检索结果-内蒙古大学图书馆

Approximate Cramer-Rao bound on Doppler error in correlation-processing relatively narrowband noise radar

IET RADAR SONAR AND NAVIGATION 2009年第3期3卷 245-252页

作者： Meller, M. Telecommun Res Inst Gdansk Div Dept Signal & Informat Proc PL-80502 Gdansk Poland

Limitations on accuracy of Doppler estimation in continuous-wave noise radar with correlation processing are studied. Second-order properties of output of the correlation receiver are evaluated and an approximate Cramer-Rao bound on errors of Doppler measurement is derived. The accuracy of Doppler measurements is found to be affected by the following factors: power spectral density of noise signal, frequency response of the low-pass filter in correlator, observation time, velocity of the target and signal to noise ratio. It is shown that the random nature of the transmitted signal induces additional fluctuations at the output of correlator which limit the accuracy even in the infinite signal to noise case. Qualitative extension of the results to a case covering multiple targets and clutter is made. It is argued that the performance will decrease and that increasing transmitted power may not provide significant improvement when clutter is present.

关键词： noise radar signal processing filtering methods in signal processing Doppler measurement error approximate Cramer-Rao bound narrowband noise radar continuous-wave noise radar low-pass filter correlation receiver CW radar low-pass filters power spectral density Radar equipment, systems and applications Doppler estimation correlation processing frequency response

来源：评论

学校读者我要写书评

暂无评论

Tunable photonic bandpass filter with high-frequency response performance

引用

ELECTRONICS LETTERS 2009年第23期45卷 1176-U47页

作者： Chan, E. H. W. Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

A continuously tunable RF/microwave photonic bandpass filter that simultaneously achieves high skirt selectivity and high stopband attenuation is presented. It is based on controlling the signal polarisation state in a reflective amplified recirculating delay line loop with a polariser at the output. A technique to overcome the phase noise limitation in the structure is also presented. Experimental results demonstrate continuous tuning of the high-performance photonic bandpass filter and a continuously tunable photonic bandpass filter with a low-noise performance.

关键词： high-performance photonic bandpass filter band-pass filters filtering methods in signal processing skirt selectivity electromagnetic wave scattering high frequency response performance signal polarisation state low-noise performance tunable photonic bandpass filter electromagnetic wave polarisation high stopband attenuation electromagnetic wave absorption

来源：评论

学校读者我要写书评

暂无评论

Infrared small target detection using directional highpass filters based on LS-SVM

引用

ELECTRONICS LETTERS 2009年第3期45卷 156-158页

作者： Wang, P. Tian, J. W. Gao, Ch. Q. Huazhong Univ Sci & Technol Inst Pattern Recognit & Arti cial Intelligence State Key Lab Multispectral Informat Proc Technol Wuhan 430074 Peoples R China

An infrared small target detection method based on the least squares support vector machine (LS-SVM) is proposed. The LS-SVM model is applied to generate a row and a column directional highpass template filters. By filtering the original infrared image with the two templates, respectively, and fusing the two filtered images, the possible small target can be extracted. Experimental results demonstrate that the presented method is robust and efficient.

关键词： Optical, image and video signal processing high-pass filters least squares support vector machine least squares approximations filtering methods in signal processing infrared imaging directional high-pass filters infrared small target detection support vector machines Learning in AI Interpolation and function approximation (numerical analysis) object detection Image recognition

来源：评论

学校读者我要写书评

暂无评论

Orientation adaptive fast marching method for contour tracking of small intestine

引用

ELECTRONICS LETTERS 2009年第23期45卷 1154-U19页

作者： Wu, X. Xi, Q. Chen, Y. W. Zhang, S. S. Shanghai Jiao Tong Univ Dept Comp Sci & Engn Shanghai 200030 Peoples R China Shanghai Jiao Tong Univ Joint Inst Univ Michigan Shanghai 200030 Peoples R China Ritsumeikan Univ Coll Informat & Sci Kusatsu Shiga Japan

The orientation of the small intestine varies among frames of a cinematic-magnetic resonance imaging (cine-MRI) sequence owing to small intestine peristalsis, which increases the complexity of its contour tracking. There are also leakage problems owing to the presence of low contrast areas in some frames. An improved fast marching method using an anisotropic Gaussian filter and a boundary penalty is presented for the contour tracking of small intestine segments. Experimental results show that the proposed method can track accurate contours of small intestine segments without leakage problems.

