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Development Of A Model For The First Order Bistatic Ocean Clutter Radar Cross Section For Ground Wave Radars
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Book Synopsis Development of a Model for the First Order Bistatic Ocean Clutter Radar Cross Section for Ground Wave Radars by :
Download or read book Development of a Model for the First Order Bistatic Ocean Clutter Radar Cross Section for Ground Wave Radars written by and published by . This book was released on 1994 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents the development of a theoretical model for the bi-static back-scattered Doppler radar cross-section of the ocean surface, for the first-order or Bragg scatter component only. The report begins with some basic scattering theory, and equations for radar cross-section are compared with previously available theory. In the development of the model, a narrow beam receive system is assumed, as well as static receiver and transmitter locations. The radar cross-section of the ocean is derived in the ensemble average sense in that no effort is made to incorporate statistical variations in the ocean surface model or statistical variations in the received ocean clutter signal. Some typical results from the model are presented and briefly discussed.
Download or read book Radio Science written by and published by . This book was released on 2008 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement and Modelling of Bistatic Sea Clutter by : W. A. M. Al-Ashwal
Download or read book Measurement and Modelling of Bistatic Sea Clutter written by W. A. M. Al-Ashwal and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a growing interest in bistatic radars; however, such systems cannot reach their full potential unless the designer has a proper understanding of the environment in which they operate. Rather little information has been published on bistatic clutter and out-of-plane bistatic sea clutter in particular. This is due to a number of factors including the inherent complexity of conducting bistatic radar trials and the resulting lack of high quality bistatic data. In this thesis the collection and analysis of a unique set of bistatic sea clutter data is described. To achieve this objective a novel multistatic radar system was developed. The nodes do not need to be physically connected. This system has a peak transmitted power of more than 500 W. Synchronisation in time and frequency was achieved using GPS disciplined oscillators built and designed at the University of Cape Town. Using the above system simultaneous bistatic and monostatic sea clutter and target signatures were recorded in the UK and South Africa at various geometries and weather conditions. Parts of this unique data set related to out-of-plane bistatic sea clutter was analysed in this thesis. The data covered both co- and cross-polarised sea clutter data at low grazing angles with bistatic angles between 30° and 120°. Data sets covering a range of conditions with sea states from 2 - 5. Using the recorded data it was shown that the ratio of the bistatic normalised radar cross section to the monostatic normalised radar cross section dropped as the scattering angle was increased until the scattering angle was around 90°. Furthermore, the cross-polarised bistatic normalised radar cross section was found to be larger than the cross-polarised monostatic normalised radar cross section when the scattering angle was around 90°. A new empirical model for predicting bistatic normalised radar cross section has been developed. The model is applicable to both in-plane and out-of-plane geometries. The model was able to provide a good fit to both UCL and external data. The temporal correlation properties of both monostatic and bistatic data were studied. It was found that the speckle component of both bistatic and monostatic clutter decorrelated in tens of milliseconds, with the decorrelation time longer for bistatic clutter. The texture of both bistatic and monostatic clutter had similar autocorrelation functions and had similar decorrelation times. By comparing the texture and intensity autocorrelation functions it was concluded that the compound model still holds. It was also found that bistatic clutter was less 'spiky' than monostatic clutter particularly at horizontal polarisation. This was due to the reduction in the intensity of the spikes due to specular reflections. By combing the effects of the reduction in reflectivity and spikiness it was shown that a bistatic radar would require a smaller signal to interference ratio than a monostatic radar for the same probability of detection and probability of false alarm. This was more evident at angles close to 90° and for horizontal polarisation. In summary this thesis reports the collection and analysis of novel simultaneous monostatic and bistatic sea clutter and target data. This was achieved by the development of a unique multistatic radar system. This work has resulted in significant advances in both netted radar technology and understanding of bistatic sea clutter.
