中文摘要：

采用旁瓣峰值电平小且旁瓣渐近衰减速率大的窗函数对信号加权可减轻非同步采样和数据截断对介质损耗因数tanδ测量的影响。本文分析了Nuttall窗的旁瓣特性，提出了基于Nuttall窗双谱线插值开叩的tanδ测量方法，运用多项式拟合求出了实用的插值修正公式，推导了信号初相角及tanδ的计算式，并介绍了基于该算法的测量系统的硬件实现方案。仿真和试验结果表明，Nuttall窗函数抑制频谱泄漏效果好，基于Nuttall窗的双谱线插值FFT方法克服了谐波干扰、基波频率波动及白噪声对tanδ测量的影响，且设计实现灵活，测量结果精确、稳定，可用于介质损耗因数tanδ的离线测量与在线监测。

英文摘要：

Windows with small side lobes and quick attenuation rate have been used to eliminate the errors of dielectric loss factor tanδ measurement caused by non-synchronized sampling and non-integral period truncation. The side lobe characteristic of Nuttall window is discussed and an approach for tanδ measurement based on Nuttall window double spectrum line interpolation FFT is proposed. The applicable correction formulas of the interpolation are obtained by using polynomial curve fitting function. The arithmetic expressions of fundamental initial phase and tanδ are deduced. The hardware implementation for the measurement system based on this approach is described. Simulation and test results show that Nuttall window function can restrain spectral leakage well, and the influences of harmonic interference, fundamental frequency fluctuation, sampling frequency and sampling time length and white noise on tanδ measurement are all overcome by using the approach presented in this paper. This approach can be realized neatly and achieve precise and steady results, which can be used in tanδ offline measurement and online monitoring.