High Dynamic Signal Simulator Of Space-based Measurement And Control System

Compared with the ocean-based and foundation-based measurement and control system,space-based measurement and control system has the absolute superiority in the coverage,developing rapidly and been widely applied.So people pay more and more attention to how to accurately verify the performance of the receiver in the spacebased measurement and control system.But if we only debug the performance of the receiver with the method of field flight,not only cost a lot of money and manpower,but also reduced the test efficiency due to the big effect of external factors.So it cannot produce specific signal according to the test requirements in real time,making the research and development cycle longer.Therefore,the simulator that can be able to simulate the real measurable signal in different test environment is indispensable.In space-based measurement and control system,there is a large high dynamic frequency offset between the transmitter and the receiver due to the large relative speed between synchronous satellite and spacecraft,and the working frequency as high as Ka band(eg.26.5 GHz).On this basis,this paper designed and developed high dynamic space-based signal simulator based on STK(Satellite Tool Kit)software and the virtex-4 FPGA series flat Xilinx company of Xilinx.The main research contents of this paper are as follows:1.The basic theory and the system frame of the Direct Sequence Spread Spectrum(DSSS)communication system are introduced,including the transmitter and the receiver in the DSSS system,pseudo random code,m sequence and Gold sequence,especially on the related characteristics of pn code and the way to generate,function and performance of the shaping filter.In view of the high dynamic,we analysis the doppler effect.2.Based on STK software and FPGA,We designed high dynamic signal simulator of space-based measurement and control system.Using STK software,we simulate the trajectory of geostationary satellite,the low orbit satellite(LEO),or the missile or the aircraft,and get the visibility analysis,and compute the doppler information.We will reflect the information about doppler to the rf signal through the FPGA.3.We completed the FPGA design of the high dynamic signals simulator of spacebased measurement and control system,,including the data doppler,the pseudo code doppler and the carrier wave doppler generation module,the spread spectrum module,the shaping filter module,the digital frequency conversion and the DA conversion module.We implements the simulation of doppler in space-based measurement and control system,and has carried on the debugging and testing of the whole system.