A MODEL SIMULATION OF ADAPTIVE FILTERS APPLIED IN MODES DATA LINK

摘要

The key function of a Mode-S transponder is , upon receiving an Uplink Format (UF) interrogation, to generate the corresponding Downlink Format (DF) reply, and the Acquisition or Extended Squitter (AS or ES) spontaneously. Especially the Extended Squitter ensures the flight safety of the aircraft. According to the principle of DO-260A, adaptive filter should be used to deal with the GPS information in Extended Squitter, for filtering the observation noise. A new kind of adaptive filter based on α-β-γ algorithm is proposed in this paper. Compared to the traditional Kalman filter, the new filter reduces amount of computation, with almost not deterioration in performances. Meanwhile using Look up Table according to current SNR to determine a, p and y ensures the fast convergence of this algorithm. The effectiveness when using the new filter in target tracking, is demonstrated by a number of flight tests.