Terminal repeater having a function for repeating DC loop signal

A terminal repeater placed in at least one communication line connecting an exchange with at least one terminal device, said terminal device having means for generating a first DC loop signal in response to the connecting condition of a DC loop formed on the communication line, and for supplying said first DC loop signal to said exchange, the terminal repeater comprising;

• DC cut-off means for passing AC signals flowing through said communication line and cutting off DC signals flowing through said communication line;
• DC power supply means, provided between said DC cut-off means and said terminal device, for supplying a DC power to said terminal device through said communication line between said DC cut-off means and said terminal device, said DC power corresponding to a DC power supplied through said communication line from said exchange;
• DC loop signal detecting means for comparing a threshold level with a level of said first DC loop signal transmitted from said terminal device to said exchange, to generate a DC loop detecting signal corresponding to said first DC loop signal;
• DC loop signal transmitting means for generating a second DC loop signal analogous to said first DC loop signal transmitted from said terminal device in response to said DC loop detecting signal derived from said DC loop signal detecting means, through the communication line between said DC cut-off means and said exchange, and transmitting said second DC loop signal to said exchange;
• DC level detecting means, provided between said DC cut-off means and said terminal device, for detecting a DC level of the communication line connected to said terminal device and for producing a DC level detecting signal;
• threshold control means for setting said threshold level to a value lower by a predetermined value than the DC level of said communication line, in accordance with each DC level detecting signal produced by said DC level detecting means;
• and
• data transmitting means for transmitting numerical data representing the threshold level set by said threshold control means.

A terminal repeater placed in at least one communication line connecting an exchange with at least one terminal device, said terminal device having means for generating a first DC loop signal in response to the connecting condition of a DC loop formed on the communication line, and for supplying said first DC loop signal to said exchange, the terminal repeater comprising:

• DC cut-off means for passing AC signals flowing through said communication line and cutting off DC signals flowing through said communication line;
• DC power supply means, provided between said DC cut-off means and said terminal device, for supplying a DC power to said terminal device through said communication line between said DC cut-off means and said terminal device, said DC power corresponding to a DC power supplied through said communication line from said exchange;
• DC loop signal detecting means for comparing a threshold level with a level of said first DC loop signal transmitted from said terminal device to said exchange, to generate a DC loop detecting signal corresponding to said first DC loop signal;
• DC loop signal transmitting means for generating a second DC loop signal analogous to said first DC loop signal transmitted from said terminal device in response to said DC loop detecting signal derived from said DC loop signal detecting means, through the communication line between said DC cut-off means and said exchange, and transmitting said second DC loop signal to said exchange;
• line current detecting means for detecting a line current of the communication line connecting said terminal device and producing a line current detecting signal;
• and
• DC power control means for controlling a DC power supplied from said DC power supply means within a predetermined value in accordance with the line current detecting signal derived from said line current detecting means.

A terminal repeater placed in at least one communication line connecting an exchange and at least one terminal device, said terminal device having means for generating a first DC loop signal in response to the connecting condition of a DC loop formed on the communication line, and for supplying said first DC loop signal to said exchange, the terminal repeater comprising:

• DC cut-off means for passing AC signals flowing through said communication line and cutting off DC signals flowing through said communication line;
• DC power supply means, provided between said DC cut-off means and said terminal device, for supplying a DC power to said terminal device through said communication line between said DC cut-off means and said terminal device, said DC power corresponding to a DC power supplied through said communication line from said exchange;
• DC loop signal detecting means for comparing a threshold level with a level of said first DC loop signal transmitted from said terminal device to said exchange, to generate a DC loop detecting signal corresponding to said first DC loop signal;
• Dc loop signal transmitting means for generating a second DC loop signal analogous to said first DC loop signal transmitted from said terminal device in response to said DC loop detecting signal derived from said Dc loop signal detecting means, through the communication line between said DC cut-off means and said exchange, and transmitting said second DC loop signal to said exchange;
• line current detecting means for detecting a line current of the communication line connecting said terminal device and producing a line current detecting signal;
• threshold control means for controlling said threshold level in accordance with the line current detecting signal derived from said line current detecting means;
• and
• DC power control means for controlling a DC power supplied from said DC power supply means within a predetermined value in accordance with the line current detecting signal derived from said line current detecting means.

A communication network system comprising:

• an exchange;
• a terminal device connected to said exchange through a first communication line and having means for generating a first DC loop signal in response to a connecting condition of a DC loop formed on the first communication line, and for supplying the first DC loop signal to the exchange;
• at least one terminal repeater arranged in said first communication line, and including:
• DC cut-off means for passing AC signals flowing through said first communication line and for cutting off DC signals flowing through said first communication line;
• DC power supply means, provided between said DC cut-off means and said terminal device, for supplying DC power to said terminal device through said first communication line between said DC cut-off means and said terminal device, the amount of said DC power corresponding to an amount of DC power supplied through said first communication line from said exchange;
• DC loop signal detecting means for comparing a threshold level with a level of said first DC loop signal transmitted from said terminal device to said exchange, and for generating a DC loop detecting signal corresponding to said first DC loop signal;
• DC loop signal transmitting means for generating a second DC loop signal analogous to said first DC loop signal transmitted from said terminal device in response to said DC loop detecting signal derived from said DC loop signal detecting means through said first communication line between said DC cut-off means and said exchange, and for transmitting said second DC loop signal to said exchange;
• DC level detecting means, provided between said DC cut-off means and said terminal device, for detecting a DC level of said first communication line connected to said terminal device;
• information transmitting means for transmitting information corresponding to the DC level of said first communication line detected by the DC level detecting means;
• and
• an information receiving device arranged outside said terminal repeater, connected to the terminal repeater through a second communication line, and including;
• receiver means for receiving the information transmitted from said terminal repeater through said second communication line;
• and
• means for outputting the information received by said receiver means as data for controlling the communication network system.