Research And Realization Of Reliable Receiving Technology Of SOQPSK-TG Telemetry Signal

Shaped Offset Quadrature Phase Shift Keying(SOQPSK)moduation is a new type of modulation emerging in recent years,which has the advantages of constant envelope,high spectrum utilization and easily combined with nonlinear power amplifiers.With a lot of excellent features,SOQPSK signal has been widely used in aerospace telemetry system,where power and bandwidth both limited.The paper focuses on the reliable reception technology of Shaped Offset Quadrature Phase Shift Keying,Telemetry Group Version(SOQPSK-TG)signal.The research achievements are as follows:We sorted out the basic principle of SOQPSK signal modulation and the spectrum of SOQPSK-TG signal and Shaped Offset Quadrature Phase Shift Keying,Military-standard Version(SOQPSK-MIL)signal.We studied the Maximum Likelihood Sequence Detec-tor(MLSD)of SQOPSK signal based on Viterbi algorithm,and analyzed the theoretical BER performance of MLSD detection of SOQPSK-TG signal and SOQPSK-MIL signal.For the problem of high implementation complexity of Viterbi demodulation algorithm,the Cross-correlated Trellis-coded Qquadrature Modulation(XTCQM)and its principle of SOQPSK-TG signal representation are also analyzed in detail.We depicted the symbol-by-symbol demodulation algorithm based on Intergrate and Dump Filter(I&D)and pro-posed the symbol-by-symbol demodulation algorithm based on XTCQM to further reduce receiver’s complexity at the cost of certain performance loss.In“low-elevation-angle”telemetry scenario,since the performance of receiver will be influenced by multipath interference,multipath channel model of telemetry system and it’s adaptive equalization technology are analyzed.The bit error rate performance of three adaptive equalization algorithms,namely LMS,RLS and CMA are simulated.We compared the bit error rate performance,band utilization and the complexity of three algorithms,which provided foundation for the design of the receiver’s equalizer.The hardware implementation structure of SOQPSK-TG IF receiver is designed,and the CMA equalizer module is implemented in FPGA.The functional simulation and hard-ware test results show that the designed CMA equalizer scheme is correct and feasible.