关键词： anisotropic Gaussian filter image segmentation Medical magnetic resonance imaging and spectroscopy image matching filtering theory biomedical MRI Biomagnetism cinematic-magnetic resonance imaging sequence Patient diagnostic methods and instrumentation boundary penalty small intestine Biomedical magnetic resonance imaging and spectroscopy cine-MRI sequence contour tracking Biology and medical computing Computer vision and image processing techniques Optical, image and video signal processing orientation adaptive fast marching method filtering methods in signal processing

来源：评论

学校读者我要写书评

暂无评论

Depth reconstruction filter for depth coding

引用

ELECTRONICS LETTERS 2009年第6期45卷 305-U5页

作者： Oh, K-J. Yea, S. Vetro, A. Ho, Y-S. GIST Sch Informat & Mechatron Kwangju 500712 South Korea MERL Cambridge MA 02139 USA

Depth images represent the distances of scene elements from a camera in 3D space;their efficient coding is crucial for emerging applications such as free-viewpoint TV and 3D video. An in-loop reconstruction filter that improves the depth-coding performance as well as the rendering quality of virtual views based upon the coded depth is proposed.

关键词： filtering theory Image and video coding filtering methods in signal processing image coding 3D space depth image coding representation rendering (computer graphics) virtual rendering quality camera image representation scene element Computer vision and image processing techniques Graphics techniques image reconstruction depth in-loop reconstruction filter

来源：评论

学校读者我要写书评

暂无评论

Improved bandwidth-synthesis method of stepped-frequency radar for non-cooperative targets

引用

ELECTRONICS LETTERS 2009年第13期45卷 708-709页

作者： Zhu, Y. Zhao, H. Zhou, J. Fu, Q. Natl Univ Def Technol ATR Lab Changsha 410073 Hunan Peoples R China

During bandwidth synthesis in stepped-frequency radar, amplitude and phase discontinuity between neighbouring pulses should be corrected by a filter. Usually, this filter is constructed by measured data from a calibrator. However, this may be infeasible in non-cooperative situations. Using the signal characteristics after IDFT across received pulses, an improved bandwidth synthesis method based on scatterer alignment is proposed, which neither requires calibration, nor has the serious deficits of the classical IDFT method, such as a limited unambiguous range-profiling window. Analysis of real data collected by a Ka-band radar has verified its advantages.

关键词： bandwidth-synthesis filtering theory Integral transforms filtering methods in signal processing non-cooperative targets radar resolution radar signal processing discrete Fourier transforms amplitude discontinuity Radar theory stepped-frequency radar Ka-band inverse discrete Fourier transforms range-profiling window phase discontinuity

来源：评论

学校读者我要写书评

暂无评论

Orthogonal frequency-division multiplexing radar signal design with optimised ambiguity function and low peak-to-average power ratio

引用

IET RADAR SONAR AND NAVIGATION 2009年第2期3卷 122-132页

作者： Sebt, M. A. Sheikhi, A. Nayebi, M. M. Sharif Univ Technol Dept Elect Engn Tehran Iran

Considering the important role of the ambiguity function (AF) of a signal regarding the performance of a matched filter bank for the detection of targets and the estimation of their ranges and velocities, the thumbtack shape is assumed to be the desirable shape of the AF and the method of least squares for the synthesis of the AF is introduced. Then, an iterative method for the allocation of a proper phase to the desired AF is proposed to obtain better results. This method is then applied to select the proper codes for the synthesis of pulsed orthogonal frequency-division multiplexing signals. It is also shown how this method can reduce sidelobes, almost uniformly, throughout the entire ambiguity plane. Finally, an efficient algorithm is presented, which modifies the produced codes in order to reach a lower peak-to-average power ratio suitable for transmission.

关键词： radar signal processing low peak-to-average power ratio pulsed orthogonal frequency-division multiplexing signals Modulation and coding methods OFDM modulation matched filters Radar equipment, systems and applications orthogonal frequency-division multiplexing radar signal design iterative method iterative methods target detection ambiguity function thumbtack shape filtering methods in signal processing ambiguity function optimisation matched filter bank Interpolation and function approximation (numerical analysis) object detection filtering theory

来源：评论

学校读者我要写书评

暂无评论

Two-dimensional pulse-to-pulse canceller of ground clutter in airborne radar

引用

IET RADAR SONAR AND NAVIGATION 2009年第2期3卷 133-143页

作者： Li, X. -M. Feng, D. -Z. Liu, H. -W. Xing, M. -D. Luo, D. Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Radar & Av Inst AIVC Wuxi 214063 Peoples R China

It is well known that in the airborne radar, the location of the ground clutter spectrum in the angle-Doppler space is dependent mainly on the platform velocity and radar parameters. The authors propose a two-dimensional pulse-to-pulse canceller (TDPC) that can make full use of such prior information. The more detailed formulations of the ground clutter model and the signal model are given in a matrix - vector form. The least-squares-typical cost function associated with the filter coefficient matrix of the TDPC is established on the basis of the ground clutter model and the signal model. Like the classical displaced phase centre antenna (DPCA) processing, the proposed TDPC is also a spatial-temporal suppressor of ground clutter and can decrease the ground clutter signals, even though the DPCA condition is not satisfied. The proposed TDPC can also be used as an efficient pre-filtering tool before the conventional moving target indication (MTI) processing and the classical adaptive processing. Moreover, if only the TDPC plus the conventional MTI is used, it takes less computational time than the adaptive canceller. Experimental results show that the proposed TDPC has the satisfactory ground clutter suppression capability by using both simulated data and measured data.

