Language selection

Search

Patent 2203276 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2203276
(54) English Title: A METHOD AND APPARATUS FOR TESTING LINES IN A TELECOMMUNICATIONS NETWORK
(54) French Title: PROCEDE ET APPAREIL POUR TESTER DES LIGNES DANS UN RESEAU DE TELECOMMUNICATIONS
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • H04M 3/28 (2006.01)
  • H04M 3/30 (2006.01)
(72) Inventors :
  • CHASKELL, ANDREW DAVID (United Kingdom)
(73) Owners :
  • BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY (United Kingdom)
(71) Applicants :
  • BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY (United Kingdom)
(74) Agent: GOWLING WLG (CANADA) LLP
(74) Associate agent:
(45) Issued: 2000-02-29
(86) PCT Filing Date: 1995-11-30
(87) Open to Public Inspection: 1996-06-20
Examination requested: 1997-04-21
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/GB1995/002802
(87) International Publication Number: WO1996/019072
(85) National Entry: 1997-04-21

(30) Application Priority Data:
Application No. Country/Territory Date
94309390.6 European Patent Office (EPO) 1994-12-15

Abstracts

English Abstract




The invention provides a method and apparatus for testing a telecommunications
network (1 to 12) in order to determine an approximate location of a fault.
The method comprises measuring a change in capacitance of a line in the
network and then determining from a known ratio of capacitance to length of
line a length of line that corresponds to that change. This length will give
an approximate location of a fault from a subscriber's equipment located at
premises (1).


French Abstract

L'invention concerne un procédé et un appareil pour tester un réseau de télécommunications (1 à 12) afin de déterminer un emplacement approximatif d'un défaut. Le procédé consiste à mesurer un changement de la capacité d'une ligne dans le réseau et ensuite à déterminer, à partir d'un rapport connu entre la capacité et la longueur d'une ligne, une longueur de ligne qui correspond à ce changement; Cette longueur va donner un emplacement approximatif d'un défaut à partir d'un équipement d'abonné se trouvant dans les locaux (1).

Claims

Note: Claims are shown in the official language in which they were submitted.






CLAIMS

1. A method of testing a telecommunications network for the presence of afault, said method comprising the steps of:
determining a first capacitance value of a line of the network at a first
time;
storing the first capacitance value;
determining a second capacitance value of the line at a second time;
determining from the first and second capacitance values a value for a
change in capacitance value;
comparing the change in capacitance value with a threshold value so as to
detect the present of a fault; and
if the threshold value is exceeded, determining from the change in
capacitance value and a known capacitance length ratio a corresponding length ofline and hence the distance of the fault from terminating equipment at the end of
the line remote from the point of measuring the capacitance values.

2. An apparatus for testing at least one line of a telecommunications network
for the presence of a fault, said apparatus comprising:
means for measuring the capacitance value of a line of the network at a
first time to obtain a first capacitance value;
means for measuring the capacitance value of said line at a second time to
obtain a second value;
means for determining a change in capacitance value from the first and
second capacitance values;
mean for comparing said change in capacitance value with a threshold
value so as to detect a fault; and
means for determining from the change in capacitance value and a known
capacitance length ratio a corresponding length of line and hence the distance of
the fault from terminating equipment at the end of the line remote from the point
of measuring the capacitance values.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02203276 1997-04-21



