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In this paper, we propose a novel orthogonal frequency-division multiplexing (OFDM) waveform with low probability of intercept (LPI) and the corresponding synthetic aperture radar (SAR) processing algorithm. The OFDM waveform has a random spectrum for each pulse, making it a good candidate for low probability of intercept system implementation. The SAR processing algorithm eliminates the influence...
Compressed sensing, as a novel framework, needs a small amount of characteristic datas to reconstruct the original datas and breakthroughs the limitation of the Nyquist sampling law, which effectively relieves the pressure of dealing with a large amount of datas in the practical application. But the noise reduction performance in traditional compressed sensing is very poor, in order to improve the...
When the signal-to-noise ratio (SNR) is reduced in case of track-before-detect (TBD) for weak target detection, the TBD algorithm based on Gaussian mixture probability hypothesis density (GM-PHD) filter cannot estimate the number or status of targets accurately. In order to solve this problem, a TBD algorithm based on GM-PHD smoothing filter (SGM-PHD-TBD) is proposed. Within the framework of TBD standard...
Filtered-X least mean square (FXLMS) algorithm is widely used in active noise control (ANC) systems when the secondary path is linear. However, the performance of FXLMS reduces when nonlinearity is present. Leaky FXLMS (LFXLMS) and minimum output variance FXLMS (MOVFXLMS) algorithms are effective in compensating the nonlinearity effects in nonlinear ANC (NANC). When using optimum leakage factors,...
Stochastic Resonance(SR) can restore the weak signal in a strong noise background more effectively by using noise. According to this, a new way to process the noised signal in a bad noised environment has been provided. A new way of image processing based on bistable Stochastic Resonance and Wavelet transform has been given. Firstly, the noised image is processed by bistable Stochastic Resonance....
The two-dimensional (2-D) direction-of-arrival (DOA) estimating for non-circular signals in highly real-time situation is addressed. A new algorithm using a single snapshot for 2-D DOA estimating is proposed. Based on the dual parallel uniform linear array (ULA), three equivalent rotationally invariant covariance matrices are constructed using the single snapshot, which are evaluated to generate the...
The next generation of space-borne synthetic aperture radar (SAR) systems will emphasize on high-resolution and wide-swath imaging. For these design purposes, multichannel technology in azimuth is a promising candidate. In the multichannel SAR system, the nonuniform azimuth signal needs to be reconstructed when the pulse repetition frequency (PRF) deviates from a specific one. The traditional digital...
Root-MUSIC algorithm is a method of DOA estimation based on polynomial rooting. It estimated based on the cost function instead of peak searching, which greatly reduces the computation compared with MUSIC algorithm. However, it came with some other errors. In this letter, we propose a new method based on the the first-order derivative of the cost function and analyze the mean and the MSE of the proposed...
In this paper, a decision-directed beamforming and channelequalization algorithm is presented for IEEE 802.11n OFDM systems in the presence of co-channel interference (CCI). Based on the minimum mean-square error (MMSE) criterion, the cost function of the proposed algorithm is to minimize the MSE on each subchannel and to improve the system performance. The beamforming compensation isprimarily used...
Robustness of digital audio watermarking algorithm against serious signal processing attacks is a big challenge in the recent trends. Many works have been reported in this field claiming high payload with good imperceptibility but good robustness at acceptable perceptual rates is still needed to be addressed. In this paper, watermark is embedded in the wavelet transformation of audio signal by using...
An acoustic noise cancellation (ANC) is a technique for removing additive noise from corrupted speech signal. This paper introduces a new Error Normalized Least Mean Square (ENLMS) algorithm in which the step size varies inversely with the squared norm of the error vector. The signed version of Normalized LMS (NLMS) algorithm requires a priori knowledge of a bound for the error magnitude, which is...
Improvement of software is the perspective line of seismic guard system development. Now it is possible to solve the problem of detection, classification, path parameter estimation by this software. But increasing system requirements lead to necessity of algorithm precision and operating speed increment. New object classification method in the seismic guard system is proposed in this paper. This method...
Dictionary learning (DL) for sparse representation is a difficult optimization problem for which several successful algorithms exist, although none can be claimed the best. A common problem is a possible stall in the evolution of the algorithm, due to nearly linearly dependent atoms. The proposed cure was to regularize the error criterion using either the norm of the representations or an atom coherence...
The faster decoding algorithm is still required in multiple-input multiple-output (MIMO) wireless communication technology. Lattice reduction (LR) technique can improve the performance of linear MIMO detection methods. LLL (Lenstra-Lenstra-Lovasz) algorithm is one of the LR techniques and it has being extensively used for better basis of channel matrix by removing noise. LR-aided detection algorithms...
In this paper, a complex block orthogonal gradient adaptive-based alogrithm is presented. In order to enhance convergence rate, a complex block conjugate normalised orthogonal gradient adaptive algorithm is introduced based on conjugate gradient principle. The orthogonal direction mechanism is used to update the filter coefficients in stead of the negative gradient direction method. Simulation results...
Direction of Arrival (DOA) estimation implies estimating the direction concerning angles of arrival of the received signals by an array of elements. This paper presents a review to a comparative analysis of several DOA estimation algorithms broadly classified into Beamforming (Classical & Capon's) and Subspace-based techniques (Multiple Signal Classification (MUSIC), Minimum Norm and Root-MUSIC)...
This paper introduces a lifting double-wavelet algorithm for electrocardiogram signal denoising by using the improved threshold function in the lifting wavelet decomposition to deal with wavelet coefficients. The results, based on data from MIT-BIT arrhythmia database, show that noise can be eliminated effectively with lower distortion and higher signal-to-noise ratio compared with the single wavelet...
Stochastic resonance is one of the theories that have been widely used in the rotating machinery diagnostics. But the original stochastic resonance method has several defects. For example, adjustment and settlement of its system parameters totally depend on artificial to complete, or only one system parameter has been optimized according to the change of the fault signal at the cost of ignoring the...
The paper presents the results of research on a histogram-based approach to numerical analysis of statistical distributions of signals in radar detection systems. The idea of this method consists in the numerical calculation of histogram equivalents of probability density functions or cumulative density functions of signals after each stage of a signal processing path. The considerations are illustrated...
The new approaches for a single source direction-of-arrival estimation in a far-field and near-field cases are proposed. The main idea is estimation of the real spatial frequency directly along the uniform linear array by the single-shot data. The algorithm based on the autoregressive moving average model of the sinewave is applied for the frequency estimation. The precision of proposed methods is...
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