Quadrature mirror filter

About: Quadrature mirror filter is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 28900 citations.

Necessary conditions on the lifting scheme for existence of wavelets in L/sub 2/(R)

Abstract: Over the years many different libraries of biorthogonal wavelets have been designed. In addition, the lifting scheme has been developed which unifies the design of biorthogonal wavelets using a simple approach. The lifting scheme allows the custom design of wavelets while maintaining the biorthogonal constraint on the filter bank. A drawback of the lifting scheme is that it does not guarantee that the wavelet associated with the iterated filter bank exists in L/sub 2/(R). In practice this raises the possibility that the filter bank may produce numerical artifacts. We present some necessary conditions on the lifting scheme for the resulting wavelets to exist in L/sub 2/(R). Using these conditions, we show how valid wavelet bases can be easily generated from randomly perturbed biorthogonal filter banks.

Design of Digital Quadrature Modulator Based on AD9957

Abstract: Digital quadrature modulator is one of the key parts of Software Radio system.Now the miniature、universal and parameter-configured digital quadrature modulator is required.Based on the features of QDUC chip-AD9957,a new design solution of universal digital quadrature modulator based on AD9957 is proposed,and it features variable parameters,simple hardware structure,high-degree integration,and digital shaping,etc.Finally,the core hardware circuit theory diagram and the experiment results of are given.Test results show that the actual signal performance is basically in consistent with reference data.

Real-time Implementation of a Class of Optimised Multirate Quadrature Mirror Filter Bank Using Genetic Algorithms

Abstract: This paper considers theoretical issues concerning reconstruction errors and conditions for perfect reconstruction (PR) of the input signal for a 2-channel multirate quadrature mirror filter (QMF) bank. The main emphasis is on the optimisation of a new design of a perfect reconstruction QMF bank using infinite impulse response (IIR) filters based on transformation of variables technique. The genetic algorithm (GA) optimisation is used for the initial design of the QMF bank and for the IIR filters using finite word length coefficients. The optimised results are then applied to a real time digital signal processing kit. Finally, some test results for data compression achievable using different values of encoded bits are included.

Low power reconfigurable sub -band filter bank ASIC for MP3 decoder

Abstract: There is an ever demanding need to develop low power audio devices using MP3 technology. From the profiled results of MP3 algorithm on ARM processors it has been observed that, the synthesis filter bank in the audio decoder consumes maximum power. Hence to reduce the power consumption of the filter bank, we developed an IEEE 754 single precision floating-point runtime re-configurable architecture. The proposed architecture consumes less power at run time as the last 12 bits of the mantissa part of the synthesis filter coefficients are zero most of the time and hence the corresponding multipliers will be switched off. Since the active multipliers during inverse polyphase quadrature mirror filter banks (IPQMF) are less, we are able to achieve low powered decoding process without significantly compromising on the accuracy and speed. We synthesized and simulated the architecture using 0.35 mum process technology under Synopsys environment. A uniform worst case power reduction of 23.7% has been achieved in the frequency range from 1MHz to 20 MHz when all the multipliers are in active state.

Bandwidth Extension of Speech Signals Using Quadrature Mirror Filter (QMF)

Abstract: Telephone networks normally transmit narrowband (NB) speech with a bandwidth restricted to 300 Hz to 3.4 kHz. While human speech comprises frequencies even further than the NB, there is a degradation of speech quality and intelligibility in such networks. This can be enhanced by recovering the speech components existing beyond the telephone bandwidth using Quadrature Mirror Filter (QMF) to give a perceptually superior wideband (WB) speech signal. QMF banks utilized as the fundamental mathematical tools to analyze and synthesize speech signals to coding of speech signal in sub-bands. Utilization of QMF's allows evading the aliasing effects due to samples decimation when signal is divide into sub-bands. In this paper, the performance of bandwidth extension (BWE) of speech through QMF was assessed by objective parameters like Log Spectral Distortion (LSD) and Itakura-Saito distance (ISD) and subjective parameters like Mean opinion score (MOS), Absolute Category Rating (ACR), Comparison Category Rating (CCR) and Perceptual Evaluation of Speech Quality (PESQ) which demonstrates that the recovered WB speech signal provides speech quality compared by original WB speech signal.