United States Patent
`McNamara et al.
`
`[19]
`
`[11] Patent Number:
`
`5,974,139
`
`[45] Date of Patent:
`
`Oct. 26, 1999
`
`US005974139A
`
`[54] LINE ISOLATION DEVICE FOR
`ASYMMETRICAL DIGITAL SUBSCRIBER
`LINE
`
`[75]
`
`Inventors: W. J. McNamara, Birmingham; Gary
`J. Tennyson, Alabaster; D. A. VVilmont,
`Birmingham, all of Ala.
`
`[73] Assignee: BellSouth Corporation, Atlanta, Ga.
`
`[21] Appl. No.: 08/812,296
`
`[22]
`
`‘
`
`;
`
`Mar. 7,1997
`
`.
`
`H04M 1/00
`.
`[51]
`..... -379/399,379/397
`..
`[52]
`[58] Field of Search ................................... .. 379/399, 419,
`379/387, 397, 93.5, 93.07, 93.1, 455/3.1,
`4.2, 6.3, 5.1, 333/171, 201, 202
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,027,426
`5,369,666
`5,408,260
`5,410,343
`5,440,335
`
`.
`6/1991 Chioeca, Jr.
`11/1994 Folwell et al. .
`4/1995 Arnon .
`4/1995 Coddington el al. .
`8/1995 Beveridge .
`
`(List continued on next page
`
`OTHER PUBLICATIONS
`
`Cook, John, “Telephony Transmission and Splitters, Passive
`and Active,” American National Standards Institute, Tele-
`communications Committee, TlEl .4/94-043 (14 pages,
`Feb. 14-18, 1994).
`Rauschmayer, Dennis J., “Effects of a Distributed POTS
`Splitter Topology on ADSL Li11e Transfer Functions,”
`American National Standards Institute, T1E1.4 Technical
`Subcommittee Report, T1E1.4/96-167 (pp. 1-9, Jul. 22,
`1996).
`Roberts, Rick, et al., “ADSL POTS LPF Placement,”Ameri-
`can National Standards Institute Work Group Report,
`T1E1.4/96-162 (7 pages, Jul., 1996).
`
`“For Telecommunications—Interface Between Carriers and
`Customer
`Installation.s—Analog Voicegrade
`Switched
`Access Lines Using Loop—Start and Ground—Start Signal-
`ing,” American National Standards
`Institute ANSI
`T1.401—1993 (pp. 1-74).
`“For Telec0mmunications—Network and Customer Instal-
`lation Interfaces—Asymmetric Digital Subscriber Line
`(ADSL) Metallic Interface,” American National Standards
`Institute Standard ANSI T1.413-1995 (pp. 1-170).
`“IEEE Standard Methods and Equipment for Measuring the
`Transmission Characteristics of Analog Voice Frequency
`Circuits,” The Institute of Electrical and Electronics Engi-
`neers, Inc., IEEE Std 743-1984 (pp. 11-60).
`
`Primary Examiner—Jack Chiang
`Attorney, Agent, or Firm James L. Ewing, IV; Geoff L.
`Sutcliffe; Kilpatrick Stockton LI P
`
`[57]
`
`ABSTRACT
`
`A line isolation device (LID) for use in an ADSL system
`provides a single low pass filter that filters out the higher
`band ADSL signals for all of the Plain Old Telephone
`Services (POTS) terminal devices within a customer’s pre-
`mises. The LID may be easily added to an existing ADSL
`system by routing signals from a customer bridge through
`the LID. The LID has a low pass filter for removing the
`ADSL signals and also has a bypass path for carrying
`unfiltered ADSL and POTS signals to an ADSL transceiver
`unit. The filtered POTS signals are supplied back to the
`customer bridge and to binding posts on the customer bridge
`where all POTS terminal devices receive their POTS sig-
`nals. The re-routing of the signals Within the NID through
`the LID can be easily accomplished by disconnecting a
`testing jack on the customer bridge and routing the signals
`through the LID. Alternatively, the customer bridge may be
`completely removed from the NID and replaced with a
`customer bridge having an integral low pass filter. As a
`further alternative, an additional customer bridge having the
`low pass filter may be installed into an empty receptacle
`within the NID and appropriately connected to the existing
`customer bridge. The low pass filter is preferably a four-pole
`filter to provide a sufficient amount of attenuation at fre-
`quencies above the voiceband.
