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本文详细地分析了强震加速度记录的数字化噪声。分析表明:数字化噪声由数字化设备的系统误差和操作者的随机读数误差迭加而成,随机数字化误差是具有各态历经性质的,其振幅按高斯规律分布的平稳随机过程,在其频谱组成中,长周期分量占明显的优势,因此将对二次积分加速度记录的位移曲线产生严重的影响。 研究表明:随机数字化“噪声位移”主要分布在周期大于25秒的频段,对加速度记录来说,分布在周期小于25秒的频段内,其随机噪声是相当小的(假定记录纸速为1厘米/秒)。因此,利用数字滤波技术,可以除去数字化加速度记录中的大部份随机数字化噪声。 作为实例,对一个典型的强震加速度记录进行了滤波,给出了低噪声的加速度记录和由此算出的位移曲线,且和未经滤波的相应记录及其位移进行了比较。
This paper analyzes in detail the digitized noise recorded by strong earthquakes. The analysis shows that the digital noise is composed of systematic error of digital equipment and operator random error of reading. The random digital error is a stationary random process with various ergodic properties and its amplitude is distributed according to Gaussian law. In its spectral composition , The long-period component accounts for obvious advantages and therefore will have a serious impact on the displacement curve recorded by the second-order integral acceleration. The results show that the randomized digitized “noise displacement” is mainly distributed in the frequency band longer than 25 seconds. For acceleration recording, the random noise is quite small in the frequency range less than 25 seconds (assuming that the recording paper speed is 1 cm /second). Therefore, using digital filtering techniques, most of the random digitized noise in digitized acceleration records can be removed. As an example, a typical strong earthquake acceleration record is filtered, the low-noise acceleration record and the resulting displacement curve are given, and compared with the corresponding unfiltered record and its displacement.