Patent Publication Number: US-RE37125-E

Title: Universal demarcation point

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a device that facilitates the delivery of communications services to subscribers. More particularly, the present invention relates to a universal demarcation point that provides an interface between a utility distribution network and subscriber owned equipment for use with the delivery of communication services to subscribers via fiber optic and copper cables. 
     When delivering communications services to subscribers, it is common for a utility to attach a service box to the subscriber&#39;s dwelling. The service box provides an interface between the utility distribution network and subscriber owned equipment. As used herein, the term “subscriber owned equipment” means equipment that a subscriber attaches either directly or indirectly to a utility distribution network to receive or transmit communications services through the utility distribution network. Examples of subscriber owned equipment include telephones, television, and modems. 
     When the subscriber subscribes to multiple types of communications services, the utility mounts a separate service box to the subscriber&#39;s dwelling for each type of communications service. Each of the separate service boxes is then connected to the appropriate utility distribution network. For example, the telephone service box is connected to the telephone distribution network and the cable television service box is connected to the cable television distribution network. 
     When the utility provides communications services in rural areas where there may be several miles between each subscriber, the utility must install separate copper wires to each service box on each subscriber&#39;s dwelling. In addition, when communications services are transmitted over long distances using certain types of copper wires, the electrical signals weaken and become distorted. To overcome these drawbacks, the utility must install amplifiers or repeaters at regular intervals in the utility distribution network so that the utility can provide the subscriber with a desirable quality of communications services. As a result of the costs associated with serving subscribers in rural areas, the utilities have been restricted in their ability to provide subscribers with a range of communications services that utilities are typically able to provide for subscribers in urban areas. 
     There are various designs for service boxes. One such design is described in Grant, U.S. Pat. No. 4,673,771. The Grant patent discloses a universal building entrance terminal for telephone service. The terminal is primarily designed for attachment to commercial buildings where it is necessary to gain access to the terminal blocks for adding, deleting or changing subscribers&#39; telephone lines. The terminal has a modular construction that allows components in the terminal to be accessed and changed. 
     Several service box designs include the ability to deliver more than one type of utility service. For example, Nickola, U.S. Pat. No. 3,614,538, discloses a pedestal, which is mounted adjacent to a mobile home, for delivering electric power, telephone service, and gas service to the mobile home. Conventional electric and gas meters, as well as a conventional telephone box, can be mounted to the post so that the utilities can be readily connected and disconnected to the mobile home. 
     Dively. U.S. Pat. No. 4,785,376, discloses a utility pedestal that is primarily designed for use in marinas. The pedestal allows for delivery of electric, telephone, television, and water service to a single point. The pedestal also contains connectors that enable the utility services to be conveniently connected and disconnected to a boat or vehicle. 
     Horn, U.S. Pat No. 5,196,988, and Horn, U.S. Pat. No. 5,184,279, disclose an adapter faceplate for use in a metal power pedestal. The adapter provides the ability to add telephone and television capabilities to the power pedestal. The adapter isolates the telephone and television cables from the electrical components in the pedestal. 
     Frouin, U.S. Pat No. 5,134,541, discloses a distribution system for water, gas, fuel, electricity, and other fluids. The system is enclosed in a container that resists vandalism and accepts payment for disbursement of the utility services. 
     SUMMARY OF THE INVENTION 
     The present invention includes a universal demarcation point for managing the delivery of communications services to a subscriber. The universal demarcation point provides an interface between a utility distribution network and subscriber owned equipment. 
     The universal demarcation point includes a utility accessible portion and a subscriber accessible portion. The utility accessible portion has an input port, an output port, a plurality of modular connectors, a power supply, and a plurality of service modules. 
     The input port allows a hybrid cable from the utility distribution network to pass into the universal demarcation point. The hybrid cable has a plurality of fiber optic cables and a plurality of copper cables. The fiber optic cables are capable of transmitting light signals and the copper cables are capable of transmitting electric power. The output port delivers the communications services from the universal demarcation point into the subscriber&#39;s dwelling. 
     The plurality of modular connectors are fixedly mounted to the universal demarcation point. The power supply, which is removably mounted to the universal demarcation point, converts the electric power into a voltage for powering the operation of the universal demarcation point. The plurality of service modules plug into the modular connectors and converts light signals that are transmitted on the fiber optic cables onto cables that are suitable for use in the subscriber&#39;s dwelling. 
