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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。
In order to study the noise performance of digital spectrometer, the noise index of digital filter is proposed and analyzed. Analytical derivation and numerical simulation methods are used to study the relationship between the noise index and the forming characteristics of the analog front end, the sampling frequency of the ADC and the digital filter parameters, and the noise figure of the digital ladder filter is calculated. The research shows that high sampling frequency and high-order anti-aliasing filter can help to improve system signal-to-noise ratio. Step noise is not sensitive to sampling frequency, while δ noise requires higher sampling frequency to achieve better performance. This study provides a theoretical basis for the noise performance analysis of digital filters.