A GPS Disciplined Rubidium Clock

Abstract

Sub-Microsecond timing accuracy for event tagging and multisite synchronization is possible using the Global Positioning System. In order to maintain a high degree of accuracy during periods when no satellites are visible, a highly stable local time base is required. For those cases which require Cesium Oscillator stability, initial cost and continuing maintenance of the Cesium Oscillator must be considered. A viable alternative is attained by using the Global Positioning System and an oscillator disciplining process. With this system, near Cesium performance can be achieved using a more rugged lower cost Rubidium oscillator. Additionally, when 24 hour satellite coverage becomes available, system performance may surpass that of a Cesium in long term stability as well as long term drift. This presentation describes the system components, including Global Positioning System receiver, Miniaturized Controllable Rubidium Oscillator and Global Positioning System Clock. Clock timing accuracy and short and long term frequency stability results are discussed along with the control algorithms used in the disciplining process. A brief discussion of the computer modeling tools used is also presented.