Abstract: Multilateration is a novel and popular technology in civil aircraft navigation. The precise algorithm to calculate target location is the key of multilateration. By setting the reference station and using corresponding transform, the nonlinear TOA equations are transferred into linear TDOA equations. After that a two-steps closed-form algorithm to calculate target position is proposed in this paper. Ignoring the TDOA measurement errors, we can obtain the initial results first. Then Taylor expansion is exploited based on initial results to overcome the dependent relationship between unknown variables. Finally, accurate target location is estimated by BLUE method. The GDOP performance of the new algorithm is apparently improved. Cramer-Rao bound of this algorithm is derived and the simulation results show that accuracy of the BLUE method based on partly Taylor expansion is approximately equal to Cramer-Rao bound.

Key words: air traffic control, multilateration, geometric dilution of precision, Cramer-Rao bound, best linear unbiased estimator