Ringtrip judging circuit
First Claim
1. A ringtrip judging circuit comprising:
- a single comparator for comparing a detection value of a ringing current with a threshold value and for outputting the result of the comparison;
a threshold value control circuit for, during a prescribed period after the initiation of ringing signal transmission, supplying to said comparator a first threshold value that is changeable as function of the result of the comparison output from said comparator, thereby determining a second threshold value optimum for ringtrip judgement, and for supplying said second threshold value to said comparator; and
a judging circuit for judging ringtrip based on the result of the comparison that said comparator outputs during application of said second threshold value.
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Accused Products
Abstract
A ringtrip judging circuit includes a single comparator for comparing a detection value of a ringing current with a threshold value and for outputting the result of the comparison, a threshold value control circuit for supplying the threshold value to the comparator, and a judging circuit for judging ringtrip based on the output of the comparator. During a prescribed period after ringing signal transmission, the threshold value control circuit changes the threshold value in a steplike manner in accordance with the result of the comparison, thereby determining a threshold value greater than a peak value during the prescribed period, and based on it, determines a threshold value for ringtrip judgement and supplies it to the comparator.
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Citations
10 Claims
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1. A ringtrip judging circuit comprising:
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a single comparator for comparing a detection value of a ringing current with a threshold value and for outputting the result of the comparison; a threshold value control circuit for, during a prescribed period after the initiation of ringing signal transmission, supplying to said comparator a first threshold value that is changeable as function of the result of the comparison output from said comparator, thereby determining a second threshold value optimum for ringtrip judgement, and for supplying said second threshold value to said comparator; and a judging circuit for judging ringtrip based on the result of the comparison that said comparator outputs during application of said second threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification