基于小波包和Markov链的低压电力线背景噪声重构

针对传统方法难以重构出时域特性和频域特性与真实低压电力线背景噪声一致的背景噪声问题，搭建了噪声测量平台实测了背景噪声，提出了一种基于小波包变换与Markov链相结合的背景噪声重构方法，通过小波包变换得到真实背景噪声在不同频带中的小波包分解系数，并利用Markov链对分解系数进行统计，模拟生成与实测噪声分解系数统计规律相同的仿真分解系数，将仿真分解系数重构后即可得到背景噪声。实例仿真结果表明，该方法重构的背景噪声在时域波形上与实测噪声极为相似，且功率密度谱变化趋势也与实测噪声基本一致，可作为电力线载波通信设备性能测试的可靠噪声源。

Low voltage Power Line Background Noise Reconstruction Based on Wavelet Packet and Markov Chain

It is difficult to use traditional method to reconstruct power line background noise whose time domain characteristic and frequency domain characteristic are similar to measurement power line background noise. This paper presentes a noise measurement platform for power line background noise measurement, and a new power line background noise reconstruction method based on wavelet packet transform and Markov chain statistics is proposed. This method calculates wavelet packet decomposition coefficient from measurement power line noise by wavelet packet transform, and obtained simulation decomposition coefficient whose statistics characteristic is similar to measurement noise decomposition coefficient by Markov chain. After wavelet packet reconstruction, the simulation decomposition coefficient can be reconstructed to power line background noise. The simulation example demonstrate that the time domain waveform of reconstructed power line noise is similar to time domain waveform of measurement noise, and the power density spectrum variation trend of reconstructed power line background noise is also similar to measurement noise, which is taken as reliable noise source for performance test of power line carrier communication equipment.