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.

Filter device for demodulated quadrature amplitude modulated signal

Abstract: The filter device has a filter circuit (10') with respective channels (17I,17Q) for the cosine and sine demodulated components of the quadrature amplitude modulated signal, with respective filter transmission functions for the demodulated components. A switching device (19,21) connects a transverse circuit path (9) between the input of one channel and the output of the other channel in one switch position and between the input of the second channel and the output of the first channel in a second switch position.

RLS-based Algorithm for Denoise of EEG Signal

Abstract: In this paper,Recursive Least Square(RLS) adaptive filter,matching filter and corresponding denoising measurements are introduced.Based on RLS,general C programe can be performed for denoise on condition that useful signal is not seriously interferred by noise.After denoising for real EEG signal and matching filter,all the results of filter output,power spectrum and matching filter output diagram are described by Matlab 7.By comparision,the results are satisfctory.

Heterogeneous filter bank filtering method based on tree structure

Abstract: The invention provides a heterogeneous filter bank filtering method based on a tree structure; the method comprises the following steps: using a dual-channel FIR quadrature mirror filter bank as a basic module, and employing the tree structure to build a heterogeneous filter bank; deriving reconstruction conditions of the whole tree structure heterogeneous filter bank, and resulting the whole system complete reconstruction conditions as to design a prototype filter satisfying specific conditions; using an iteration passband cut-off frequency to enable the designed prototype filter to satisfy reconstruction conditions In a prototype filter special designing process, the method can employ a discrete weight square error criterion; compared with other methods, the criterion can better realize the passband flat characteristics and bigger stop band attenuation; the design scheme can effectively reduce the iteration complexity, can obtain bigger stop band attenuation and excellent system reconfiguration performance, thus providing important application values for a radar broadband channelization receiver and voice and picture signal processing

Radar signal classification method based on QMFB and convolutional neural network

Abstract: A modern radar generally uses a low probability intercept (LPI) radar signal to detect a target so that LPI signal classification is needed in radar countermeasures. Currently, a traditional artificial characteristic extraction algorithm is used to classify, and during practical application, the classification correct rate of the algorithm is not ideal. The invention provides a classification method based on the combination of a quadrature mirror filter group and a convolutional neural network. The method comprises the following steps of firstly, carrying out QMFB processing on an interceptedradar signal to obtain radar layered time frequency images; then, based on the novel convolutional neural network, classifying the radar layered time frequency images; and finally, outputting a LPI radar signal classification result. In the invention, based on the convolutional neural network, a plurality of LPI signal characteristics can be automatically extracted, and compared with the traditional algorithm, the method of the invention has improved classification efficiency and an improved identification correct rate.

DOA Estimation of Moving Target under the Clutter Environment by Applying MUSIC to the QMF Doppler Filter Bank

Abstract: This paper proposes a new angular measurement system to a moving target in the presence of clutter. We apply MUSIC (MUltiple SIgnal Classification) to the outputs of a Doppler filter bank consisting of quadrature mirror filter (QMF). The comparison between QMF and the short time Fourier transform (STFT) as a preprocessor of MUSIC is also discussed. DOA estimation performance by QMF-MUSIC is nearly equal to that of STFT-MUSIC. On the other hand, QMF-MUSIC overcomes STFT-MUSIC in the aspect of computational cost. In a specific example in this paper, the proposal QMF bank by Daubechies (4th order) wavelet requires 80% fewer the number of multiplications and 25% fewer the number of additions than the FFT-based STFT filter bank.