     The subscriber accessible portion is adjacent to the utility accessible portion and has ports that enable the subscriber to test the integrity of the communications services delivered from the utility distribution network. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of the universal demarcation point of the present invention. 
     FIG. 2 is a flow diagram illustrating a pathway for communications signals through the universal demarcation point. 
     FIG. 3 is a flow diagram illustrating another pathway for communications signals through the universal demarcation point. 
     FIG. 4 is a flow diagram illustrating yet another pathway for communications signals through the universal demarcation point. 
     FIG. 5 is a flow diagram illustrating still another pathway for communications signals through the universal demarcation point. 
     FIG. 6 is a logic flow diagram for a control service module. 
     FIG. 7 is a flow diagram illustrating a pathway for video signals through a filter module. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention includes a universal demarcation point, which is illustrated at  10  in FIG.  1 . The universal demarcation point  10  provides an interface between a utility distribution network and subscriber owned equipment for managing the delivery of communications services to subscribers. 
     The universal demarcation point  10  is particularly suited for managing the delivery of audio, video, and computer data services over fiber optic cables and copper cables to subscribers in rural areas. The universal demarcation point  10  provides a single interface for delivering the audio, video, and computer data services to subscribers. As a result, the utility only needs to install one hybrid cable to connect each subscriber to the utility distribution network. Installing only a single hybrid cable to each subscriber in rural areas also allows the utility to reduce the costs that are associated with maintaining several separately installed cables that run to each subscriber. 
     Because of the cost associated with transmitting electrical signals over long distances to sparsely populated areas, utilities serving subscribers in rural settings are limited in their ability to deliver a variety of communications services to its subscribers. However, by delivering various communications services to subscribers through a single interface, the universal demarcation point  10  allows audio, video, and computer data services to be transmitted on a single fiber optic cable or in a single bundle of fiber optic cables. 
     The fiber optic cables have a greater bandwidth than conventional twisted pair cables. As a result, the fiber optic cables are capable of handling more information than twisted pair copper cables or coaxial cables. Because the fiber optic cables are capable of handling a greater throughput of information, it is possible to simultaneously transmit more than one type of signal, such as audio and video signals, on a single fiber optic cable. 
     Fiber optic cables also do not require the frequent use of amplifiers or repeaters that are required when communications services are transmitted over twisted pair copper cables or coaxial cables. As a result, transmission of the audio, video, and computer data services over the fiber optic cables allows the quality of the communications services to be improved while lowering the cost of transmitting the communications services. 
     Utilities that serve urban areas where there are greater densities of subscribers have found that they can reap the benefits of transmitting communications services with fiber optic cables in a cost effective manner by installing fiber optic cables to a central neighborhood location. From this point, the communications services are delivered to subscribers with twisted pair copper cables or coaxial cables. 
     However, the sparsely populated nature of rural areas makes it impractical to install fiber optic cables to either subscribers&#39; dwellings or central neighborhood locations. The universal demarcation point, however, now provides a cost effective mechanism for delivering communications services to rural area subscribers with fiber optic cables. 
     The universal demarcation point  10  has a modular configuration that allows the universal demarcation point  10  to be modified to manage the delivery of any type of communication service that is provided by a utility. The modular configuration of the universal demarcation point  10  allows the universal demarcation point  10  to be installed with a limited number of components. When the subscriber requests additional services or the utility raises the capital to install the ability to provide additional services, the utility can readily modify the configuration of the universal demarcation point  10  by adding or changing components. 
     The universal demarcation point is generally divided into a utility accessible portion  12  and a subscriber accessible portion  14 . The utility accessible portion  12  includes a motherboard  16 . The motherboard  16  has a plurality of connectors  20  for attaching components to the universal demarcation point  10 . 
     The connectors  20  are preferably a plurality of modular edgeboard connectors  20 . Each of the modular edgeboard connectors  20  is adapted to receive a complementarily shaped end portion of a service module  22 . The modular edgeboard connectors  20  retain the service modules  22  in a desired position in the universal demarcation point  10  while allowing the service modules  22  to be readily removed from the universal demarcation point  10 . Modular edgeboard connectors  20  possessing the above characteristics can be obtained from EDAC Systems Inc. (Colmar, Pa.), Texas Instruments, Inc. (Houston, Tex.) and Sullins Electronics Corporation (San Marcos, Calif.). 
