Research On Acquisition Technology Of GPS Dual-frequency Receiver

With the development of satellite navigation technology, especially for the constant proposing and improvement of GPS Modernization signals, Dual-frequency GPS receivers has increasingly become the focus and hotspots of the research. It can eliminate ionospheric interference, improve positioning accuracy and fight against multi-path effects effectively. This thesis will focus some of the key issues of the dual-frequency acquisition.For the signal model of dual-frequency receiver, this thesis analyzed the key technology of the dual-frequency acquisition. For the bit transition in the acquisition process, we proposed a BTC method to overcome the bit transition problem. For the hardware resource consumption, this thesis proposed an optimized implementation structure of the correlator. The subject of this article chapter includes the following aspects:(1)According to the characteristics of GPS dual-frequency signal PRN code, we introduce a dual-frequency GPS receiver model and analysis the output characteristics of the correlator which is the key part of the signal processor module.(2) According to the characteristics of double-frequency signal, we give the acquisition system process of dual-frequency GPS receiver. We introduce two kinds of L2C acquisition algorithm and analyze two methods of enhancing detection signal-to-noise ratio method. By formula derivation and simulation, we proposed various kinds of constraints in the methods above.(3) For a long time coherent integration of bit transition problem, we propose a BTC method. For the high consumption of the hardware resources in L2C acquisition process and the BTC method, we propose an optimized correlator structure, so that the adder consumption can save up to91%.(4) For the technology of the signal-to-noise ratio improvement and the performance of BTC method, we analyze the detection and judgment method. And the thesis analyzed the detection performance of non-coherent integration, coherent integration and the the BTC method.(5) Based on FPGA implementations of all-digital dual-frequency GPS receiver, we show the performance of acquisition system and the actual test results.