Development And Implementation Of Satellite Positioning And Navigation Terminal Module

With the advancement of science and technology and the development of public transportation,people's requirements for travel have become higher and higher.Location information in real time has become a requirement for many people.In order to meet this demand,it is necessary to combine satellite navigation and positioning technology with wireless communication technology,and finally realize the function of collecting the position information of the terminal,and send the positioning information to the server via wireless communication.The user accesses the server via mobile clients or the PC web terminal to complete the query of the location of the target object(vehicle).The administrator user can also send control commands to the terminal through the client to control the positioning behavior of the terminal.In this thesis,a navigation module composed of a satellite positioning module and an inertial navigation module is used to realize real time calculation of positioning points.At the same time,the mature and stable GSM/GPRS wireless communication technology is used to send the positioning point information to the server to feed responding data to user's location queries.Firstly,this thesis reviewed the principle of satellite positioning and the principle of inertial navigation.A satellite positioning module that integrates the homebrew RF chip is chosen as the main positioning module,combining with the MEMS inertial module to form an integrated navigation module.This work designs peripheral hardware circuits,using Cadence OrCAD,Cadence Allegro software to design circuit schematic and PCB respectively.The layered structure of PCB is Top-GND-Power-Bottom four-layer structure.The main control MCU uses STMicroelectronics' STM32F103C8T6,the inertial module employsMPU9250 from TDK,and the GSM/GPRS wireless communication module adopts SIM800C from SIMCOM.For the reliable operation of the power circuit,the hardware circuit of the power input protection part is functionally simulated using Multisim hardware simulation software.Then,according to many hardware circuit devices' model,software drivers are adopted.Supporting software such as satellite data analysis,positioning data storage in FLASH,inertial device data filtering,attitude fusion solution,integrated navigation,and wireless data transmission were also developed for system integration.In the process of sending positioning data to the server by the terminal,the data may not be sent successfully in time due to poor wireless communication signals.In order to solve this problem,this work proposes buffering algorithm that temporarily stores the data while GPRS signal is weak,and transmit data while network signal strength is good.Finally,the functions of receiving,parsing,and storing satellite positioning navigation NMEA-0183 protocol data were successfully realized,and the inertial navigation data was updated and the positioning data was sent to the server in time based on the GSM/GPRS wireless communication technology.Field tests show that the system can continuously update the positioning points with the assistance of the inertial navigation module during the short period of satellite signal loss.