Bias-free estimates of the variance of time of arrival differences

In the frequency domain estimation of time of arrival differences, phase data of the cross spectrum may show correlation between frequency bins due to either insufficient time-bandwidth product or the use of a nonrectangular window on the input signal samples. This correlation severely biases variance estimates if standard results of generalized least square theory are applied indiscriminately. A technique has been developed to eliminate the bias of variance estimates. Simulation results are provided.