appropriate stacking of sub band weights. Experimental results show the improvement of performance and computational complexity of the proposed method in comparison to two commonly used sub band and block adaptive filtering algorithms. Sub band adaptive filtering (SAF) techniques play a prominent role in designing active noise control (ANC) systems. They reduce the computational complexity of ANC algorithms, particularly, when the acoustic noise is a broadband signal and the system models have long impulse responses. In the commonly used uniform-discrete Fourier transform (DFT) -modulated (UDFTM) filter banks, increasing the number of sub bands decreases the computational burden but can introduce excessive distortion, degrading performance of the ANC system. In this paper, we propose a new UDFTM-based adaptive sub band filtering method that alleviates the degrading effects of the delay and side-lobe distortion introduced by the prototype filter on the system performance
