Signal Design of High Accuracy Terrestrial Pseudolites System in BeiDou RDSS Frequency Band

摘要

Beidou high precision terrestrial navigation system is a passive and independent navigation system composed of terrestrial pseudolites and built for high precision positioning purpose. In the frequency band (2.4835-2.5 GHz) where RDSS works, a comprehensive analysis was made to such design factors as bandwidth, modulation, message, and time-hopping pattern in the signal design of BeiDou terrestrial pseudolites system from the perspective of compatibility and high-precision ranging, with the emphasis on the signal ranging performance, compatibility between ground signal and signal in space as well as the influence of near-far effect between terrestrial pseudolite signals to receiver ranging. Upon it, another analysis was made to the design requirements for subcarrier modulation mode and pseudolite time-hopping pattern. On the basis of 10,230-long Weil code, a time-hopping terrestrial pseudolite signal was developed. Besides, a semi-physical verification platform was built, which was used to verify the high precision positioning performance of the interested signal. The signal test results showed that it enabled the receiver to gain a near 4 cm static positioning accuracy.