Dielectric loss factor measurement based on nuttall self-convolution window phase difference correction

Some windows which have small side-lobe level and quick fall off rate have been used to eliminate the measurement errors of dielectric loss factor tandelta caused by non-synchronized sampling and non-integral period truncation conditions. A new kind of window called Nuttall Self-Convolution Window (D-Nuttall Window for short) developed by convolving Nuttall Window is presented in this paper. D-Nuttall Window time domain and frequency domain functions are built, an approach for tandelta measurement based on D-Nuttall Window phase difference correction is proposed. The formulas of fundamental initial phase and tandelta are deduced, and the hardware implementation for the measurement system based on this approach is described. D-Nuttall Window with simple structure has smaller side-lobe level and quicker fall off rate than traditional combined cosine windows, and it is unnecessary to solve the high-order equations for spectrum phase difference correction algorithm, which is easy for embedded system realization. The simulation and experiment test results show that D-Nuttall Window function can well suppress spectral leakage, and the influences on tandelta measurement caused by harmonic disturbance, fundamental frequency fluctuation, change in sampling time length and white noise are all restricted by the approach presented in this paper. This approach can be designed and realized easily and has precise and steady measurement results, which can be used in tandelta offline measurement and online monitoring.