共查询到19条相似文献,搜索用时 93 毫秒
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本文基于射线跟踪法在时域研究超宽带系统的传播特性。经过MATLAB的仿真实现,在发射端和接收端比较电场波形,研究环境因素对波形失真的影响,包括电场的极化类型、墙壁的电磁参数、入射射线的入射角大小等。 相似文献
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为了知道入射到光探测器上的短脉冲的真正波形,提出一种新的修正方法。此法将被探测脉冲的累积量从探测器系统函数的累积量中扣除。特别指出将失真系数与过超系数的概念用于准高斯脉冲,能方便地修正探测脉冲波形。 相似文献
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长时间波形失真在电视传输设备中将导致瞬时非线性失真恶化。本文介绍了长时间波形失真和瞬时非线性失真的测试方法以及测试结果。 相似文献
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超宽带无线信道的频率依赖特性直接影响到超宽带接收机的设计和以脉冲波形为基础的多址技术。本文针对频率依赖特性对超宽带脉冲信号波形产生的影响,分别从相位谱和幅度谱两个方面分析超宽带脉冲信号的相位失真和幅频失真特性,建立了描述脉冲波形失真特性的数学模型。使用该模型对高斯二阶导数脉冲信号的波形失真进行仿真分析,得到了只发生相位响应失真、只发生幅度响应失真、以及同时发生相位—幅度响应失真的脉冲波形。 相似文献
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本文设计并制作了一种基于晶体管放大器的非线性失真研究装置。本装置以频率为1kHz、峰峰值为20mV的正弦波作为晶体管放大器输入信号,输出峰峰值不低于2V的无明显失真波形及其余四种失真波形,并对输出波形进行AD采集后,通过FFT方式计算输出信号的总谐波失真值(Total Harmonic Distortion)。本装置由STM32F407核心控制板、晶体管及偏置电路组成。通过改变五个通道的放大器偏置电路调节静态工作点,同时采用4051模拟开关进行五种波形通道的切换,实现“无明显失真”、“顶部失真”、“底部失真”、“双向失真”、“交越失真”五种波形输出,并在TFT LCD屏上显示波形以及THD值。 相似文献
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在假设媒质参数与频率有关的情况下,给出了探地雷达用于地下目标探测时的理论计算模型;研究了脉冲波在土壤中传播时的失真特性;并指出了引起脉冲波失真的原因及从失真波形中恢复原始波形的方法。 相似文献
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在此运用LabVIEW软件仿真了模拟电路中的典型阻容耦合共发射极放大电路,此电路有放大状态、饱和失真状态和截止失真状态。针对放大状态给出了它的静态工作点和正常的放大输出波形;针对饱和失真状态和截止失真状态给出了相应的失真波形。在典型阻容耦合共发射极电路基础上,设计了电压串联负反馈电路,验证了负反馈对整个电路输入/输出电阻及放大倍数的影响。 相似文献
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研究超宽带(UWB,ultra-wideband)的传播特性,是UWB信道理论研究的核心内容。利用Fourier变换对各种超宽带(UWB)脉冲波形的室内反射、透射和绕射进行了研究,并提出了一种新的n阶修正Bessel函数的渐近公式,仿真结果和时域的精确结果对比,一致性吻合较好。 相似文献
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《Photonics Technology Letters, IEEE》2008,20(22):1869-1871
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The influence of stimulated Raman scattering (SRS) taking into account the random modulation and the walk-off effect on wide-band wavelength division multiplexing (WDM) transmission systems are studied theoretically. First, it is shown that power depletion due to SRS can be separated into average power loss and waveform distortion. The waveform distortion is evaluated for various types of pulse shapes and fibers, and simple equations for evaluating the waveform distortion due to SRS are derived. These equations can be easily applied for designing wide-band WDM transmission systems from the viewpoint of the SRS waveform distortion. We also compare results obtained from our method with those from the split-step Fourier method, and confirm validity of our method. Our method should be useful in the design of wide-band WDM transmission systems, in which SRS is expected to be a serious limitation 相似文献
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In this paper, an optical time-domain fractional Fourier transformation (FRFT) system is proposed to achieve the minimum distortion
transmission under combined effects of chromatic dispersion and self-phase modulation (SPM). In the new method, the pulses
operated as FRFT will propagate in a new domain, in which the waveform in time domain will keep nearly unchanged through the
transmission. The novel method achieves a 400 km optical transmission for an optical pulse with the full width at the 1/e point of peak power of 80 ps without any dispersion compensation and the pulse offers a nice performance with negligible
nonlinear distortion. Compared with the soliton communication, this scheme shows more advantages on linear and nonlinear distortions
without strict restriction to input pulses. 相似文献
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Hsiung Cheng Lin 《Industrial Electronics, IEEE Transactions on》2007,54(1):43-52
Nowadays, harmonic distortion in power systems is attracting significant attention. Traditional technical tools for harmonic distortion analysis using either fast Fourier transform or discrete Fourier transform are, however, susceptible to the presence of noise in the distorted signals. Harmonic detection by using Fourier transformation also requires input data for more than one cycle of the current waveform and requires time for the analysis in the next coming cycle. In this paper, an alternative method using neural network algorithm has achieved satisfactory results for fast and precise harmonic detection in noisy environments by providing only 1/2 cycle sampled values of distorted waveforms to neural network. Sensitivity considerations are conducted to determine the key factors affecting the performance efficiency of the proposed model to reach the lowest errors of testing patterns 相似文献
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超宽带CI脉冲是由多个相干载波合成的窄脉冲信号.该文在此基础上,提出了扩频CI合成窄脉冲技术.由此降低了功率谱密度,提高了频带使用效率和便于多址应用.通过对每个相干载波信号CI扩频且合成,其效果很好.在信道传播上拥有超宽带信号的抗多径高分辨率性能,同时又能对扩频相干副载波进行相关接收,这样大大地提高了相关接收增益,减少了码间串扰.该文运用信号最佳设计方法,将超宽带SSCI信号设计成符合FCC标准和ETSI标准的最佳信号,减少与其他无线系统的相互干扰.文中给出了理论分析、设计方法和计算机模拟仿真结果.该设计方法对于提高UWB通信系统的性能有很重要的意义. 相似文献
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