| High-Frequency Surface-Wave Radars (HFSWR) has many advantages in remote-sensing of sea-state and sea environment monitoring, which can extracting surface current field or tides, key wave parameters, wave spectrum and surface wind field from Doppier spectrum in time. HFSWR has high accuracy and economy. Meanwhile it can survey a wide range. However, lots of interference prevent HFSWR's normal work, which reduces the quality of Doppier spectra and detecting distances, limits the work time as well.In fund of the 863 High Technology Project (HTP) of China, the HFSWR Technology in Monitoring Ocean Environment (818-01-02), the Radio Propagation Lab (RPL) in Wuhan University develops two middle-range-surveying HFSWRs, named OSMAR (Ocean State Measuring and Analyzing Radar) to detect the wind, wave, current and low-speed targets in 2000. OSMAR's lever reaches the foreign radars' lever in 90s of twenty century, and OSMAR achieves good application effect. None of interference-removal technology is used in OSMAR, while it is required to monitor long range, minimize antenna system and detect targets in the subsequent 863 HTP, the HFSWR Monitoring Technology (HFSWRMT) for long range (2001AA631050). But the interference reduces the quality of Doppier spectra, and is the obstacle to detect long range and detect targets, which needs suitable method to cancel.To solve the interference problem in the HFSWRMT for long range supported by the Subject of the 863 High Technology Project of China, the dissertation studies the methods to remove the night and daytime interference. According to the frame, the main contributions in this dissertation are as follows:The former five chapters discuss the methods to cancel the night interference.1 To provide theoretical guidance to remove interference in HFSWR, the dissertation expatiates the first-order and second-order reciprocity theory of sea current and radio wave, whose mathematical equations are given. Then the application of first-order and second-order theory is summarized, and the HFSWR's working principle is explained. Since OSMAR employ FMICW (Frequency Modulated Interrupted Continuous Wave) system, the dissertation begins the analysis of FMICW system with the composition of FMICW signal, and the sample data structure, the signal-processing procedure are given. Then the main interference of OSMAR is summarized: at first the emergence time and the reason of the night interference is expatiated. Afterward the frequency, polarization, and DOA are analyzed. The time and distances of the daytime interference are explained. At last the dissertation discussed the requirement and limits of HFSWR to interference-cancellation methods, which establish the basis of the choice and employment of interference-cancellation methods.2 The dissertation discussed whether the polarization filter can be used to remove the night interference. To explain the theory and methods of polarization filter, the dissertation explains polarization denotations: polarization ellipse, Jones vector, polarization ratio, Stokes vector, Poincare sphere, orthogonal polarization, based on which the principle of polarization filter and the reason of polarization loss is expounded. Then the principle of weighting in the horizontal polarized channel is analyzed and the signal-to-noise (SIR) equation is concluded, based on which the conditions of SIR improvement are presented. Afterwards the principle and realization method of multi-disturbance polarization suppression are discussed. At last, the dissertation analyzed the realization difficulties of polarization filters in HFSWR.3 In order to improve the traditional correlation filtering method to cancel the night interference using horizontal antennas, the principle and procedure of correlation filtering are expounded at first. Then the dissertation introduces the realization method of correlation filtering in FMICW radars. The two methods of weight computation are expatiated. To explain the experiment result, the dissertation defines some denotation: the...
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