Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Testing of network terminating interface – subscriber trunk...
Reexamination Certificate
1998-08-25
2001-05-15
Le, Huyen (Department: 2643)
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Testing of network terminating interface, subscriber trunk...
C379S022000, C379S027010, C379S031000
Reexamination Certificate
active
06233312
ABSTRACT:
BACKGROUND OF THE INVENTION
1. This invention relates to a method for locating circuit to circuit faults in a telecommunications network and also to a fault location system for locating circuit to circuit faults in the terminating circuits of a telecommunications network.
2. Related Art
A conventional public telecommunications network comprises a relatively small number of interconnected main switches and a much larger number of local switches, each of which is connected to one or two main switches. The local switches are connected to the terminating circuits of the network and the far ends of these circuits are connected to terminal equipment such as telephone instruments provided for users of the network. The network formed from the main switches and local switches is known as the core network while a network formed from the terminating circuits is known variously as an access network or a local loop. In this specification, it will be referred to as an access network. Some terminating circuits are connected to a remote concentrator, which may or may not have switching capability. The remote concentrator is then connected to a local switch. In this specification, the term “local switch” is to be interpreted to cover both local switches and remote concentrators.
In a conventional access network, each terminating circuit is formed from a pair of copper wires. Typically, each pair of copper wires passes through a series of nodes between the local switch and terminal equipment. Examples of such nodes are primary cross-connect points, secondary cross-connect points, distribution points and joints.
Unfortunately, terminating circuits are prone to faults. In the case of a terminating circuit carried by a pair of copper wires, example of such faults are disconnection, a short circuit between two wires of a pair of wires and a short circuit between one of the wires and earth. In the case of a conventional access network formed from pairs of wires, the causes of the faults include ingress of water into a node and also physical damage to a node.
Local switches are each provided with a line test apparatus which may be used to test its terminating circuits. Such test systems are useful for detecting and locating faults in individual terminating circuits. However, the present practice suffers from the disadvantage that current line test apparatus are notoriously bad at correctly locating pair-pair faults. Current techniques involve testing only one pair. The measurements on a pair suffering from a circuit to circuit fault can determine that a fault exists, but they cannot give any indication as to the location of the fault within the access network. It is time consuming for an engineer to have to open several nodes before locating and repairing a fault. Furthermore, as the nodes are of a delicate construction, each time an engineer opens a node he may damage the node with the result that there is another fault on a terminating circuit.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a method of locating a fault in a telecommunications network, said network including a local switch and a set of circuits extending between the local switch and terminating equipment provided for users of the network, each of said terminating circuits passing through a series of nodes between said local switch and its terminating equipment, said method comprising the steps of:
generating a test signal on a particular circuit;
accessing a routing database to determine the identity of all circuits which are adjacent to said particular circuit at any point between the local switch and the terminal equipment associated with said particular circuit;
testing all such adjacent circuits for the presence of said test signal to determine a set of circuits exhibiting the test signal; and
using the set to locate any fault between said particular circuit and another circuit.
Preferably in said step of using the set to locate any fault, a fault is located by determining the furthest point from the local switch where said set of circuits are adjacent to the particular circuit.
The test signal may be a speech band signal and optionally may be a pseudo random binary sequence.
According to another aspect of the present invention, there is provided a fault location system for locating circuit to circuit faults in a telecommunications network including a local switch and a set of terminating circuits extending between the local switch and terminal equipment provided for users of the network, each of said terminating circuits passing through a series of nodes between said local switch and its respective terminal equipment, said fault location apparatus comprising:
signal generating apparatus arranged to send a test signal along an individual terminating circuit;
signal detecting apparatus arranged to detect the presence of said test signal on terminating circuits;
a store containing data relating to the routing of said terminating circuits through said nodes; and
means for controlling said test signal generating apparatus and said test signal detecting apparatus, said control means being arranged to:
instruct said test signal generating apparatus to generate a test signal on a particular circuit;
access said store to determine the identity of all circuits which are adjacent to said particular circuit at any point between the local switch and the terminal equipment associated with said particular circuit;
instruct the test signal generating apparatus to test all such adjacent circuits for the presence of said test signal to determine a set of circuits exhibiting the test signal; and
use the set to locate any fault between said particular circuit and another circuit.
Preferably the fault location system locates faults on terminating circuits from a location remote from the local switch.
Preferably a fault is located by determining the furthest point from the local switch where said set of circuits are adjacent to the particular circuit.
The signal generation apparatus generates a speech band test signal and the test signal may be a pseudo random binary sequence.
In a preferred embodiment the fault location system carries out said tests using common channel signalling.
The fault location system may be an interactive speech applications platform.
This invention provides a new technique which will augment current measurements, to provide additional information for the location of such pair-pair faults.
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British Telecommunications public limited company
Le Huyen
Nixon & Vanderhye P.C.
Tran Quoc D.
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