Study On Multi-path Suppression Synchronization Of BOC Modulated Signals

Spread spectrum technology is an important technology that has been rapidly developed in the current communication research field.Among them,the Direct Sequence Spread System(DSSS)has a wide range of applications in the military field,satellite communications,navigation,and ranging with excellent features such as anti-interference,anti-multipath,and anti-fading.With the continuous development of the direct-spread system,in order to make the anti-interference and anti-interception performance of the direct-spread system have a greater improvement,new modulation methods have emerged.BOC modulation is one of the new modulation methods that have good signal characteristics and are widely used.In order to be suitable for different application backgrounds,BOC family signals such as AltBOC modulation signal and MBOC modulation signal are derived from the BOC modulation signal.The signal tracking and acquisition at the receiving end of the DSSS system is an important part of the realization of the entire system.Its accurate tracking of the received signal is a necessary prerequisite for successfully reproducing the local BOC signal and completing the despreading operation of the received signal.However,in the signal receiving environment,interference signals of reflection,refraction and diffraction will be generated due to the influence of buildings and potholes in the environment,so that the direct signal received by the receiving end is mixed with interference signals with a certain time delay,namely Multipath signal.The effect of multipath effects on the tracking process is relatively large and difficult to eliminate.Therefore,based on the study of BOC family modulation signals,this article considers the multipath suppression performance of the existing BOC family modulation signal synchronization methods,and aims at multipath For the problem of obvious error,an improved method of multipath suppression based on gate function is proposed.The analysis of simulation results shows that this method can effectively suppress the multipath error envelope amplitude under short time delay.Furthermore,in order to solve the problems of poor compatibility of some multipath suppression methods and obvious multipath errors under long delays,this thesis proposes an improved method for multipath suppression based on code-related reference waveforms.In order to verify the multipath suppression performance of the method,this thesis firstly sets the parameters and indicators,analyzes the output curve of the discriminator,and then simulates the multipath error envelope of the improved method from the perspective of the BOC signal order and chip width and other influencing parameters.The simulation curve analysis shows that this method can effectively improve the ability to suppress multipath errors under long delays by designing local reference chip waveforms.On this basis,the existing multipath suppression method and the improved method are simulated and compared,which further verifies the improved method's excellent multipath suppression ability under long time delay and higher tracking accuracy under different carrier-to-noise ratios.