Study of an Application of Hybrid Spread Spectrum Technology in Satellite Communication

This study is aiming at the application of DS (Direct Sequence)/FFH (Fast Frequency Hopping) hybrid spread spectrum technology in satellite communications. A system model was established and key technologies were analyzed. The DS/FFH synchronization of hybrid spread-spectrum satellite communication system includes two stages, such as acquisition and tracking. In the acquisition stage, the acquisition is based on the parallel waiting through PMF-FFT structure, which can achieve rapid acquisition; in the tracking stage, through the carrier phase lock loop and the pseudo code tracking loop, the accurate alignment of the carrier phase of the received signal and the phase of the direct spread pseudo code is realized respectively. Due to the group delay distortion the carrier phase is no longer continuous, which affects the reception synchronization. This paper proposes group delay equalization for the channel through the analysis of four type of group delay and corresponding cause in the signal transmission process. Finally, comparisons analysis of the anti-interference performance of the system under the conditions of broadband, narrowband, multi-frequency and partial frequency band interference is performed through simulation. The results can provide certain guiding significance for the system anti-interference design and engineering implementation.