Accession Number:

ADA326252

Title:

Correlations between Global Positioning System and U.S. Naval Observatory Master Clock Time.

Descriptive Note:

Final rept. Nov 95-May 97,

Corporate Author:

ARMY RESEARCH LAB ADELPHI MD

Personal Author(s):

• Bahder, Thomas B.

Report Date:

1997-06-01

Pagination or Media Count:

35.0

Abstract:

The U.S. Naval Observatory Master Clock is used to steer Global Positioning System GPS time. Time transfer data consisting of the difference between the Master Clock time and the GPS time were recorded from all satellites in the GPS constellation over a time period covering 10 October to 12 December 1995. A Fourier analysis of these data shows a distinct peak in the Fourier spectrum, corresponding approximately to a one day period. For a more accurate determination of this period, correlations are computed between successive days of data. An average of 25 correlation functions shows a correlation equal to 0.52 at a delay time of 23 hr 56 min which corresponds to twice the average GPS satellite period. This correlation indicates that GPS time, as measured by the U.S. Naval Observatory, is periodic with respect to the Master Clock, with a period of 23 hr and 56 min. An autocorrelation of a five day segment of data indicates that these correlations persist for four successive days.

Descriptors:

• *GLOBAL POSITIONING SYSTEM
• *TIME SIGNALS
• *ATOMIC CLOCKS
• ALGORITHMS
• TIME INTERVALS
• AUTOCORRELATION
• ARTIFICIAL SATELLITES
• SYNCHRONIZATION(ELECTRONICS)
• FOURIER ANALYSIS
• DIURNAL VARIATIONS
• TIME STANDARDS

Subject Categories:

• Test Facilities, Equipment and Methods
• Navigation and Guidance
• Unmanned Spacecraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE