| 摘要 |
PROBLEM TO BE SOLVED: To provide a dial pulse detection circuit that has provision for any of the 10PPS system and the 20PPS system of a DC impulse signal sent from a telephone set and the signal with a standard of a different impulse make ratio. SOLUTION: The dial pulse detection circuit consists of a shift register 1 that receives a DC impulse sent from a telephone set and shifts the impulse signal based on a prescribed sampling clock, an AND gate 2 consisting of a 7-input AND gate 21 and a 4-input AND gate 22 that receives an output of the shift register 1 and a counter 3 that receives an output of the AND gate 2.
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