Design And Implementation Of Satellite Communication Positioning Device

The flight recorder is a device for recording and storing experimental data during the experiment of the vehicle,which plays an important role in promoting the research and development of our country’s aircraft,but the problem of its slow recovery speed and low efficiency has always existed.For this reason,after combining the research status of positioning and communication technology at home and abroad,this paper proposes a scheme based on Radio Navigation Satellite System(RNSS)passive positioning and Bei Dou short message communication technology,and designs and implements a communication and positioning device.Firstly,according to the design scheme,the hardware of the device is modular design,which is divided into four parts: main control module,positioning module,communication module and power supply module.Secondly,to address the problem of limited communication frequency of Beidou,the communication frequency is increased from 1min/ time to 30s/ time by adopting dual-SIM card rotation and multiplexing.Then,to increase the service life of lithium batteries,three modes of pre-charging,constant current charging and constant voltage charging are designed in the battery charging management circuit to avoid sudden high current and over-charging problems that can damage the batteries.At the same time,The battery was also tested for charge and discharge and static loss management,and it was concluded that if the battery drops from a full charge of 8.4V to a predetermined shutdown threshold of 7.0V,the device can operate normally for about 120 min and the static power consumption current of the battery in standby is only 1μA.Then,according to the analysis of specific functional requirements,the STM32L431,the main control chip,was designed using In Application Programming(IAP)online programming to implement the online update function of the program.The software also completes the logic design for the positioning communication module,the 422 status down and feedback logic design,the timing logic design,the realization of parameter binding and back reading,device shutdown and other functions.Finally,functional self-tests were carried out on some of the important functions of the device in modules,and performance tests were carried out in simulated environments.The test results show that the cold start positioning time of the device is within 50 s,the positioning error does not exceed 2.5m,and the communication success rate is above 85%.At present,the device has been successfully applied to the ground recovery of a flight recorder,verifying that the device has the independent positioning and communication capability to achieve the landing point positioning recovery of the flight recorder.