Absolute Calibration of Time Receivers With DLR’s GPS/Galileo HW Simulator

S. Thölert, U. Grunert, H. Denks, and J. Furthner

Abstract:	A usual way for time transfer between atomic clocks operated at different locations is the use of the well known GNSS Common View technique. This technique is based on time receivers measuring the time differences between the connected atomic clock and the GNSS satellite clocks. The results obtained can be used for time scale generation, such as UTC or TAI. In order to produce a very accurate time scale from all time differences measured with different GNSS time receivers, the accurate calibration of them is essential. In recent years, two main methods for time receiver calibration have been proposed. One is to compare the obtained time differences relative to a calibrated receiver. In the second method, one performs an absolute calibration of time receivers using a GPS HW simulator. In this paper, the absolute calibration of time receivers with DLR’s GPS/Galileo HW simulator is analyzed and described in detail. The primary step is to calibrate the simulator itself. In this context, the most important facts and values that have to be measured are explained. After the calibration of the simulator, the receiver is fed with satellite signals generated by the simulator belonging to a standard GPS satellite constellation in order to determine the absolute offset of the receiver (internal delay) compared to the simulator output. Additionally, the precision of a combined GPS/Galileo receiver for frequency transfer is investigated and determined.
Published in:	Proceedings of the 39th Annual Precise Time and Time Interval Meeting November 27 - 29, 2007 Hyatt Regency Long Beach Long Beach, California
Pages:	323 - 330
Cite this article:	Thölert, S., Grunert, U., Denks, H., Furthner, J., "Absolute Calibration of Time Receivers With DLR’s GPS/Galileo HW Simulator," Proceedings of the 39th Annual Precise Time and Time Interval Meeting, Long Beach, California, November 2007, pp. 323-330.
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