| Title of Invention | SUBSCRIBER-TERMINAL CIRCUIT |
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| Abstract | This invention relates to a Subscriber-terminal circuit for the connection of an analog subscriber line (TL) to a digital time-division multiplex telephone exchange, characterized in that an interface circuit (SLIC2) which is equipped for performing test functions, and also carrying a multifunctional relay circuit (MR), which has two change-over contacts (u1, u2), with the aid of which the interface circuit ( SLIC2) can be disconnected from the wires (a, b) of the subscriber line (TL) and can be connected instead to a test circuit (TS), and which also serves during operations other than those concerning the performance of a test function for disconnecting the subscriber line from the interface circuit ( SLIC2). |
| Full Text | - 1A- This invention relates to subscriber terminal circuit. The invention further relates to a subscriber terminal circuit for the connection of an analog subscriber terminal to a digital time-division multiplex telephone exchange. In spite of the trend with subscriber terminal circuits of modern digital time-division multiplex telephone exchanges towards semiconductor solutions which are as complete as possible and towards integration of the components, there remain functions which, for technological reasons and reasons of cost, continue as before to be performed using relays. These include disconnection functions, in which the wires of the subscriber line are disconnected from the subscriber-line circuit. Such disconnection comes into consideration in the case of the "Precut over" feature, in which entire groups of subscriber-line circuits have to be disconnected from the main distribution frame during the installation of a new exchange. It also comes into consideration in the case of the "Power Cross" feature, in which the subscriber line is disconnected from the subscriber-line circuit because of the occurrence of inadmissibly high interfering voltages on the line, in order to prevent the overvoltages affecting the semiconductor elements of the subscriber-line circuit. Another of the functions performed by means of relays is that of test access to the subscriber-line circuit and to the wires of the subscriber line by a testing device. In the case of existing solutions, three separate relays are used for the relay functions mentioned, one for disconnecting the wires of the subscriber line in the case of the Precut over and Power Cross functions and two relays for the test access, one of which serves for connecting the testing device to the subscriber-line .... - 2 - circuit, while disconnecting the subscriber line from the inputs of the subscriber-line circuit, so that a check can be carried out on the operation of the subscriber-line circuit, and the other of which serves for connecting the testing device to the subscriber line, likewise while disconnecting the subscriber line from the subscriber-line circuit, in order to be able to carry out a check on the subscriber line. The object of the invention is to reduce the effort required for performing the relay functions mentioned. This object is achieved by a subscriber-line circuit having the features specified in Patent Claim 1. In the case of the subscriber-line circuit according to the invention, just a single switching relay is required for the said relay function, this relay consequently being as it were a multifunctional relay. This is made possible ,by the fact that the subscriber-line circuit is such that it can itself perform test functions. As a consequence of this, in the simplest case a resistor suffices as the test circuit which, according to the invention, is connected by means of the relay to the subscriber-line circuit when performing tests. The invention is explained in more detail below on the basis of an exemplary embodiment with reference to accompanying Figure. In the Figure, the only elements of a subscriber-line circuit having the features according to the invention that are indicated are its interface part SLIC2, the multifunctional relay circuit MR, provided according to the invention, and a test circuit TS. The interface part SLIC2 is divided in practice into a high-voltage part and into a low-voltage/signal-processor part. In the high-voltage part there are performed essentially the functions of feeding programmable feeding characteristics to the subscriber line in the idle state and call state and of detecting the current on the wires a and b of the subscriber line. Important functions of - 3 - the low-voltage/signal-processor module are the programmable fixing of relative transmitting and receiving levels, the realizing of a programmable input impedance, the performance of the 2/4-wire conversion with programmable balancing impedance and the coding/decoding of the voice signals. In the case of the subscriber-line circuit according to the invention, apart from the functions referred to, there are performed in the interface part SLIC2 test functions concerning not only a self-test of the subscriber-line circuit but also checking of the subscriber line for interruption of the line or earth faults of the line wires and a check of the subscriber terminal connected to the subscriber line. The multifunctional relay MR provided according to the invention has two change-over contacts ul and u2, with the aid of which the a-wire and the b-wire of the subscriber line can be disconnected from