Peng Liangfu

A cooperative localization method based on conjugate gradient and Taylor series expansion algorithms

Taylor series expansion method based on TDOA (Time Difference of Arrival) is a typical location algorithm in cellular mobile telecommunication system, but its performance depends highly on the selection of initial position because of convergence problem. A new cooperative localization method based on conjugate gradient and Taylor series expansion algorithms is presented to solve this problem. The convergence and computation efficiency are improved by using the result of conjugate gradient method as the initial position in Taylor series expansion method. By comparing with those analogous algorithms, one is using the result of Chan algorithm, and the other is using the result of least square method, as the initial position in Taylor series expansion method, the computer simulation results indicate that the new algorithm has higher computation efficiency than that two analogous algorithms. Simulation results also show that the location accuracy and computation efficiency of the new algorithm can approach the performance obtained by Taylor series expansion method based on true position as the initial position.

A position self-calibration method in multilateration

This paper presents a self-calibration method for estimating receiver position errors using TDOA measurements for targets with unknown positions. The method uses two LS minimization steps to estimate the related receiver position errors. The method estimates the initial TDOA LS for the unknown target position with the measured receiver positions. A second weighted LS using the total differential of the TDOA equations estimates the related receiver position error. Therefore, the estimated receiver position error can be used to modify the measurement of the receiver positions. Computer simulations demonstrate the statistical performance of this method, and the results of Table IV show that the related receiver position errors estimated meet the multilateration (MLAT) requirements.

Transmit power of interrogations controlling method in TCAS

The methods of controlling the transmit power of integration to limit the interferences which are resulted from air-to-air communication in the Traffic alert Collision Avoidance System are proposed. The dynamic controlling of tracking integration power for mode S targets and the variable steps Whisper/Shout interrogation for mode A/C targets are presented. In order to analyze the validity of the methods, the distribution model of aircraft traffic density is established. Additionally, the procedure for interrogations power controlling and the implementation in surveillance function are described.