Characterizing the Performance of GPS Disciplined Oscillators with Respect to UTC(NIST)

Published

August 29, 2005

Author(s)

Michael A. Lombardi, Andrew N. Novick, Victor S. Zhang

Abstract

Global Positioning System Disciplined Oscillators (GPSDOs) are now the primary standard of time and frequency at many laboratories and calibration facilities. They are generally treated as self-calibrating standards, and their users generally assume that they meet the manufacturer¿s specifications. To gain a better understanding of the actual performance of GPSDOs, this paper presents a method of characterizing both their long and short-term performance using the UTC(NIST) time scale as a reference. It then describes how this method is used to characterize four GPSDOs, including two that use an oven controlled quartz oscillator (OCXO) as their time base, and two equipped with a rubidium oscillator. All four devices are simultaneously tested using the same antenna over two 60 d measurement intervals. During the first 60 d measurement, a previously surveyed antenna position is used and the same coordinates are applied to all four devices. During the second 60 d measurement, each GPSDO performs an independent survey of the antenna¿s position and applies its own coordinates. Both the timing output (1 pulse per second) and the frequency output (10 MHz) of each GPSDO is measured during both 60 day intervals. A low-noise dual mixer time difference system is used to characterize the short-term frequency stability of each device¿s 10 MHz output, and all measurement results are presented and summarized.

Proceedings Title

Proc. Joint Mtg. IEEE Intl. Freq. Cont. Symp. and PTTI Mtg.

Conference Dates

August 29-31, 2005

Pub Type

Conferences

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Keywords

calibration, frequency, GPS, measurement methods, time

Citation

Lombardi, M. , Novick, A. and Zhang, V. (2005), Characterizing the Performance of GPS Disciplined Oscillators with Respect to UTC(NIST), Proc. Joint Mtg. IEEE Intl. Freq. Cont. Symp. and PTTI Mtg., [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50196 (Accessed April 18, 2024)