`
`27 Claims, 4 Drawing Sheets
`
`“’%lr;_F'—-
`
`A
`-}u|\<\\‘.J/
`
`Dish
`Exhibit 1013, Page 1
`
`

`
`5,974,139
`Page 2
`
`US. PATENT DOCUMENTS
`uz
`1.
`uk.
`10/1995 S
`11/1995 Beveddge .
`.
`1/1996 Elder et al.
`4/1996 Norsworthy et £11..
`5/199.5 Cigffi,
`
`,
`,
`5 461 616
`5,459,495
`5,488,413
`5,512,898
`5,519,731
`
`6/1996 Ashley et al. .
`5,528,630
`,
`.
`,_
`7/1996 Kostreski.
`5,534,912
`3/1996 5P‘e“¥““‘~
`5>5‘}8>235
`9/1996 Be"e“dge ~
`5»539>838
`5,561,424 10/1996 N°1’5W°"“‘Y Ct 91--
`5,848,150 12/1998 Bingel
`................................... .. 379/399
`
`Dish
`Exhibit 1013, Page 2
`
`

`
`Sheet 1 of 4
`
`5,974,139
`
`omu
`
`)WWEA
`
`U S Patent
`
`LQ
`
`D/GI7.'4L
`NETWORK
`
`FIG ./I
`
`(PRIOR ART}
`
`Dish
`Exhibit 1013, Page 3
`
`

`
`Oct. 26, 1999
`
`Sheet 2 of 4
`
`5,974,139
`
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`Exhibit 1013, Page 4
`
`

`
`Oct. 26, 1999
`
`Sheet 3 of 4
`
`5,974,139
`
`Dish
`Exhibit 1013, Page 5
`
`

`
`Oct. 26, 1999
`
`Sheet 4 of 4
`
`5,974,139
`
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`Exhibit 1013, Page 6
`
`

`
`5,974,139
`
`1
`LINE ISOLATION DEVICE FOR
`ASYMMETRICAL DIGITAL SUBSCRIBER
`LINE
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to a line isolation
`device and, more particularly, to a line isolation device for
`use in an Asymmetrical Digital Subscriber line (ADSL)
`system. The line isolation device provides low—pass filtering
`for all conventional or so-called plain old telephone services
`(POTS)
`terminal devices located within a customer’s
`premises, and it provides a bypass path for the ADSL
`signals.
`
`BACKGROUND OF THE INVENTION
`
`In general, modems designed for use with conventional
`telephone lines accommodate relatively low data transmis-
`sion rates. While current modems can process a high-end bit
`rate at about 33.6 Kbits/second, they are nonetheless sig-
`nificantly slower than a digital modem, such as one on an
`ISDN line which can operate at 64 Kbits/second. These
`rates, unfortunately, remain too low for many desired types
`of communication, such as full-motion video which requires
`a minimum of 1.5 Mbits/second for VHS quality using
`MPEG-1 (Motion Pictures Expert Group) compression and
`3 to 6 Mbits/second for broadcast quality using MPEG-2
`compression.
`A recently pronounced standard in telecommunications
`defines an Asymmetrical Digital Subscriber Line (ADSL)
`system which executes a high speed transfer of data over a
`single twisted—wire pair, such as an existing telephone line.
