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High Frequency Surface Wave Radar Propagation Over Arctic Seas
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Book Synopsis High Frequency Surface Wave Radar Propagation Over Arctic Seas by : Alan D. (Alan Douglas) Thomson
Download or read book High Frequency Surface Wave Radar Propagation Over Arctic Seas written by Alan D. (Alan Douglas) Thomson and published by Defence R&D Canada - Ottawa. This book was released on 2004 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The High Frequency Surface Wave Radar Cross Section for Ocean Swell by : Chengxi Shen
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:
Book Synopsis Ionospheric Clutter Models for High Frequency Surface Wave Radar by : Shuyan Chen
Download or read book Ionospheric Clutter Models for High Frequency Surface Wave Radar written by Shuyan Chen and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High frequency surface wave radar (HFSWR), operating at frequencies between 3 and 30 MHz, has long been employed as an important ocean remote sensing device. These high frequency (HF) radars can provide accurate and real-time information for sea state monitoring and hard-target detection, which is greatly beneficial for planning and executing oceanographic projects, search and rescue events, and other commercial marine activities. Ideally, in HFSWR operation, the radio waves may be coupled with ocean waves and propagate along the curvature of the ocean surface with ranges well beyond 200 km. However, during transmission, a portion of the radar radiation may travel upwards to the ionosphere from the transmitting antenna. This may be partially reflected back to the receiving antennas directly (vertical propagation) or via the ocean surface (mixed-path propagation). This ionospheric clutter may significantly impact the performance of HFSWR. Furthermore, the high intensity and random behaviour of the ionospheric spectral contamination of radar echoes make the suppression of this kind of clutter challenging. In this thesis, comprehensive theoretical models of the ionospheric clutter are investigated. The physical influences of the ionospheric electron density on HF radar Doppler spectra are taken into account in the ionospheric reflection coefficient. Next, based on previous modeling involving the scattering of HF electromagnetic radiation from the ocean surface and a first-order mixed-path propagation theory, the second-order received electric field for mixed-path propagation is derived for a monostatic radar configuration. This is done by considering the reflection from the ionosphere and scattering on the ocean surface with second-order sea waves. Then, the field integrals are taken to the time domain, with the source field being that of a vertically polarized pulsed dipole antenna. Subsequently, the second-order received power model is developed by assuming that the ocean surface and the ionosphere may be modeled as stochastic processes. The ionospheric clutter model including a pulsed radar source is further investigated for the case of vertical propagation for a monostatic configuration and mixed-path propagation for a bistatic configuration. Next, a theoreticalmixed-path propagationmodel is developed by involving a frequencymodulated continuous waveform (FMCW) radar source. In order to investigate the power spectrum of the resulting ionospheric clutter and its relative intensity to that of the first-order ocean clutter, the normalized ionospheric clutter power is simulated. Numerical simulation results are provided to indicate the performance of the ionospheric clutter under a variety of radar operating parameters, ionospheric conditions and sea states.
Book Synopsis Mitigation of Ionospheric Effects on High Frequency Surface Wave Radar by :
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.
Book Synopsis Radar Imaging of the Ocean Waves by : Mikhail B. Kanevsky
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
Book Synopsis Adaptive Waveform Design and CFAR Processing for High Frequency Surface Wave Radar by : Alison Cheeseman
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.
Book Synopsis Remote Sensing of Ocean Surface Current and Current Shear by HF Backscatter Radar by : Eng-Chong Ha
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.
Book Synopsis Suppression of Power Line Harmonic Interference in HF Surface-wave Radar (U). by : Hank Leong
Download or read book Suppression of Power Line Harmonic Interference in HF Surface-wave Radar (U). written by Hank Leong and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental high-frequency surface-wave radar (HFSWR) data was collected in summer 1989 for a set of time series of the radar's sea echoes from individual range gates to study the characteristics of sea clutter, noise and possible targets. This report presents a new process based on optimizations in which the received radar signal is modelled as sea clutter plus modulation of the sea clutter by the power line harmonics.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Adaptive Processing in High Frequency Surface Wave Radar by : Oliver S. Saleh
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.
