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Analysis of exponentially decaying pulse signals and weak unsteady signals using statistical approach.

机译:使用统计方法分析指数衰减的脉冲信号和微弱的不稳定信号。

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摘要

Using statistical test in engineering is becoming common in these few years. In this thesis, several statistical techniques are investigated to solve acoustical engineering problems. A stochastic volatility model incorporated the exponential power distributions and Student-t distributions are adopted in this thesis to analyze exponentially decay pulses in the presence of background noises of various magnitudes. It is found that the present stochastic volatility model can retrieve the instant of the pulse initiation and the decay constant within engineering tolerance even when the noise is slightly stronger that the pulse amplitude. The results suggest that both these distributions can give accurate recovery of the instants when the abrupt changes take place if the background noise level is lower than that of the changes by 3dB. They also indicate that the exponential-power distribution is more useful when the signal-to-noise ratio falls below 0dB. The results are compared with those obtained by the conventional short-time Fourier transform and its performance is considerably better than that of the latter when the frequency of the decay pulse fluctuates.;To recover the initialization of an exponentially growing wave embedded inside a stationary background noise is very important especially in building services engineering where the early detection of very small alien signal is crucial to the smooth operation of machines. A parameter derived from two statistical tests, namely the Jarque-Bera and the D'Agostino's tests, which are used for checking data normality, is introduced. It is found that the newly derived parameter is very sensitive to the change incurred by the wave to the background noise statistics and is very helpful in locating the instant of the wave initialization even when the signal-to-noise ratio drops to -30dB. The corresponding accuracy of the recovery can be as low as 3 time steps. A simple numerical function together with the Fourier Transform analysis in the detection of very weak sinusoidal signals embedded in a non-stationary random broadband background noise is proposed in the present study. Its performance is studied through the use of two numerical examples. It is found that the present method enables good recovery of the sinusoidal signals and the instants of their initiations even when the signal-to-noise ratio is down to -17dB.
机译:近年来,在工程中使用统计测试已变得越来越普遍。本文研究了几种统计技术来解决声学工程问题。本文采用了包含指数功率分布和Student-t分布的随机波动率模型,以分析存在各种幅度背景噪声时的指数衰减脉冲。已经发现,即使当噪声比脉冲幅度稍强时,本随机波动率模型也可以在工程公差范围内检索脉冲启动的瞬间和衰减常数。结果表明,如果背景噪声水平比变化的背景噪声水平低3dB,则这两种分布都可以使突变发生时的瞬间准确恢复。它们还表明,当信噪比降至0dB以下时,指数功率分布会更有用。将结果与通过常规短时傅立叶变换获得的结果进行比较,并且当衰减脉冲的频率波动时,其性能明显优于后者。噪声非常重要,尤其是在建筑服务工程中,在该工程中,及早发现非常小的外来信号对于机器的平稳运行至关重要。引入了一个参数,该参数来自两个统计检验,即Jarque-Bera和D'Agostino检验,用于检验数据的正态性。结果发现,新推导的参数对电波对背景噪声统计数据的变化非常敏感,即使在信噪比降至-30dB的情况下,也有助于定位电波初始化的瞬间。恢复的相应精度可能低至3个时间步长。本研究提出了一种简单的数值函数,并结合傅立叶变换分析来检测嵌入在非平稳随机宽带背景噪声中的非常微弱的正弦信号。通过使用两个数值示例来研究其性能。已经发现,即使当信噪比降低到-17dB时,本发明的方法也能够良好地恢复正弦信号及其启动的瞬间。

著录项

  • 作者

    Chan, Chun Man.;

  • 作者单位

    Hong Kong Polytechnic University (Hong Kong).;

  • 授予单位 Hong Kong Polytechnic University (Hong Kong).;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;
  • 关键词

  • 入库时间 2022-08-17 11:38:35

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