`In addition to Plain Old Telephone Services (POTS), an
`ADSL system also permits full-duplex and simplex digital
`services with data rates from about 1.5 Mbits/second to 7
`Mbits/second. An ADSL system uses a spectrum from about
`26 kHz to 1.1 MHZ for broadband data transmission and
`leaves the spectrum from about DC to 4 kHz for POTS. An
`ADSL system provides at least fo11r downstream simplex
`channels having rates ranging from about 1.5 Mbits/second
`to 6 Mbits/second and four full duplex channels with rates
`ranging from about 64 Kbits/second to 640 Kbits/second. An
`ADSL system is therefore more than capable of providing
`video-on-demand capability, video conferencing, data file
`transfer capability and can provide all of this capability ,
`simultaneously with POTS. For additional information, ref-
`erence may be made to American National Standards Insti-
`tute Standard ANSI-T1413-1995 which describes an ADSL
`system and an interface between a telecommunications
`network and a customer's installation and which is incor-
`porated herein by this reference.
`With reference to FIG. 1, a standard ADSL system 10 may
`comprise an ADSL transceiver unit 12 at a central office
`(ATU—C) which communicates with an ADSL transceiver
`unit 14 at a customer premises U-R). The ADSL trans-
`ceiver unit 12 at the central office receives data from a digital
`network 15, performs various processing on the data, and
`transfers the processed data to a splitter 16. The splitter 16
`combines the signals from the transceiver unit
`[2 with
`signals from a public switched telephone network (PSTN)
`18 and transfers the combined signals onto a line 20. At the
`customer end, a splitter 22 supplies a lower-band set of
`signals to one or more POTS terminal devices 24 and a
`higher-band set of signals to the ADSL transceiver unit 14.
`The ADSI. transceiver unit 14 at the customer’s end pro-
`cesses the received signals and supplies the processed sig-
`nals to one or more service modules (SM) 26. The processed
`
`_
`
`2
`data from the ADSL transceiver unit 14 may be supplied
`directly to the service modules 26 or may be supplied
`through a customer installation distribution network 28. The
`network 28 may be any type of network, such as a star or bus
`network. Reference may be had to ANSI T1.413—1995 for
`additional information on the ADSL transceiver units 12 and
`14 and on other aspects of the ADSL system 10.
`One difliculty with ADSL, however, is that the signals
`supplied to the ADSL transceiver 14 and the signals supplied
`to the POTS terminal device 24 n1ust be isolated from each
`other. One reason requiring this isolation is that the POTS
`terminal device 24, which may be a telephone or other
`non—hnear device, produces inter—modulation harmonics
`from the ADSL system both iii the frequency range of the
`ADSL signals and in the voice band. Likewise, the ADSL
`transceiver unit 14 can generate interference with the signals
`supplied to the POTS terminal device 24. Consequently,
`some type of filtering must occur between the ADSL trans-
`ceiver 14 and the POTS terminal devices 24.
`The signals supplied to the POTS terminal devices 24
`may be isolated from the signals supplied to the ADSI.
`transceiver unit 14 in any one of a multitude of ways. One
`of these ways is to place a low—pass filter at each POTS
`terminal device 24 and to place a high-pass filter at either the
`ADSL transceiver unit 14 or at a network interface device
`(NID). For instance, the low pass filters may be placed in
`series between the POTS terminal devices 24 and their
`connection to a wall jack. These low pass filters would then
`filter out the higher band ADSL signals and prevent the
`ADSL signals from interfering with the POTS signals.
`The placement of the low—pass filter at each POTS ter-
`minal device, however, adversely effects the overall perfor-
`mance of the ADSL system 10. The lines connecting the
`POTS terminal devices 24 to the low pass filters look like
`bridge taps to the ADSL line and produce significant losses
`_ at
`the top end of the downstream ADSL band transfer
`function, such as losses from 5 dB to 15 dB between 400
`kHz and 1.1 MHZ. The reason for these losses and their
`effects on the ADSL system 10 are explained in more detail
`in Dennis J. Rauschmayer, “Effects of a Distributed POTS
`Splitter Topology on ADSL Line Transfer Functions,”
`American National Standards Institute T1 E1.4 Technical
`Subcommittee Report T1El .4/96-1 67, Jul. 22, 1996, which
`is incorporated herein by this reference. The placement of
`low—pass filters at each POTS terminal device 24 is therefore
`undesirable due to their effects on the ADSL signals.
