Predicted performance of a symmetric-pair direction finding system in low signal-to-noise environments

The detection probability of an antenna pair of a symmetric-pair direction finding (DF) system in the presence of Gaussian noise is investigated. The question of system sensitivity as a function of the signal´s angle of arrival is addressed. Expressions for false-alarm rate and probability of detection of a single symmetric-pair for different widths of the intermediate zone, a symmetric-pair specific parameter, are derived. It is shown that the width of the intermediate zones hardly affects the peak sensitivity but has an effect on the probability of detection for certain angles of arrival. A technique that yields hardly changing detection probability of the DF system for constant threshold and varying signal and noise levels is discussed