Research On The Anti-jamming Techniques For Navigation Satellite System Based On Hybrid Spresd Spectrum

Satellite navigation signals are very easy to be interfered, which severely impairs system performance, and thus breaks down system function. With the satellite navigation systems widely used in the military, the research on anti-jamming techniques of navigation system has become imperative. This thesis focuses on the anti-jamming techniques for navigation system by means of hybrid spread spectrum and LDPC coding. The main contributions are as follows:1. Based on the DS/TH hybrid spread spectrum, a navigation satellite system is proposed by applying time-hopping to the existing navigation system. Anti-jamming performance of the navigation link is simulated under four typical jamming modes. Simulation results show that when the snr is-33dB and ber is10-4, the proposed satellite navigation system can provide more than17dB anti-jamming performance improvement than conventional scheme. Especially for pulse jamming, the anti-jamming performance can be raised about20dB.2. A direct acquisition scheme for the DS/TH navigation satellite system is presented, with the help of the relation between DS and TH codes in the system. The simulation results show that the scheme can effectively achieve the acquisition of navigation satellite signal.3. Satellite navigation system scheme combining LDPC coding, DS, TH and FH is presented. Simulation results show that this scheme has better overall anti-jamming performance under a variety of jamming modes.