Design And Evaluation Of Data Transmission And TT&C Integrated Service System

With the development of society and the progress of science and technology,the application of satellite navigation system gradually expands from the military field to the fields of economy,transportation and other people's livelihood.Therefore,the lack of spectrum resources in satellite navigation system is becoming more and more obvious,and the way of signal modulation also gradually evolves with the needs of users.In order to solve these problems,Binary Offset Carrier(BOC)modulation system and its derivative system were created.It has the characteristic of splitting spectrum which can free the bandwidth of the central frequency,so BOC can be used as the pilot signal.In addition,it has excellent performance in anti-interference and anti-multipath fields.Besides the communicating field of satellite navigation systems,the research and application of the BOC modulation system are relatively few.According to the actual project requirements,this paper proposes the data transmission and TT&C integrated service system based on BOC(15,2.5)cos + 16 APSK,and proves that the performance of this signal transmission system can meet the requirements under the complex motion environment of airborne communication.The TT&C service needs measurements of distance and angle,and implement signal acquisition and tracking,so it uses the BOC signal with spread spectrum system.The data transmission service needs to transmit large amounts of data,so it uses the APSK signal with high modulation efficiency.The studying contents of this article are mainly divided into four parts: signal system design,signal scheme design,simulation evaluation and system implementation:1.The design of the signal system mainly implements the data transmission and TT&C integrated service system from aspects as follows: multiple access methods,signal frequency,spread spectrum code,waveform design and modulation system,etc.2.The design of the scheme is divided into three parts: data transmission,transmission channel,and signal reception.The signal reception is also divided into acquisition module and tracking module.The purpose of this part is to solve the Doppler frequency shift and time delay in signal transmission process.3.The simulation evaluation is divided into two parts: TT&C service and data transmission service.The TT&C service part implements the simulation of signal transmission,acquisition,and tracking under the specified quota.In addition,it also studies the impact of different environmental factors on TT&C service.The data transmission service part implements the modulation and demodulation of data signal,and gives the relationship between the error rate and signal-to-noise ratio.4.The system implementation part mainly uses FPGA simulation platform to implement the hardware design of the scheme.The platform has capabilities of signal emission,acquisition and tracking.The whole hardware system can guarantee the communication under the specified quota,and the data obtained is similar to the data from software simulation.In summary,the data transmission and TT&C integrated service system proposed in this paper can meet the requirements of the quota given by the project.Although it has Doppler shift and time delay in high dynamic environment,the signal system can still achieve synchronous communication function of data transmission measurement and TT&C services.