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Determination of Clock Temperature
There are over 50 temperature sensors in the Ginga satellite, each of which is sampled every 8, 64, or 256 sec depending on the data recording rate. Most of these temperatures are recorded in steps of only 0.5°C. This low resolution is not a serious drawback, because there is a fairly large number of measurements which can be averaged over the course of a temperature variation of ~1°C during the satellite day-night cycle (see Section 2d). The temperature sensors used in this analysis are denoted as BDR (bubble data recorder); CP-1, CP-3, and CP-4 (on center panels 1, 3, and 4, respectively); and BP-3 and BP-4 (on the inside and outside surfaces of the base panel, respectively). The sensors closest to the DP (data processor, within which the clock circuit is mounted) are CP-4 (just above the DP) and BDR (just below the DP). There is no temperature sensor within the DP itself. A more complete description of satellite temperature and other housekeeping data is given by Makino et al. (1986).The time history of the temperature from the CP-4 sensor is shown in Figure 2, for the same data span used in Figure 1. In this figure, the temperature was averaged over intervals of 97 minutes duration (approximately one satellite orbit). In particular, during contact orbits the temperature averages are over almost identical intervals as the corresponding average clock periods shown in Figure 1. The excursions in CP-4 temperature have a total range of some 5°C, and it is apparent that these variations are correlated with the variations in period shown in Figure 1. The next step is to determine a relationship between clock period and temperatures of CP-4 and other sensors. [Next: Clock Period] [Previous: Clock Rate] [Back to Analysis] |
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