地震信号子样幅值的概率分布及数字地震仪的量化信噪比

Probability Distribution of Seismic Signal Subsample Amplitudes and Quantized SNR of Digital Seismic Instruments

要计算数字地震仅对每次记录的量化信噪比,须首先知道地震信号子样幅值的概率分布密度根据对地震信号子样幅值的统计,可取瑞利分布作为冲击型振源(?)发的地震信号子样幅值的概率分布。在讨论了效字地震仅量化信噪比之后,给出了仪器的量化信噪比与地震子样幅值均值的关系以及使仪器获得最佳量化信噪比的仪器前放增益的选择范围、即:欲使仅嚣对某一道量化信噪比不低于120 dB,该道每次接收的地震信号经前放放大后的子样幅值的均值(?)应在V/25～V/3(V为量化器的最大量化值)之间。

In order to calculate the quantized SNR (signal-to-noise ratio) of a digital seismic instrument for each record, it needs first to know the amplitude distribution function of seismic signal samples. Based on the statistical analysis of seismic signal subsample amplitudes, it is found that the Rayleigh's distribution can be used as a probability distribution of seismic signal subsample amplitudes when signals are excited by impulse vibration sources. After discussion of the quantized SNR of digital seismic instruments, a relationship between the quantized SNR of seismic instruments and the mean amplitude value of seismic signal samples is presented in this paper. Also, a gain selection range of pre-amplifier of instruments is given which allows instruments to obtain optimal quantized SNR, that is, to make the quantized SNR of instruments be not less than 120 dB, after preamplified, the mean amplitude value for received seismic signals each time should be between V/25—V/3.