| 摘要 |
PURPOSE:To generate an earth scanning period signal without being affected by celestial body interference by suppressing the generation of a trigger signal according to the time widths of generation time of a leading and a trailing edge pulse. CONSTITUTION:Earth infrared-ray radiation obtained by scanning the earth by an earth sensor mounted on an artificial satellite is converted 1 into an electrical signal 8. The signal 8 is waveform-processed 2 into a signal 9, which are inputted to voltage comparators 3 and 4 for a leading edge pulse 10 and a trailing edge pulse 11 respectively. A timer circuit 15 inputs the pulse 10 and outputs a gate control signal 18 to a gate circuit 16. The pulse 11, on the other hand, is inputted to a gate circuit 6. When a trigger signal to be inputted to an earth scanning period signal generating circuit 7 is generated by those circuits 15 and 16 by using the pulse 11, the generation of the signal 18 is suppressed according to the time widths of the pulses 10 and 11. Further, the pulse 10 is inputted to a two-pulse counter circuit 5 which receives the output of the circuit 16 as a reset signal. Then when the count number of the circuit 5 is '2', all pulses 11 are inputted to the circuit 7 as a trigger signal.
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