Research On Multifunctional Modular Satellite Application Terminal Based On Software Defined Radio

In recent years,my country's space industry has developed rapidly,with more than 200 satellites in orbit.These satellite applications have brought great convenience to the construction and development of our country,but the systems and frequency bands of different satellites are different,and each type of satellite requires a special set of equipment to manage and apply the satellites.For outdoor,scientific research,emergency and other application scenarios,there is a lack of portable universal equipment that can manage and apply satellites of different systems in a unified manner.This paper proposes a multi-functional modular satellite application terminal based on software radio.Reconfigurable,to manage and apply satellites of different systems on a set of equipment,mainly to achieve meteorological cloud image receiving function,data transmission function and conventional measurement and control function.The main research contents of this article include:First,the system architecture of the multi-functional modular satellite application terminal is designed,including hardware architecture and software architecture.And on this basis,the functional requirements of the terminal are analyzed,and the realization plan of the meteorological cloud image receiving function,data transmission function and measurement and control function is designed.Secondly,the channel coding and modulation and demodulation technologies involved in the meteorological cloud image function implementation scheme and the measurement and control function implementation scheme are studied,including the RS code and convolutional code in the FEC coding technology,and the FM,GMSK,BPSK modulation and demodulation technology To provide a theoretical basis for subsequent software implementation.Then the DQPSK modulation and demodulation of the FPGA part of the digital transmission function implementation scheme is implemented,which mainly includes a digital automatic gain control module,a polar Costas loop module,a bit synchronization loop module and a differential codec module.In the digital automatic gain control module,the CORDIC algorithm in the module calculation circuit,the linear interpolation algorithm in the unequal region in the power calculation circuit,and the compressed ROM lookup table method in the antilogarithmic calculation circuit are implemented;in the Polar Costas loop module,The traditional polar Costas loop is improved to adapt to the demodulation of the zero-IF receiver;and the simulation verifies the DQPSK in three cases where only the initial frequency offset,only the frequency ramp and both the initial frequency offset and the frequency ramp exist Demodulation performance of the demodulation module.Finally,the GRC flow chart of data transmission function,meteorological cloud image receiving function and measurement and control function is designed according to the function implementation plan,and the three functions are verified on a set of equipment.The results show that the multi-functional modular satellite application terminal based on software radio designed in this paper meets the expected demand,and the reconfigurability of software radio can be used to achieve general satellite management and application.