| 摘要 |
PROBLEM TO BE SOLVED: To measure a solar angle in an ultra-high accuracy by calculating solar angle data based on a residual difference of the angle and a feedback amount of the angle. SOLUTION: An integrator 16 integrates a replica waveform signal and an output of a linear CCD 11, and outputs an integrated signal to an integrator 18. The integrator 18 integrates the integrated signal to calculate a feedback amount of a solar angle. An A-D converter 19 digitally converts the amount, and its six less significant bits are input to a B system integrator 28' through a second switch 21 and held in therein. A divider 29 divides the feedback amount of the one bit shifted state from the integrator 28 by that of the angle held in an A system integrator 27 to obtain a residual difference of the angle and to output it to a synthesizer 25. Simultaneously, the feedback amount held in a phase register 23 is input to the synthesizer 25, which synthesizes the feedback amount and the difference of the angle to calculates solar angle data. As a result, the angle can be measured finely more than resolution of a null point control by interpolating the feedback amount obtained by the null point control, calculating the difference of the angle, and calculating the angle data based on the difference and the feedback amount.
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