中文摘要：

为了能够在低信噪比下实现微弱信号的快速捕获，必须增加处理增益。要提高增益就要进行累积，而累积易受导航电文翻转和多普勒频偏的影响。为了克服两者的影响，传统的捕获方法通常采用相干加非相干累加的捕获算法，但是非相干累加又引入了平方损耗，并且对频率走动效应补偿有限。随着积分时间长度的加长，数据翻转和多普勒变化的影响会愈加突出，传统的算法已不能满足要求。对此，一种新的弱信号快速捕获算法被提出。该算法采用奇偶相间分别相干累加的方法进行数据补偿和并行多普勒搜索的方法进行多普勒补偿，从而在尽量延长单次相干积分时间的基础上，实现了多次相干积分结果的多次相干累加。最后计算机仿真验证，该方法是有效的和正确的，并且与传统方法相比，同样条件下，改进算法的累加次数是传统算法的1／8，捕获时间缩短了1／4以上。

英文摘要：

In order to achieve rapid acquisition in low SNR, the processing gain must be increased. To increase the gain is to accu- mulate, and accumulating is easily influenced by the navigation message flip and Doppler frequency offset. To overcome the above two factors, the traditional acquisition method usually adopts coherent and the non-coherent accumulation, but the non-coherent accumulation lead to the square loss, and the frequency moving compensation effect is limited. With the increase of the length of integral time, the influence of the data inversion and Doppler change will become more prominent. The traditional algorithm can＇ t meet the requirements. Therefore, a new fast acquisition algorithm of weak signals is proposed. The algorithm uses parity inter- phase cumulative method for data compensation and parallel Doppler search element method for Doppler compensation, in the base of trying to extend a single coherent integration, the multiple coherent integration result of multiple coherent accumulation is realized. Finally, the computer simulation shows that the program is correct and effective, and compared with the traditional algorithm, in the same conditions, cumulative number of improved method is reduced about 1/8, and the captured time of the method is improved more than a quarter.