Citation
Abstract
There are two hydrogen maser clocks located at each signal processing center (SPC) in the DSN. Close coordination of the time and frequency of the SPC clocks is needed to navigate spacecraft to the outer planets. A recent example was the Voyager spacecraft's encounter with the planet Uranus in January 1986. The clocks were adjusted with the goal of minimizing the time and frequency offsets between the SPCs at encounter. This article describes how the time and frequency at each SPC is estimated using data acquired from Global Positioning System Timing Receivers operating on the NBSBIH (National Bureau of Standards-Bureau International de U'Heure) tracking schedule. These data are combined with other available timing receiver data to calculate the time offset estimates. The adjustment of the clocks is described. It was determined that the long range hydrogen maser adrift is quite predictable and adjustable within limits. This enables one to minimize time and frequency differences between the three SPCs for many months by matching the drift rates of the three standards. The article will describe the data acquisition and processing techniques using a Kalman filter to make estimates of time and frequency offsets between the clocks at the SPCs and UTC (NBS) (Coordinated Universal Time realized at NBS).
Details
- Volume
- 42-89
- Published
- May 15, 1987
- Pages
- 67–72
- File Size
- 460.2 KB