Evaluation of Doppler frequency aiding for GPS/INS integration system

High dynamic condition will cause Doppler shit acutely, then digital carrier loop may fail to track signal and wrong demodulation may occur in GPS receiver. So the design of tracking loop becomes a crux problem in designing of software receiver under high dynamic environment. The Inertial Navigation System (INS) and GPS are highly complementary to each other. Besides, the MEMS IMU is preferred in an integrated GPS/INS system due to the lower cost, lower power-consumption and smaller size. So the full fusing INS with GPS can meet the high accuracy, high continuity and high reliability navigation requirements. Ultra-tight integration changes the structure of traditional GPS tracking loops. It can enhance receiver's signal processing and anti-jamming capability. This paper evaluates the performance of Doppler frequency aiding for GPS/INS integration systems. Firstly, the principles of the tracking loops which would be used in the software-defined GPS receiver are reviewed. Secondly, the experiment platform for GPS/INS integration is elaborated, and both hardware and software requirements for GPS/INS integration are analyzed. Finally, the algorithm based on the receiver's tracking loop is designed. The tracking performance, such as tracking noise and frequency requirement by using this proposed scheme is evaluated. The results of this paper will have a potential contribution to the GPS/INS ultra-tight integration implementation.