Hardware System Design Of Multi-mode And Multi-frequency GNSS Receiver Based On ARM

Global Navigation Satellite System(GNSS)is a radio navigation and positioning system based on artificial satellites that can provide users with all-weather three dimensional coordinates,speed and time on the global or near-Earth surface.With the development and improvement of GNSS,the old single-mode and single-frequency receivers gradually can not satisfy the requirements of high precision,and the development of multi-mode and multi-frequency GNSS receivers has become a popular research.Nowadays,most of GNSS receivers in China are based on foreign OEM products,which generally have some problem,such as high cost,high power consumption,large size and low universality.The main object of this research is about GPS,GLONASS and BDS systems,and develops embedded multi-mode and multi-frequency GNSS hardware system based on ARM + Linux integration.Through an in-depth study the present research situation of GNSS and the present application situation of GNSS receiver's,point out the development trend of GNSS receiver,from the functional requirements and performance requirements of receiver analysis.The design goal of this topic is to improve the reliability of GNSS receiver and generality,optimize hardware cost,power consumption and volume.According to the goal of this topic for overall system architecture design,the paper demonstrates the embedded design of each module of the receiver hardware platform and the software platform.In this topic,the device is selected based on performance indicators such as power consumption and volume.The mature OEM board BDM683 is used as the navigation receiver board and AM3358 based on the Cortex-A8 core is used as the main processor chip,and the serial and network circuits of the navigation receiver module and AM3358 is designed.According to the functional requirements of the receiver,this design has the simplest modular design of the AM3358 minimum system and start-up circuit to achieve the low cost and low power consumption of the hardware system.A multi-channel communication interface module is designed around the board,which can realize serial RS232 communication,RS485 communication,USB port communication,Ethernet communication and CAN bus communication,which can meet the data transmission requirements of the platform in complex scenarios,and effectively improve the universality and integration.In order to meet the high reliability requirements of the hardware system,a large-capacity data storage module is designed to expand 512 MB Nand Flash storage and 2GB DDR3 SDRAM storage,and SD cards can be inserted.According to the functional requirements,design power modules and user interaction modules.This topic in-depth researches how to implement the key technology of the navigation receiving module program in the embedded system.The specific research and transplantation work includes: determining the software platform to use the embedded Linux system to develop the AM3358,establishing an embedded Linux development environment,implementing Uboot porting,kernel cutting and porting,and file system production,designing a navigation receiving module driver and navigation receiving Module program to complete the embedded integration design of software and hardware systems.This paper designs a GNSS receiver based on ARM Cortex-A8 processor and compatible with GPS,GLONASS and BDS navigation systems.Experiments show that each module of the GNSS receiver functions normally,the static positioning accuracy can reach 5m,and the dynamic positioning can be seen by the large number of satellites and the optimal position distribution,proving that this multi-mode and multi-frequency GNSS receiver can achieve normal positioning.The size of hardware PCB board is 150mm�6mm�10mm,and the power consumption is 3W,which meets the requirements of low power consumption and small size.Cold start time: less than 60 s,hot start time: less than 30 s,supporting BDS B1/B2/B3 + GPS L1/L2/L5 + GLONASS L1/L2 signals.The receiver's signal acquisition and tracking method is correct and feasible with good universality and expansibility.