Research On Low-complexity Demodulation And Synchronization Algorithm Of Hign Dynamic Soqpsk Signal

With the rapid development of aerospace technology, the flight speed of spacecraftis increasing, telemetry data is also growing, and meanwhile as a modulation systemwhich has good spectrum, SOQPSK (Shaped Offset Quadrature Phase Shift Keying) hasbeen highly valued in TT&C domain. Therefore researching low-complexitydemodulation and synchronization algorithm of SOQPSK which adapt to high dynamicand high-rate requirements has great theoretical significance and application value.Firstly, SOQPSK modulation and optimal receiver which based on the maximumlikelihood detection theory are researched. Secondly, for the high complexity of theSOQPSK optimal detection receiver, we investigate low-complexity demodulationalgorithm based on frequency pulse truncation (PT) technique, Walsh spacedecomposition and Laurent decomposition, then with SOQPSK-MIL and SOQPSK-TGas an simulation example, giving BER performance. Finally, the difficulty of SOQPSKsignal synchronization in highly dynamic environment is researched. For the problemthat cannot be directly traced to start the loop for large±1MHz offset, proposed thesolution that firstly use the Hilbert transform complex vector FFT technology toestimate carrier frequency, then carrier frequency drawn into a small range like±200Hz, then start timing and phase tracking loop. Next with SOQPSK-MIL signal asan example, joint timing phase algorithm based on direct Maximum Likelihoodjudgment is researched. Then with SOQPSK-TG signal as an example, for the highcomplexity of optimal receiver, a joint timing phase synchronization estimationalgorithm based on Laurent Decomposition is researched, which greatly reduces thecomplexity of the signal reception and synchronization module.On the basis of the above research, we propose the solution for solving SOQPSKsignal receiver which adapt to high dynamic and high-rate requirements. Simulationresults show that the solution achieve the expected effect.