| Zugriffsnummer | 23017 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Strengthen the Asia-Europe time links by combining TWSTFT and GPS data |
| Autor(in); Institution |
Jiang, Z.; Bureau International des Poids et Mesures (BIPM), Sèvres, FRANCE
Tseng, W. H.; Telecommunication Laboratories, Chungwha Telecom, Taoyuan, TAIWAN
Lin, S. Y.; Telecommunication Laboratories, Chungwha Telecom, Taoyuan, TAIWAN
Fujieda, M.; National Institute of Information and Communications Technology, Tokyo, JAPAN
Maeno, H.; National Institute of Information and Communications Technology, Tokyo, JAPAN
Yang, S. H.; Korea Research Institute of Standards and Science, Yuseong Daejeon, KOREA
Piester, Dirk; 4.4, Zeit und Frequenz, PTB-Braunschweig
|
| Quelle/Jahr | AFT 2008 proceedings : Asia-Pacific Workshop on Time and Frequency 2008:(2008) |
| Verlag | Serpong-Tangerang: KIM-LIPI |
| Konferenzangaben | Asia-Pacific Workshop on Time and Frequency 2008, Serpong-Tangerang, 30, October - 01, November, 2008, Indonesia |
| Freie Schlagworte | UTC ; Time Transfer ; TWSTFT ; GPS ; PPP ; Time Deviation ; Triangle Closure |
| Zusammenfassung | The time laboratories in the Asia-Pacific region actively contribute to the UTC (Coordinated Universal Time) generation, e.g. with increasing weights of the clocks and primary frequency standards. These data are introduced in the UTC generation through the Asia-Europe intercontinental time links. Very long distance time transfer is always a big challenge in UTC practice. In the recent years, important investments have been made in GPS and TWSTFT (Two-Way Satellite Time and Frequency Transfer, TW for short) facilities. Many laboratories operate both techniques. However, only one link, either TW or GPS, is presently used for UTC. TW and GPS, both have their advantages and disadvantages. GPS PPP (time transfer using the Precise Point Positioning technique) is advantageous because of its short term stability assigned by the carrier phase information and the independence between the precision and the link distance. But its accuracy is≈5ns; TW is characterized by its absolute calibration uncertainty uB≈1ns and its long-term stability. However, studies have proven that TW is disturbed by diurnal variations up to nanoseconds, especially for the long distance links. Combining the two techniques is a reasonable solution. The Vondrak-Cepek combined smoothing is adapted for this purpose. We give first a brief recall of the state-of-the-art in the study of combining TW with GPS and then concentrate on the improvement of the very long distance Asia-Europe time transfer links. Although some of the Asia-Pacific TW laboratories are not linked directly to the PTB (the pivot of the UTC network), they are linked "indirectly" to PTB via the Asia pivot NICT. We show by numerical examples that the result of combining the indirect TW and PPP is as accurate as the direct TW combination in view of UTC time transfer. This implies that the indirect Asia-Europe TW links could be linked to PTB with the help of GPS PPP. We also prove that the combination GPS and TW can considerably improve the stabilities of time transfer: reducing the influence of biases and gaps in the observations, and increasing the robustness employing the complete independence between TW and GPS. |
Zitierung
Jiang, Z., Tseng, W. H., Lin, S. Y., Fujieda, M., Maeno, H., Yang, S. H., & Piester, D. (2008). Strengthen the Asia-Europe time links by combining TWSTFT and GPS data. Asia-Pacific Workshop on Time and Frequency 2008, Serpong-Tangerang, 30, October - 01, November, 2008, Indonesia.