发明名称 |
LOW RESISTANCE ORIGINATION SCAN CIRCUIT |
摘要 |
<p>LOW RESISTANCE ORIGINATION SCAM CIRCUIT An origination scan circuit for detecting circuit closure state in a loop circuit has a much lower impedance than does the typical loop circuit. Its source impedance is split into separate resistive parts for connecting opposite terminals of an office battery to the tip and ring leads of the loop. Currents in the separate resistive parts are sensed and summed for comparison against a threshold current to indicate whether or not a subscriber station on the loop is off hook. Threshold current magnitude is variable to accommodate loop start and ground start applications. When the off-hook state is detected, the origination scan circuit is disabled by switching open the resistive part connections, and loop current is thereafter provided by other suitable means. Automatic current limiting arrangements are included for converting the switching functions to high impedance circuit elements.</p> |
申请公布号 |
CA1238733(A) |
申请公布日期 |
1988.06.28 |
申请号 |
CA19850490921 |
申请日期 |
1985.09.17 |
申请人 |
AMERICAN TELEPHONE AND TELEGRAPH COMPANY |
发明人 |
ARNTSEN, TOM D.;EMBREE, MILTON L.;HAVENS, JOSEPH H.;TOUMANI, ROUBEN |
分类号 |
H04Q3/72;H04M3/22;(IPC1-7):H04M3/22 |
主分类号 |
H04Q3/72 |
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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