`In contrast to the placement of a low—pass filter at each
`POTS terminal device 24, the use of a single low pass filter
`for all POTS terminal devices 24 produces more favorable
`results. For instance, a comparison between the placement of
`the low—pass filter at each phone drop versus the placement
`of the low—pass filter at a split is described in a report by Rick
`Roberts et al., “ADSL POTS LPF Placement,” American
`National Standards Institute Working Group Report T1E1.4/
`96-162, July, 1996, which is incorporated herein by this
`reference. This report suggests that a single low—pass filter at
`the split is preferred since a distributed low—pass filter at
`each phone causes several problems, such as a reduced bit
`rate and reduced reach of the ADSL system, an increase in
`line driver current, a hybrid/echo cancellation stress, and
`risk of improper installation or improper network modifica-
`tion. Thus, rather than placing a low—pass filter at each POTS
`terminal device 24, the ADSL system 10 should preferably
`have a single low—pass filter installed at the split so that the
`signals supplied to all of the POTS terminal devices 24 are
`filtered by this single low pass filter.
`Asingle low—pass filter, however, is not as easily installed
`at a split as are multiple low—pass filters at each POTS
`
`Dish
`Exhibit 1013, Page 7
`
`

`
`5,974,139
`
`3
`terminal device 24. With multiple low—pass filters, a low-
`pass filter can be easily incorporated to the telephone
`network by simply adding a filter between each POTS
`terminal device 24 and its connection to the customer’s
`telephony wiring, such between the POTS terminal device
`24 and a wall jack. The single low-pass filter, on the other
`hand, must be located at a point along the customer’s wiring
`which is shared by all POTS terminal devices 24 but not at
`a location which might effect ADSL signals traveling to and
`from the ADSL transceiver unit 14.
`
`This difliculty in placing a single low pass filter at the split
`will be explained with reference to FIGS. 2A and 2B, which
`depict a conventional ADSL installation within a network
`interface device (NID). In many households and businesses,
`especially those more recently constructed, a telephone
`company‘s wiring is interconnected to the particular cus-
`tomer’s telephone wiring within the NID and this intercon-
`nect
`is protected from the elements of the environment
`within the NID. The point at which the customer’s wiring is
`connected to the telephone company’s wiring is termed the
`customer demarcation point.
`With reference to FIG. 2A, a typical NID 32 has a station
`protector 38 for receiving an incoming service wire 34 and
`a ground wire 36. Typically, the service wire 34 is attached
`to the station protector 38 so that a tip signal is supplied to
`a left post 33A on the protector 38 and a ring signal is
`supplied to a right post 3313 on the protector 38. A pair of
`leads 40 from a customer bridge 42 couples the tip and ring
`lines from the station protector 38 to the customer bridge 42
`which, in this example, is through an RJ11 female connector
`44. The RJll female connector 44 defines the customer
`demarcation point and thus defines the intersection of the
`telephone company’s wiring and that of the customer’s
`telephone wiring. An RJll male connector 45 is connected
`to a cord 46 which couples the tip and ring signals to the
`binding posts 50 on the customer bridge 42. The RJ11 male
`connector 45 and the RJll female connector 44 provide a
`convenient
`testing jack whereby test equipment can be
`coupled to the R111 female connector 44 to ensure that
`telephony signals are properly reaching the customer’s pre-
`mises. An ADSL interconnect wire 52, connected to posts
`50, supplies signals to and from the ADSL transceiver unit
`14 and a telephony or POTS interconnect wire 54, also
`connected to posts 50, supplies telephony signals to and
`from the POTS terminal devices 24 located within the ,
`customer’s premises. Although each of the service wire 34,
`ADSL interconnect wire 52, and POTS interconnect wire 54
`has been referred to as a wire, as shown in FIG. 2A, each of
`these wires 34, 52, and 54 is a line comprised of a pair of
`conductors for carrying signals.
`The customer bridge 42, as shown in FIG. 2B, is a unitary
`modular structure that is releasably secured to the NID 32 by
`snapping the bridge 42 within a receptacle 35 formed within
`the NID 32. The NID 32 has engaging members 37 for
`engaging edges of the customer bridge 42 so as to secure the
`bridge 42 to the NID 32. The station protector 38, service
`wires 34, and grounding wire 36 are each located within a
`central compartment of the NID 32 and this central com-
`partment
`is often locked under separate cover so as to
`prevent any tampering with the wires 34 and 36.
