Results of the Calibration of the Delays of Earth Stations for TWSTFT Using the VSL Satellite Simulator Method

Gerrit de Jong, Dieter Kirchner, H. Ressler, Peter Hetzel, John Davis, Peter Pears, Bill Powell, Angela Davis McKinley, Bill Klepczynski, James DeYoung, Christine Hackman, Steve R. Jefferts, Thomas E. Parker

Abstract:	Introduction - No Abstract Available Two-Way Satellite Time and Frequency Transfer (TWSTFT) is the most accurate and precise method of comparing two remote clocks or time scales. The accuracy obtained is dependent on the accuracy of the determination of the non-reciprocal delays of the transmit and the receive paths. When the same transponders in the satellite at the same frequencies are used, then the non-reciprocity in the Earth stations is the limiting factor for absolute time transfer. In each Earth station, the clock signal (1 pulse per second = 1PPS) is modulated on an IF carrier frequency, then up-converted to the transmit up-link frequency, amplified by a high-power amplifier (HPA), and radiated to the satellite by the antenna. The signal from the companion station clock is received at the satellite down-link frequency by the same antenna, amplified by a low-noise amplifier (LNA), and then down-converted to the IF frequency and demodulated to the received clock signal. The cables used in the station in the transmit path may differ from the cables in the receive part; the filter and tuned circuit delays may differ as well. The stability of these delays may also be affected by difference in temperature coefficients, temperature gradients, and thermal time constants; these limit the frequency transfer capability of TWSTFT. During September, October, and December 1994, six Earth stations participating in a TWSTFT experiment on the INTELSAT satellite at 307' East were calibrated in an absolute way using the NMi-VSL Satellite Simulator method. They were also calibrated in a relative way by a visiting small USNO Eearth station called Fly Away Satellite Terminal (FAST). Calibration results and the difference with preliminary FAST co-location results are presented.
Published in:	Proceedings of the 27th Annual Precise Time and Time Interval Systems and Applications Meeting November 29 - 1, 1995 The Doubletree Hotel at Horton Plaza San Diego, California
Pages:	359 - 372
Cite this article:	de Jong, Gerrit, Kirchner, Dieter, Ressler, H., Hetzel, Peter, Davis, John, Pears, Peter, Powell, Bill, McKinley, Angela Davis, Klepczynski, Bill, DeYoung, James, Hackman, Christine, Jefferts, Steve R., Parker, Thomas E., "Results of the Calibration of the Delays of Earth Stations for TWSTFT Using the VSL Satellite Simulator Method," Proceedings of the 27th Annual Precise Time and Time Interval Systems and Applications Meeting, San Diego, California, November 1995, pp. 359-372.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In