Spatial resolution of a cable fault location attempt by frequency domain reflectometry

We have demonstrated that frequency domain reflectometry (FDR) can locate the position of degradation or abnormality in a cable with the assistance of inverse fast-Fourier transform (IFFT). Although it is easily understandable that this FDR-IFFT method can be applied for a location attempt of a cable with more than one abnormality, we have not demonstrated this so well experimentally. Therefore, we heated two different positions on a coaxial cable of 31.5 m insulated with low-density polyethylene using two heating chambers with an effective chamber width of around 45 cm set at positions 19.7 and 24.7 m from the cable end connected to the analyzer. As a result, it is clearly indicated that the two positions can be located if we heated there only by 10 °C. In addition, the two positions at which the cable enters and goes out of the heating chamber can be recognized clearly. This means that the FDR-IFFT method we are developing exhibits a good spatial resolution in a way that the two positions with a mutual distance of 45 cm are clearly recognizable.