数字均值滤波器在高精度测温系统中可以有效降低噪声,提高信噪比,但也会造成信号的失真,引入不确定度,而采集到的温度信号一般为离散时间序列信号,现有的滤波器评价方法很难量化这种信号带来的失真。为了解决该问题,分析了温度缓变对象的温度变化特性,通过低噪声、高精度测量仪器采集被测物的典型温度信号序列,并由此构建数字均值滤波器的输入序列,从而得到该滤波器在当前输入信号模型下的不确定度,建立了一套评价数字均值滤波器在高精度测温系统中所引入不确定度的方法。对温度稳定条件下的黑体进行测温实验,得到了该黑体的温度波动范围为(30.874±0.002)℃,其温度变化率服从正态分布函数,验证了本文建立的温度特性模型的正确性。使用Fluke 1595A测温仪采集典型温度序列,对数字均值滤波器进行了不确定度分析,得到了在不同采样间隔时间、不同滤波器长度条件下,均值滤波器所引入的不确定度。基本解决了数字均值滤波器在高精度测温系统中引入不确定度难以评估的问题。

Digital mean filter can effectively reduce noise and improve signal-to-noise ratio in high-precision temperature measurement systems, but it will also cause signal distortion and become a source of uncertainty. The collected temperature signal is generally discrete-time series signal, so the existing filter evaluation method is difficult to quantify the distortion caused by this kind of signal. In order to solve this problem, the temperature variation characteristics of the object with slowly varying temperature are analyzed in this work. The typical temperature signal sequence of the measured object is collected by low-noise and high-precision measuring instrument, and then the input sequence of digital mean filter is constructed. A method to evaluate the uncertainty introduced by digital mean filter in high precision temperature measurement system is established. Temperature measurement experiments on a black-body under stable temperature conditions are performed. The temperature range of this black-body is (30.874±0.002)℃, and its rate of the temperature change obeys normal distribution function, which verifies the correctness of the proposed temperature characteristics model. Fluke 1595A thermometer is used to collect typical temperature sequences, and the uncertainty of digital mean filter is analyzed. Under the condition of different sampling intervals and filter lengths, the uncertainty introduced by digital mean filter in high-precision temperature measurement system is difficult to evaluate is basically solved.