Weak and Dynamic GNSS Signal Tracking Strategies for Flight Missions in the Space Service Volume

• Main Authors: Shuai Jing, Xingqun Zhan, Baoyu Liu, Maolin Chen
• Format: Article
• Language: English
• Published: MDPI AG 2016-09-01
• Series: Sensors
• Subjects: GNSS; adaptive Kalman filter; INS-assisted navigation; maximum likelihood estimation; space service volume; Doppler frequency estimation
• Online Access: http://www.mdpi.com/1424-8220/16/9/1412

Weak-signal and high-dynamics are of two primary concerns of space navigation using GNSS (Global Navigation Satellite System) in the space service volume (SSV). The paper firstly defines a reference assumption third-order phase-locked loop (PLL) as the baseline of an onboard GNSS receiver, and proves the incompetence of this conventional architecture. Then an adaptive four-state Kalman filter (KF)-based algorithm is introduced to realize the optimization of loop noise bandwidth, which can adaptively regulate its filter gain according to the received signal power and line-of-sight (LOS) dynamics. To overcome the matter of losing lock in weak-signal and high-dynamic environments, an open loop tracking strategy aided by an inertial navigation system (INS) is recommended, and the traditional maximum likelihood estimation (MLE) method is modified in a non-coherent way by reconstructing the likelihood cost function. Furthermore, a typical mission with combined orbital maneuvering and non-maneuvering arcs is taken as a destination object to test the two proposed strategies. Finally, the experiment based on computer simulation identifies the effectiveness of an adaptive four-state KF-based strategy under non-maneuvering conditions and the virtue of INS-assisted methods under maneuvering conditions.