147 research outputs found

    A Heuristic Task Scheduling Method for Multifunction Radar

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    Modern radar systems are required to perform various tasks within a given time window in order to ascertain the presence of a new target or update information about an existing target. The scheduling of such tasks is therefore important in order to efficiently utilize the radar timeline. This paper describes a novel heuristic approach for scheduling tasks on a multifunction radar. The proposed approach is based on tabu search, and computational results are presented to assess the efficacy of the proposed method

    Target recognition techniques for multifunction phased array radar

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    This thesis, submitted for the degree of Doctor of Philosophy at University College London, is a discussion and analysis of combined stepped-frequency and pulse-Doppler target recognition methods which enable a multifunction phased array radar designed for automatic surveillance and multi-target tracking to offer a Non Cooperative Target Recognition (NCTR) capability. The primary challenge is to investigate the feasibility of NCTR via the use of high range resolution profiles. Given stepped frequency waveforms effectively trade time for enhanced bandwidth, and thus resolution, attention is paid to the design of a compromise between resolution and dwell time. A secondary challenge is to investigate the additional benefits to overall target classification when the number of coherent pulses within an NCTR wavefrom is expanded to enable the extraction of spectral features which can help to differentiate particular classes of target. As with increased range resolution, the price for this extra information is a further increase in dwell time. The response to the primary and secondary challenges described above has involved the development of a number of novel techniques, which are summarized below: ā€¢ Design and execution of a series of experiments to further the understanding of multifunction phased array Radar NCTR techniques ā€¢ Development of a ā€˜Hybridā€™ stepped frequency technique which enables a significant extension of range profiles without the proportional trade in resolution as experienced with ā€˜Classicalā€™ techniques ā€¢ Development of an ā€˜end to endā€™ NCTR processing and visualization pipeline ā€¢ Use of ā€˜Doppler fractionā€™ spectral features to enable aircraft target classification via propulsion mechanism. Combination of Doppler fraction and physical length features to enable broad aircraft type classification. ā€¢ Optimization of NCTR method classification performance as a function of feature and waveform parameters. ā€¢ Generic waveform design tools to enable delivery of time costly NCTR waveforms within operational constraints. The thesis is largely based upon an analysis of experimental results obtained using the multifunction phased array radar MESAR2, based at BAE Systems on the Isle of Wight. The NCTR mode of MESAR2 consists of the transmission and reception of successive multi-pulse coherent bursts upon each target being tracked. Each burst is stepped in frequency resulting in an overall bandwidth sufficient to provide sub-metre range resolution. A sequence of experiments, (static trials, moving point target trials and full aircraft trials) are described and an analysis of the robustness of target length and Doppler spectra feature measurements from NCTR mode data recordings is presented. A recorded data archive of 1498 NCTR looks upon 17 different trials aircraft using five different varieties of stepped frequency waveform is used to determine classification performance as a function of various signal processing parameters and extent (numbers of pulses) of the data used. From analysis of the trials data, recommendations are made with regards to the design of an NCTR mode for an operational system that uses stepped frequency techniques by design choice

    Radar Technology

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    In this book ā€œRadar Technologyā€, the chapters are divided into four main topic areas: Topic area 1: ā€œRadar Systemsā€ consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: ā€œRadar Applicationsā€ shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: ā€œRadar Functional Chain and Signal Processingā€ describes several aspects of the radar signal processing. From parameter extraction, target detection over tracking and classification technologies. Topic area 4: ā€œRadar Subsystems and Componentsā€ consists of design technology of radar subsystem components like antenna design or waveform design

    SETI science working group report

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    This report covers the initial activities and deliberations of a continuing working group asked to assist the SETI Program Office at NASA. Seven chapters present the group's consensus on objectives, strategies, and plans for instrumental R&D and for a microwave search for extraterrestrial in intelligence (SETI) projected for the end of this decade. Thirteen appendixes reflect the views of their individual authors. Included are discussions of the 8-million-channel spectrum analyzer architecture and the proof-of-concept device under development; signal detection, recognition, and identification on-line in the presence of noise and radio interference; the 1-10 GHz sky survey and the 1-3 GHz targeted search envisaged; and the mutual interests of SETI and radio astronomy. The report ends with a selective, annotated SETI reading list of pro and contra SETI publications

    Processing of Space Surveillance Observations

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    This thesis covers the processing of different types of space surveillance measurements. The emphasis is on the initial build-up of a catalogue. Most experiments focus on the identification of objects from pairs of observations by testing whether these two observations could originate from the same object. The advantage of this approach is that an orbit from two passes is usually more precise than that from a single pass and thus the chance of associating subsequent measurements with this newly derived orbit is higher. The main contribution is the introduction of a method for perturbed initial orbit determination and observation correlation from two radar tracklets. The perturbed initial orbit determination provides the solutions for all possible numbers of revolutions from two positions under consideration of the secular J2-perturbations, which causes for example the rotation of the orbital plane. The perturbations are considered analytically in an iterative process. From the different numbers of revolutions, the most probable solution can either be selected via the minimum Mahalanobis distance, using the range-rate as a remaining observable, or after an additional post-processing. The robustness and applicability of the method is shown using real radar measurements, which includes a large percentage of successful initial orbit determinations for tracklets which are more than 20 days apart. This method is also extended to the combination of optical and radar measurements for objects in Highly Elliptical Orbits. Concerning the simulation of a cold-start of a catalogue, two different processing strategies are introduced. One is adding a least squares orbit determination using a pair of possibly correlated tracklets, while the other approach collects data over a longer time span and generates a graph network from which clusters of tracklets are derived as new candidate objects. Further analysis focuses on aspects of operational processing of space surveillance measurements. This includes the automated decision making process for the monitoring of the quality of existing catalogue objects and the design of an autonomous processing pipeline for optical measurements at the Zimmerwald observatory. A potential space mission to observe the Geostationary Orbit is also analysed with regard to its performance during the catalogue build-up

    Solid Earth science in the 1990s. Volume 3: Measurement techniques and technology

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    Reports are contained from the NASA Workshop on Solid Earth Science in the 1990s. The techniques and technologies needed to address the program objectives are discussed. The Measurement Technique and Technology Panel identified (1) candidate measurement systems for each of the measurements required for the Solid Earth Science Program that would fall under the NASA purview; (2) the capabilities and limitations of each technique; and (3) the developments necessary for each technique to meet the science panel requirements. In nearly all cases, current technology or a development path with existing technology was identified as capable of meeting the requirements of the science panels. These technologies and development paths are discussed

    Viking '75 spacecraft design and test summary. Volume 3: Engineering test summary

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    The engineering test program for the lander and the orbiter are presented. The engineering program was developed to achieve confidence that the design was adequate to survive the expected mission environments and to accomplish the mission objective
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