【摘要】：對于傳統(tǒng)微弱信號檢測方法，輸入信號信噪比難以降低，受到一定限制。而基于混沌理論檢測微弱信號的方法彌補了這一缺陷，能夠達到極低的信噪比，提高了檢測精度。本文針對此展開了研究。論文在研究混沌理論基礎(chǔ)之上，設(shè)計了微弱信號檢測系統(tǒng)，通過對系統(tǒng)建模、仿真、實際電路的設(shè)計，驗證了利用混沌理論檢測微弱信號的有效性。 在對混沌基本特點分析研究基礎(chǔ)上，給出了類洛倫茨系統(tǒng)的具體模型，并做詳細分析。提出雙參數(shù)控制的混沌控制方法，可將系統(tǒng)控制在所期待的周期軌道內(nèi)。此方法避免計算精確的激勵信號幅值，提高工作效率，，可控性強。根據(jù)特定混沌系統(tǒng)對于參數(shù)敏感性而對噪聲免疫的特性，利用雙參數(shù)控制方法，構(gòu)造了基于類Lorenz（洛倫茨）系統(tǒng)的微弱信號檢測模型，理論分析驗證了該檢測系統(tǒng)具有檢測中低頻微弱周期信號的特性。通過具體的仿真實驗，成功實現(xiàn)了噪聲背景下微弱信號的檢測，效果顯著，達到較低信噪比，表明利用類Lorenz系統(tǒng)進行微弱信號檢測是可行的。針對目前混沌系統(tǒng)檢測微弱信號尚停留在仿真的現(xiàn)狀下，為驗證混沌檢測方法的實際應(yīng)用的有效性，本文搭建了混沌檢測實驗電路。根據(jù)電路特性的分析，組織架構(gòu)具體實現(xiàn)微弱信號檢測的原理框圖,采用模塊化設(shè)計，利用DSP數(shù)字信號處理技術(shù)，產(chǎn)生周期激勵信號，幅值和頻率可靈活控制。然后利用運算放大器以及電阻電容等元器件做出實際檢測電路。完成微弱信號混沌檢測實際電路的搭建，通過示波器中判斷相軌跡的明顯變化來檢測微弱信號。 本文創(chuàng)新之處在于，提出雙參數(shù)控制法控制混沌，并將此方法應(yīng)用于基于類Lorenz系統(tǒng)的微弱信號檢測中。matlab仿真實驗以及具體實際電路實驗同時驗證了方法的有效性。同時分析當前混沌系統(tǒng)檢測微弱信號對具體的電路實現(xiàn)上還沒有充分應(yīng)用的情況下，本文對所建立的類Lorenz混沌檢測系統(tǒng)做出了具體的電路實驗，電路實驗分析結(jié)果與理論分析達到一致性,為實際工程應(yīng)用檢測微弱信號提供了一個簡單有效的檢測裝置，具有良好應(yīng)用前景，對微弱信號檢測進行了有意義的探索。
[Abstract]:For the traditional weak signal detection method, the SNR of the input signal is difficult to reduce and is limited to some extent. The method of detecting weak signal based on chaos theory makes up for this defect, and can achieve extremely low signal-to-noise ratio (SNR) and improve the accuracy of detection. In this paper, the research is carried out. Based on the study of chaos theory, a weak signal detection system is designed in this paper. The effectiveness of using chaos theory to detect weak signal is verified by modeling, simulation and practical circuit design. On the basis of analyzing and studying the basic characteristics of chaos, the concrete model of Lorenz-like system is given and analyzed in detail. A two-parameter chaos control method is proposed, which can control the system in the desired periodic orbit. This method avoids calculating the exact amplitude of excitation signal and improves the working efficiency and controllability. According to the characteristic that a particular chaotic system is immune to noise due to its sensitivity to parameters, a weak signal detection model based on Lorenz (Lorentz)-like system is constructed by using the two-parameter control method. The theoretical analysis verifies that the detection system has the characteristic of detecting low frequency weak periodic signal. Through the concrete simulation experiment, the weak signal detection under the background of noise is successfully realized, the effect is remarkable and the signal-to-noise ratio is low, which indicates that it is feasible to use the similar Lorenz system to detect the weak signal. In order to verify the effectiveness of the practical application of the chaotic detection method, a chaotic detection experimental circuit is built in this paper in view of the fact that the weak signal detection in the chaotic system is still in the state of simulation. According to the analysis of the circuit characteristics, the principle block diagram of the organization structure to realize the weak signal detection is presented, the modular design is adopted, and the DSP digital signal processing technology is used to generate the periodic excitation signal. The amplitude and frequency can be controlled flexibly. Then the operational amplifier and resistive capacitance and other components to make the actual detection circuit. The actual circuit of weak signal chaotic detection is built, and the weak signal is detected by judging the obvious change of phase locus in oscilloscope. The innovation of this paper is that the two-parameter control method is proposed to control chaos, and this method is applied to weak signal detection based on Lorenz system. The effectiveness of the method is verified by the matlab simulation experiment and the actual circuit experiment at the same time. At the same time, under the condition that the weak signal detection in the current chaotic system has not been fully applied to the realization of the specific circuit, this paper makes a concrete circuit experiment on the Lorenz like chaotic detection system. The experimental results of the circuit are consistent with the theoretical analysis, which provides a simple and effective detection device for the practical engineering application of weak signal detection. It has a good application prospect, and makes a meaningful exploration for the weak signal detection.
【學位授予單位】：杭州電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN911.23

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