Optimum Path Based Differential Coherent Integration Algorithm for GPS C/A Code Acquisition under Weak Signal Environment

Differential Coherent Integration method is an effective method for weak GPS acquisition. But the traditional differential method has a problem that the coherent integration time could not be too long and can hardly acquire very weak GPS signal. This paper introduces an improved differential coherent integration algorithm based on optimum path method, which can find the path of the maximum sum of differential blocks by estimating every possible product of the adjacent navigation data bits. So it could overcome the influence of navigation data bit transition and the long time coherent integration can be used in the differential method. Another advantage of this new method is that the loss of the square is reduced, because of the differential operation. Simulations show that, in the weak signal environment, if the same C/N0 and processing data length are provided, the performance of the new method is much better than the legacy half-bits method and full-bits method. With the increasing of the processing data length, the advantage of the new method on signal to noise ratio improvement is more significant.