The improved TCAR by adding small search spaces

Ambiguity resolution is very important to precise position and attitude determination with GNSS. Conventional ambiguity resolution methods can hardly reach the good performance in simplicity and time effectiveness. Considering that several frequency signals will be exploited in the GNSS systems (GPS, GALILEO and BEIDOU e.g.) in the future, an improved three-carrier ambiguity resolution (TCAR) is proposed in this paper. The principle and success probability of TCAR in every ambiguity approaching step are studied, and then small ambiguity searching spaces are added in each calculating stage to enhance the success probability of integer ambiguity solution. With the help of simulation platform, the new method is simulated in aero-plane attitude determination. The simulation results indicate that the proposed algorithm can effectively improve the success probability of TCAR, and it is suitable for the real-time GNSS attitude determination application.