One of the analysis/synthesis filter banks, time domain aliasing cancellation (TDAC) filter bank is widely used in audio coding systems because of its good frequency resolution, overlapped output, computational efficiency and low delay. TDAC filter bank system is perfect reconstruction (PR) system only if some conditions for the analysis/synthesis filters is satisfied. But in real systems, TDAC filter bank is used with quantization process between the analysis and the synthesis part. Therefore the SNR in TDAC system becomes an important factor, and the SNR enhancement is requested as possible as can be.
In this paper, the SNR is measured when the quantization error is introduced and the multiple overlap-add TDAC filter bank system is proposed for the SNR enhancement. The extended PR conditions is also derived for the proposed system and multiple overlap-add structure - the last step of synthesis part - is described in detail, and finally through several simulation results it is showed that the proposed system reveals the better performance in the SNR aspect in comparison to the existing system in case of using same quantization bits. When the amout of data about subband signals is fixed as same in both system, propsed system is advantageous in congestion control of data network because of the shorter block size.
