| 摘要 |
PURPOSE:To improve the start bit detection error by using the 1st threshold value subjected to offset in detecting a start bit, changing it into the 2nd threshold value afte the detection of the start bit and restoring it into the 1st threshold value after a required information string is detected. CONSTITUTION:A prescribed correct threshold value (1st threshold value) is set by a threshold value setting circuit 2 as the initial state to an inverting input of a comaprator 1, and when the leading of the start bit of a signal (a) does not exceed the 1st threshold value, no positive output appears at an output terminal (c) of the comparator 11. When the start bit leading of the output signal (c) of the comparator 1 is detected, the output of the start bit leading detection circuit 3 is inputted to the circuit 2, and the output of the circuit 2 goes to 0V (2nd threshold value). A transmission bit length counter circuit 5 counts the prescribed transmission code length 8-bit and the 1st threshold value is set to the output of the circuit 2 when the final bit is detected.
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