基于子带累积的DS/FH卫星测控信号捕获算法

An Acquisition Algorithm for DS/FH Satellite TT&C Signal Based on Sub-Band-Accumulation

DS/FH(直接序列扩频/跳频扩频)混合扩频信号的快速捕获问题亟待研究。电离层色散效应增加了BPSK(二相相移键控)调制的DS/FH信号捕获的复杂度,并导致不同频点信号载波相位难以保持连续。通过估计电波传播路径上TEC(电子浓度),可以消除电离层色散效应的影响,利于应答机精确测速。提出一种划分子带的信号捕获方法,放宽TEC搜索步进,缩短搜索TEC的时间,从而实现信号的快速捕获。分析了划分子带个数与捕获时间及捕获能量损失的关系,在实现过程中可通过调整子带的个数来控制捕获能量损失,使得捕获模块设计更加灵活。

The urgency of research on fast acquisition of DS/FH （Direct Sequence/Frequency Hopping） spread spec- trum signals is described. With the existence of ionospheric dispersion, the carrier phase continuity of a phase-coher- ent FH system is disrupted and the complexity of acquisition is drastically increased. Through search of TEC （Total Electron Count） along the path, the receiver is able to compensate for phase discontinuity and to perform coherent acquisition. A new acquisition strategy named Band Division Accumulation is proposed. It is proved that the strategy can broaden TEC search period and thus reduce search complexity. The relationship between the number of sub- bands and energy loss in acquisition is analyzed. The accumulation loss of acquisition can be adjusted by altering the number of sub-bands and this is beneficial to receiver adaptability.