Bias free estimation 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.