Advanced Signal Sensing Method With Adaptive Threshold Curve Based on Time Frequency Domain Reflectometry Compensating the Signal Attenuation

Adaptive fault detection method, which is compensating the wave attenuation along the propagation, is proposed in this article. Long cable system installed in the factory need to develop precise fault detection method considering propagation dispersion. Using the derived time delay between the incident and reflected wave which is generated from the fault, fault can be localized. The time-frequency cross correlation (TFCC) is a signal scanning process based on the similarity of the energy spectrum for detecting the reflected signal mixed with the noise. The threshold value in TFCC is a reference constant value for judging whether or not a fault is present. Due to the attenuation and dispersion of signal along the propagation, a new threshold value function considering attenuation and dispersion is needed. We propose the adaptive threshold curve for compensating the signal attenuation. We design the equivalent circuit of target cable (7m length) and optimal reference signal based on the comparative analysis between the results of computer simulation and actual experiments of 7m length cable. Based on the designed equivalent circuit of target cable(7 m length), a long cable system is modeled by simulation and the performance of the proposed method is proved through the simulation under the various noise level environments.