Research Of Some Problems In Signal System Of The CPAS

With the tide of prosperous development of Global NavigationSatellite System(GNSS) undergoing on the earth, it is the pursuit of allpositioning systems includong the GPS that to provide users a moreaccurate positioning service. Pinpoint navigation service will be thetrend of future GNSS, which lies significance in both military and civiluse.In2002, a group of Chinese astronomers led by Prof.Guoxiang Ai, whois a member of the Chinese Academy of Sciences, took advantages of theknowledges and experiences on gravitational astronomy and timesynchronization, which have been acquired in their long time research onastronphysics., and issued a brand new navigation system based on retiredcommunication satellites. Since the development of more than10years，the system has become increasingly mature and applicable. Now researchersare striving for the success in respect of pinpoint positioning.For the intention of optimizing the performence of distancemeasurement, in this dissertation I will show you an idea of a new kindof pseudo-random code, with bit rate of20MHz, which adjust to the CAPSthat use C band carrier, with little interference from other navigationsignal, as well as plenty frequency resources. This code we call it superbroad code.In this dissertation, we will make a appraisal of the new code inrespects of correlation function, power density, noise precision,capacity of resisting disturbance, anti-multipath performance, and groupdelay.The results tell that the performance of super broad code is muchbetter than the C/A code,1.023MHz,and short precision code,10.23MHz, in aspects of correlation function, power density, noise precision,capacity of resisting disturbance, anti-multipath performance. However,it is susceptible to group delay.In addition, optimization scheme is issued，which is aimed atrelieving the adverse impact of group delay.