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本文讨论了PN码步进搜索捕获的双门限判决。它把同步检测输出分作三种情形:没有达到同步,步进搜索到下一个状态;已经实现了同步,进行锁定跟踪;对是否实现同步不能作出判决,对该状态再作一次同步检测。在比较PN码捕获的各种方法时,应以最短平均捕获时间为准则,以平均假锁滞留时间为约束条件或以锁定后的平均寿命为约束条件,此外还应考虑不同同步检测器的影响。本文所作的数值分析表明:在固定检测时间的各种PN码步进搜索捕获方式中,以双门限判决方式最好,能使最短平均捕获时间缩短20-50％。本文也给出双门限判决方法与可变检测时间多次驻留检测PN码步进搜索捕获的性能比较。
This article discusses the double-threshold decision for PN code stepping search capture. It divides the synchronization detection output into three situations: the synchronization is not reached and the next state is searched by the step-by-step search; the synchronization has been implemented and the locking tracking has been performed; the judgment can not be made on whether the synchronization is realized or not; When comparing PN code acquisition methods, the shortest average capture time should be used as the criterion, the average dummy lock retention time as the constraint or the average locked life as the constraint condition, and the influence of different synchronous detectors should also be considered . The numerical analysis in this paper shows that the best two-threshold decision method in short-term average acquisition time can be shortened by 20% -50% in all kinds of PN code stepping search and acquisition methods with fixed detection time. This paper also gives a comparison between the performance of two-threshold decision-making method and PN code stepping search and acquisition with multiple detection of variable detection time.