A METHOD AND APPARATUS FOR TESTING A TELE~OMMUNICATIONS
NFTWORK

This invention relates to a method and apparatus for testing a
5 telecommunications network.
When describing a public telecommunications network it is usual to
subdivide the network into two parts a first part being a core network and the
other part being an access network. The access network is that part of the
network which extends from a subscriber's equipment to a local telephony
10 exchange. The access network includes telephone poles, drop wires, cables,
junction boxes, primary cross connection points and secondary cros~-connection
points which are familiar features o-f the urban and rural landscapes. These are the
components which are most exposed to the elements and a large number of faults
can occur in this part of the network as a consequence. ~The core network
15 includes the local and trunk exchanges.
US Patent 4 103 225 describes an apparatus for measuring the
capacitance of a telephone cable in order to determine the distance of an open
circuit fault from a measurement point.
In the past network operators have relied upon subscribers to report faults.
20 This may take place some time after the fault has occurred because some
subscribers on!y use their equipment infrequently.
According to one aspect of the invention there is provided a method of
testing a method of testing a telecommunications network for the presence of a
fault, said method comprising the steps of:
determining a first capacitance value of a line of the network at a first
time;
storing the first capacitance value;
determining a second capacitance value of the line at a second time;
determining from the first and second capacitance values a value for a
change in capacitance value;
comparing the change in capacitance value with a threshold value so as to
detect the present of a fault; and


~MENDED SHEET

CA 02203276 1997-04-21



if the threshold value is exceeded, determining from the change in
capacitance value and a known capacitance length ratio a corresponding length ofline and hence the distance of the fault from terminating equipment at the end of
the line remote from the point of measuring the capacitance values.
The corresponding length of line will be a change in length of that part of
the line which is operational. This change in length will be due to a fault occurring
between the subscriber's equipment and the exchange. The fault may be caused
by an increase in series resistance in the line due, for example, to corrosion, or the
fault may be due to a break or disconnection in the line. Such faults have the
10 effect of cutting-off the subscribers equipment. Where the series resistance
increases gradually, the quality of transmission over the line will deteriorate
gradually until the equipment is effectively cut-off. In the case of a break or
disconnection, the cut-off will be immediate. The change in length will be
indicative of the location of the fault. The fault will be located by determining a
15 position along the line from the subscriber's equipment equal to the determined
change in length of line.
By monitoring the line in this way it is possible to detect and rectify faults
before a subscriber discovers a fault exists. This greatly enhances the subscriber's
perceived view of the service.
According to another aspect of the invention, there is provided an
apparatus for testing at least one line of a telecommunications network for the
presence of a fault, said apparatus comprising:
means for measuring the capacitance value of a line of the network at a
first time to obtain a firs~ capacitance value;
means for measuring the capacitance value of said line at a second time to
obtain a second value;
means for determining a change in capacitance value from the first and
second capacitance values;
mean for comparing said change in capacitance value with a threshold
30 value so as to detect a fault; and
means for determining from the change in capacitance value and a known
capacitance length ratio a corresponding length of line and hence the distance of
the fault from terminating equipment at the end of the line remote from the point
of measuring the capacitance values.

~QENDED SHEET

CA 02203276 1997-04-21

2a : . ` ' ~ ;


A specific embodiment of the invention will now be described, by way of
example only, with reference to the drawings in which:-
Figure 1 shows in schematic form part of a telecommunications networkfrom a local exchange to a subscriber's premises, the exchange including testing
5 equipment in accordance with the invention;
Figure 2 shows in schematic block diagram form the testing equipment
shown in Figure 1; and
Figure 3 is a flowchart illustrating the operation of the testing equipment
shown in figure 1.
Part of a public telecommunications network is shown in Figure 1 and it
comprises a subscriber's network terminating equipment located at a subscriber'spremises 1, a drop wire 2 connected between the subscriber's equipment and a
pole mounted distribution point (DP) 3, a cable 4 extending from the DP 3 to a
secondary cross connection point (SCP) 5, further cables generally indicated at 6
15 extending from other DPs (not shown) to the SCP 5, a cable 7 extending from the
SCP 5 to a primary cross connection point 8, further cables generally indicated at
9 extending from other SCPs not shown and the PCP 8, a cable 10 extending from
the PCP 8 to a local area exchange 11, a trunk cable 12 linking the local area
exchange 1 1 to other exchanges (not shown), and test equipment 13 located in
20 the exchange 11. The part of the network between customers' equipment and the local exchange is known as the access network.




AMENDEL~ sHEET

CA 02203276 1997-04-21



The drop wire 2 comprises a pair of copper wires held parallel and apart by
an insulating sheath. The individual wires are called "legs". There is an A leg and
a B leg. The DP 3 usually serves up to eight or so houses.
The wire pairs continue from the DP 3 as part of the cable 4. Thus the
5 cable 4 could include eight or more wire pairs plus a further eight or more spare
pairs making a total of typically twenty wire pairs. Similarly, each of the other
cables 6 could include twenty wire pairs.
In a similar way, the cable 7 will carry about eighty wire pairs and cable
10 about two hundred and forty wire pairs.
The PCP 8 and the SCP 5 are in effect junction boxes which are usually in
the form of streetside cabinets or posts.
The access network may be conveniently split into two parts. An
exchange side which is that part of the network situated between the PCP 8 and
the exchange 11 and a distribution side which is that part of the network between
15 the PCP 8 and the subscribers' network terminating equipment. The exchange
side may extend for many kilometres. Thus the cable 10 may be many kilometres
long. The distribution side is normally less than this distance say about one or two
kilometres in length.
Figure 2 shows in greater detail the test equipment 13 used to detect
20 faults on the wire pairs. This includes a capacitance measuring device 14
connected to the wire pairs that form the cable 10 and a computer 15.
The computer 15 includes a processor 16, an input/output device 17, an
output device 18 and memory 19. The input/output device 17 is in this case an
input/output port to which the capacitance measuring device 14 passes values of
2~ capacitance and from which the capacitance measuring device 14 receives
instructions from the processor 16. These values pass to the processor 16 along a
databus in a manner well known.
Memory 19 is of a type that can be read and also written to such as
Random Access Memory RAM. It holds instructions which can be accessed and
30 acted on by the processor 16. (The instructions are held in accessible memorylocations which can be addressed by the processor 16). The processor 16 is also
able to store data in the memory by writing the data into a memory location. The19 may take the form of a hard disc, silicon chips or other memory

CA 02203276 1997-04-21



device. The data flows between l:he memory 19 and the processor 16 along a
databus 21 in a well known manner.
The output device 18 is a device for displaying information generated by
the processor 16 and typically could include a Visual Display Unit (VDU) and/or a
5 printer. Alternatively, it may be a device for transmitting the information toanother location which accepts and then processes the information from a number
of exchanges. The information may then be collated and used to generate
instructions for service personnel.
The capacitance measuring device 14 may take any convenient form but it
10 must be capable of monitoring the large number of wire pairs on the cable. One
way in which this could be achieved is by including means to sequentially or
randomly connect the device to each wire pair.
The instructions for which wire pair to test come from the processor 16
via the input/output device 17 or could be generated by the means to connect the15 device to each wire pair. If the latter alternative is adopted, capacitance values
passed by the capacitance measuring device 14 would have to be accompanied by
information identifying the wire pair being tested that is to say the wire pair having
that capacitance value. (It may be convenient to do this even if the processor 16
instructs the capacitance measuring device 14 which wire pair to test).
As earlier described, the processor 16 acts in accordance with processor
instructions stored in memory locations of memory 19. A more detailed
explanation will now be given wi1:h reference to an illustrative flowchart of the
operation of the testing equipment which is shown in figure 3.
A first step 30 in the operation is system initialisation. The next step 31
is for the processor 16 to instruct the capacitance measuring device 14 to measure
the capacitance of the first wire pair.
In a step 32, the capacitance measuring device 14 then measures the
capacitance C of the wire pair. This value is passed via the input/output device 17
to the processor 16 where it is held in short term memory (not shown).
In a step 33, the processor 16 then decides whether this is the first pass
through the steps shown in Figure 3. Since it is the first pass, in a step 34 the
value of C is stored in memory 19 as old C together with a wire pair identifier.