the inputs al and bl of the interface-part SLIC2 of the subscriber-line circuit and these inputs al and a2 can be connected instead to a test, circuit TS. In the simplest case, the test circuit TS may comprise a single resistor, by which, in the case of connection, the inputs al and bl of the interface part SLIC2 of the subscriber circuit are connected to each other. The multifunctional relay circuit serves on the one hand during the Precut over and Power Cross functions for the purpose of disconnecting the subscriber-line circuit or its part SLIC2 from the wires of the subscriber line. The fact that, during this disconnection, the test circuit TS is connected to the inputs al and bl of the subscriber-line circuit is of no significance in this case. During the performance of tests by the test functions integrated in the interface part SLIC2 of the subscriber-line circuit, first of all, for performing a self-test, by actuating the multifunctional relay MR the wires of the subscriber line are disconnected from the -4- inputs al and bl and the test circuit is connected to these inputs, which in the abovementioned simplest case of their embodiment simply effects a connection of the inputs al and bl via a resistor. For the performance of more complex self-tests, the test circuit may also be of a more complex construction, to be specific represent a passive network with complex resistance behaviour. For performing the actual tests concerning the subscriber line and the subscriber terminal, in the other switched position of the multifunctional relay circuit MR the wires a and b of the subscriber line are again connected to the inputs al and a2, whereas the test circuit TS is disconnected and out of operation in this stage of the test. In configurations of the exchange area of a digital telephone exchange in which the subscriber-line circuits are combined in groups, the test circuit may be provided only group-individually instead of line-individually, in which case there is a group-internal test bus, to which the group-individual test circuit is connected and by means of which the line-individual multifunctional relay circuits establish a connection. -5- We Claim: 1. Subscriber-terminal circuit for the connection of an analog subscriber line (TL) to a digital time-division multiplex telephone exchange, characterized in that an interface circuit (SLIC2) which is equipped for performing test functions, and also carrying a multifunctional relay circuit (MR), which has two change-over contacts (u1, u2), with The aid of which the interface circuit (SLIC2) can be disconnected from the wires (a, b) of the subscriber line (TL) and can be connected instead to a test circuit (TS), and which also serves during operations other than those concerning the performance of a test function for disconnecting the subscriber line from the interface circuit (SLIC2). 2. Subscriber-line circuit as claimed in claim 1, wherein the test circuit (TS) comprises a passive network with complex resistance behaviour, by means of which, when the circuit is connected, the inputs (a1, bl) of the interface circuit (SLIC2) which have been disconnected from the wires of the subscriber line are connected to each other. This invention relates to a Subscriber-terminal circuit for the connection of an analog subscriber line (TL) to a digital time-division multiplex telephone exchange, characterized in that an interface circuit (SLIC2) which is equipped for performing test functions, and also carrying a multifunctional relay circuit (MR), which has two change-over contacts (u1, u2), with the aid of which the interface circuit ( SLIC2) can be disconnected from the wires (a, b) of the subscriber line (TL) and can be connected instead to a test circuit (TS), and which also serves during operations other than those concerning the performance of a test function for disconnecting the subscriber line from the interface circuit ( SLIC2). |
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01718-cal-1997 correspondence.pdf
01718-cal-1997 description(complete).pdf
01718-cal-1997 letters patent.pdf
01718-cal-1997 priority document.pdf
1718-cal-1997-granted-abstract.pdf
1718-cal-1997-granted-acceptance publication.pdf
1718-cal-1997-granted-claims.pdf
1718-cal-1997-granted-correspondence.pdf
1718-cal-1997-granted-description (complete).pdf
1718-cal-1997-granted-drawings.pdf
1718-cal-1997-granted-examination report.pdf
1718-cal-1997-granted-form 1.pdf
1718-cal-1997-granted-form 2.pdf
1718-cal-1997-granted-form 3.pdf
1718-cal-1997-granted-form 5.pdf
1718-cal-1997-granted-letter patent.pdf
1718-cal-1997-granted-priority document.pdf
1718-cal-1997-granted-reply to examination report.pdf
1718-cal-1997-granted-specification.pdf
1718-cal-1997-granted-translated copy of priority document.pdf
| Patent Number | 193123 | |||||||||
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| Indian Patent Application Number | 1718/CAL/1997 | |||||||||
| PG Journal Number | 30/2009 | |||||||||
| Publication Date | 24-Jul-2009 | |||||||||
| Grant Date | 07-Jan-2005 | |||||||||
| Date of Filing | 17-Sep-1997 | |||||||||
| Name of Patentee | SIEMENS AKTIENGESELLSCHAFT | |||||||||
| Applicant Address | WITTELSBACHERPLATZ 2, 80333 MUNCHEN | |||||||||
Inventors:
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| PCT International Classification Number | H04M 001/24 | |||||||||
| PCT International Application Number | N/A | |||||||||
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