发明名称 |
TELEPHONE LINE INTERFACE CIRCUIT |
摘要 |
A circuit for coupling digital or analog data signals to a telephone line. A direct coupled transistorized circuit is disclosed having three different impedance conditions: on-hook, off-hook, and loop-test. Consequently, data can be transmitted regardless of the on-hook or off-hook status of the associated telephone sets and regardless of whether or not the telephone sets are in use. In addition, data transmission can range over a frequency spectrum of approximately d-c to frequencies in the data-over-voice range. Because of the variable bridging impedance, the drive impedance is not too low during on-hook ringing and the circuit need not be disconnected during ringing or testing. |
申请公布号 |
DE3378558(D1) |
申请公布日期 |
1988.12.29 |
申请号 |
DE19833378558 |
申请日期 |
1983.06.14 |
申请人 |
APPLIED SPECTRUM TECHNOLOGIES, INC. |
发明人 |
MOSES, DONALD W.;HUSTIG, CHARLES;BALLARD, RAY C. |
分类号 |
H04Q3/42;H04M11/06;H04Q3/72;(IPC1-7):H04M11/06 |
主分类号 |
H04Q3/42 |
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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