`Consequently, once the customer bridge 42 has been
`installed and the leads 40 have been connected to the station
`protector 38,
`the customer bridge 42 cannot be removed
`while the central compartment is locked except by cutting
`the leads 40.
`
`The installation shown in FIG. 2A lacks any type of
`filtering for either the POTS signals or the ADSL signals. If
`
`4
`the filters for the POTS and ADSL signals are to be con-
`sidered part of the customer’s own telephone wiring, the low
`pass filter and high pass filter must be placed after the
`customer demarcation point, which in this example is the
`RJ11 female connector 44. Additionally, the low pass filter
`must be located before any branching occurs to separate
`POTS terminal devices 24 in order for the single low pass
`filter to provide filtering for all of the POTS terminal devices
`24. The filters should also be protected from the elements of
`the environment to prevent moisture or dirt from damaging
`the filters.
`
`The filters are not readily placed in its desired position
`within the customer’s telephone wiring if it is to be placed
`in a protected enclosure and located before any branching to
`separate POTS terminal devices 24. One possible location
`for the low pass filter satisfying all of these desires is within
`the NID 32 itself The typical NID 32, however, is a fairly
`small enclosure and does not have much space for any extra
`components since mucl1 of the space is consumed by the
`customer bridge 42. The low and high pass filters therefore
`are not readily located within the NID 32.
`Another possible location for the filters is external to the
`NID 32 but before the interconnect wire 54 enters the
`customer’s premises. At such a location, the interconnect
`wire 54 may have to be cut in order to splice in the low pass
`filter, which consequently would increase the chance of a
`service interruption due to a faulty splice. This option is also
`undesirable since the splice must be encased and protected
`from the environment, thereby complicating the installation
`of the low pass filter.
`Athird general location for the low pass filter is within the
`customer’s premises at a point prior to any branching to the
`separate POTS terminal devices 24. This option is often
`plagued with problems since the customer’s wiring is usu-
`T ally completely hidden behind a wall or floor. Simply
`locating the wiring behind the wall or underneath the floor
`may be quite diflicult and, even if the wiring is found, the
`wall or floor may have to be partially removed to access the
`wiring, which just presents the customer with the additional
`task of repairing the wall or floor. The placement of the low
`pass filter Within the custorner’s premises therefore may
`involve the most amount of effort and is thus likely to be the
`least desirable location for the low pass filter.
`A further difficulty in the placement of the low pass filter
`is that
`the customer or one with a minimal amount of
`training should preferably be capable of installing the low
`pass filter. Because ADSI. relies upon existing telephone
`wires and does not require any additional digital lines,ADSL
`by its very nature can be easily incorporated into many
`households or businesses. To help minimize the number of
`obstacles to the provision of ADSL services, the low pass
`filter should be designed and located so that potential
`customers with little or no experience in working with
`electrical lines or circuits can install the low pass filter. This
`goal of simplifying the installation of the low pass filter may
`be difficult to achieve given the minimal amount of space
`within the NID 32 and the level of expertise needed to splice
`the low pass filter external to the NID 32.
`SUMMARY OF THE INVENTION
`
`invention solves the problems described
`The present
`above by providing a line isolation device (LID) which
`filters the POTS signals for all POTS terminal devices
`within a customer’s premises. The LID includes a low pass
`filter that has a relatively flat response over the voiceband
`yet provides sufficient attenuation for the higher band ADSL
`
`Dish
`Exhibit 1013, Page 8
`
`

`
`5,974,139
`
`5
`signals. Although a three—pole filter may be adequate, the
`low pass filter preferably is a four-pole filter which provides
`30 dB of attenuation at frequencies above 15 kHz.
