  Electromagnetic time reversal (EMTR) is drawing increasing interest in
short-circuit fault location. In this letter, we investigate the classic EMTR
fault location methods and find that it is not necessary to reverse the
obtained signal in time which is a standard operation in these methods before
injecting it into the network. The effectiveness of EMTR fault location method
results from the specific similarity of the transfer functions in the forward
and reverse processes. Therefore, we can inject an arbitrary type and length of
source in the reverse process to locate the fault. Based on this observation,
we propose a new EMTR fault location method using direct convolution. This
method is different from the traditional methods, and it only needs to
pre-calculate the assumed fault transients for a given network, which can be
stored in embedded hardware. The faults can be located efficiently via direct
convolution of the signal collected from a fault and the pre-stored calculated
transients, even using a fraction of the fault signal.
