Modelling a system for direction finding based on TDOA

This masters thesis details an attempt to build a short-wave radio direction finding device based on the principle of Time Difference Of Arrival, TDOA. Some basic principles of radio direction finding are presented, followed by two methods for estimating time differences: the cross-correlation function and the phase slope of the cross-spectral density. The properties of the methods are investigated through simulations. Estimation by means of the phase slope makes less demand on the sample rate but is more sensitive to low signal to noise ratios. Two field experiments were conducted to investigate the real-life performance of the phase slope method. The test platform consisted of a 2-channel receiver and a mobile transmitter. Due to technical problems, the planned measurements could not be completed, probably caused by the receiver being modified and used for other purposes between the experiments. The results show, however, that it is feasible to use TDOA and phase slope measurements for shortwave signals. The method needs refining: high signal to noise ratios are currently necessary and the type of modulation of the signal affects the results. New algorithms must therefore be developed.