Synchronized Joint Airborne and Ground-Based Regional Positioning System

Ground-based positioning systems have some limitations such as low vertical accuracy, blockage, and multipath effect. Compared with ground-based positioning systems, joint airborne, and ground-based positioning systems can provide better observation geometry and reduce the influence of terrain occlusion on navigation signals received by user receivers. A synchronized joint airborne and ground-based regional positioning system is proposed, which is composed of ground-based stations (GS) and airborne nodes (AN). The ANs relay the signals broadcast by GSs in the way of frequency division multiple access and synchronize the time and frequency between the ANs and GBs as well as the invisible GSs by using the relayed navigation signals, which effectively solves the signal conflict problem and the frequency drift problem of the AN. The prototype system of synchronized joint airborne and ground-based regional positioning system was built and verified by two tests. The test results of time and frequency synchronization performance based on a moving platform show that the maximum deviation of time synchronization error is 974.5 ps, and the frequency stability is 4.49e-11@1s. The comprehensive positioning test results (root mean square) show that the positioning accuracy is 2.36 m and the velocity accuracy is 0.02 m/s.