Research On SINS-aided GPS Signal Doppler Shift Analysis And Related Technologies

In order to keep the navigation system under high-accuracy and stabilization in the long run, SINS (Strapdown Inertial Navigation System)/GPS(Global Positioning System) integrated navigation system has been widely used in the field of aviation, aerospace, voyage, etc. SINS and GPS share complementary advantages, so their integration can not only help them play respective advantages, but has a positive effect on overall performance as well. According to different depth, integration can be divided into loose scheme and tight scheme, both of which cover a wide application range. However, with the improvement of aerocraft's maneuvering characteristics, ultra-tight integration has gradually became the first choice to meet the requirement of high dynamic and strong interference circumstance, which is based on tight scheme. In the Ultra-tight integration scheme, SINS plays a assistant role for GPS module. The key point of ultra-tight integration lies in how to utilize SINS output and ephemeris to estimate the GPS signal Doppler, how to assist GPS acquisition and tracking through estimated Doppler to improve the GPS signal processing ability. In order to provide a precise Doppler Shift, relevant techniques have been discussed in this thesis.Firstly, a deep analysis about GPS signal acquisition and tracking principle is given. Then the negative effect caused by GPS signal Doppler Shift is pointed out.Secondly, do the research on the basis principle of initial alignment and then strapdown gyrocompass alignment and application of Kalman Filter in initial alignment are discussed respectively. In order to reduce the alignment time, this paper proposed a new converse method. Simulation results show that the method can effectively meet the requirement of gyrocompass self-alignment accuracy and shorten sampled date and alignment time.Thirdly, strapdown algorithm under highly dynamic circumstance is introduced, including attitude updating and velocity updating. Analysis about the Coning error and Sculling error is given and then corresponding compensation algorithm is proposedFinally, through theoretical analysis, GPS satellite's motion state is calculated on the basis of ephemeris. Assisted by SINS, GPS receiver's motion state is estimated and then simulation of GPS signal Doppler Shift carried out.