Design And Implementation Of Beidou/GPS Satellite Analog Signal Transmission System For Train Positioning

Satellite-based train autonomous positioning is the development trend of train control systems.The new train control system of the Qinghai-Tibet Railway adopts a satellite-based multi-sensor fusion speed measurement positioning method.The vehicle-mounted equipment comprehensively uses satellites,wheel speed sensors,inertial navigation,transponders and other multi-source data according to the operating environment and satellite signal conditions,combined with electronic maps,which realize accurate speed measurement and autonomous positioning of trains.And the train tail equipment that implements the train integrity check function also uses satellite positioning signals.The newly developed train control system must undergo full-function test in the laboratory before going to the test.For this reason,it is necessary to add Beidou / GPS satellite analog signal transmission system on the basis of the existing simulation test platform of the train control system.The satellite signals received during the simulation of the train operation in the laboratory implement related functional tests based on satellite positioning,provide technical support for the laboratory test verification of the new train control system,and are of great significance to the finalization of the new train control system.In this paper,as a background,the research of Beidou / GPS satellite analog signal transmission system for train positioning is carried out,and the following main work is completed.(1)The functional requirements of Beidou / GPS satellite analog signal transmission system for train positioning are analyzed.By sorting out the role of GNSS in the new train control system and its supporting environment,and combining with the test objectives in the train system room,the functional requirements of the Beidou / GPS satellite analog signal transmission system for train positioning are analyzed and summarized,including Beidou / GPS satellite signal simulation,electronic maps and satellite differential signals.(2)Designed the overall scheme and interface scheme of Beidou / GPS satellite analog signal transmission system for train positioning.Combined with the structure of the existing test platform of the train control system laboratory,the Beidou / GPS satellite analog signal transmission system for train positioning is composed of GNSS simulator,GNSS control module,data management,track geographic information database and differential base station simulation and other modules.Use GSS8000 signal simulator and SimGEN as the signal output hardware;manage the data through the Access database;obtain the content of the rail track's geographic information database based on the interpolation method and the calculation positioning method;use the RTCM3.2 differential protocol to design the satellite differential signal.(3)The basic functions of Beidou / GPS satellite analog signal transmission system for train positioning are realized.By using a combination of software and hardware,the hardware uses the GSS8000 signal simulator as the source of satellite radio frequency signals,and uses Microsoft Visual Studio 2017 to write software to control the GNSS signal simulator,as well as display the train status during the system operation.Display interface for information such as satellite status and satellite signal simulator feedback status.And the orbit geographic information database and the satellite difference simulation unit are established to provide data support for the satellite positioning of the train.55 charts,24 tables,50 references.