| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a time device for reducing adjustment costs with low electric power consumption while maintaining the required time accuracy. <P>SOLUTION: An error of an oscillation frequency of a voltage controlled crystal oscillator 15 is measured by frequency error measurement parts 12, 13a on the basis of a reference one-second pulse from a GPS receiver 11. A control part 13 controls a control voltage of a D/A converter 14 on the basis of the measurement results, and repeats a frequency calibration operation for the voltage controlled crystal oscillator 15 at a time interval. Each time when the frequency calibration operation is finished, control voltage data are associated with the temperature of the voltage controlled crystal oscillator 15 and stored in a nonvolatile memory 17 as temperature compensation data. In a duration excluding the time of the frequency calibration operation, a power supply of the GPS receiver 11 is turned off by a power supply control circuit 19. In the duration excluding the time of the frequency calibration operation, the control voltage data corresponding to the current temperature of the voltage controlled crystal oscillator 15 are output from the control part 13 to the D/A converter 14 on the basis of the temperature compensation data. <P>COPYRIGHT: (C)2010,JPO&INPIT |
