There is a strong demand for the multi-constellations compatible Global Navigation Satellite System (GNSS) acquisition scheme, since it is able to acquire signals from different constellations to increase availability of satellites. However, the presence of multiple modulation modes and diverse Pseudo-Random-Noise (PRN) code lengths makes the design challenging. Moreover, existing schemes consume a lot of hardware resources. Hence, we present an innovative Field Programmable Gate Array

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... sed lowcomplexity and multi-constellation compatible GNSS acquisition scheme to provide a solution for the above-mentioned challenges. This scheme is based on the proposed Improved Serial-Parallel Matched Filter structure that not only requires less hardware resources than conventional structures but also performs all operations in a pipeline to simplify the implementation in FPGA. Additionally, the maximum likelihood criterion is used to obtain decision statistics, which ensures the compatibility between BPSK and sBOC (1,1) signals. Furthermore, a three-step method to acquire signals with a long PRN code is proposed. This also guarantees the compatibility among signals with different PRN code lengths. Finally, a new aided acquisition method to accelerate the acquisition process of signals with a long PRN code is proposed. Experimental results show this scheme is capable of acquiring multi-constellations civil GNSS signals, and therefore it has high practical value. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.