Showing papers on "Quadrature mirror filter published in 2016"

Two-channel perfect reconstruction (PR) quadrature mirror filter (QMF) bank design using logarithmic window function and spline function

Abstract: In this work, two-channel perfect reconstruction quadrature mirror filter (QMF) bank has been proposed based on the prototype filter using windowing method. A novel window function based on logarithmic function along with the spline function is utilized for the design of prototype filter. The proposed window has a variable parameter ‘ $$\alpha $$ ’, which varies the peak side lobe level and rate of fall-off side lobe level which in turn affects the peak reconstruction error (PRE) and amplitude distortion ( $$e_{am}$$ ) of the QMF bank . The transition width of the prototype is controlled by the spline function using the parameter ‘ $$\mu $$ ’. The perfect reconstruction condition is satisfied by setting the cutoff frequency ( $$\omega _{c}$$ ) of the prototype low-pass filter at ‘ $$\pi /2$$ ’. The performance of the proposed design method has been evaluated in terms of mean square error in the pass band, mean square error in the stop band, first side lobe attenuation ( $$A_{1}$$ ), peak reconstruction error (PRE) and amplitude error ( $$e_{am}$$ ) for different values of ‘ $$\alpha $$ ’ and ‘ $$\mu $$ ’. The results are provided and compared with the existing methods.

An efficient closed-form design method for nearly perfect reconstruction of non-uniform filter bank.

Abstract: In this paper, an efficient closed form method for the design of multi-channel nearly perfect reconstruction of non-uniform filter bank with the prescribed stopband attenuation and channel overlapping is presented. In this method, the design problem of multi-channel non-uniform filter bank (NUFB) is considered as the design of a prototype filter whose magnitude response at quadrature frequency is 0.707, which is exploited for finding the optimum passband edge frequency through empirical formula instead of using single or multivariable optimization technique. Two main attributes used in assessing the performance of filter bank are peak reconstruction error (PRE) and computational time (CPU time). As compared to existing methods, this method is very simple and easy to implement for NUFBs. To implement this algorithm, a Matlab program has been developed, and several examples are presented to illustrate the performance of proposed method.

Subband-based upmixing of stereo to 5.1-channel audio signals using deep neural networks

Abstract: In this paper, we propose a subband-based stereo to 5.1-channels upmixing method using deep neural networks (DNNs) in MPEG-H 3D audio framework. In the training stage, DNN models of rear and center channels are respectively trained by using log-spectral magnitudes of quadrature mirror filter (QMF) sub-bands. In the upmixing stage, stereo input signals are converted into rear and center channels by feed-forward decoding with the trained DNN models. The performance of the proposed method is evaluated using both objective and subjective measures and it is compared with those of conventional methods. Consequently, the proposed method outperforms the conventional methods.

Passive method for rescale detection using quadrature mirror filter based higher order statistical features

Abstract: High resolution digital cameras and state-of-the-art image editing software tools has given rise to large amount of manipulated images leaving no traces of being subjected to any manipulation. Passive or blind forgery detection algorithms are used in order to determine its authenticity. In this paper, an algorithm is proposed that blindly detects global rescaling operation using the statistical models computed based on quadrature mirror filter (QMF) decomposition. Fuzzy entropy measure is employed to choose the relevant features and to remove non-important features whereas artificial neural network classifier is used for forgery detection. Experimental results are presented on grayscale and G-component images of UCID database to prove the validity of the algorithm under different interpolation schemes. Results are provided for the detection of rescaled images with JPEG compression, arbitrary cropping and white Gaussian noise addition. Further, results are shown using USC-SIPI database to prove the robustn...

Programmable super-resolution pupil phase filter with a deformable mirror

Abstract: Compared with binary diffractive super-resolving elements, programmable super-resolution pupil filters permit the analysis of various filter designs and allow the filters to be changed rapidly to modify the response of an optical system. In this Letter, a deformable mirror is employed as a programmable super-resolution pupil phase filter. Continuous phase-only filters based on the Zernike polynomial series are designed by the genetic algorithm and fitted through closed-loop adaptive optics with a piezoelectric deformable mirror. Experimental super-resolution results are in agreement with the theoretical predictions. This method has no polarization light requirement and is convenient for application.