Book Synopsis The Scattering of High Frequency Electromagnetic Radiation from the Ocean Surface, an Analysis Based on a Bistatic Ground Wave Radar Configuration by :
Download or read book The Scattering of High Frequency Electromagnetic Radiation from the Ocean Surface, an Analysis Based on a Bistatic Ground Wave Radar Configuration written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Analysis of the Experimental Data Measured with the Modified HF Surface-wave Radar at Cape Bonavista by :
Download or read book An Analysis of the Experimental Data Measured with the Modified HF Surface-wave Radar at Cape Bonavista written by and published by . This book was released on 1997 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: A high-frequency (HF) surface wave radar can take advantage of the relatively high conductivity of sea water in order to propagate along the ocean surface beyond the horizon. The Surface Radar Section has been undertaking research on long range detection with HF radar at Cape Bonavista, Newfoundland. Recent modifications to the radar include an on-board receiver preprocessor and solid-state transmitter, enabling detection on-line and operation throughout the HF band. This report presents results of an analysis of data collected in trials with the new radar over frequencies from 4.3 to 27.8 megahertz. Two types of targets were used: low-flying aircraft and a half-wavelength copper wire carried by a balloon. The latter wire resonates with the transmitted radar signal and has a known radar cross-section. Results are compared with simulations, showing degree of agreement between theoretical and experimental performance in the range interval from 35 to 95 kilometres.
Book Synopsis Surface Current and Wave Validation of a Nested Regional HF Radar Network in the Mid-Atlantic Bight by :
Download or read book Surface Current and Wave Validation of a Nested Regional HF Radar Network in the Mid-Atlantic Bight written by and published by . This book was released on 2009 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The National High Frequency Surface Current Mapping Radar Network is being developed as a backbone system within the Integrated Ocean Observing System (IOOS). Of the core variables recognized in the IOOS Development Plan, two can be measured by High Frequency Radar (HFR): ocean surface currents and ocean surface waves. Rutgers University operates a nested multi-frequency network of HF Radar systems along the coast of New Jersey. The network provides near real-time current observations with varying coverage from the coast to the shelf break. This is a subset of the larger regional coverage of the 26 site Mid-Atlantic HF Radar Consortium. The primary goal of this consortium is to operate the regional system in a coordinated way to guarantee the delivery of quality ocean current and wave data. In this paper we present the validation of both wave and current observations measured with this nested network. Particular emphasis is placed on surface current comparisons with Coast Guard deployed surface drifters (SLDMBs) and nearshore wave comparisons with moorings. The Coast Guard comparisons have a specific focus on quantifying the uncertainty in the HF radar surface current estimates as applied to search and rescue operations. These metrics will be used to ensure that quality data is going to the Coast Guard and that this information is properly incorporated into existing search planning tools. The nearshore measurements focus on algorithm development projects to incorporate shallow water effects into the estimates of nearshore waves.
Book Synopsis Adaptive Processing in High Frequency Surface Wave Radar by : Oliver Saleh
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.
Book Synopsis Extraction of Wind Speed from High Frequency Ground Wave Radar Oceanic Backscatter by : David W. Green
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 :Kenneth A. Butt Publisher :St. John's : Centre for Cold Ocean Resources Engineering, Memorial University of Newfoundland ISBN 13 :9780889010673 Total Pages :136 pages Book Rating :4.0/5 (16 download)
Book Synopsis HF Radar Technology Transfer Project by : Kenneth A. Butt
Download or read book HF Radar Technology Transfer Project written by Kenneth A. Butt and published by St. John's : Centre for Cold Ocean Resources Engineering, Memorial University of Newfoundland. This book was released on 1981 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Enhanced Detection of Small Targets in Ocean Clutter for High Frequency Surface Wave Radar by :
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.
