Abstract: A system for locating a transmitter in an unknown location comprising apparatus and the method of receiving transmitted signals from said transmitter at the separated locations, demodulating the transmitted signals, performing a Fourier transformation of each of the demodulated signals to represent them as complex functions of frequency, while performing a complex division of pairs of the signals represented as complex functions of frequency, to obtain signals represented by the phase differences between pairs of signals as functions of frequency, and determining from the difference in phase between pairs of signals as a function of frequency the time differences existing between the said pairs of functions. From these time differences the position of the origin of the transmitted signals are determined and displayed.