Accurate single-observer passive coherent location estimation based on TDOA and DOA

This paper investigates the problem of target position estimation with a single-observer passive coherent location (PCL) system. An approach that combines angle with time difference of arrival (ATDOA) is used to estimate the location of a target. Compared with the TDOA-only method which needs two steps, the proposed method estimates the target position more directly. The constrained total least squares (CTLS) technique is applied in this approach. It achieves the Cramer–Rao lower bound (CRLB) when the parameter measurements are subject to small Gaussian-distributed errors. Performance analysis and the CRLB of this approach are also studied. Theory verifies that the ATDOA method gets a lower CRLB than the TDOA-only method with the same TDOA measuring error. It can also be seen that the position of the target affects estimating precision. At the same time, the locations of transmitters affect the precision and its gradient direction. Compared with the TDOA, the ATDOA method can obtain more precise target position estimation. Furthermore, the proposed method accomplishes target position estimation with a single transmitter, while the TDOA-only method needs at least four transmitters to get the target position. Furthermore, the transmitters’ position errors also affect precision of estimation regularly.