Design of maximally decimated linear phase orthogonal filter bank using iterative SVD technique and its applications

Abstract: Filter Banks traditionally designed by the factorization method which is complex and time consuming. Singular valued decomposition technique is introduced to design Linear Phase Orthogonal filter bank which yields efficient and fast results in time critical applications. Signal splitting and efficient reconstruction of the original signal is studied achieving perfect reconstruction condition due to the orthogonal nature of designed filter bank. Ultimate aim of proposed methodology is to design two approximation scenarios in terms of square matrices which apparently maps into the filter bank matrix. Singular valued decomposition is iteratively employed to compute both of these square matrices until achievable convergence is achieved between to alternate iterations. Proposed algorithm starts with the design of least square filter bank and ends with the filter bank which ensures orthogonality conditions as well as all filters in the filter bank satisfying linear phase condition. Thus, faster design of the filter bank along with linear phase orthogonal condition yields multiple applications in signal processing, image processing, communication etc.

Estimation of modulation parameters for LPI radar using Quadrature Mirror Filter Bank

Abstract: The performance of Electronic warfare system mostly depends on the design of LPI radar and ESM receivers. The objective of LPI radar is to detect the target at long ranges and to hide from intercept receiver available at the short range. New modulation techniques were developed to reduce the peak transmitted power for LPI radar. For the design of efficient ESM receiver, many signal processing algorithms were developed which extracts the modulation parameters from the received signal. Quadrature Mirror Filter Bank (QMFB) method is applied to estimate the various parameters of the LPI radar under different types of modulation techniques namely P1, P2, P3, P4 for various noisy conditions. It is observed that QMFB method is efficient to extract all modulation parameters for SNR values under no noise, 0dB, and up to −4dB.

Automatic Display-Camera Extrinsic Calibration Method Using an Annular Mirror

Abstract: 1079 Received September 16, 2014; revised July 8, 2015; accepted January 14, 2016. Communicated by Tyng-Luh Liu. * This work was supported by the National Natural Science Foundation of China under Grant No. 51375476. An earlier version of this paper was present at the International Conference on CYBER, 2015, Shenyang, China, IEEE. Automatic Display-Camera Extrinsic Calibration Method Using an Annular Mirror

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.

Linear-in-the-parameter model for an ideal voltage comparator

Abstract: This paper introduces linear-in-the-parameters model for strong nonlinear systems such as an ideal voltage comparator. This system characteristics (input-output) are approximated by even mirror fourier nonlinear filter based on Stone-Weierstrass approximation theorem. The performance of the proposed filter compared against the volterra filter for high and low input amplitudes. Also this paper discusses mean square error convergence and minimization of steady state error for calculating optimal filter coefficients of even mirror fourier nonlinear filter and volterra filter.

Continuous polynomials combination for the design of quadrature mirror filters

Abstract: This material proposes an efficient method for the design of the two channel quadrature mirror filters (QMF) bank, by using continuous polynomial functions. It is important to know that linear phase FIR filters cannot exactly satisfy the power complementarity condition. The proposal is to approximate the amplitudes of the two frequency transition bands by using continuous polynomial functions. The result is a good frequency selectivity. In the proposed approach, the prototype filter is optimized, by using continuous polynomials in the transition band. Many simulation results are presented to sustain the proposed method.

Dilation-3 PR QMF for image processing

Abstract: Perfect reconstruction (PR) quadrature mirror filter (QMF) banks with finite impulse response (FIR) filters are constructed from systems of dilation-3 biorthogonal refinable functions and wavelets. Such filters can be applied to image processing applications, such as image compression, image denoising, etc. These filters are linear due to the symmetry property of their underline biorthogonal refinable functions and wavelets, which satisfy functional equations with dilation factor 3. Image compression experiments show that the proposed dilation-3 QMFs outperform the popular CDF 9/7 filter bank.