关键词： angle-Doppler space Electromagnetic compatibility and interference Radar theory 2D pulse-to-pulse canceller spatial-temporal suppressor moving target indication displaced phase centre antenna Radar equipment, systems and applications least-squares-typical cost function adaptive processing filter coefficient matrix filtering methods in signal processing least squares approximations radar clutter Interpolation and function approximation (numerical analysis) ground clutter suppression filtering theory airborne radar signal model interference suppression

来源：评论

学校读者我要写书评

暂无评论

Contrast enhancement and phase-sensitive boundary detection in ultrasonic speckle using Bessel spatial filters

引用

IET IMAGE processing 2009年第2期3卷 41-51页

作者： Shankar, P. M. Drexel Univ Dept Elect & Comp Engn Philadelphia PA 19104 USA

Speckle in ultrasonic image systems adversely impacts the contrast and resolution in the image. This poses serious problems in the interpretation of B mode images of internal organs such as breast, liver, kidney and so on. In the absence of sufficient contrast, classifying the regions of interest into benign and malignant masses becomes error prone. Since some of the masses are uniquely identified in terms of the boundaries, poor contrast and resolution will result in difficulties with their identification. A new class of spatial filters based on cylindrical Bessel functions of the first kind is proposed for speckle reduction. These filters with complex impulse responses were explored for enhancing the contrast of speckled images. Hypothesising that the phase of the filtered image carries boundary information, the phase characteristics of four speckled images are also studied for detecting boundaries. Results indicate that these filters do improve the contrast and enhance the boundaries. It is shown that the phase map clearly indicates the existence of boundaries. A simple thresholding applied to the phase highlights the boundaries. The results show the strength of the Bessel spatial filters in improving contrast and highlighting boundaries without resorting to any additional edge-detection algorithms.

关键词： image resolution ultrasonic imaging health physics Sonic and ultrasonic applications Patient diagnostic methods and instrumentation filtering methods in signal processing image enhancement ultrasonic image systems Biology and medical computing Computer vision and image processing techniques Bessel spatial filters Optical, image and video signal processing speckle reduction cylindrical Bessel functions impulse responses edge detection edge-detection algorithms medical image processing Biomedical measurement and imaging spatial filters ultrasonic speckle phase map Bessel functions regions of interest Medical and biomedical uses of fields, radiations, and radioactivity phase-sensitive boundary detection transient response

来源：评论

学校读者我要写书评

暂无评论

Extraction of mixed-order multicomponent ship target signals from broadened sea clutter in bistatic shipborne surface wave radar

引用

IET RADAR SONAR AND NAVIGATION 2009年第3期3卷 214-223页

作者： Li, B. Xu, B. Yuan, Y. Harbin Inst Technol Elect Engn Res Inst Harbin 150001 Peoples R China

A dynamic geometry model was built to describe the Doppler-broadening characteristics of the first-order Bragg lines for bistatic shipborne surface wave radar. They are time-varying because the Doppler frequency shifts of sea echoes are simultaneously modulated by the velocity components projected from the unavoidably different motions of both platforms, which is more complex than its counterpart in the monostatic mode. The geometrical relation is used to obtain the received signal model: strong first-order sea clutter interferences and submerged ship targets with constant and non-constant speeds are considered as mixed-order multicomponent polynomial-phase signals (mc-PPSs) and both second-order sea clutter continuum and atmospheric noise as additive noise. Then, a scheme based on the product high-order ambiguity function is proposed to extract the targets;it is a recursive procedure in which the first-order sea clutter is removed by an existing time-space cascaded filtering method. Monte Carlo simulations show the validity and efficiency of the proposed scheme.

关键词： radar signal processing Doppler frequency shifts additive noise first-order sea clutter interferences second-order sea clutter continuum dynamic geometry model Radar equipment, systems and applications sea echoes first-order Bragg lines Doppler-broadening characteristics Monte Carlo simulations broadened sea clutter filtering methods in signal processing mixed-order multicomponent ship target signals recursive procedure radar clutter bistatic shipborne surface wave radar time-space cascaded filtering method atmospheric noise Monte Carlo methods filtering theory

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：