1. School of Electronics and Information Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China;
2. Institute No.25 of the Second Academy, China Aerospace Scientific and Industrial Corporation, Beijing 100854, China;
3. Research Institute of Unmanned Aerial Vehicle, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
To aim at short-time pilot pulse carrier-frequency synchronization, a rapid acquisition and tracking approach was proposed. In this approach, a phase deduction frequency estimator (PDFE) was employed to perform initial carrier-frequency coarse estimation and accomplish frequency acquisition in short time. The PDFE obtains the phase angle estimation of real signal samples by least square method, and then computes the frequency value by phase unwrapping, unary linear regression and least square fitting. Its estimation accuracy exceeds Prony-s method and its estimation error normalized variance approaches the Cramer-Rao bound of real sinusoid signal at high signal-to-noise ratio. Digital down conversion loop and Kay-s method were adopted to perform frequency tracking, its performance exceeds cross product automatic frequency control (CPAFC) loop. The tracking accuracy was evaluated by simulation. An example was given, its maximum frequency tracking error is not more than 3 Hz at input SNR above 13dB for 1ms pilot pulse width.