Detection limitation of high frequency signal travelling along underground power cable

High frequency pulse injection is part of many diagnostics techniques, e.g. cable fault location. An injected pulse along an underground power cable will reflect at an impedance impurity, for instance a cable joint. These joints can be identified based on pulse reflections only if sufficiently high-frequency components can be detected. Signals with higher frequency components can provide more accurate spatial resolution but experience stronger attenuation and dispersion. This paper discusses whether pulse reflection from a cable joint can be better distinguished if detection is focused on high frequency signal content. Two aspects, considering effects of noise level and applied equipment, are discussed in detail: averaging and highpass filtering. It is shown that in presence of noise, averaging can improve signal to noise ratio also for signals below the quantization error of digital detection equipment. High-pass filtering is realized in hardware but similar results can be achieved by software implementation. However, simulation study shows that a high-pass filter itself hardly improves reflection recognition.