Research On PN Code Ranging Technology And Design Based On FPGA

With the development of the intersatellite technology,the small satellites with autonomous navigation capabilities is being paid more and more attention. Satellite autonomous navigation is one of the basic requirements for small sate- llites to achieve its space mission. One of the prerequisites for the autonomous navigation satellites is to ranging precise positioning between the satellites. In a variety of positioning technologies, relying on wireless applications, the pseudo-code Ranging technology has certain advantages. It has important sci- entific significance and application value to do indepth research on pseudo- code Ranging technology.In this paper, based on the existing literature, to the Institute with CETC54 cooperative projects precise intersatellite ranging as the background, indepth study of the pseudo-code Ranging technology, and carried out simulation of FPGA Design.Pseudo-code Ranging is based on the theory of pseudo- code sequence of the relevant characteristics. In the transmitter, ranging pseudo-code is loaded into the wireless carrier with a certain frequency. After receiving the signal is received on them under the front-end processing and the output IF frequency separation of the information carrier, pseudo-code acquisition and code track- ing, calculate the pseudo-code in the inter-satellite trans- mission delay time, thus solving the relative distance of satellite, achieve the formation of satellite positioning.The hot and difficult technical studies in Pseudo-code Ranging focuse on the carrier separation, pseudo-code acquisition and tracking links. This paper studied the carrier separation technique in the phase-locked loop to achieve phase synchronization with the input of local phase of the theory; followed by analysis of the traditional phase-locked loop - Costas loop basic principle and mathematical model; On this basis there is for the traditional Costas loop the non-coherent mode, can not measure the phase difference, frequency difference of the defect, has designed a new type of cycle-based Costas loop feedback mode, a new type Costas loop in the realization of the original function to be completed on the basis of the non-coherent mode, the phase and frequency measurements poor function. Simulation verify the feasibility of the method. Studied serial search capture, recycling- related search capture, dual threshold CFAR capture to capture these three commonly used methods. Analysis of jitter-related ring and ahead - two typical hysteresis loop tracking filter loop.Finally, basing on ISE and ModelSim platform, this Paper designed the pseudo- code acquisition and tracking part of the before the simulation design with the design VHDL language. In the test file, set a delay parameters.Then design is verified by comparison with the output data ranging.