基于频谱缝合的脉冲信号低成本频域测量技术
发布时间：2018-12-10 20:14
【摘要】：脉冲信号的时域波形测量是时间反演(Time Reversal,简称TR)技术实际应用中的关键环节之一。时间反演技术在2004年被成功引入到电磁学领域,该技术在复杂媒介中目标的探测与成像、超宽带无线通信等电磁学领域具有重要的价值。而本论文以电磁信号时间反演技术为研究背景,研究了一种基于频谱缝合的脉冲信号低成本频域测量技术。论文的主要研究内容如下:(1)基于频谱缝合的脉冲信号频域测量技术的理论分析与系统建模首先提出了基于频谱缝合的脉冲信号频域测量技术的核心思想,其中包括基于外差式下变频电路的频谱分割和基于重叠谱线幅度和相位线性拟合的频谱缝合;在该测量技术的思想上将该脉冲信号测量技术的原理分析过程分成脉冲信号的频谱分割、子频带的频谱缝合和频谱外推、脉冲信号的重建四个部分进行详细分析,得出相邻子频带之间重叠区域对应频点上幅度的比值是个固定值和对应频点上的相位差是关于频率的线性函数;根据相邻子频带之间重叠区域幅度和相位的关系通过频谱缝合和频谱外推得出了最终恢复出的幅度和相位的公式,然后再利用得出的公式逆傅里叶变换得到重建的脉冲信号,推导出完整的基于频谱缝合的脉冲信号测量模型。(2)基于频谱缝合的脉冲信号频域测量技术的可行性验证根据上述研究的基于频谱缝合的脉冲信号频域测量理论,设计并实现了四通道频谱分割和频谱缝合脉冲信号测量实验设计方案和硬件电路实现系统,通过对400MHz带宽的脉冲信号进行四通道频谱分割和频谱缝合得出最终恢复出的频域上完整的幅度谱和相位谱并逆傅里叶变换重建原始的脉冲信号,实验结果表明重建的脉冲信号与原始脉冲信号的时域波形是基本吻合的,由此验证了基于频谱缝合的脉冲信号频域测量技术理论的可行性。(3)基于频谱缝合的脉冲信号频域测量技术的误差分析首先研究下变频硬件电路系统中混频器的非线性特性,分析并测量得出实验用的混频器的线性工作范围。通过调整脉冲信号测量验证实验中射频输入和本振注入功率大小,分析研究混频器非线性特性对测量误差的影响。实测结果表明,通过控制射频输入功率(由-5dBm减小为-10dBm)和本振注入功率(由0dBm增大为7dBm)使混频器工作在线性范围内,能够明显降低实验误差(误差由24.41%降至11.85%)。其次研究相邻子频带重叠谱线数目对脉冲信号测量误差的影响。通过补充多个实验,计算在不同重合谱线数的条件下缝合频谱的实测误差。实验结果表明,增加相邻子频带重合谱线数有利于减小频谱缝合误差,提高脉冲测量精度。典型的实验结果中,当重合谱线数由5条增加至15条时,测量误差可由23.08%降至5.36%。综上分析得出混频器的非线性特性和相邻子频带之间的重叠谱线数是该测量技术的主要误差来源。
[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.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911
本文编号：2371137
[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.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911
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