Short-Term Characterization of GPS Disciplined Oscillators and Field Trial for Frequency of Italian Calibration Centres

F. Cordara, V. Pettiti

Abstract:	Quartz and rubidium oscillators disciplined by the signals of the Global Positioning System satellites (GPSDOs) are increasingly used as reference standards in calibration centers and in telecommunication networks, thanks to their cesium-like long-term instability, and several investigations are undergoing in the metrological laboratories of different countries concerning their use for the traceability to the national standards of time. Some of these devices were tested in the past at the Time and Frequency Laboratory of IEN, as regards to their use as frequency and time references in secondary laboratories and their traceability to the Italian standard of time. In further investigations performed, evidence was found of short-term frequency instabilities, not previously detected, mainly due to temperature effects and to the disciplining algorithms used, that must be taken into account especially in the frequency calibration field The long and short-term instability results obtained at ZEN on some GPSDOs, that show the real uncertainty limits in calibration, are reported in this paper. They are also checked by means of afield-trial on frequency, carried on among some Italian Calibration centers equipped with GPSDOs or other frequency references, using either a free rubidium or a quartz oscillator as travelling standards.
Published in:	Proceedings of the 30th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 3, 1998 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	161 - 172
Cite this article:	Cordara, F., Pettiti, V., "Short-Term Characterization of GPS Disciplined Oscillators and Field Trial for Frequency of Italian Calibration Centres," Proceedings of the 30th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 1998, pp. 161-172.
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