珞珈一号低轨卫星导航增强系统信号质量评估

低轨卫星导航信号增强能够弥补现有中高轨导航卫星信号收敛慢、信号弱的不足，在下一代导航定位技术中占有重要地位。武汉大学研制的珞珈一号科学实验卫星搭载了导航增强载荷，能够在轨自动计算轨道和钟差，并自主生成和播发双频测距信号，首次实现了低轨卫星平台的导航信号增强。就珞珈一号卫星导航增强信号的质量，包括信号载噪比、伪距和载波相位测量精度以及单星授时精度进行了评估，结果显示，珞珈一号卫星高仰角的伪距和载波相位测量精度分别优于1.5 m和1.7 mm，能够满足导航信号增强的需求。珞珈一号卫星单星授时的精度在10~30 ns量级，证明了珞珈一号卫星星地测距链路的正确性和有效性。

Quality Assessment of the LEO Navigation Augmentation Signals from Luojia-1A Satellite

Navigation signal augmentation from low earth orbit (LEO) can improve the slow convergence and weak signal problem of the high/medium earth orbit navigation satellites, so it plays an important role in next generation navigation technique. Luojia-1A scientific experimental satellite deve-loped by Wuhan University carried the navigation augmentation payload, and it is capable of automatically calculating its orbit and clock by it self, generating and transmitting dual-frequency ranging signals. Luojia-1A satellite successfully demonstrates the navigation signal augmentation from LEO platform. This paper assesses the quality of the navigation augmentation signals from Luojia-1A from C/N0, precision of pseudorange and carrier phase and timing precision from single satellite. The results indicates the precision of the pseudorange and carrier phase at high elevation angle is 1.5 m and 1.7 mm respectively, which can meet the requirement of the navigation signal augmentation. Single satellite based timing precision from Luojia-1A is approximately 10-30 ns, which proves the correctness and validity of the satellite-ground ranging signals.