Chirp Noise Waveform Aided Fast Acquisition Approach for Large Doppler Shifted TT&C System

In the next generation Ka-band telemetry, track, and command (TT&C) system, the received TT&C signal will suffer from more than 800 kHz of Doppler shift. Even with code phase-Doppler parallel search algorithm based on FFT, the mean acquisition time (MAT) will be more than several seconds. By exploiting the Doppler tolerance of chirp noise waveform (CNW), the authors propose a novel CNW aided spread spectrum signal fast acquisition algorithm for large Doppler shifted TT&C system. Through this article, the authors first describe the ambiguity function (AF) of CNW, and then design a simplified quadrature modulation model, in which the data symbol and the CNW are transmitted simultaneously. At the receiving end, a fast acquisition method based on dual match filters (MFs) is proposed. Due to the delay-Doppler coupling feature, the receiver can achieve both code synchronization and Doppler shift estimation through only 1-Dimensional (1D) delay search, and then MAT can be reduced to a few milliseconds. Simulation results demonstrate the effectiveness of the proposed method.