| Spatial spectrum estimation is an important area in array signal processing, which is widely used in radar, communication and sonar etc.The disseratation is the research about over-the-horizon radar (OTHR). In military, OTHR is mainly used to make early warning of ballistic missile, low air bomber, cruise missile and attack fleet at sea.OTHR usually uses the ADBF to process array's signal. So during the ADBF's prcession, the direction of target's signal and noise's signal must be estimated. So the direction of arrival (DOA) estimation is very important in the OTHR. However, kinds of uncerntainty make very big effection on the DOA estimation, thereby distort and even abate the DOA estimation. Therefore the effection of the uncerntainty on the DOA estimation must be calibrated to assure its advantages of long-distance detection, antistealth and early warning ability.This dissertation studies the effection of the array uncertainty on the DOA estimation of the OTHR and the calibration on that.Firstly, this dissertation introduces the mode of OTHR's signal procession, and principle of DOA estimation and tentative of the target's signal. In order to get the azimuth information, the DOA method of OTHR is analyzed.Secondly, the effection of the array uncertainty, including the array sensor positon uncertainties, the elements'gain and phase uncertainty on the DOA estimation is studied and analyzed, then introduce the formula of the sensitivity of the MUSIC algorithm. According to the formula, the different effection of the kinds of array uncertainty to the MUSIC algorithm is analyzed.Finally, the two techniques for calibration are introduced. The technique for calibration of the array sensor position uncertainties is based on subspace principle and three calibration signals which need not be precisely known. The technique for calibration for the elements'gain and phase uncertainty is base on ML estimation and Toeplitzation and utilizes the Toeplitz character of the array covariance matrix. |
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