Effects of Observation Geometry on Accuracy Distribution Characteristic of TDOA Localization System in Deep Sea

To stably localize an acoustic target in a large area of deep sea, the accuracy and coverage characteristic are required to be evaluated under pre-selected observation geometry condition in the measurement system design. Aiming at this problem, a simulation method was presented for analyzing the distributional characteristics of accuracy in underwater acoustic localization with multiple base stations by time difference of arrival(TDOA). The climatological environment in the center of Northern Pacific was selected as background, and the sound field was calculated by BELLHOP Gaussian ray model. Main errors were randomly superimposed by Monte-Carlo method and propagated to finally estimated locations, such that the distribution of root mean square error(RMSE) was established by grid calculation with large samples under typical geometry condition of 4-receiver, 5-receiver or 6-receiver array. The results indicated that the localization performance using direct waves was clearly different from that using first-seabed-reflected waves, and the former was more accurate while the later was better in coverage. For the localization with direct waves, the accuracy was better in the central area of array than that in the marginal one. For the localization with first-seabed-reflected waves, the accuracy became worse in the area several kilometers around the center of array. In another case, the RMSE showed an asymmetric distribution when one corner station was invalid or the central station shifted, the relatively high accuracy area was confined to the active station number, but the full measurement area failed to be covered. Compared with the existing researches, this research provides an applicable way to evaluate and analyze the influence of observation geometry on accuracy distribution and coverage characteristic.