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.

Direct conversion wireless receiver with digital phase equalization

Abstract: A direct conversion receiver (DCR) with a pair of quadrature conversion paths. Each of the quadrature conversion paths receives an RF input signal and converts the RF input signal to a digital baseband signal. The quadrature conversion paths each include a mixer mixes the RF input signal with a carrier phase signal. Quadrature baseband signals from the mixer pass through an analog filter which provides a filtered baseband signal. An analog to digital converter (ADC) converts the quadrature baseband component to a digital baseband signal. A 5 th order elliptical filter filters the quadrature baseband component. The 5 th order elliptical filter may be before or after the ADC. A digital baseband component from the ADC and filtered by the 5 th order elliptical filter passes to a phase equalizer which compensates for phase distortion from the analog filter. The quadrature digital baseband outputs from the quadrature conversion paths are passed to a baseband processor.

A Proof of the Necessary Condition for Perfect Reconstruction of Signals Using the Two-channel Wavelet Filter Bank

Abstract: Wavelet representation of signals and images is very useful for compression purposes. To obtain a wavelet representation by splitting a digital signal into two subsampled sygnals in a two-channel filter bank, the filters must satisfy perfect reconstruction conditions. This paper presents a theorem that formulates perfect reconstruction conditions for two-channel filter bank and a complete proof of both necessary and sufficient conditions. Additional requirements for filters guaranteeing the existence of the wavelets are reviewed.

Design of Two Channel Quadrature Mirror Filter using Cuckoo Search Algorithm

Abstract: In this paper a two channel quadrature mirror filter(QMF) bank design method is proposed using Cuckoo Search Algorithm (CSA) The CSA is used to optimize the coefficients of prototype filter bank in order to match the response characteristics of the prototype filter bank with the ideal system response The weighted sum of square error at the pass band, square error at the stop band and filter bank response at the quadrature frequency are used to formulate the objective function The CSA is used as the constrained nonlinear optimization tool to solve the objective function The performance of the proposed method is analysed through mean square error (MSE) in the pass band and stop band and reconstruction error (RE) A comparative statement has been prepared between the different optimization techniques for optimization of coefficients of QMF Two examples are considered to illustrate the efficacy of the proposed algorithm

Design of low-delay FIR QMF banks using the Lagrange-multiplier approach

Abstract: A new approach for the design of two-channel perfect reconstruction FIR filter banks with short reconstruction delays is presented. A low-order filter is first designed and the objective function of the filter bank is formulated as a quadratic programming problem with linear constraints. The Lagrange-multiplier method is then used to design a higher-order filter. The method is simple, efficient, and flexible and leads to a closed-form solution. A design example is included to illustrate the advantages of the method.

Quadrature demodulator and wireless receiver

Abstract: A quadrature demodulator includes a quadrature demodulating circuit configured to generate an analog in-phase signal and an analog quadrature signal based on an output signal of a low noise amplifier, and a controller configured to cause a thermal noise, instead of the output signal of the low noise amplifier, to be input to the quadrature demodulating circuit, when a correction parameter to correct a mismatch between the in-phase and quadrature signals is being calibrated.