Improved ETSI advanced front-end for automatic speech recognition using quadrature mirror filter synthesis based on robust complex speech analysis

Abstract: An automatic speech recognition (ASR) is commonly used in these days. Current ASR systems perform well in ideal environment; however, it does not perform well in realistic noisy environment. As a robust ASR, ETSI has standardized Advanced Front-End (AFE) that adopts two-stage of iterative Wiener filter (IWF) to realize a speech enhancement as the front-end of ASR. In the ETSI AFE, 16 kHz speech is divided uniformly by QMF (Quadrature Mirror Filter) into lower-band and higher-band signal and only lower-band signal is emphasized by the IWF and MFCC (Mel Frequency Cepstral Coefficient) is extracted from both the second-stage of emphasized lower-band signal and non-emphasized higher-band signal. FFT is used to estimate speech spectrum that designs the Wiener filter. On the other hand, we have already proposed robust complex speech analysis for an analytic signal. It can estimate more robust and more accurate speech spectrum due to the introduced robust criterion and nature of analytic signal. This paper propo...

Serialization of tree structured Quadrature Mirror Filter bank

Abstract: Efficient implementations of multichannel tree-structured filter banks require sharing of the tree nodes at each stage. While there exist many implementation structures and methods of tree-structured filter banks, most of them are based on some ad hoc tricks requiring application dependent data manipulations/buffering and/or careful scheduling of process control. This paper presents a serialized QMF tree structure that shares a common 2-channel Quadrature Mirror Filter (QMF) in each tree stage. With simple and well defined regular data permutation between tree stages, it eliminates the need for data buffering and scheduling. The proposed Serial QMF Tree structure is in essence a single rate multi stage filter that is fully pipelined and retains the throughput of the original tree structure. For an M-stage tree filter bank, the complexity of the Serial QMF Tree is equivalent to that of M prototype filters. The proposed method and architecture can be extended to serialize and pipeline other decimation/interpolation tree structures such as discrete wavelet transforms and frequency domain channelizers/synthesizers.

Image reconstruction in complex media by the fourth moment wavelet

Abstract: The discrete wavelet transform (DWT) is generally used in digital image processing to compress or filter images, its operation is based on a quadrature mirror filter that can analyze images in different frequency components. The DWT decomposes images into different sub-matrices representing the original image but in different frequencies analysis. The sub-images obtained is the representation of a low-pass filter and high-pass filter (LL), low-pass filter and high-pass filter (LH), high-pass filter and low-pass filter (HL), finally high-pass filter and high-pass filter (HH). In these sub-images the average noise is zero, but when an image is sent in a wireless channel changes the nature of the image by performing a shift of the mean value. The noise added to images can be eliminated by designing filters with high complexity and high costs, sometimes is diminished the rate of sending and receiving data sent due to the above conditions. Digital images tend to visually impaired decreasing its quality and sometimes tends to lose relevant information about this. By applying the wavelet fourth moment as a mechanism for reconstruction of digital images in noisy environments, together with a reducing estimator of the mean square error, variance and standard deviation, as detector noise in the coefficients of the sub-matrix LH of wavelet decomposition results in simulations showing up to 31 dB for the PSNR.

Performance improving of quadrature filter bank using group delay equalizer

Abstract: In this paper improving of the group delay characteristic of the quadrature filter bank has been presented. As an example, QMF bank with fifth order Transitional Butterworth-Elliptic filter as a prototype filter, has been considered. Using this procedure, a QMF bank with almost perfect reconstruction has been obtained.

Method and apparatus for quadrature mirror filtering with modulo addressing

Abstract: A method of performing quadrature mirror filter (QMF) synthesis filtering includes recording new samples corresponding to a current time slot at positions of samples to be discarded in a first array that includes modulated QMF sub-band samples. The method further includes extracting samples from the first array to remove aliasing between adjacent sub-bands, determining filter coefficients corresponding to the extracted samples by using modulo operation, and synthesizing a time domain sample where aliasing is removed by using the extracted samples and the filter coefficients.