Research And Implemention On Acquisition And Tracking In High Dynamic Multi-Constellation Receiver

GNSS (Global Navigation Satellite System) is used for positioning the user location all over the world. GNSS includes GPS, GLONASS and the first Beidou system now. So the multi-constellation receiver will greatly improve the reliability, the precision and the real-time performance of navigation and position.The acquisition and tracking technology of high dynamic receiver has always been the research hotspot and difficulty. Many scholars have done some fruitful research and put forward a variety of design options on high dynamic special application, with a focus on pseudo-code rapid acquisition and Doppler frequency tracking. The main methods of pseudo-code acquisition are as following: parallel method based on the FFT and the matched filter, and sliding correlation based on serial acquisition and parallel acquisition The acquisition performance and complexity of these methods have their own advantages and disadvantages. In this paper, the methods of sliding correlation based on serial acquisition and parallel acquisition is used. The acquisition performance of this method is better and hardware implementation is easier.The mainstream method of Doppler frequency tracking is using FLL + PLL. FLL is used to track the rapid changing frequency. When the frequency is guided to the scope of PLL, PLL tracks the change of phases and precisely locks the carrier frequency. In this thesis, it has great dynamic tracking performance by using third-order PLL loop structure assisted by the second-order frequency-locking loop.The main comtents of this paper are as follows:1. The multi-constellation receiver has been designed and implemented, which makes a hardware platform for the system.2. Analyzing the pseudo-code characteristics of GPS, GLONASS and the first Beidou system, this paper adopts the time-domain correlation method of sliding correlation based on serial acquisition and parallel acquisition, which greatly reduces the acquisition time.3. The paper has researched and designed a DLL circuit, and tested to verify the correctness of the design of DLL.4. A method of basing on FLL+PLL (FPLL) is used to track carrier. A third-order digital Costas loop and a second-order four-quadrant FLL are used; which effectively eliminates the high dynamic impact.In this paper, the design of acquisition and tracking has been realized in the high dynamic multi-constellation receiver. The test results show that the design meets the system requirement.