Station checking network for telecommunication system
First Claim
1. In a telecommunication system with a terminal, at least one link with an outgoing branch and an incoming branch originating at said terminal, a local line with a transmitting branch and a receiving branch extending between said terminal and a subscriber station, connector means at said terminal for respectively coupling the transmitting and receiving branches of said local line to the outgoing and incoming branches of said link to facilitate the exchange of messages between said local line and a remote junction, and switching means at said subscriber station with a plurality of positions corresponding to different operational modes, the combination therewith of mode-checking means comprising:
- a source of direct current at said terminal;
conductor means for inserting said source in a phantom circuit extending by way of said transmitting and receiving branches of said local line to said subscriber station, said phantom circuit including said switching means and further including impedance means at said subscriber effective in different position of said switching means to vary the magnitude of a direct current flowing from said source through said phantom circuit;
current-sensing means connected to said phantom circuit at said terminal for discriminating between direct currents of different levels indicative of said different operational modes , andswitchover means connected to said source at said terminal for reversing the polarity of said direct current;
said impedance means including two oppositely poled diodes respectively insertable in said phantom circuit in different positions of said switching means.
1 Assignment
0 Petitions
Accused Products
Abstract
A marker at a central-office terminal, controlling the establishment of connections between local subscriber lines and inter-office links via an associated line concentrator/distributor, includes a source of d-c test signals of reversible polarity connectable in a phantom circuit which extends from the central office via a transmitting and a receiving branch of a local line to a subscriber station tied to that line. The subscriber station has a master switch, establishing either an inactive position or a standby position, and a hook switch closable in the standby position to initiate or accept a call. Depending on the positions of these two switches, a current discriminator at the marker detects one of three current levels (zero, low or high) with either polarity of the test signal to determine whether a call can go through or whether an alarm condition exists.
33 Citations
15 Claims
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1. In a telecommunication system with a terminal, at least one link with an outgoing branch and an incoming branch originating at said terminal, a local line with a transmitting branch and a receiving branch extending between said terminal and a subscriber station, connector means at said terminal for respectively coupling the transmitting and receiving branches of said local line to the outgoing and incoming branches of said link to facilitate the exchange of messages between said local line and a remote junction, and switching means at said subscriber station with a plurality of positions corresponding to different operational modes, the combination therewith of mode-checking means comprising:
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a source of direct current at said terminal;
conductor means for inserting said source in a phantom circuit extending by way of said transmitting and receiving branches of said local line to said subscriber station, said phantom circuit including said switching means and further including impedance means at said subscriber effective in different position of said switching means to vary the magnitude of a direct current flowing from said source through said phantom circuit;current-sensing means connected to said phantom circuit at said terminal for discriminating between direct currents of different levels indicative of said different operational modes , and switchover means connected to said source at said terminal for reversing the polarity of said direct current; said impedance means including two oppositely poled diodes respectively insertable in said phantom circuit in different positions of said switching means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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- 9. In a telecommunication system with a terminal, at least one link with an outgoing branch and an incoming branch originating at said terminal, a local line with a transmitting branch and a receiving branch extending between said terminal and a subscriber station, connector means at said terminal for respectively coupling the transmitting and receiving branches of said local line to the outgoing and incoming branches of said link to facilitate the exchange of messages between said local line and a remote junction, and switching means at said subscriber station with a plurality of positions corresponding to different operational modes, the combination therewith of mode-checking means comprising:
- 10. a source of direct current at said terminal;
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11. conductor means for inserting said source in a phantom circuit extending by way of said transmitting and receiving branches of said local line to said subscriber station, said phantom circuit including said switching means and further including impedance means at said subscriber station effective in different positions of said switching means to vary the magnitude of a direct current flowing from said source through said phantom circuit;
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current-sensing means connected to said phantom circuit at said terminal for discriminating between direct currents of different levels indicative of said different operational modes; a first transformer at said terminal coupling said transmitting branch to said outgoing branch; and a second transformer at said terminal coupling said incoming branch to said receiving branch; said transmitting branch including a first pair of leads connected across a primary winding of said first transformer, said receiving branch including a second pair of leads connected across a secondary winding of said second transformer, said conductor means connecting said source across respective center taps of said primary and secondary windings, said connector means being inserted in said leads.
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Specification