本文選題：高頻天波超視距雷達(dá)　切入點：展寬海雜波　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：天波超視距雷達(dá)具有探測范圍遠(yuǎn)、監(jiān)測范圍大等優(yōu)點，是預(yù)警系統(tǒng)的重要組成部分；同時也是各國監(jiān)測海洋專屬經(jīng)濟區(qū)的常用手段。然而對于低速運動的目標(biāo)的檢測問題，由于電離層相徑擾動的存在使得海雜波回波譜展寬，又由于艦船目標(biāo)的Doppler頻移和海雜波一階布拉格峰頻率相差不大，導(dǎo)致展寬的海雜波極易淹沒艦船目標(biāo)，嚴(yán)重影響天波雷達(dá)對艦船目標(biāo)的探測能力。海雜波展寬的原因除了電離層相徑擾動之外還有電離層造成的多徑傳播、多模傳播、幅度衰落等，這些因素往往和電離層相徑擾動疊加在一起，使得海雜波多普勒譜展寬的原因非常復(fù)雜，給展寬海雜波的抑制和被展寬海雜波淹沒目標(biāo)的檢測帶來巨大障礙。以往對展寬海雜波回波譜的抑制主要采用對電離層相徑擾動進(jìn)行補償校正的方法，這類方法往往僅在慢相徑擾動的情況下才能取得一定的效果。然而，實際工程中海雜波展寬的原因不僅僅是由于存在慢相徑擾動，這導(dǎo)致這類算法的應(yīng)用受到極大限制。 進(jìn)入二十一世紀(jì)，美國Duke大學(xué)從廣義似然檢測的角度出發(fā)對被展寬海雜波淹沒的艦船目標(biāo)進(jìn)行檢測，將自適應(yīng)匹配濾波等算法應(yīng)用到天波體制雷達(dá)系統(tǒng)中，通過從臨近距離分辨單元選擇雜波訓(xùn)練樣本實現(xiàn)對展寬海雜波的抑制。然而這類算法存在兩個顯著缺陷，一是運算復(fù)雜度較大，不符合實時性運算要求；二是對天波雷達(dá)來說，由于其距離分辨力較差，加上海態(tài)變化等原因，使得從臨近距離分辨單元選取的訓(xùn)練樣本往往不能很好的表征當(dāng)前待處理分辨單元的雜波特性，因而算法性能較差。本文針對這兩種問題提出了較好的解決方法，主要內(nèi)容如下： (1)對天波雷達(dá)海雜波產(chǎn)生的機理，海雜波Doppler譜展寬的原因進(jìn)行了分析，并簡要介紹了幾種常見的電離層相徑擾動校正方法，然后分析了這類方法的特性。 (2)分析了美國杜克大學(xué)基于目標(biāo)的平穩(wěn)性比海雜波平穩(wěn)性強而提出的一種廣義似然比檢測算法，并通過仿真實驗對該算法性能進(jìn)行了分析。 (3)提出了一類基于平滑處理的目標(biāo)檢測算法，該算法與傳統(tǒng)時域自適應(yīng)匹配濾波算法相比可以大大降低計算復(fù)雜度，其中復(fù)乘法計算次數(shù)降低五個數(shù)量級左右，使得算法符合工程實時性運算要求。 (4)針對從臨近距離分辨單元所選擇訓(xùn)練樣本不能很好表征雜波特性的難點，本文提出一種基于空時級聯(lián)處理的目標(biāo)檢測算法，該算法通過空域陷波處理濾掉雷達(dá)回波中的目標(biāo)信息，從當(dāng)前距離分辨單元獲取訓(xùn)練樣本，因而能夠較好的實現(xiàn)對展寬海雜波的抑制，，然后通過所提的基于平滑處理的方法實現(xiàn)對被淹沒目標(biāo)的檢測。
[Abstract]:Sky wave over-the-horizon radar has the advantages of long detection range and large monitoring range. It is an important part of the early warning system, and is also a common means of monitoring the ocean exclusive economic zone. However, for the detection of low-speed moving targets, it is also a common method of monitoring the ocean exclusive economic zone. Due to the existence of the ionospheric phase diameter disturbance, the echo spectrum of sea clutter is widened, and the Doppler frequency shift of ship target and the frequency of first order Bragg peak of sea clutter are not different. In addition to ionospheric phase diameter disturbances, there are also multipath propagation, multimode propagation and amplitude fading caused by ionosphere. These factors are often superimposed with ionospheric phase diameter disturbances, which make the reasons for broadening the Doppler spectrum of sea clutter very complicated. It brings great obstacles to the suppression of broadened sea clutter and the detection of submerged targets. In the past, the method of compensating and correcting the ionospheric phase diameter disturbance was used to suppress the echo spectrum of broadened sea clutter. This kind of method can only get certain effect under the condition of slow phase path disturbance. However, the reason of the clutter broadening in practical engineering is not only because of the existence of slow phase path perturbation, but also because the application of this kind of algorithm is greatly limited. In 21th century, Duke University of the United States started from the point of view of generalized likelihood detection to detect ship targets submerged by extended sea clutter, and applied adaptive matched filtering and other algorithms to the radar system of sky wave system. The clutter training samples are selected from the near range resolution unit to suppress the outspread sea clutter. However, there are two significant shortcomings in this algorithm, one is that the computation complexity is large, which does not meet the real-time operation requirements, and the other is the sky wave radar. Because of the poor range resolution and the variation of the Shanghai state, the training samples selected from the near range resolution unit often can not well characterize the clutter characteristics of the current resolution units to be processed. Therefore, the performance of the algorithm is poor. In this paper, a better solution to these two problems is proposed, the main contents are as follows:. In this paper, the mechanism of sea clutter generation in sky-wave radar and the cause of Doppler broadening are analyzed, and several common methods for correction of ionospheric phase diameter disturbance are briefly introduced, and then the characteristics of these methods are analyzed. (2) A generalized likelihood ratio detection algorithm proposed by Duke University is analyzed, and its performance is analyzed by simulation experiments. A class of target detection algorithm based on smoothing processing is proposed. Compared with the traditional time domain adaptive matched filtering algorithm, this algorithm can greatly reduce the computational complexity, in which the number of times of complex multiplication is reduced by about five orders of magnitude. The algorithm meets the requirements of engineering real-time operation. 4) aiming at the difficulty that the training samples selected from the near range resolution unit can not well characterize the clutter characteristics, a target detection algorithm based on space-time cascade processing is proposed in this paper. The algorithm can filter the target information in radar echo by spatial notch processing and obtain training samples from the current range resolution unit. Then the submersible targets are detected by the proposed smoothing processing method.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN958.93

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