Review on augmentation schemes of double-star navigation system

The Double-Star navigation system in the stand- alone mode cannot accomplish real-time three dimensions passive navigation due to the limited number of satellites. In order to solve the contradiction between the lack of passive 3-D navigation resource controlled by our country and the urgent need for the system, in these years, the rubidium clock method, pseudolite method and Loran-C method are developed as augmentation schemes based on Double-Star. These augmentation approaches' motivation, operational principle and performance is reviewed in details, furthermore, some underlying assumptions, flaws and future challenges are pointed out. It is important to recognize that the augmentation technologies not only can meet the desire of 3-D passive navigation currently, but also have important application merits for future second generation satellite navigation system.