: The broad utility of GPS is widely recognized and appreciated. Less well known is the critical role played by the Naval Research Laboratory in its invention, concept demonstration, operational configuration, inception, and continued development. Perhaps this is in part due to the quiet way the Laboratory goes about pursuing scientific and technical excellence. Although ample documentation on the NRL role in GPS still remains, it is largely in the form of memoranda, technical reports, series of proceedings from specialized technical conferences, and a relatively few widely published articles. Many of the key technical reports were classified when originally produced, were not declassified until the mid 1990s, and were not disseminated at that time. This bibliography is offered as an aid to those who are interested in better understanding the NRL role in the origins of GPS. Bibliographic citations, primarily of published works, are presented. These are annotated with abstracts, photos, and figures, to facilitate selecting which of the referenced papers to examine more closely. A timeline is provided to aid in setting the citations in their context of historical development.

NRL GPS Bibliography - An Annotated Bibliography of the Origin and Development of the Global Position System at the Naval Research Laboratory

: NTS-2 was successfully launched on June 23, 1977, and maneuvered into a preassigned constellation position as part of the Phase I demonstration for NAVSTAR GPS. NTS-2 carried two cesium frequency standards. Precise timing signals, derived from one of the cesium frequency standards, were continuously transmitted. Time differences were then measured by the NTS ground stations. The NTS-2 time differences were used to fit an orbit to the observations over a (typical) 6-day span. Clock offsets were then obtained using the reference orbit and other measured parameters; these clock offsets were then used to estimate the cesium frequency stability. Estimates of frequency stability have been obtained for one of the two cesium frequency standards for sample times of from 1 to 9 days. Analysis of the results indicates a white frequency noise of 0.00000000011 divided by the square root of the sample time in days for sample times of 1 to 5 days with a flicker floor of 0.00000000000017 for sample times from 5 to 9 days. For sample times of 10 days or longer an attempt was made to check for cesium aging with respect to the Universal Time Coordinated of Master Clock 1 at the United States Naval Observatory. The value for aging was not significantly different from zero; that is, no cesium aging was found.

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Joseph White

Papers

Stability Analysis of the Cesium Frequency Standard on Board Navigation Technology Satellite 2 (NTS-2).