摘要 :
Owing to the decametric wavelength, large aperture antenna array is needed for high frequency (HF) ground radar to obtain high angular resolution with conventional beam forming (CBF); for the case of compact antenna or small apert...
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Owing to the decametric wavelength, large aperture antenna array is needed for high frequency (HF) ground radar to obtain high angular resolution with conventional beam forming (CBF); for the case of compact antenna or small aperture array, spatial super-resolution algorithms are used to get satisfactory angular resolution. Wuhan University's ocean state measuring and analyzing radar (OSMAR2000) is expected to real time extract ocean surface current, wave and surface wind at medium- and long-range. To obtain long-range (i.e. 200km) current mapping, radar frequency must be selected in the lower region of the HF band, e.g. 7.5MHz. Digital beam forming (DBF) is applied with the 120m-long phased array to determine the bearings of sea echo with 150 resolution for wave and wind extraction. The angular resolution is, however, too coarse for current mapping, especially when the ocean current detection range is as far as 200km. Consequently, a super-resolution ocean surface current algorithm based on multiple signal classification (MUSIC) is developed for OSMAR2000. The relative theory basis, processing procedure and preprocessing and post-processing associated with the algorithm are given in this paper. The comparison of OSMAR2000 measurements with the measurements from current meter and the Seasonde system shows the ocean surface current algorithm based on MUSIC for OSMAR2000 can meet the requirements of the project contract successfully.
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摘要 :
Owing to the decametric wavelength, a large aperture antenna array is needed for high frequency (HF) ground radar to obtain high angular resolution with conventional beam forming (CBF); for the case of a compact antenna or small a...
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Owing to the decametric wavelength, a large aperture antenna array is needed for high frequency (HF) ground radar to obtain high angular resolution with conventional beam forming (CBF); for the case of a compact antenna or small aperture array, spatial super-resolution algorithms are used to get satisfactory angular resolution. Wuhan University's ocean state measuring and analyzing radar (OSMAR2000) is expected to real-time extract ocean surface current, wave and surface wind information at medium-range and long-range. To obtain long-range (i.e. 200 km) current mapping, the radar frequency must be selected in the lower region of the HF band, e.g. 7.5 MHz. Digital beam forming (DBF) is applied with the 120 m-long phased array to determine the bearings of the sea echo with 15/spl deg/ resolution for wave and wind extraction. The angular resolution is, however, too coarse for current mapping, especially when the ocean current detection range is as far as 200 km. Consequently, a super-resolution ocean surface current algorithm based on multiple signal classification (MUSIC) is developed for OSMAR2000. The relative theory basis, processing procedure and preprocessing and postprocessing associated with the algorithm are given. The comparison of OSMAR2000 measurements with the measurements from a current meter and the Seasonde system shows the ocean surface current algorithm based on MUSIC for OSMAR2000 can meet the requirements of the project contract successfully.
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摘要 :
A multiplication-free digital down converter (DDC) based on the Walsh transform for intermediate frequency (IF) digital receiver is presented. The novel structure mainly consists of a fast Walsh transform (FWT)and an inverse fast ...
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A multiplication-free digital down converter (DDC) based on the Walsh transform for intermediate frequency (IF) digital receiver is presented. The novel structure mainly consists of a fast Walsh transform (FWT)and an inverse fast Walsh transform (IFWT), both of which can be implemented only by addition and subtraction .Since the transform kernel of the FWT and the IFWT are the same,the implementation complexity of the proposed DDC is significantly reduced. Performances illustrative are compared with those of other DDCs, which include convolution operation. Experimental results show that the proposed method outperforms others and is more suited for real time signal processing of software digital down conversion in digital signal processor (DSP).
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摘要 :
A multiplication-free digital down converter (DDC) based on the Walsh transform for intermediate frequency (IF) digital receiver is presented. The novel structure mainly consists of a fast Walsh transform (FWT)and an inverse fast ...
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A multiplication-free digital down converter (DDC) based on the Walsh transform for intermediate frequency (IF) digital receiver is presented. The novel structure mainly consists of a fast Walsh transform (FWT)and an inverse fast Walsh transform (IFWT), both of which can be implemented only by addition and subtraction .Since the transform kernel of the FWT and the IFWT are the same,the implementation complexity of the proposed DDC is significantly reduced. Performances illustrative are compared with those of other DDCs, which include convolution operation. Experimental results show that the proposed method outperforms others and is more suited for real time signal processing of software digital down conversion in digital signal processor (DSP).
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This paper presents a field test of UHF radar system on the Bridge of Yangtze River in China. Recently a set of UHF radar system has been developed for vessel surveillance and estimation of surface velocity profile across the rive...
