【摘要】：脈沖信號的時域波形測量是時間反演(Time Reversal,簡稱TR)技術(shù)實際應用中的關(guān)鍵環(huán)節(jié)之一。時間反演技術(shù)在2004年被成功引入到電磁學領(lǐng)域,該技術(shù)在復雜媒介中目標的探測與成像、超寬帶無線通信等電磁學領(lǐng)域具有重要的價值。而本論文以電磁信號時間反演技術(shù)為研究背景,研究了一種基于頻譜縫合的脈沖信號低成本頻域測量技術(shù)。論文的主要研究內(nèi)容如下:(1)基于頻譜縫合的脈沖信號頻域測量技術(shù)的理論分析與系統(tǒng)建模首先提出了基于頻譜縫合的脈沖信號頻域測量技術(shù)的核心思想,其中包括基于外差式下變頻電路的頻譜分割和基于重疊譜線幅度和相位線性擬合的頻譜縫合;在該測量技術(shù)的思想上將該脈沖信號測量技術(shù)的原理分析過程分成脈沖信號的頻譜分割、子頻帶的頻譜縫合和頻譜外推、脈沖信號的重建四個部分進行詳細分析,得出相鄰子頻帶之間重疊區(qū)域?qū)l點上幅度的比值是個固定值和對應頻點上的相位差是關(guān)于頻率的線性函數(shù);根據(jù)相鄰子頻帶之間重疊區(qū)域幅度和相位的關(guān)系通過頻譜縫合和頻譜外推得出了最終恢復出的幅度和相位的公式,然后再利用得出的公式逆傅里葉變換得到重建的脈沖信號,推導出完整的基于頻譜縫合的脈沖信號測量模型。(2)基于頻譜縫合的脈沖信號頻域測量技術(shù)的可行性驗證根據(jù)上述研究的基于頻譜縫合的脈沖信號頻域測量理論,設(shè)計并實現(xiàn)了四通道頻譜分割和頻譜縫合脈沖信號測量實驗設(shè)計方案和硬件電路實現(xiàn)系統(tǒng),通過對400MHz帶寬的脈沖信號進行四通道頻譜分割和頻譜縫合得出最終恢復出的頻域上完整的幅度譜和相位譜并逆傅里葉變換重建原始的脈沖信號,實驗結(jié)果表明重建的脈沖信號與原始脈沖信號的時域波形是基本吻合的,由此驗證了基于頻譜縫合的脈沖信號頻域測量技術(shù)理論的可行性。(3)基于頻譜縫合的脈沖信號頻域測量技術(shù)的誤差分析首先研究下變頻硬件電路系統(tǒng)中混頻器的非線性特性,分析并測量得出實驗用的混頻器的線性工作范圍。通過調(diào)整脈沖信號測量驗證實驗中射頻輸入和本振注入功率大小,分析研究混頻器非線性特性對測量誤差的影響。實測結(jié)果表明,通過控制射頻輸入功率(由-5dBm減小為-10dBm)和本振注入功率(由0dBm增大為7dBm)使混頻器工作在線性范圍內(nèi),能夠明顯降低實驗誤差(誤差由24.41%降至11.85%)。其次研究相鄰子頻帶重疊譜線數(shù)目對脈沖信號測量誤差的影響。通過補充多個實驗,計算在不同重合譜線數(shù)的條件下縫合頻譜的實測誤差。實驗結(jié)果表明,增加相鄰子頻帶重合譜線數(shù)有利于減小頻譜縫合誤差,提高脈沖測量精度。典型的實驗結(jié)果中,當重合譜線數(shù)由5條增加至15條時,測量誤差可由23.08%降至5.36%。綜上分析得出混頻器的非線性特性和相鄰子頻帶之間的重疊譜線數(shù)是該測量技術(shù)的主要誤差來源。
[Abstract]:Time domain waveform measurement of pulse signal is one of the key links in the practical application of time inversion (Time Reversal, (TR) technology. Time inversion was successfully introduced into the field of electromagnetism in 2004. It is of great value in the fields of target detection and imaging in complex media, ultra-wideband wireless communication and so on. In this paper, a low cost frequency domain measurement technique of pulse signal based on spectrum suture is studied based on the time inversion of electromagnetic signal. The main contents of this paper are as follows: (1) theoretical analysis and system modeling of frequency domain measurement technology of pulse signal based on spectrum stitching. Firstly, the core idea of frequency domain measurement technology of pulse signal based on spectrum stitching is put forward. It includes spectrum segmentation based on heterodyne down-conversion circuit and spectrum suture based on overlapping spectral line amplitude and phase linear fitting. In the idea of the measurement technology, the principle analysis process of the pulse signal measurement technology is divided into four parts: spectrum division of pulse signal, spectrum suture and extrapolation of sub-band, reconstruction of pulse signal. It is concluded that the ratio of the amplitude of the corresponding frequency point in the overlapping region between adjacent sub-bands is a fixed value and the phase difference on the corresponding frequency point is a linear function of the frequency. According to the relation between amplitude and phase of overlapping region between adjacent subbands, the formula of amplitude and phase is obtained by spectrum suture and extrapolation, and then the reconstructed pulse signal is obtained by inverse Fourier transform. A complete pulse signal measurement model based on spectrum suture is derived. (2) the feasibility of frequency domain measurement of pulse signal based on spectrum suture is verified. A four-channel spectrum division and spectrum suture pulse signal measurement experimental design scheme and hardware circuit implementation system are designed and implemented. By dividing and suturing the four-channel spectrum of the pulse signal with 400MHz bandwidth, the whole amplitude spectrum and phase spectrum in the frequency domain are obtained and the original pulse signal is reconstructed by inverse Fourier transform. The experimental results show that the reconstructed pulse signal is consistent with the original pulse signal in time domain. This verifies the feasibility of frequency domain measurement theory of pulse signal based on spectrum suture. (3) error analysis of frequency domain measurement technology of pulse signal based on spectrum stitching. The nonlinear characteristics of the device, The linear range of the mixer used in the experiment is obtained by analyzing and measuring. The influence of nonlinear characteristics of mixer on measurement error is analyzed by adjusting the power of RF input and local oscillator injection in the experiment of pulse signal measurement and verification. The measured results show that the mixer operates in a linear range by controlling the RF input power (from-5dBm to-10dBm) and local oscillator injection power (from 0dBm to 7dBm). The experimental error can be reduced obviously (from 24.41% to 11.85%). Secondly, the influence of the number of overlapping lines in adjacent subbands on the measurement error of pulse signal is studied. By adding several experiments, the measured error of suture spectrum is calculated under the condition of different number of overlapped spectral lines. The experimental results show that increasing the number of overlapped lines in adjacent subbands can reduce the spectral stitching error and improve the accuracy of pulse measurement. In typical experimental results, when the number of coincidence lines is increased from 5 to 15, the measurement error can be reduced from 23.08% to 5.36%. The nonlinear characteristics of the mixer and the number of overlapped spectral lines between adjacent sub-bands are the main error sources of the measurement technique.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN911

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本文編號：2371137