核电子学中数字滤波器的噪声指数分析

Noise index analysis of digital filters in nuclear electronics

为研究数字谱仪的噪声性能,提出并分析了数字滤波器的噪声指数。采用解析推导和数值仿真的方法,研究噪声指数与模拟前端成形特性、模数转换器采样频率以及数字滤波器参数的关系,计算了数字梯形滤波的噪声指数。研究表明,高采样频率和高阶反混叠滤波器有助于提高系统信噪比;阶跃噪声对采样频率不敏感,而δ噪声则需要较高的采样频率才能获得较好的指标。该研究为数字滤波器的噪声性能分析提供了理论依据。

The noise index of digital filters was studied to evaluate the noise in digital spectrometers. Theoretical analyses and numerical simulations were used to evaluate the dependence of the noise index on the characteristics of the analog front-end, the sampling frequency of the analog-to digital converter, and the filter shaping parameters. The noise index of a digital trapezoidal filter was also calculated based on a general analysis. Higher sampling frequencies and higher order anti-aliasing filters help suppress noise. The step noise is not sensitive to sampling frequency, while the delta noise needs a higher sampling frequency to achieve better performance. This study offers a theoretical criterion for noise analyses of digital filters.