The Positioning Precision Influenced by the Frequency Reference of a GPS Receiver

Ta-Kang Yeh, Guochang Xu, Chieh-Hung Chen

Abstract:	This study examines to which extent the frequency offset and the frequency stability of the internal quartz oscillator or of an externally supplied rubidium oscillator have an influence. Observations were made at the tracking station, where a quartz oscillator and a rubidium oscillator were applied alternatively on a monthly basis throughout a 16-month period. Moreover, the performance of the local oscillators used in the test were traceable to UTC via the National Standard Time and Frequency Laboratory, Taiwan has been made. The frequency offset and frequency stability calculated via the remote method were compared with values (uncertainty is 3.0E-13) measured directly at the National Standard Time and Frequency Laboratory, Taiwan. Analytical results show that the two methods vary by 1.4E-10 in terms of frequency offset and by 6.5E-12 in terms of frequency stability, demonstrating that the remote method can yield computational results almost as accurate as direct measurement. Positioning precision results also show that rubidium oscillator accuracy improved by 5, 11, and 15% for short, medium and long-baseline positioning, respectively, indicating that clock quality is more influential for long-baseline GPS relative positioning, and that the frequency stability of a receiver clock is far more critical than the frequency offset.
Published in:	Proceedings of the ION 2015 Pacific PNT Meeting April 20 - 23, 2015 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	993 - 998
Cite this article:	Yeh, Ta-Kang, Xu, Guochang, Chen, Chieh-Hung, "The Positioning Precision Influenced by the Frequency Reference of a GPS Receiver," Proceedings of the ION 2015 Pacific PNT Meeting, Honolulu, Hawaii, April 2015, pp. 993-998.
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