147 research outputs found
A Heuristic Task Scheduling Method for Multifunction Radar
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
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 āHybridā stepped frequency technique which enables a significant extension
of range profiles without the proportional trade in resolution as experienced with āClassicalā
techniques
ā¢ Development of an āend to endā NCTR processing and visualization pipeline
ā¢ Use of āDoppler 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
In this book āRadar Technologyā, the chapters are divided into four main topic areas: Topic area 1: āRadar Systemsā consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: āRadar Applicationsā shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: āRadar 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: āRadar Subsystems and Componentsā consists of design technology of radar subsystem components like antenna design or waveform design
SETI science working group report
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
Recommended from our members
SDI: Technology, Survivability, and Software
This report is the unclassified version of a classified document delivered to Congress at the end of August 1987. In attempting to reach agreement with the Department of Defense on what information could be included in an unclassified report, OTA found the wheels of bureaucracy to turn very slowlyāwhen they turned at all. Only through the active intervention of the Strategic Defense Initiative Organization, beginning in late in November 1987, and extending to the end of March, 1988, was a partial resolution of the problem achieved
Processing of Space Surveillance Observations
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
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
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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