无人机高速DS/FH混合扩频通信系统关键模块设计

Design of Key Blocks of a High Speed DS/FH Communication System for UAVs

针对UAV(Unmanned Aerial Vehicle,无人机)测控链路高抗干扰需求,给出了实现跳频速率20 000次/s的扩跳混合无人机测控数据链系统实现方案。系统采用跳频频率并行捕获模式。跳频源设计采用直接频率合成、DDS(Direct Digital Synthesis,直接数字频率合成)和PLL(Phase-Locked Loop,锁相环)相结合的混合频率合成技术。利用相位响应滤波器,通过正交调制技术完成MSK(Minimum Shift Keying,最小频移键控)、GMSK(Gaussian Minimum Shift Keying,高斯最小频移键控)调制。通过推导得出2bit差分解调输出与载波频率选择有关,且为四分之数据率的整数倍关系。然后通过实例分析给出了跳频频率间隔选取方法,即跳频间隔应当将临近跳频的主瓣分开,同时跳频载波频率应当设在其他跳频频谱的零点处。最后总结了高速扩跳频系统参数设计一般步骤。

A design solution is given for a Direct Sequence/Frequency Hopping （DS /FH） communication system with 20 000 h/ s hopping rate to meet anti-jamming requirements of Unmanned Aerial Vehicle （UAV） telemetry and command link. The hopping frequencies are captured in parallel. The hopping frequency source is constructed by di-rect frequency synthesizer, Direct Digital Synthesis （DDS） and Phase-Locked Loop （PLL） . Phase response filter is adopted in orthogonal modulation to realize Minimum Shift Keying/Gaussian Minimum Shift Keying （MSK/GMSK） modulation. The performance of 2 bits differentiated demodulation is correlative with carrier frequency, that is , the carrier frequency must be integral times of a quarter of data frequency. The hopping frequency spacing should sepa-rate adjacent main lobes while the hopping frequency should set at zero point in other hopping frequency spectrum at the same time. Finally, approaches are summarized for DS/FH parameter choice.