| 摘要 |
A system 10 is disclosed for reducing user range error URE in GPS signals due to temperature changes experienced by a GPS transponder onboard a satellite. The system 10 comprises at least one GPS transponder 14,16. An atomic clock 34 provides a highly accurate clock signal to a navigation data unit NDU 36 and transponders 14,16. The NDU 36 uses the clock signal to generate time stamped navigation signal at its output 36a. The output 40,42 of the transponders 14,16 are filtered and summed 38 and fed to a coupler 46 that provides an interface to antenna 48 and a sample of the modulated signal to demodulator 50 where the coded navigation data is recovered. A phase comparator 52 receives code signals from both GPS transponders 14,16 via demodulator 50 and a reference code from NDU 36 via a thermally stable transmission line 54 and generates phase correction signals 64,66 for each transponder 14,16 to remove temperature induced phase shift affecting the system 10. |
