噪声特性对多次采样累加平均技术的影响

Influence of noise feature on multiple sampling, accumulation and averaging technology

在加性白噪声干扰下,对长驻留时间成像光谱仪运用多次采样累加平均技术可以使信噪比随采样累加平均次数的平方根增长。实际系统中的噪声可能包含有色噪声成分,使得多次采样累加平均技术存在一定的应用限制。通过对数字累加平均处理后信噪比的变化进行理论推导与分析,得出了噪声的自相关特性对信噪比的影响。根据对暗信号和积分球面源信号分别进行2至300次累加平均并计算信噪比,证明CCD成像光谱仪系统及输入信号中存在有色噪声。当有色噪声相关性小时,累加次数低于50仍能得到理想白噪声时的效果。

Multiple sampling,accumulation and averaging technology can be applied in long residence-time spectrometer system.In additional white noise jamming condition,the signal-to-noise rate（SNR） can be increased by multiplying the square root of accumulation and averaging time.However,the real system may contain colored noise such as 1/f noise,which leads to application constraints of the technology.In order to investigate the variation of system SNR after digital accumulation and averaging,theoretical derivation and analysis were presented which indicated the relationship between noise auto-correlative coefficients and system SNR.Then two groups of samples were acquired through two experiments,one without input light source while the other with an input source of integral sphere.Through 2 to 300 times accumulation and averaging,colored noise was approved in CCD imaging spectrometer.The comparison of the experimental and the theoretical results indicate the existence of colored noise in spectrometer system and input light source.But when the accumulation time is no larger than 50,the weak auto-correlative colored noise can be ignored which can lead to an ideal result.