发明名称 |
Constant current line circuit with class features |
摘要 |
A line circuit utilizing a differential amplifier whose output is regulated to zero volts D.C. (when the subscriber's set is off-hook) by a negative feedback circuit, for controlling a voltage controlled power supply which provides a constant current feed to the subscriber's loop. The differential amplifier also transmits audio signals received from the subscriber's loop directly to a PABX via an unbalanced terminal. When the loop range exceeds a predetermined threshold, the circuit reverts to a voltage feed operation thereby allowing operation over long loop lengths and the ability to provide on-hook CLASS services.
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申请公布号 |
US6865271(B2) |
申请公布日期 |
2005.03.08 |
申请号 |
US20010822943 |
申请日期 |
2001.03.30 |
申请人 |
MITEL NETWORKS CORPORATION |
发明人 |
SETO CHUK |
分类号 |
H04M19/00;(IPC1-7):H04M19/00 |
主分类号 |
H04M19/00 |
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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