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Download or read book Signal Processing Methods to Improve Ocean Surface Wave Estimation from a High Frequency Surface Wave Radar written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhanced Detection of Small Targets in Ocean Clutter for High Frequency Surface Wave Radar written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The small target detection in High Frequency Surface Wave Radar is limited by the presence of various clutter and interference. Several novel signal processing techniques are developed to improve the system detection performance. As an external interference due to local lightning, impulsive noise increases the broadband noise level and then precludes the targets from detection. A new excision approach is proposed with modified linear predictions as the reconstruction solution. The system performance is further improved by de-noising the estimated covariance matrix through signal property mapping method. The existence of non-stationary sea clutter and ionospheric clutter can result in excessive false alarm rate through the high sidelobe level in adaptive beamforming. The optimum threshold discrete quadratic inequality constraints method is proposed to guarantee the sidelobe-controlling problem consistently feasible and optimal. This constrained optimization problem can be formulated into a second order cone problem with efficient mathematical solution. Both simulation and experimental results validate the improved performance and feasibility of our method. Based on the special noise characteristics of High Frequency radar, an adaptive switching Constant False Alarm Rate detector is proposed for targets detection in the beamformed range-Doppler map. The switching rule and adaptive footprint are applied to provide the optimum background noise estimation. For this new method about 14% probability of detection improvement has been verified by experimental data, and meanwhile the false alarm rate is reduced significantly compared to the original CFAR. The conventional Doppler processing has difficulty to recognize a target if its frequency is close to a Bragg line. One detector is proposed to solve this co-located co-channel resolvability problem under the assumption that target/clutter have different phase modulation. Moreover with the pre-whitening processing, the Rever.
Author : Jian Wang (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)
Download or read book High resolution methods for small target detection and estimation in high frequency radar written by Jian Wang (Ph. D.) and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The detection and tracking of small slow moving targets by High Frequency Surface Wave radar are limited by the presence of a dominate sea clutter spectrum. The ocean surface behaves as a distributed source in contrast to targets that are point sources. It is shown that by mapping data to eigenspaces, the sea clutter level decreases due to its nondeterministic behaviour while point targets' levels remain unchanged. The high resolution (subspace-based or eigenspace) methods and frequency tracking method for slowly time varying frequencies are evaluated to suppress this sea clutter to enhance detection of weak signals. Experimental results verify the advantage of subspace-based methods over the traditional processing techniques. Conventional subspace methods can be utilized to enhance the detection, but they deteriorate dramatically in the presence of correlated sea clutter. In our thesis some adaptive sea clutter pre-filtering schemes are introduced which improve the threshold and accuracy of subsequent subspace methods. Both simulated and real ship targets are used to verify the effectiveness of our proposed method. Furthermore, we propose another novel subspace algorithm to estimate the directions of arrival of superimposed cisoidal radar echoes from far-field targets in the radar pulse domain. The improvement provided by this algorithm is based on the use of a state space model that more accurately represents the received Doppler radar array signal prior to spatial processing such as MUSIC. A 2-d (spatial and temporal) pre-filtering matrix is structured and applied to the received array signal, which is finally combined with the high-resolution (MUSIC) method for DOA estimation. Lower resolution threshold and estimation variance are achieved by this algorithm compared to conventional beam-space MUSIC and sensor-space MUSIC. A simplified theoretical resolution threshold is derived, and both the theory and simulations verify the effectiveness of our proposed algorithm. Results from an experiment using a simulated target superimposed on real HF radar sea clutter also confirm the algorithm.
Author : Alison Cheeseman
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)
Download or read book Adaptive Waveform Design and CFAR Processing for High Frequency Surface Wave Radar written by Alison Cheeseman and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High frequency surface wave radar (HFSWR), used for coastal surveillance, operates in a challenging environment as the clutter signals returned from the ocean surface can be several orders of magnitude larger than returns from targets. Reliably detecting small boats in severe sea states, is therefore quite difficult. In this thesis we take a two-fold approach to improving the detection performance of Raytheon Canada's third generation HFSWR system. First, we consider the design of transmit waveforms with improved range resolution, thus reducing the area of the clutter cell. We develop an algorithm to design practical spectrally-compliant waveforms which achieve high bandwidths while simultaneously avoiding interference with concurrent communications users. We then propose a new detection algorithm based on the best known statistical model for sea clutter, the K-distribution. We show that both the proposed transmit waveforms and detection algorithm can lead to improved detection performance in a sea clutter environment.
