Abstract：A new way for TWACS (two way power frequency automatic communication system) outbound signal demodulation is presented in this paper to determine the modulation signal time domain by time-frequency method, facing the fact that the transmission delay of the TWACS modulated signal is much smaller than the zero crossing time difference of the frequency voltage at the signal receiving point. The preface information is modulated before the send of the outbound signal at the communication master side, and the synthesized signal whose modulation component is greatly enhanced is received at the receiving end with the preface information. Then the Winger-Ville distribution and short-time Fourier transform are used to obtain the energy distribution of the synthesized signal, taking the moment of peak energy as the reference to form the reference signal and determine the modulation signal time domain;In the data information period, the cross-correlation operation is done between the voltage difference signal and the reference signal in this determined time domain, and the positive and negative of the result is used to achieve the data demodulation. Simulation and the field tests of the industrial distribution network prove that the demodulation method is not effected by the voltage phase difference between the receiving and sending ends, and its capacity of anti-interference is also obviously improved.
卢文冰, 罗应立, 闫迎. 基于时频分析与互相关技术的工频通信下行解调[J]. 电工技术学报, 2011, 26(4): 192-199.
Lu Wenbing, Luo Yingli, Yan Ying. Demodulation for TWACS Outbound Signals Based on Time-Frequency Analysis and Cross-Correlation Technique. Transactions of China Electrotechnical Society, 2011, 26(4): 192-199.
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2011, Vol. 26 
