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A two-scale model modified by improved geometrical optics (GO) is proposed. The improved geometrical optics considers the short waves diffraction and obtains the same accuracy as zero order Kirchhoff. Simulation shows that the modified two-scale model obtains satisfied accuracy as well as retains the simple representation in the frequency band which classical two scale model can not be applied. The...
Synthetic aperture sonar has the characteristics of high resolution imaging which is not limited by the detection range. It can be used for imaging and mapping of the seafloor. However, the product value of detection range and speed of navigation is limited by the physical length of the array in the traditional synthetic aperture sonar. When the speed of navigation is improved on condition that the...
In the field of underwater acoustic communication, because of the signal transmission distance is shorter, generally uses the copper cable transmission. When the signal is needed to be transmitted in a long distance, its anti interference and attenuation will seriously affect the reliability of the transmission. Optical fiber transmits in higher speed and stronger antijamming. Its application is more...
In beamforming, maximum likelihood estimation is used to estimate the covariance matrix by using the received data. In order to improve the estimation accuracy of covariance matrix and reduce noise, based on array domain, an preceding method for broadband beamforming using subband smooth is proposed which smoothes of each subband before the covariance matrix of the received data is estimated. The...
Coordinated multi-points (CoMP) transmission has been widely proved to be effective to combat inter-cell interference in 3GPP LTE-Advanced systems. However, implementation complexity of inter-site CoMP and relatively low capacity gain of intra-site CoMP motivate us propose a beam coordinated multipoints (Beam-CoMP) transmission scheme for 5G millimeter-wave cellular network. Considering the specific...
Weak target detection is one of the key problems facing the foreign object debris (FOD) surveillance radar at the airport runway. A novel FOD detection algorithm based on higher order statistics features and support vector domain description (SVDD) classifier for 77GHz millimeter wave (mm-wave) radar is proposed in this paper. Clutter map constant false alarm rate (CFAR) is firstly applied to the...
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...
The micro-Doppler (m-D) feature is regarded as a unique characteristic for target recognition. Sparse recovery based approaches for m-D parameter estimation using the single measurement vector (SMV) model have shown their effectiveness recently. However, SMV only fits for narrowband m-D signals, and accurate parameters can hardly be estimated using SMV in strong noise. The signals with the same sparse...
As a kind of commonly background signal, Ocean ambient noise is interference in the underwater acoustic channel. Although there are a lot of marine noise sources, the parameter influencing ocean ambient noise field are closely related to the state of the marine environment. From the perspective of theory, the change law of the ocean ambient noise at a fixed-point was difficult to describe. And from...
In this paper, an advanced joint jammer with deceptive jamming and blanket jamming is proposed for countering linear frequency modulated (LFM) radar. Multiple preceded and hysteretic false targets are produced by convolution operation and the blanket jamming is obtained by modulating the intercepted hostile radar signal according to pseudo-random sequences. The jamming algorithm is implemented on...
Auto ship detection for high frequency (HF) skywave over-the-horizon (OTH) radar, being a valuable application, has not been achieved virtually within short coherent integration times (CITs). Because the ships' lines in the spectrum can be covered by the ocean clutter's easily as a result of the poor resolution, which attenuates the validities of ocean clutter suppression algorithms. Besides, when...
Reverberation is the main interference in active sonar detection, due to its special properties, reverberation suppression is a difficult problem in active sonar signal processing. In this paper, the method of reverberation suppression is studied, and a new method based on the normalization of the beam space data is proposed. The basic idea of this method is to normalize the time waveform of the beam...
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