噪声对介质损耗角正切计算结果的影响

Influence of noise on accuracy of dielectric loss factor calculation

为了获得噪声类型及其含量对介质损耗角正切(简称介损)计算准确性的影响,用正态分布的随机变量模拟白噪声,用限幅后的柯西分布随机变量模拟脉冲噪声,编程获得了模拟到数字转换(A/D)的量化噪声。仿真分析了信噪比、信号长度对以上噪声导致的介损测量误差的影响,同时对以上噪声给介损测量造成的误差进行了拟合。结果表明:存在白噪声或脉冲噪声时,误差随信噪比和信号长度的增加而减小;存在量化噪声时,误差随量化位数的增加而减小,不随信号长度的变化而变化。给出了白噪声、脉冲噪声和量化噪声给介损测量带来误差的计算公式。

To evaluate the influence of noise type and content on the accuracy of dielectric loss factor calculation,the white noise is simulated by a random variable with normal distribution and the impulsive noise by a random variable with Cauchy distribution and limited amplitude,while the quantization noise of analog-digital conversion is programmed.The influence of SNR（Signal-Noise Ratio） and signal length on the error of dielectric loss factor is investigated and the calculation formulas of errors caused by mentioned noises are fitted.Results show that：the error caused by white noise or impulsive noise decreases along with the increase of SNR or signal length while the error caused by quantization noise decreases only along with the increase of digitalizing bits,immune to signal length.The formulas of errors caused by different noises are given.