`The LID, in one embodiment, is encased within a sealed
`enclosure that can be located either internal or external to a
`network interface device (NID). The LID is added to the
`customer’s telephone network by disconnecting a testing
`jack within the NID and adding the LID in series between
`the two connectors forming the testing jack. The LID
`receives POTS signals and ADSL signals from one connec-
`tor of the testing jack and provides filtered POTS signals to
`the connector of the testing ack that supplies the filtered
`POTS signals to a POTS interconnect wire. A bypass line
`within the LID carries the unfiltered POTS signals and the
`ADSL signals to an ADSL interconnect wire so that the
`ADSL signals can be carried to an ADSL transceiver unit.
`The LID conveniently has connectors that mate with the
`connectors of the testing jack whereby the LID can be easily
`and quickly added to the customer’s telephone network with
`minimal effort.
`In a second embodiment, the LID is integrated onto the
`body of a customer bridge, such as underneath the customer
`bridge. The low pass filter within the LID supplies filtered
`POTS signals to a testing jack on the customer bridge
`whereas the unfiltered POTS signals and the ADSL signals
`are routed over a bypass line to the ADSI. interconnect wire.
`The customer bridge having the integral LID can quickly
`and easily replace an existing customer bridge and provide
`the necessary filtering for the POTS terminal devices. Since
`the LID is placed underneath the customer bridge, the LID
`can be easily accommodated within the tight confines of the
`NID.
`the LID is
`In a third embodiment of the invention,
`incorporated onto a customer bridge, such as on an upper
`surface of the customer bridge. The customer bridge witl1 the
`integral HT) is placed within an empty receptacle within the
`NID,
`interconnects with the testing jack on an existing
`customer bridge, and provides the necessary low pass fil-
`tering of the POTS signals. The filtered POTS signals are
`supplied from the customer bridge modified to have the
`integral LID to the existing customer bridge and the POTS
`interconnect wire carries the filtered POTS signals to all
`POTS terminal devices within the customer’s premises. The
`ADSL signals, on the other hand, are not routed over to the
`existing customer bridge but rather are preferably carried /
`over a bypass line from the LID to the ADSL interconnect
`wire. Since the existing customer bridge ca11 be left intact
`within the NID and since the POTS interconnect wire does
`not have to be removed,
`the modified customer bridge
`having the low pass filter can be easily and quickly added to
`the customer’s telephone network.
`Accordingly, it is an object of the present invention to
`provide a line isolation device that provides low pass
`filtering for all POTS terminal devices within a custon1er’s
`premises.
`It is another object of the present invention to provide a
`line isolation device that can be conveniently located within
`an existing network interface device.
`It is a further object of the present invention to provide a
`line isolation device that can be easily and quickly installed.
`It
`is a yet another object of the present invention to
`provide a customer bridge that has a line isolation device
`attached to its body.
`It is a yet a further object of the present invention to
`provide a customer bridge having an integral line isolation
`device which can replace an existing customer bridge to
`provide filtering of all POTS signals.
`
`6
`It is a also an object of the present invention to provide a
`customer bridge having a low pass filter which can be
`inserted into an empty receptacle within a network interface
`device and interconnect with an existing customer bridge to
`provide filtering of all POTS signals.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`5
`
`The accompanying drawings, which are incorporated in
`and form a part of the specification,
`illustrate preferred
`embodiments of the present invention and, together with the
`description, serve to explain the principles of the invention.
`In the drawings:
`FIG. 1 is a block diagram of a typical ADSL system;
`FIG. 2A is a front internal View of a network interface
`device conventionally wired for ADSL;
`FIG. 2B is an enlarged partial view of a customer bridge
`and its receptacle within the network interface device of
`FIG. 2A;
`FIG. 3 is front internal view of a network interface device
`and an ADSL line isolation device according to a preferred
`embodiment of the invention;
`FIG. 4 is a schematic view of an ADSL Line Isolation
`Device according to a preferred embodiment of the inven-
`tion;
`FIG. 5 is a circuit schematic of a low-pass filter according
`to a preferred embodiment of the invention;
`FIG. 6 is a rear perspective view of a customer bridge and
`ADSL line isolation device according to a second embodi-
`ment of the invention; and
`FIG. 7 is a front internal view of a network interface
`device and an ADSL line isolation device according to a
`third embodiment of the invention.
