基于 FRFT-TFDR 的语音通信双绞线故障检测研究

语音通信双绞线故障点定位对断路、短路故障检测，以及防止机密信息窃听等具有重要意义。在基于时域反射法(TDR)和扩频时域反射法(SSTDR)的语音通信双绞线故障检测与定位中，由于双绞线的低频传输特性，反射信号衰减严重，无法实现远距离故障点定位。针对这一问题，提出了基于分数阶傅里叶变换的时频域反射法(FRFT-TFDR)。首先使用线性调频信号(LFM)作为检测信号，接着对接收信号加窗以提高信号的分辨力，然后进行分数阶傅里叶变换将接收信号变换到分数域，最后通过分析入射信号和反射信号谱峰值在u域内的位置差，并将其转换到时域内，从而定位故障位置。经实验验证，该方法可有效定位出不同断路故障点，实测时在1 557 m处的定位误差小于7%,满足语音通信双绞线远程故障检测需求。

Research on fault detection of voice communication twisted pair based on FRFT-TFDR

To locate the fault point of twisted pair in voice communication is of great significance for the detection of open circuits, short circuit faults, and the prevention of eavesdropping on confidential information. In the fault detection and localization of voice communication twisted pair based on time domain reflectometry (TDR) and spread spectrum time domain reflectometry (SSTDR), due to the low-frequency transmission characteristics of twisted pair, the reflected signal is seriously attenuated, and long-distance fault point location cannot be realized. Given this problem, a time-frequency domain reflectometry ( FRFT-TFDR) based on fractional Fourier transform is proposed. First, the chirp signal (LFM) is used as the detection signal, the received signal is windowed to improve the resolution of the signal, then the fractional order Fourier transform is performed to transform the received signal into the fractional domain. Finally, the position difference of incident signal and reflected signal spectral peak in the u domain is analyzed and converted into the time domain, so that the location of errors can be determined. The experiment verifies that the method can effectively locate different circuit-breaking fault points, and its positioning error at 1 557 meters is less than 7%, meeting the requirement of remote fault detection of twisted pair in voice communication.