The GPS acquisition method based on Nios Ⅱ soft core

In order to solve the problem that the traditional GPS receiver cannot adjust the frequency search space and integration time adaptively according to the characteristics of the received signal, the GPS acquisition method based on Nios Ⅱ soft core is presented by this paper. The Nios Ⅱ soft core is responsible for accommodate the frequency search space, the coherent integration time and the non-integration time. The VHDL part of assembly line structure is responsible for the parallel data processing. Therefore, the parameters can be adjusted adaptively by the method. By using the conception product which embeds 1 Stratix Ⅲ chip, real test result shows that the acquisition works well, the frequency search space can be changed within 100 Hz-80 kHz and the integration time can be changed within 1ms-30s.