星载GNSS反射信号时-空性能仿真分析

The mean of spatial coverage number, the percentage of global coverage, and the mean of revisiting time are defined based on first-order statistics to evaluate spatiotemporal performance of spaceborne Global Navigation Satellites System (GNSS) reflectometry, in addition develops the GNSS and LEO orbits to simulate the influence of LEO orbit height, inclination and right ascension of ascending node on spatiotemporal performance. The results show that the mean of spatial coverage number, the percentage of global coverage, and the mean of revisiting time are respectively 1.6, 36.5, and 8 h with the orbit height of 1300 km, inclination of 98.7°, and the beam width of 40° so that the requirement of global observation could not be met. When the number of satellites in same orbital plane is 4 and the orbit height, inclination, and the beam width are respectively 1300 km, 98.7°, 40°, the spatiotemporal performance is higher than the 65% of single ASCAT. For the case of 8 satellites, spaceborne GNSS reflectometry could observe the area of 88.9% of the earth in 4.5 h.