Author :
Publisher :
ISBN 13 :
Total Pages : 39 pages
Book Rating : 4.:/5 (318 download)
Download or read book Mitigation of Ionospheric Effects on High Frequency Surface Wave Radar written by and published by . This book was released on 2006 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Frequency Surface Wave Radar (HFSWR) takes advantage of the di raction of electromagnetic waves over the conducting ocean surface to detect, locate, and track surface vessels beyond the line-of- sight horizon of the earth. However, long-range surface vessel detection is often confounded by radar clutter comprising echoes from the ionospheric plasma. In this paper, we characterize the angular spectrum of these re ections, and from this information deduce the signal-to-clutter processing gain that can be realized by various adaptive receive antenna array con gurations. In particular, it is shown that there is advantage to be realized by sampling ionospheric echoes with a planar two-dimensional array rather than a conventional linear one-dimensional HFSWR array. Using a planar array, the radar can distinguish high-elevation ionospheric clutter signals from low-elevation surface target echoes.
Author : Chengxi Shen
Publisher :
ISBN 13 :
Total Pages : 264 pages
Book Rating : 4.:/5 (995 download)
Download or read book The High Frequency Surface Wave Radar Cross Section for Ocean Swell written by Chengxi Shen and published by . This book was released on 2013 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Weimin Huang
Publisher : IET
ISBN 13 : 1839531614
Total Pages : 654 pages
Book Rating : 4.8/5 (395 download)
Download or read book Ocean Remote Sensing Technologies written by Weimin Huang and published by IET. This book was released on 2021-12-17 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a systematic introduction to the principles, state-of-the-art methods and applications of high frequency surface/sky wave radar and microwave marine radar, as well as an exploration of ongoing challenges in the field. It is a valuable resource for the radar and remote sensing communities.
Author : Oliver Saleh
Publisher :
ISBN 13 : 9780494588291
Total Pages : 266 pages
Book Rating : 4.5/5 (882 download)
Download or read book Adaptive Processing in High Frequency Surface Wave Radar written by Oliver Saleh and published by . This book was released on 2008 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Frequency Surface Wave Radar(HFSWR) is a radar technology that offers numerous advantages for low-cost, medium accuracy surveillance of coastal waters beyond the exclusive economic zone. However, target detection and tracking is primarily limited by ionospheric interference. Ionospheric clutter is characterized by a high degree of nonhomogeneity and nonstationarity, which makes its suppression difficult using conventional processing techniques. Space-time adaptive processing techniques have enjoyed great success in airborne radar, but have not yet been investigated in the context of HFSWR. This thesis is primarily concerned with the evaluation of existing STAP techniques in the HFSWR scenario and the development of a new multistage adaptive processing approach, dubbed the Fast Fully Adaptive (FFA) scheme, which was developed with the particular constraints of the HFSWR interference environment in mind. To this end an analysis of measured ionospheric clutter is conducted, which allows for a characterization of the underlying statistical behavior of the HFSWR interference. Several popular low-complexity STAP algorithms are assessed for their performance in HFSWR. Focus is then shifted towards the development of the FFA approach. Three different spatio-temporal partitioning schemes are introduced. A thorough investigation of the performance of the FFA is conducted in both the airborne radar and HFSWR setups under a variety of sample-support scenarios.