Book Synopsis The Second-order High Frequency Bistatic Radar Cross Section of the Ocean Surface for "patch Scatter" by : Weimin Huang
Download or read book The Second-order High Frequency Bistatic Radar Cross Section of the Ocean Surface for "patch Scatter" written by Weimin Huang and published by . This book was released on 2004 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coastal Ocean Dynamics Applications Radar by : Thomas Martin Georges
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 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Nonlinear Approach to Ocean Wave Spectrum Extraction from Bistatic HF-radar Data by : Murilo Teixeira Silva
Download or read book A Nonlinear Approach to Ocean Wave Spectrum Extraction from Bistatic HF-radar Data written by Murilo Teixeira Silva and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a new approach to the extraction of the directional ocean wave spectrum from bistatic high frequency (HF) radar data is proposed. The proposed method relies on the simplification of the second-order bistatic radar cross-section, analogous to the one presented by Shahidi and Gill [1] for the monostatic case, to facilitate the use of nonlinear optimization methods, such as regularized nonlinear least-squares. Initially, the historic development of the techniques related to the extraction of the ocean wave spectrum from HF radar data is provided in order to contextualize the work of this thesis. Then, an overview of the theory related to ocean waves and the bistatic radar cross-section is shown. Later, the nonlinear optimization method used in this thesis, Tikhonov regularization in Hilbert spaces, is explained, as well as the theoretical background necessary to understand the method. Once the theory is laid out, the simplification of the second-order bistatic HF radar cross section is presented. The simplification consists of a change of variables that allow the use of the "sifting" property of the Dirac delta function. This reduces the dependence of the second-order bistatic cross-section to a single variable. After the simplification process is shown, the methodology for extracting the directional ocean wave spectrum from bistatic HF radar data is discussed. As a proof-of-concept, the method is initially applied to the second-order bistatic cross section, without the presence of noise. The method successfully extracted the directional ocean wave spectrum without assuming any function model for the nondirectional ocean wave spectrum, and assuming a cosine-power model for the directional spreading function. Next, the first-order bistatic HF radar cross section is added to the second-order cross section, and the proposed method is applied, still without noise present. The proposed method was also able to extract the directional ocean wave spectrum and very low error is added by the inclusion of the first-order cross section. Finally, different levels of noise are added to the cross section including the first and second- orders, and the presented method is applied for the extraction. Again, the method yields good results, with acceptable levels of error for the different noise levels. This new approach to the extraction of the directional ocean wave spectrum from bistatic HF radar data presents, to the author's knowledge, the first nonlinear extraction method for bistatic HF radar data. Further developments of the technique, such as the use of different nonlinear extraction methods, or a general directional spreading function, are suggested.
Book Synopsis An Algorithm for the Extraction of Ocean Surface Current Velocity from Bistatic HF Groundwave Radar Data by : Qiu Jin
Download or read book An Algorithm for the Extraction of Ocean Surface Current Velocity from Bistatic HF Groundwave Radar Data written by Qiu Jin and published by . This book was released on 2007 with total page 180 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 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 Time-domain Modelling of Ocean Clutter for Ground Wave Radar by :
Download or read book Time-domain Modelling of Ocean Clutter for Ground Wave Radar written by and published by . This book was released on 1989 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detection performance of high frequency ground wave (HFGW) radar systems, for over-the-horizon detection of surface targets, is limited by the back scattering returns from the ocean surface. An improved modelling of the ocean clutter is the key to enhanced target detection with HFGW radar; this would enable clutter suppression techniques to be refined and a higher signal-to-noise ratio to be achieved. This paper proposes a wave packet model for the dominant components of the ocean back scattering signal and suggests a technique to exploit this non-stationary characteristic of the ocean clutter to improve target detection performance. The technique is based on the Wigner-Ville distribution, which is an emerging tool for non-stationary spectral analysis. Results are presented to demonstrate the enhanced detection performance of the proposed technique.
Book Synopsis Fifth International Conference on HF Radio Systems and Techniques, 22-25 July 1991 by :
Download or read book Fifth International Conference on HF Radio Systems and Techniques, 22-25 July 1991 written by and published by . This book was released on 1991 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conference Publication written by and published by . This book was released on 1991 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Advances in Bistatic Radar by : Nicholas J. Willis
Download or read book Advances in Bistatic Radar written by Nicholas J. Willis and published by SciTech Publishing. This book was released on 2007-06-30 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive reference updates bistatic and multistatic radar developments since the publication of Nicholas Willis' seminal book Bistatic Radar published in 1991 and revised in 1995. The book is organized into two major sections: Bistatic/ Multistatic Radar Systems and Bistatic Clutter and Signal Processing. New and recently declassified military applications are documented. Civil applications are detailed for the first time, including commercial and scientific systems. Several of the most honored radar engineers of this era provide expertise in each of these applications. Professionals in radar and sonar will find this book a valuable resource
Book Synopsis Radar Sea Clutter by : Luke Rosenberg
Download or read book Radar Sea Clutter written by Luke Rosenberg and published by IET. This book was released on 2021-12-17 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents comprehensive coverage of new research into sea clutter characterisation and modelling, radar performance prediction and maritime target detection. The book also includes a summary of sea-clutter scattering characteristics and datasets provided that can be used for modelling.
Author :North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development Publisher : ISBN 13 : Total Pages :526 pages Book Rating :4.:/5 (31 download)
Book Synopsis AGARD Index of Publications by : North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development
Download or read book AGARD Index of Publications written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1989 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt:
