基于Σ-Δ调制技术的TWACS通信信号特征提取

Study on TWACS modulated signal detecting methodbased on Σ-Δ modulation technique

针对双向工频自动通信系统(TwoWayAutomaticCommunicationSystem———TWACS)通信信号时域检测方法特征量少和抗干扰能力差,而时频分析方法数据处理复杂,装置成本高,提出了基于Σ-Δ增量调制技术提取TWACS通信信号的新方法.该方法在电网信号的调制区域将Σ-Δ调制器输出的1位数据流信息进行累加,将前后两抽样值的差值进行量化编码来代表连续信号所包含的信息,即采用增量调制的方式对相邻两个电网波形的位流和求差值来判断通信信号的有无,同时推导了有效的时域检测算法.对实际电网的测试表明,这种方案能够提取强干扰下电网中的调制信号,扩展了TWACS通信系统的应用范围.

There are two common methods to detect the modulated signal of TWACS (two way automatic communication system), the time-domain detecting method and time-frequency analysis. The traditional time-domain detecting method extracts few characters and has low counter-noise ability. The time-frequency analysis has complex calculation and costs high. According to this, the paper presents a new TWACS modulated signal detecting method based on sigma-delta modulation technique and proposes a valid time-domain detecting algorithm. The method adds the bit-stream codes outputted from sigma-delta modulator in modulating area, and then detecting the modulated signal by the difference of the bit-stream summation between nearby two cycles. After applying the method to power distribution network, shows that the method can detect the modulated signals well in a bad noise condition, which expends the application range of TWACS.