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Underwater acoustic (UA) channel is often affected by strong impulsive noise. In this paper, a compressive sensing based iterative algorithm is proposed to accurately estimate the channel state information and mitigate the impulsive noise, which is important to ensure high-speed data transmission in UA orthogonal frequency-division multiplexing communication systems. By exploiting the sparsity of...
In this paper, a joint synchronization and Doppler scaling factor estimation algorithm has been proposed for underwater acoustic communications. The training sequence, which consists of two Zadoff-Chu (ZC) sequences being conjugate with each other, is utilized to synchronize and estimate Doppler scaling factor, time delay and carrier frequency offsets (CFOs). ZC sequences are well designed to show...
Subspace based techniques for direction of arrival (DOA) estimation need large amount of snapshots to detect source directions accurately. This poses a problem in the form of computational burden on practical applications. The introduction of compressive sensing (CS) to solve this issue has become a norm in the last decade. In this paper, a novel CS beamformer root-MUSIC algorithm is presented with...
This paper presents an new approach to noise reduction for voice communication over Bluetooth technology. In the literature, several authors have compared the performance of different filtering techniques, such as the well-known Spectral Subtraction (SS), and Wiener Filter (WF) using simulated data, whereas this research uses real-time data samples collected from cars subjected to a noisy environment...
The DOA estimation problem for wideband signals has attracted much attention in the past years, and how to utilize and derive the common DOA information among frequency bins is the essential question. We address the wideband DOA estimation problem in this paper, and to solve this problem we propose a joint sparse Bayesian learning algorithm based on the sparse signal representation (SSR) of the covariance...
A novel blind time-frequency joint synchronization based on the cyclostationary of orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM) systems is conceived in multipath channels conditions. The cyclic cumulants of OFDM/OQAM signals are derived firstly, symbol timing offset (STO) and carrier frequency offset (CFO) are estimated by employing two groups...
This paper proposes a Doppler estimation algorithm for underwater acoustic communication by constructing the guide function of the objective function based on linear frequency modulation (LFM) signal. The algorithm employs the least square principle and the particle swarm method, to build the objective function and solves the global optimal solution, respectively. Computer simulations show that the...
Automatic Modulation classification lays important role in the systems of electromagnetic spectrum monitoring. However performance of the algorithms is depreciated due to inaccurate estimation of signal parameters. The problem of unknown parameters is well documented in the literature however, authors usually propose improved algorithms in order to maximize probability of correct classification when...
Viterbi algorithm (VA) applied to time frequency (TF) distribution is a highly performed instantaneous frequency (IF) estimator, but it suffers from switch problem (SP) at the intersected points of multi-components on the TF plane. In order to suppress the SP in VA, an improved VA (IVA) in this paper assumes the IF variation trends between two adjacent IF points are not large, then a new penalty function...
DOA estimation in array processing uses MUSIC (Multiple Signal Classification) algorithm, mainly. It's the most investigated technique and is very attractive because of its simplicity. However, it meets drawbacks and fails when only very few samples are available and the sources are very close or highly correlated. In these conditions, the problem is more intricate and the detection of targets becomes...
Parameters estimation is a crucial and challenging component for Frequency-Hopping (FH) communication. Time-frequency analysis is a valid signal processing tool to estimate parameters of FH signal. However, the existing Time-Frequency analysis methods have several shortcomings such as weak suppression noise interference and feeble concentration of Time-Frequency, resulting in inaccurate parameter...
In this paper, a matrix pencil characteristic equation-based source number estimator is proposed. An enhanced matrix is defined through partition-and-stacking process by the original data on the uniform linear array, and its covariance matrix is computed, which is proved to be a toeplitz conjugate symmetry matrix. The covariance matrix elements are aligned to from a vector. A measurement matrix is...
Multi-channel speech enhancement algorithms rely on a synchronous sampling of the microphone signals. This, however, cannot always be guaranteed, especially if the sensors are distributed in an environment. To avoid performance degradation the sampling rate offset needs to be estimated and compensated for. In this contribution we extend the recently proposed coherence drift based method in two important...
In this paper, we consider the direction-of-arrivals (DOAs) estimation of coherent narrowband signals impinging on an arbitrary linear array in a computational efficient way. A new interpolation transform based modified Capon beam-forming method is proposed without eigendecomposition, where the arbitrary linear array is transformed to a virtual uniform linear array (ULA) by utilizing the interpolation...
In the underwater passive target detection system, direction of arrival (DOA) estimation of traditional uniform linear array (ULA) becomes poor when targets come from the direction of end-fire. To solve this problem, this paper develops a new DOA estimation method for the wideband signal based on A-shaped array, which is implemented via two ULAs distributed with a specific angle. Firstly, the A-shaped...
Synthetic aperture Radar tomography has been widely used in 3D reconstruction in urban area. It can distinguish multi persistent scatterers in the same range-azimuth resolution cell. But how to detect and estimate the number and parameters of persistent scatterers is still an important and difficult problem need to be resolved. In this paper, a new method based on RELAX and generalized likelihood...
Knowing the wind speed is an important factor that includes several scientific areas. For the types of existing anemometers, the ultrasonic model is what can be used in most applications. As part of the necessary calculus for wind speed acquisition, it is needed to find the correct ultrasonic echo emitted that has been corrupted by the environmental conditions imposed on it, and is the bigger challenge...
Distributed coherent aperture radar (DCAR) can be applied to improve the target tracking and identification performance through adjusting transmitting/receiving timing and phase of spatial distributed radars via the coherent parameters (CPs). Therefore, estimating high precision of CPs is the core and prerequisite for DCAR to realize coherent synthesis. In this paper, we introduce the workflow of...
A novel two dimension direction-of-arrival (2D-DOA) estimation method for L-shaped array using atomic norm minimization based on the cross-correlation matrix is proposed in this paper. We first reconstruct the autocorrelation matrix of observed signals in the Toeplitz structure by cross-correlation matrix-based atomic norm minimization (CCMANM), and then employ the reconstructed autocorrelation matrix...
This paper proposed a low probability of identification (LPID) radar signal parameter interval design method to control recognition probability in intercept receiver. The method introduced in this paper use identification capacity theory to study recognition process in intercept receiver. The relationship between identification capacity and error recognition probability is established. Then, the radiation...
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