Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 6 Articles
Co-prime arrays can estimate the directions of arrival (DOAs) of O(MN) sources with\nO(M+ N) sensors, and are convenient to analyze due to their closed-form expression for the locations\nof virtual lags. However, the number of degrees of freedom is limited due to the existence of holes\nin difference coarrays if subspace-based algorithms such as the spatial smoothing multiple signal\nclassification (MUSIC) algorithm are utilized. To address this issue, techniques such as positive\ndefinite Toeplitz completion and array interpolation have been proposed in the literature. Another\nfactor that compromises the accuracy of DOA estimation is the limitation of the number of snapshots.\nCoarray-based processing is particularly sensitive to the discrepancy between the sample covariance\nmatrix and the ideal covariance matrix due to the finite number of snapshots. In this paper, coarray\ninterpolation based on matrix completion (MC) followed by a denoising operation is proposed to\ndetect more sources with a higher accuracy. The effectiveness of the proposed method is based on the\ncapability of MC to fill in holes in the virtual sensors and that of MC denoising operation to reduce\nthe perturbation in the sample covariance matrix. The results of numerical simulations verify the\nsuperiority of the proposed approach....
Signal frequency estimation is a problem of significance in many applications including audio signal processing.\nCompressed domain audio frequency estimators that directly use the modified discrete cosine transform (MDCT)\ncoefficients are suitable for low-complexity audio applications. A new frequency estimation approach, which can\nobtain the estimated value from a simple combination of three MDCT coefficients, is proposed herein. It exploits\nthe underlying relation among adjacent MDCT values and provides a general form of this type of estimators. The\nestimator manifests obvious computational advantages over other MDCT domain estimators and is suitable for high\nsignal-to-noise ratio (SNR) conditions....
This paper outlines a package synchronization scheme for blind speech watermarking in the discrete wavelet\ntransform (DWT) domain. Following two-level DWT decomposition, watermark bits and synchronization codes are\nembedded within selected frames in the second-level approximation and detail subbands, respectively. The\nembedded synchronization code is used for frame alignment and as a location indicator. Tagging voice active\nframes with sufficient intensity makes it possible to avoid ineffective watermarking during the silence segments\ncommonly associated with speech utterances. We introduce a novel method referred to as adaptive mean\nmodulation (AMM) to perform binary embedding of packaged information. The quantization steps used in mean\nmodulation are recursively derived from previous DWT coefficients. The proposed formulation allows for the direct\nassignment of embedding strength. Experiment results show that the proposed DWT-AMM is able to preserve\nspeech quality at a level comparable to that of two other DWT-based methods, which also operate at a payload\ncapacity of 200 bits per second. DWT-AMM exhibits superior robustness in terms of bit error rates, as long as the\nrecovery of adaptive quantization steps is secured....
Techniques for generating multichannel audio from stereo audio signals are supposed to\nenhance and extend the listening experience of the listener. To assess the quality of such upmix\nalgorithms, subjective evaluations have been carried out. In this paper, we propose an objective\nevaluation test for stereo-to-multichannel upmix algorithms. Based on defined objective criteria and\nspecial test signals, an objective comparative evaluation is enabled in order to obtain a quantifiable\nmeasure for the quality of stereo-to-multi channel up mix algorithms. Therefore, the basic functional\nprinciple of the evaluation test is demonstrated, and it is illustrated how possible results can be\nvisualized. In addition, the proposed issues are introduced for the optimization of upmix algorithms\nand also for the clarification and illustration of the impacts and influences of different modes\nand parameters....
Under the complex oceanic environment, robust and effective feature extraction is the key issue of ship radiated noise recognition.\nSince traditional feature extraction methods are susceptible to the inevitable environmental noise, the type of vessels, and the\nspeed of ships, the recognition accuracy will degrade significantly. Hence, we propose a robust time-frequency analysis method\nwhich combines resonance-based sparse signal decomposition (RSSD) and Hilbert marginal spectrum (HMS) analysis. First, the\nobserved signals are decomposed into high resonance component, low resonance component, and residual component by RSSD,\nwhich is a nonlinear signal analysis method based not on frequency or scale but on resonance. High resonance component is\nmultiple simultaneous sustained oscillations, low resonance component is nonoscillatory transients, and residual component is\nwhite Gaussian noises. According to the low-frequency periodic oscillatory characteristic of ship radiated noise, high resonance\ncomponent is the purified ship radiated noise. RSSD is suited to noise suppression for low-frequency oscillation signals. Second,\nHMS of high resonance component is extracted by Hilbert-Huang transform (HHT) as the feature vector. Finally, support vector\nmachine (SVM) is adopted as a classifier. Real audio recordings are employed in the experiments under different signal-to-noise\nratios (SNRs).The experimental results indicate that the proposed method has a better recognition performance than the traditional\nmethod under different SNRs....
The article discusses the problem of estimating the psychophysiological state of aircraft pilots by\ntheir speech. For this purpose, a new concept of an individual speaker�s transfer function is proposed. This\ndefinition is based on the classical results of automatic control theory. The article presents the algorithms\nfor calculating transfer function and the examples of using this feature for medical purposes....
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