Research on the application of Beidou and GPS dual-mode timing system in the space flight tracking ship

Keywords: GPS; GNSS; timing system; reliability

HF wave timing was the earliest to be introduced by by the Americans. It transmits time information and standard signals by making use of the HF wave. The transmission path of the HF wave is between the grand and the ionized layer, and then, the transmission quality is influenced by the ionized layer. When the ionized layer is unstable, the influence is bigger, and the carrier frequency needed is higher, the synchronization precision falls short of the millisecond.