Author : David W. Green
Publisher :
ISBN 13 :
Total Pages : 152 pages
Book Rating : 4.:/5 (811 download)
Download or read book Extraction of Wind Speed from High Frequency Ground Wave Radar Oceanic Backscatter written by David W. Green and published by . This book was released on 2005 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Oliver S. Saleh
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)
Download or read book Adaptive Processing in High Frequency Surface Wave Radar written by Oliver S. Saleh and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Frequency Surface Wave Radar (HFSWR) is a radar technology that offers numerous advantages for surveillance of coastal waters beyond the exclusive economic zone. However, target detection and tracking is primarily limited by ionospheric interference. Ionospheric clutter is characterized by a high degree of nonhomogeneity and nonstationarity, which makes its suppression difficult using conventional processing techniques. Space-time adaptive processing techniques have enjoyed great success in airborne radar, but have not yet been investigated in the context of HFSWR. This thesis is primarily concerned with the evaluation of existing STAP techniques in the HFSWR scenario and the development of a new multistage adaptive processing approach, dubbed the Fast Fully Adaptive (FFA) scheme, which was developed with the particular constraints of the HFSWR interference environment in mind. Three different spatio-temporal partitioning schemes are introduced and a thorough investigation of the performance of the FFA is conducted.
Author : Mikhail B. Kanevsky
Publisher : Elsevier
ISBN 13 : 0080932517
Total Pages : 207 pages
Book Rating : 4.0/5 (89 download)
Download or read book Radar Imaging of the Ocean Waves written by Mikhail B. Kanevsky and published by Elsevier. This book was released on 2008-09-15 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to studying the ocean with radar tools, in particular, with space radars. Being intended mainly for the scientists preoccupied with the problem (as well as senior course students), it concentrates and generalizes the knowledge scattered over specialized journals. The significant part of the book contains the results obtained by the author. Systematically collects and describes the approaches used by different laboratories and institutions Deals with the physics of radar imagery and specifically with ocean surface imagery Useful for students and researchers specializing in the area of ocean remote sensing using airborne or space-borne radars, both SAR and RAR
Author : Qilian Liang
Publisher : Springer Nature
ISBN 13 : 9811394091
Total Pages : 2720 pages
Book Rating : 4.8/5 (113 download)
Download or read book Communications, Signal Processing, and Systems written by Qilian Liang and published by Springer Nature. This book was released on 2020-04-04 with total page 2720 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together papers from the 2019 International Conference on Communications, Signal Processing, and Systems, which was held in Urumqi, China, on July 20–22, 2019. Presenting the latest developments and discussing the interactions and links between these multidisciplinary fields, the book spans topics ranging from communications to signal processing and systems. It is chiefly intended for undergraduate and graduate students in electrical engineering, computer science and mathematics, researchers and engineers from academia and industry, as well as government employees.
Author : Al-Abbass Y. Al-Habashneh
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (132 download)
Download or read book Enhanced Methods of Ocean Wave Spectra and Sea State Parameter Estimation from X-band Marine Radar Data written by Al-Abbass Y. Al-Habashneh and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the ocean's importance in human lives, researchers have been studying the ocean and developing systems to estimate its state since the 19th century. During the last three decades, remote sensing of the ocean surface using X-band marine radars has emerged as a reliable tool to estimate ocean wave spectra and sea state parameters such as mean wave period and direction and significant wave height. The purpose of this thesis is to develop methods that produce accurate and reliable estimates of ocean wave spectra using X-band marine radar data. The approach taken in this thesis is to determine the sources of ocean wave spectra estimation error in existing methods and then to develop new methods that minimize those errors. In this thesis, four sources of error are addressed: the dependency of spectra estimation on the orientation of the analysis windows; the effect of the radar sampling process; the effect of the scan conversion process; and the accuracy of surface current estimation. The azimuthal location of the X-band radar data analysis window affects the estimation of ocean wave spectra. it has been reported in the literature, and supported by our results, that using the up-wave directions for analysis windows produces higher signal to noise ratios and hence more accurate ocean wave spectra estimates. In order to minimize error due to dependency on the orientation of the analysis windows, a new method referred to as the Adaptive Recursive Positioning Method (ARPM) is