Research On SOQPSK-TG Transmission Technology In Telemetry System

With the development of aerospace technology and the increase in flight test requirements,the one-way and low-speed data transmission of the original telemetry network system is far from meeting the needs of people.In the new generation of telemetry network system,an efficient waveform scheme is required for the telemetry system with long distance,large amount of processed data,and real-time transmission.Shaped-offset quadrature phase-shift keying modulation technology has the characteristics of high frequency band utilization and constant envelope,and thus has attracted much attention in telemetry systems.First,the basic principles of SOQPSK modulation and demodulation are studied in this paper,including SOQPSK signal model,recursive and non-recursive precoding,full response MIL-STD SOQPSK standard waveform set,phase trellis diagram and its four-state demodulation.Aiming at the problems of full response MIL-STD SOQPSK,the partial response SOQPSK-TG modulation and its four-state demodulation are studied,and the bit error performance is simulated.Second,three typical channel models of telemetry system are studied,and their corresponding impulse response and frequency response are given.In order to reduce the influence of multipath fading and noise as much as possible,the principle of adaptive equalization and LMS and RLS equalization algorithms are studied.And the basic principles of blind adaptive equalization and CMA algorithm are studied in detail.Third,the signal arrival detection technology is studied,including signal power spectrum detection and pilot detection.Signal detection is mainly detected by traditional power spectrum estimation method,and pilot detection is a time domain correlation detection method based on i NET frame structure.Aiming at the problem of poor performance detection of "long correlation" and "segment autocorrelation" function,the idea of "segment overlap autocorrelation" is proposed and its performance is simulated.Finally,the cascade coding SOQPSK-TG system is studied.Combining Turbo,TPC and LDPC codes with SOQPSK-TG,the corresponding cascade coding system is constructed and its system simulation is carried out.Combined with the complexity of the algorithm and the bit error performance,a cascade coding SOQPSK-TG system with relatively good bit error performance is given.