In order to improve the performances of software receiver

an ultra-tight Micro-Inertial Measurement Unit (MIMU)/software receiver integration method is studi ed.The nonlinear tracking loop filter and integrated navigation filter are desig ned by analyzing the nonlinear characteristics of receiver tracking loop and MIM U.The performance of closed-loop ultra-tight integrated system is evaluated by experimental software receiver and Micro-Electro-Mechanical Systems (MEMS) in ertial data collected in real dynamic environments.The results show the improvem ent in the performance of the tracking loop in this ultra-tight aided configura tion under faintish In-phase/Quadra-phase conditions.