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This paper presents a field test of UHF radar system on the Bridge of Yangtze River in China. Recently a set of UHF radar system has been developed for vessel surveillance and estimation of surface velocity profile across the river. The radar operates at 300 MHz to match the dimension of water wavelengths. Another aim of ship surveillance is to protect the pier against ship collision. The transmit power of the radar is under 5W and the maximum range is 2 km. This paper gives the design methods and waveform parameters of the system, some results of field test are also presented.
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摘要 :
Super-resolution ocean surface current algorithm based on MUltiple SIgnal Classification (MUSIC) is used for current mapping of Wuhan University's ocean state measuring and analyzing radar (OSMAR2000), in which MUSIC is applied to...
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Super-resolution ocean surface current algorithm based on MUltiple SIgnal Classification (MUSIC) is used for current mapping of Wuhan University's ocean state measuring and analyzing radar (OSMAR2000), in which MUSIC is applied to estimate the bearings of the first-order sea echo signals. The premise of MUSIC processing is that the number of signals is known in advance. In fact, the number of signals is unknown, and needs to be estimated from received data. In the case of discrete targets, the problem can be perfectly solved using information theoretic criteria such as the Akaike Information Criterion (AIC) or the Minimum Description Length (MDL) criterion. However, these criteria are proved unsuccessful for sea echo signals both in simulation and in actual application, since sea surface is essentially a continuum. Therefore, an ad hoc method of detection of number of signals, a bit different from the existent methods, is developed for the current algorithm of OSMAR2000. The underlying idea is to determine the number of signals based on the variance of MUSIC spectra structure under different candidate number of signals.
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摘要 :
Super-resolution ocean surface current algorithm based on MUltiple SIgnal Classification (MUSIC) is used for current mapping of Wuhan University's ocean state measuring and analyzing radar (OSMAR2000), in which MUSIC is applied to...
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Super-resolution ocean surface current algorithm based on MUltiple SIgnal Classification (MUSIC) is used for current mapping of Wuhan University's ocean state measuring and analyzing radar (OSMAR2000), in which MUSIC is applied to estimate the bearings of the first-order sea echo signals. The premise of MUSIC processing is that the number of signals is known in advance. In fact, the number of signals is unknown, and needs to be estimated from received data. In the case of discrete targets, the problem can be perfectly solved using information theoretic criteria such as the Akaike Information Criterion (AIC) or the Minimum Description Length (MDL) criterion. However, these criteria are proved unsuccessful for sea echo signals both in simulation and in actual application, since sea surface is essentially a continuum. Therefore, an ad hoc method of detection of number of signals, a bit different from the existent methods, is developed for the current algorithm of OSMAR2000. The underlying idea is to determine the number of signals based on the variance of MUSIC spectra structure under different candidate number of signals.
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Based on chaotic characteristic of High Frequency Ground-Wave Radar (HFGWR) sea clutter, a new adaptive artificial neural networks ensemble method for sea clutter predicting is presented in this paper. In phase space reconstructed...
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Based on chaotic characteristic of High Frequency Ground-Wave Radar (HFGWR) sea clutter, a new adaptive artificial neural networks ensemble method for sea clutter predicting is presented in this paper. In phase space reconstructed, when one sea clutter sample is to be predicted, some artificial neural networks are choosed adaptively by evaluating their performance and error correlation in neighborhood of the sample, and outputs of these artificial neural networks are combining dynamically as the result of prediction for the sample. The adaptive artificial neural networks ensemble method is designed to improve precision of sea clutter predicting, and server sea clutter modeling in HF ground wave radar objects detecting. In order to improve the adaptive ability of the ensemble method and reduce computational complexity, the corresponding active learning algorithm is designed. Result of testing the sea clutter predicting method on practical echo data of HFGWR for objects detecting shows precision of sea clutter predicting and generalization ability can be impoved effectively by the adaptive artificial neural networks ensemble method.
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Multi-agent based intelligent video monitoring of unattended substation is designed in this paper.Moving objects detecting and tracking methods are used to analyse video streams collected by remote-viewing system of unattended sub...
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Multi-agent based intelligent video monitoring of unattended substation is designed in this paper.Moving objects detecting and tracking methods are used to analyse video streams collected by remote-viewing system of unattended substation.Also,cameras’ negotiation mechanism of moving objects tracking is designed according to multi-agent theory and technology,in order to extract route and figure characters of objects moving in whole unattended substation region,such as person and vehicle.All information gained by the system can be used to guard against theft and analyse quality of patrol,examine,repair,and other missions,and it will improve the infomatization,automation,and intelligentization level of unattended substation.
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