`
`DETAILED DESCRIPTION
`Reference will now be made in detail to embodiments of
`the invention,
`including preferred embodiments of the
`invention, non-limiting examples of which are illustrated in
`the accompanying drawings. With reference to FIG. 3, a
`customer installation according to a preferred embodiment
`of the invention includes the network interface device (NID)
`32 and customer bridge 42. As with the conventional instal-
`lation shown in FIG. 2A,
`the NID 32 has the station
`protector 38 for coupling with the incoming service wires 34
`and the ground wire 36. The leads 40 from the customer
`bridge 42 carry tip and ring signals from the station protector
`38 to the RJ11 female connector 44 of the customer bridge
`42.
`In contrast to the installation of FIG. 2A, the RJ11 female
`connector 44 is connected to an RJ11 male connector 68
`rather than to the RJ11 male connector 45. The RJ11 male
`connector 68 is connected to a cord 66 which supplies both
`the POTS signals and the ADSL signals to an ADSL Iine
`Isolation Device LID) 70. The LID 70, as will be described
`in more detail below, includes a low pass filter for the POTS
`signals and also provides a bypass line 75 for the ADSL
`signals. The bypass line 75 preferably terminates in a jack 53
`and provides an interconnect point for the interconnect wire
`52 whereby ADSL signals can be carried to and from the
`ADSL transceiver unit 14. Preferably, the jack 53 is color-
`coded and has punch-down connectors 77 for interconnect-
`ing shielded wires of the ADSL interconnect wire 52 to the
`individual wires of the bypass line 75. The filtered POTS
`signals from the low pass filter within LID 70 are routed
`over cord 64 to an RJ11 female connector 62. The existing
`RJ11 male connector 45 is connected to the RJ11 female
`
`Dish
`Exhibit 1013, Page 9
`
`

`
`5,974,139
`
`7
`connector 62 and routes the filtered POTS signals over cord
`46 to the binding posts 50. The POTS interconnect wire 54
`is connected to these binding posts 50 and supplies the
`filtered POTS signals to the POTS terminal devices 24
`located within the customer’s premises.
`As is apparent from FIG. 3, the low pass filter within the
`ADSL LID 70 can be easily added to an existing ADSL
`installation having a customer bridge 42, such as the one
`shown in FIG. 2A. The customer bridge 42 need not be
`removed and the interconnect wire 54 for POTS signals need
`not be removed from the binding posts 50. Rather, the RJ11
`male connector 45 is disconnected from the RJ11 female
`connector 44, the additional RJ11 female connector 62 is
`connected to the RJ11 male connector 45, a11d the additional
`RJII male connector 68 is connected to the RJII female
`connector 44. The RJ11 connectors 62 and 68 and the extra
`cords 64 and 66 consume only a nominal amount of space
`and can easily be accommodated within most NIDs, as is
`apparent with NID 32. The modification to an existing
`ADSL installation, such as the one in FIG. 2A, to have a
`single low pass filter does not require splicing any compo-
`nents together and can therefore be performed by someone
`having little guidance or expertise.
`The LID 70 is located external to the NID 32 and provides
`appropriate shielding for the low pass filter within the LID
`70 and for the cables and wires traveling between the LID
`70 and the NID 32. The exact location of the LID 70 relative
`to the NID 32 is not critical but can conveniently be mounted
`in close proximity to the NID 32, such as to the same
`exterior wall of the customer’s premises where the NID 32
`is mounted. The LID 70, however, need not be located
`external
`to the NID 32 but can be conveniently located
`internal the NID 32. If the LID 70 is mounted internal to the
`NID 32, the size of the LID 70 can be reduced significantly
`since the low pass filter can rely upon the protection afforded
`by the NID 32 and need not be encased within a separate
`housing. The LID 70, for instance, may be located within the
`NID 32 near the customer bridge 42 or in an empty recep-
`tacle 35 reserved for a second customer bridge. The LID 70
`could also be mounted within the customer’s premises and
`may be located near or within the ADSL transceiver unit 14.
