发明名称 |
A DIGITAL SUPERVISORY CIRCUIT FOR A TELEPHONE SYSTEM |
摘要 |
The digital supervisory circuit comprises an amplitude comparator and EXCLUSIVE-OR gate to provide an output signal indicating the difference in time an input signal is above and below a predetermined reference potential. This output signal is integrated in an up-down binary counter and also is coupled to a first logic circuit under control of the counter which provides a ring present supervisory signal when a first threshold is exceeded and a second logic circuit under control of the counter which provides a switch hook detection supervisory signal when a second threshold is exceeded. A hit-timing circuit is provided coupled to the counter and the first and second logic circuits to prevent response of the counter and second logic circuit to line transients. |
申请公布号 |
ZA8302522(B) |
申请公布日期 |
1984.01.25 |
申请号 |
ZA19830002522 |
申请日期 |
1983.04.11 |
申请人 |
ISEC |
发明人 |
COCHRAN WILLIAM THOMAS |
分类号 |
H04Q1/32;H04M3/02;H04M3/22;H04M19/02;H04Q3/00;H04Q3/72 |
主分类号 |
H04Q1/32 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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