A Multi-Frequency Acquisition Algorithm for a Gnss Software Receiver

Globalization and digitization of the economy increase the demand for fast and precise positioning services. Existing and new global navigation satellite systems (GNSS) add flexibility and adaptability to the list of requirements. To cope with these demands GNSS receivers have been built as software solutions. For software receivers satellite signal acquisition is a hard problem. In this paper we have focused on improving the efficiency of the acquisition in the receiver. The proposed method combines multiple frequency steps into a single one to acquire the satellites. By this means we reduce memory demand and the number of FFT /IFFT calculations for correlation calculation, which is crucial for the performance of a software receiver, in particular on an embedded platform. To eliminate the influence and ambiguity of the multi-frequency approach, we introduce a correction procedure after the basic acquisition process. In our approach we choose several candidate results to implement a more precise acquisition. Our experiments show that the multi-frequency acquisition method saves a significant amount of resources in the acquisition phase, even in a weak GPS signal environment.