`Other locations for the ADSI. LID 70 will be apparent to
`those skilled in the art.
`The LID 70, as shown in more detail in FIG. 4, has a low
`pass filter 80 for providing the low pass filtering of the POTS /
`signals for all POTS terminal devices 24. The low pass filter
`80 has its input connected to the cord 66 carrying both the
`POTS signals and the ADSL signals and its output connected
`to the cord 64 carrying the filtered POTS signals. The bypass
`line 75 supplies all of the incoming signals,
`the POTS _
`signals and the ADSL signals,
`to the jack 53 where the
`ADSL interconnect wire 52 is connected. Although each of
`the cords 64 and 66 are shown as a single line, it should be
`understood that the cords 64 and 66 actually consist of
`twisted pairs of conductors and have been illustrated as a
`single line to simplify the drawings.
`With the LID 70, all incoming ADSL signals and POTS
`signals are supplied over cord 66 to the low pass filter 80.
`The low pass filter 80 filters the incoming signals by
`removing the ADSL signals and outputs the filtered POTS
`signals over cord 64 to RJ11 female connector 62 and
`eventually to the POTS interconnect wire 52. The ADSL
`signals, along with the POTS signals, are routed over bypass
`line 75 to the ADSL interconnect wire 52 via ack 53. The
`ADSI.interconnect wire 52 therefore carries both the ADSL
`signals and the POTS signals to the ADSL transceiver unit
`14. Al1igl1 pass filter may be located at the ADSL transceiver
`
`8
`unit 14 to filter out the POTS signals and to only supply the
`ADSL signals to the ADSL transceiver 11nit 14. This high
`pass filter may be a separate device that is placed in series
`between the ADSL transceiver unit 14 and the ADSL inter-
`connect wire 52 or may be integral to the ADSL transceiver
`unit 14.
`
`In general, the low pass filter 80 must sufficiently attenu-
`ate ADSL signals while passing through all POTS signals.
`To determine the amount of attenuation that the filter 80
`must provide, an ADSL transceiver 14, such as one manu-
`factured by Westell Technologies, I11c., was bridged across a
`pair of 500-type telephone sets along with a network simu-
`lator and the amount of intermodulation products was mea-
`sured by a transmission measurement set. With a 13 dBn1
`ADSL signal, the transmission measurement set indicated
`that a value of about -39 dBm of noise power was intro-
`duced into the voice band. This noise level was found to be
`fairly independent of the loop current
`level or switched
`status of the telephone sets. The ADSL to voiceband con-
`version loss was therefore determined to be approximately
`52 dB.
`
`The measurements of the noise level was performed in
`accordance with IEEE Standard 743 relating to the mea-
`surement of transmission characteristics of analog voice
`frequency circuits. The noise level was C—message weighted
`whereby the noise was weighted according to its perceived
`annoyance to a typical listener of standard telephone ser-
`vices. The -39 dBm of noise introduced by the ADSL
`transceiver corresponds to about 50 dB relative noise
`C—message weighting (dBrnC). To lower the noise level in
`the voice band to an acceptable limit of 20 dBrnC, approxi-
`mately 30 dB of attenuation is needed by the filter 80.
`The filter 80 preferably comprises a four-pole filter which
`provides a low loss at
`the high end of voiceband and
`_ provides about 30 dB of attenuation for frequencies at and
`above 15 kHz. Although a three-pole filter may provide a
`sufiicient amount of roll-ofl‘ above 15 kIIz, the four-pole
`filter is preferred since it presents a high bridging impedance
`to the ADSL line. The filter 80, as shown in more detail in
`FIG. 5, includes a first transformer T1, a first capacitor C1,
`a second transformer T2, and a seconc capacitor C2. The
`first transformer T1 receives the incoming ADSL signals and
`POTS signals over cord 66 and has an inductance of 14.6
`,uH. The first capacitance Cl, having a capacitance of 0.098
`‘HF, is connected across an output from he first transformer
`T1. The second transformer T2, which has its inputs con-
`nected to