A reference-free time difference of arrival source localization using a passive sensor array

Least squares source position estimation techniques from time difference of arrival measurements are based on choosing a reference sensor. Selecting different reference sensors may affect the positioning accuracy by a considerable amount. We suggest a closed-form least squares position estimation using all the available distinct time differences, which does not involve the selection of a reference sensor. The nonlinear terms, associated with the distances between the sensors and the source, are eliminated with an orthogonal projection matrix. Simulation results show that the proposed approach outperforms previous closed-form least squares solutions.