~MENDED SHEET

CA 02203276 1997-04-21
5 ,


In a step 35, the processor 16 considers whether that wire pair is the last
wire pair. If it is not the last wire pair, then a return is made to step 31 and the
next wire pair is selected. The series of steps described above are then repeated.
Thus, after measuring the capacitance C of the last wire pair, the memory
19 will hold wire pair identifiers and associated values of old C for all the selected
wire pairs. Then, in a step 40, the processor 16 waits for a time internal T. T
may be any time interval but, in this case, it is twenty four hours.
After twenty four hours, a return is made to step 31 and the first wire pair
is again selected. Then, in step 32, the capacitance of the first wire pair is
10 measured. Then, in step 33, since this is not the first pass, it is decided that the
next step will be step 36. In step 36, the newly measured value of C is comparedby the processor 16 with the old C stored in the memory 19 for the same wire
pair. The difference of the values is determined that is to say, old C - C.
The difference is then compared in a step with a predetermined threshold
15 value stored in memory 19 in order to determine whether it represents a significant
difference. (A significant difference being one which is caused by a fault on the
wire pair as opposed to a minor variation perhaps caused by climatic conditions
which does not perceivably affect the service experienced by a subscriber).
From the difference, in a step 38 a difference in the length of the wire pair
20 is determined by the processor 16, the wire pair having a known relationship of
capacitance per unit length. This difference in the length of the wire is the
distance of the fault from the subscribers' terminating equipment.
The processor 16 outputs this data along with a wire identifier such as a
telephone number to the output device 19 where it is displayed.
The newly measured value of C is then stored in a step 39 as old C by
overwriting the previous old C value. The process is repeated for the next wire
pair.
Thus a printout of faulty telephone lines is printed out together with the
distance of the fault from the subscriber's terminating equipment.
Service personnel may then be dispatched to rectify the faults.




~MENDED SHEET

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2000-02-29
(86) PCT Filing Date 1995-11-30
(87) PCT Publication Date 1996-06-20
(85) National Entry 1997-04-21
Examination Requested 1997-04-21
(45) Issued 2000-02-29
Deemed Expired 2011-11-30

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $400.00 1997-04-21
Registration of a document - section 124 $100.00 1997-04-21
Application Fee $300.00 1997-04-21
Maintenance Fee - Application - New Act 2 1997-12-01 $100.00 1997-09-26
Maintenance Fee - Application - New Act 3 1998-11-30 $100.00 1998-09-23
Maintenance Fee - Application - New Act 4 1999-11-30 $100.00 1999-10-19
Final Fee $300.00 1999-12-01
Maintenance Fee - Patent - New Act 5 2000-11-30 $150.00 2000-10-11
Maintenance Fee - Patent - New Act 6 2001-11-30 $150.00 2001-10-15
Maintenance Fee - Patent - New Act 7 2002-12-02 $150.00 2002-10-15
Maintenance Fee - Patent - New Act 8 2003-12-01 $150.00 2003-10-15
Maintenance Fee - Patent - New Act 9 2004-11-30 $200.00 2004-10-13
Maintenance Fee - Patent - New Act 10 2005-11-30 $250.00 2005-10-17
Maintenance Fee - Patent - New Act 11 2006-11-30 $250.00 2006-10-16
Maintenance Fee - Patent - New Act 12 2007-11-30 $250.00 2007-10-15
Maintenance Fee - Patent - New Act 13 2008-12-01 $250.00 2008-10-17
Maintenance Fee - Patent - New Act 14 2009-11-30 $450.00 2010-01-29
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY
Past Owners on Record
CHASKELL, ANDREW DAVID
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

To view selected files, please enter reCAPTCHA code :



To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 1997-04-21 1 42
Drawings 1997-04-21 3 34
Description 1997-04-21 6 261
Claims 1997-04-21 1 36
Cover Page 1997-09-01 2 46
Cover Page 2000-02-01 1 39
Representative Drawing 1997-09-01 1 5
Representative Drawing 2000-02-01 1 4
Assignment 1997-04-21 5 180
PCT 1997-04-21 20 657
PCT 1997-08-14 1 34
PCT 1997-08-14 3 89
Correspondence 1999-12-01 1 27
Prosecution-Amendment 1999-05-26 2 3
Prosecution-Amendment 1999-08-25 4 169
Correspondence 1998-04-08 3 96
Assignment 1997-04-21 8 276