【摘要】：天波超視距雷達(dá)(OTHR)是一種特殊的雷達(dá)體制,利用電離層對雷達(dá)信號(hào)的反射作用進(jìn)行目標(biāo)探測。OTHR作用距離遠(yuǎn),覆蓋范圍大,具有很高的國防和軍事價(jià)值。但是目前天波超視距雷達(dá)短相干積累條件下的艦船檢測比較困難,這主要是因?yàn)榕灤秃ｋs波的多普勒頻率接近,雷達(dá)回波譜中艦船目標(biāo)容易被海雜波一階回波遮蔽。本文主要研究OTHR的艦船檢測問題,各章節(jié)的主要工作如下:說明了天波雷達(dá)的工作原理和軍事價(jià)值,結(jié)合其發(fā)展歷史和現(xiàn)狀介紹了OHTR艦船檢測的研究意義和存在的問題。闡述了OTHR的信號(hào)處理流程,介紹了時(shí)域、空域和多普勒域的處理方法;分析了高頻雷達(dá)海洋回波譜的特性,基于Barrick導(dǎo)出的散射強(qiáng)度公式模擬了海洋回波譜,介紹了海態(tài)、雷達(dá)工作參數(shù)和電離層等因素對回波譜的影響。目前工程上解決海雜波遮蔽問題的方法主要有兩類,一類是海雜波循環(huán)對消法,通過減去正弦信號(hào)的方法抑制海雜波;另一類是高分辨譜估計(jì)方法,通過較高的頻率分辨率在多普勒域?qū)⒛繕?biāo)和海雜波區(qū)分開。本文首先研究了海雜波循環(huán)對消法的理論知識(shí)和實(shí)現(xiàn)方法,分別使用Root法,FFT相位分析法和APES方法進(jìn)行海雜波對消,實(shí)現(xiàn)了海雜波的抑制。然后介紹了兩種超分辨譜估計(jì)方法,即Capon和MUSIC算法,通過仿真和實(shí)測數(shù)據(jù)的處理分別驗(yàn)證了兩種算法的有效性并對其性能做了簡要的分析。某些情況下,電離層的層次性分布會(huì)導(dǎo)致多模傳播的發(fā)生,使得一個(gè)距離單元內(nèi)的多普勒譜中存在多對Bragg峰,傳統(tǒng)方法海雜波對消和高分辨譜估計(jì)方法均無法將目標(biāo)和多個(gè)海雜波一階譜峰區(qū)分開來。本文針對多模傳播的情況,研究一種基于雜波統(tǒng)計(jì)特性的一階峰匹配算法,該算法利用同一傳播模式下的正負(fù)一階峰多普勒頻率差恒定的特性對海雜波一階譜峰配對從而區(qū)分艦船目標(biāo)和海雜波一階譜峰,實(shí)現(xiàn)艦船目標(biāo)的檢測。仿真和實(shí)測數(shù)據(jù)的處理驗(yàn)證了該算法的有效性。
[Abstract]:Sky-wave over-the-horizon radar (OTHR) is a special radar system, which detects targets by ionospheric reflection of radar signals. The OTHR has a long range and a wide coverage, which has high national defense and military value. However, it is difficult to detect ship under the condition of short coherent integration of sky wave over-the-horizon radar. This is mainly due to the fact that the Doppler frequency of ship and sea clutter is close, and the ship target in radar echo spectrum is easy to be obscured by the first order echo of sea clutter. This paper mainly studies the ship detection of OTHR. The main work of each chapter is as follows: the working principle and military value of sky-wave radar are explained, and the research significance and existing problems of OHTR ship detection are introduced according to its development history and present situation. The signal processing flow of OTHR is described, and the processing methods of time domain, spatial domain and Doppler domain are introduced. The characteristics of ocean echo spectrum of high frequency radar are analyzed. The scattering intensity formula derived by Barrick is used to simulate the ocean echo spectrum. The influence of sea state, radar operating parameters and ionosphere on the echo spectrum is introduced. At present, there are two kinds of methods to solve the sea clutter masking problem. One is the sea clutter cyclic pair elimination method, which can suppress the sea clutter by subtracting sinusoidal signals. The other is the high-resolution spectral estimation method, which distinguishes the target from the sea clutter in the Doppler domain by high frequency resolution. In this paper, the theoretical knowledge and implementation method of sea clutter cyclic pair cancellation method are studied. Root method, FFT phase analysis method and APES method are used to eliminate sea clutter, respectively, and the suppression of sea clutter is realized. Then two super-resolution spectral estimation methods, Capon and MUSIC, are introduced. The effectiveness of the two algorithms is verified by the processing of simulation and measured data, and their performance is analyzed briefly. In some cases, the hierarchical distribution of the ionosphere will lead to the occurrence of multimode propagation, resulting in the existence of multiple pairs of Bragg peaks in the Doppler spectrum of a distance unit. The traditional methods, such as sea clutter cancellation and high resolution spectral estimation, can not distinguish the first order spectral peaks between targets and multiple sea clutter. In this paper, a first-order peak matching algorithm based on the statistical characteristics of clutter is proposed for multimode propagation. The algorithm makes use of the constant Doppler frequency difference between positive and negative first order peaks in the same propagation mode to match the first order spectral peaks of sea clutter to distinguish the ship targets from the first order spectral peaks of sea clutter and to realize the detection of ship targets. The validity of the algorithm is verified by simulation and the processing of measured data.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：E925.6;TN958.93

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相關(guān)碩士學(xué)位論文 前1條

1 邵昕;天波超視距雷達(dá)（OTHR）抗瞬態(tài)干擾及海雜波抑制研究[D];電子科技大學(xué);2007年

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本文編號(hào)：2409353