The invention provides a combined positioning method and
system based on the Chan's
algorithm and Newton method, and the method comprises the following steps: S1, determining the position ui, being equal to [xi, yi] T, i being equal to 1,..., M, of each
base station, an arrival distance difference measured value di1, i being equal to 1,..., M, and a variance sigma2 of the measurement error, the arrival distance difference being the measured value of the difference between the target position and the distance between the first
base station and the ith
base station; S2, according to the parameters determined in the S1, performing weighted
least squares twice by using a Chan's
algorithm to obtain initial coordinates of the target position calculated by the Chan's
algorithm; S3, taking the initial coordinate of the target position calculated by the Chan's algorithm as an
initial point, performing iterative calculation by using a Newton method, during each step of iterative calculation, judging a Hessian matrix of the current iterative coordinate, if the Hessian matrix is 0, ending iteration, and returning a result of the Chan's algorithm as a final coordinate of the target position; and if the Hessian matrix is not 0, when the Newton method iteratively converges to a minimum value, obtaining a final coordinate of the target position. According to the method, the
divergence problem of the Newton method in passive positioning is solved.