Transmission Cable Fault Detection Based On Broadband Chaotic Signal And High-speed Random Sequence

The huge transmission cable network, which is developing at a full speed with the power and communication system, is threatened by anthropic factors and natural disasters that may cause serious economic losses and safety hazard by open circuit, short circuit or impedance mismatch of cable. Therefore, detecting the type and location of cable malfunction exactly has great significance for protection of communication and recovery of power system. In this paper, broadband chaotic signal and high-speed random sequence were introduced into the time domain reflectometer measurement technology, and two methods of cable fault detection were proposed:One approach is to use the broadband chaotic signal from the semiconductor laser with optical feedback as probe signal, and use the correlation technique as measurement method. Another approach is to use the high-speed random sequence as probe signal, and use the correlation technique as measurement method. Both of these methods can achieve high-precision detection for the cable faults such open circuit, short circuit and impedance mismatch.Focusing on transmission cable fault detection, this thesis is mainly summarized as follows:1. We introduce the principles, advantages and disadvantages of the existing cable fault detection methods and propose the introduction of broadband chaotic signal and high-speed random sequence to the cable fault detection. 2. Numerical simulation and experimental study of the principles and devices of the semiconductor laser with optical feedback to generate broadband chaotic signal and high-speed random sequence based on the broadband chaotic signal.3. Using broadband chaotic signal from the semiconductor laser with optical feedback as the probe signal, and the correlation technique as measurement method, we can achieve high-precision detection of the cable faults such as open circuit, short circuit and impedance mismatch. We also demonstrate the ability for testing live cable using this method.4. Using high-speed random sequence from the broadband chaotic signal as the probe signal, and the correlation technique as measurement method, we can achieve high-precision detection of the cable faults such as open circuit, impedance mismatch and real damage. We also demonstrate the ability for testing live cable using this method.