| 摘要 |
A digital sun sensor having an ND filter, a prism, an opaque layer formed on the prism and having a slit, a band-pass filter, and a linear array sensor. A sunbeam passes through ND filter, and is diffracted as it passes through the slit, and is refracted by prism. The diffracted sunbeam, which has a specified wavelength, passes through the band-pass filter and reaches the linear array sensor. The sensor is driven by a first clock signal, thereby generating electrical signals. An automatic gain control circuit maintains these signals at a constant peak value. The output signal of automatic gain control circuit is compared with a reference level. When this output is at a level lower than the reference level, the first clock signal is supplied to an N-bit counter. When the output is at a level higher than the reference level, a second clock signal having a frequency half that of the first clock signal is supplied to the N-bit counter. N-bit counter counts the pulses of either clock signal. Any pulse of the second clock signal, that has been counted by the counter, is input to the lowest bit-input terminal of an (N+1)-bit latch circuit, and the pulses of the first clock signal, which have been counted by the counter, are input to the other N-bit input terminals of the latch circuit.
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