proposed. The ARPM is a recursive approach that dynamically determines the optimal number of analysis windows and their corresponding orientation toward the up-wave directions. Second, in this thesis, it has been demonstrated that the sampling process of the ocean surface by X-band marine radar during data collection significantly affects the estimation of ocean save spectra from X-band marine radar data. Therefore, a method referred to as the Inverse Sampling Averaging Filter (ISAF) is proposed to mitigate the effect of the radar sampling process of the ocean surface on the ocean wave spectra estimation using X-band marine radars. ISAF was designed based on a novel understanding of the radar sampling process to involve an averaging process or low pass filtering of the ocean wave spectra. Third, in this thesis, a method referred to as the Polar Fourier Transform (PFT) is proposed to eliminate the distortion presented by the scan conversion process to the estimated wave spectra. Unlike the existing methods which use the Cartesian Fourier Transform (CFT) to acquire the ocean wave spectra, the PFT method is designed to apply a Fourier-type transformation on the radar data in its native format, which is sampled in the polar coordinates, without the need for the intermediate stage of scan conversion used to map the data into Cartesian coordinates. The performance of the proposed methods, the ARPM,ISAF and PFT, are individually validated by comparing their ocean wave spectra estimates to those acquired using the existing methods with respect to ground truth wave spectra acquired using a wave rider buoy. Furthermore, the proposed methods were also combined together to seek further enhancement. The wave spectra estimation results from different combinations of the proposed methods were validated in comparison to the ground truth data. Finally, a new method to estimate surface current using X-band marine radar is proposed. This method is referred to as the Hybrid Least Squares (HLS) method. The HLS combines two existing approaches: the Iterative Least Squares (ILS) method and the Normalized Scalar Product (NSP). The HLS is designed to inherit the short computational time of ILS and the high reliability of NSP. To validate its accuracy and reliability, the proposed HLS method was applied on a number of simulated X-band marine radar image sets and the results were compared to the estimates acquired using the ILS and the NSP.
Author : Hany Mohamed Assal
Publisher :
ISBN 13 :
Total Pages : 118 pages
Book Rating : 4.:/5 (318 download)
Download or read book Measurements of Ocean Surface Waves Using Synthetic Aperture Radar written by Hany Mohamed Assal and published by . This book was released on 1981 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Belinda J. Lipa
Publisher :
ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.3/5 (91 download)
Download or read book Analysis Methods for Narrow-beam High-frequency Radar Sea Echo written by Belinda J. Lipa and published by . This book was released on 1982 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Eng-Chong Ha
Publisher :
ISBN 13 :
Total Pages : 158 pages
Book Rating : 4.F/5 ( download)
Download or read book Remote Sensing of Ocean Surface Current and Current Shear by HF Backscatter Radar written by Eng-Chong Ha and published by . This book was released on 1979 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Doppler spectrum of radar return from the sea at HF contains two narrow lines displaced upward and downward from the carrier frequency, resulting from backscatter off ocean surface waves moving toward and away from the radar, respectively. These Bragg lines indicate resonant backscatter which occurs for the ocean waves of length one-half the radio wavelength. The phase velocity of these gravity waves consists of two components; the first is determined by the wavelength and the second by the current component in the direction of wave propagation averaged over depth with an exponential weighting function that has a characteristic scale proportional to the wavelength. The Doppler shift of the radar carrier is determined by the wave phase velocity. Its variation with carrier frequency is thus related to the vertical profile of the current component in the radar direction by a Laplace transform; therein lies the principle of radio measurement of ocean current and its vertical shear. Radio backscatter experiments to verify the feasibility of such measurements were conducted using the radar operating at four frequencies covering the range from 3 to 30 MHz. The depth-averaged radial current deduced from the centroid of the Doppler-shifted sea echo experiments at 6.8, 13.3, 21.7, and 29.8 MHz showed fluctuations on the order of 1 cm/sec superimposed on temporal trends that reached maximum values of about 40 cm/sec. It is concluded that multifrequency backscatter ground-wave radar at HF constitutes a powerful technique for mapping current and its vertical profile in the top few meters of the ocean.
Author : Thomas Martin Georges
Publisher :
ISBN 13 :
Total Pages : 360 pages
Book Rating : 4.:/5 (318 download)
Download or read book Coastal Ocean Dynamics Applications Radar written by Thomas Martin Georges and published by . This book was released on 1985 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
