Research On Modulation Recognition Algorithm Of Satellite TT&C Signal

In satellite communication,to transmit information quickly,accurately and securely,communication signals are usually modulated in different ways,while the diversity of the modulation makes it difficult to identify the TT&C signal accurately.The secondary modulation signal is widely used in TT&C link,for its complicated and varied modulation types,it has high transmission security,and it is difficult to be recognized.This paper focuses on the modulation recognition algorithm of satellite TT&C signals,and studies the modulation recognition of common satellite communication signals,secondary modulation signals with one internal modulation and multiple internal modulations.Based on the instantaneous feature and decision theory,the corresponding algorithm of modulation recognition is proposed,and its effectiveness is verified through simulation and analysis.The main work and innovation of this paper are as follows:1.The modulation recognition algorithm of common analog siganls,digital signals and secondary modulation signals is studied.Begin with signal time and frequency domain,a recognition algorithm of various signals is proposed base on the jiont feature parameters,which can meet the requirements of a variety of signal's recognition.The simulation results show that the proposed algorithm can achieve high recognition probability with relatively low SNR.2.For secondary modulation signals with one internal modulation,a direct modulation recognition algorithm based on feature parameters and decision theory is proposed to compare with the algorithm of recognition after demodulation,which improves the recognition performance of secondary modulation signals.The simulation results show that the recognition performance of the former one is better.3.For secondary modulation signals with multiple internal modulations,the idea is: demodulation first,and then adopt the subcarrier separation method to separate the internal modulation sigals,finally,respectively identificate them.Based on the above recognition idea,a recognition algorithm is proposed to further identify the internal modulation signals,which can be applied to common situation.The simulation results show that a high recognition probability can be achieved with relatively low SNR.