Identification of transfer functions with time delay and its application to cable fault location

A Gaussian frequency-domain maximum likelihood estimator (MLE) to estimate the transfer function of linear continuous-time systems with time delay is presented. The stochastic framework is an errors-in-variables model, which means that the input as well as the output of the system is disturbed with noise. The estimator is applied to a practical measurement problem, namely the estimation of the location of discontinuities, e.g. faults in electrical cables from a reflectogram. Experimental results for coaxial lines show that it is possible to identify simultaneously the location of the discontinuity and a rational approximation of the generator mismatch, the fault impedance, and some of the cable parameters.>