     The end portion of the service module that is shaped complementary to the modular edgeboard connectors  20  preferably includes conductive traces. The motherboard  16  preferably also includes conductive traces or wires (not shown) for delivering electrical power from a power supply  24  to the modular edgeboard connectors  20  so that the modular edgeboard connectors  20  can transmit the electrical power to the service modules  22  that are plugged into the modular edgeboard connectors  20 . 
     The operation of the universal demarcation point  10  is entirely powered by electric power from the utility distribution network. Local power from the subscriber is not required to operate any of the components in the universal demarcation point  10 . The ability of the utility to provide telephone service without the use of local power is one of the design requirements for rural utilities to obtain loans from the Rural Electrification Administration under the State Telecommunications Modernization Plan. 58 Fed. Reg. 66,259 (1993). 
     The universal demarcation point  10  includes a power supply  24  that is removably mounted in the utility accessible portion  12 . The power supply  24  converts the electric power from a transmission voltage that is transmitted through the utility distribution network to a usage voltage that is required to power the operation of the universal demarcation point  10 . Power supplies that convert electric power at one voltage to electric power at a different voltage are known. 
     In one preferred embodiment, the power supply  24  converts the electric power from a transmission voltage of approximately −48 volts DC to a usage voltage of ±12 volts DC. The power supply  24  is preferably selected to exhibit a 10 second peak to peak surge rating at an RF (radio frequency) output of 400 volts. The power rating or capacity of the power supply  24  is selected based upon the number of service modules  22  that are used in the universal demarcation point  10 . When four service modules  22  are used in the universal demarcation point  10 , the power supply  24  is preferably selected with a 250 watt power rating. 
     The power supply  24  preferably plugs into the modular edgeboard connector  20  on the motherboard  16 . The modular edgeboard connector  26  connects the power supply  24  to the conductive traces or wires (not shown) on the motherboard  16  while allowing the power supply  24  to be removed from the motherboard  16 . 
     The utility accessible portion  12  has a fixedly mounted power terminal strip  28 . The power terminal strip  28  provides connections for the copper cables that power the operation of the universal demarcation point  10 . The power terminal strip  28  also provides connections for the twisted pair copper cables when the twisted pair copper cables are used to provide telephone service to the subscriber. For example, the utility may transmit the telephone service over twisted pair copper rather than fiber optic cables to reduce the initial cost of installing the universal demarcation point  10 . 
     The utility accessible portion  12  includes an output port  30  and an input port  32 . The output port  30  allows cables carrying the communications services to pass from the universal demarcation point  10  to the subscriber&#39;s dwelling. The input port  32  allows cables carrying the communications services from the utility distribution network to pass into the universal demarcation point  10 . The output port  30  and the input port  32  are preferably positioned on a lower surface  34  or a back surface  36  of the universal demarcation point  10  to minimize problems associated with substances leaking into the universal demarcation point  10 . 
     The utility accessible portion  12  preferably also includes a fiber optic cable management area  40  that is located adjacent to the service modules  22 . The fiber optic cable management area  40  preferably has a tray  42  that is suitable for holding excess or unused portions of the fiber optic cables. The fiber optic cable management area  40  thereby helps to protect the fiber optic cables from damage. 
     The universal demarcation point  10  includes a cover (not shown) for the utility accessible portion  12 . The cover protects the components inside the utility accessible portion  12  from damage that may arise from a variety of sources, such as vandalism or the environment. When the cover is in a closed position, the cover preferably creates a water-tight seal with the utility accessible portion  12 . The cover preferably includes a locking mechanism (not shown) to prevent unauthorized access to the components inside the utility accessible portion  12 . 
     The subscriber accessible portion  14  enables the subscriber to ascertain whether a problem with communications services is caused by a problem in the utility distribution network or the subscriber owned equipment. Such a device is commonly known as a network interface device. Preferably, the network interface device includes a test port for each of the communications lines that enter the subscriber&#39;s dwelling. For example, an RJ-11 plug and socket  44  are preferably provided for each telephone line and a coaxial plug and socket  46  are preferably provided for each video line. 
     Other types of devices can be used in the subscriber accessible portion  14  to ascertain whether there is a problem with the utility distribution network or the subscriber owned equipment. For example, the subscriber accessible portion  14  may include a sensor and an LED (light emitting diode)  48  to indicate if the communications signal drops below a threshold level. 
     Similar to the utility accessible portion  12 , the subscriber accessible portion  14  includes a cover (not shown) that protects the test ports from damage that may result from a variety of sources, such as vandalism or the environment. When the cover is in a closed position, the subscriber portion cover preferably creates a water-tight seal with the subscriber accessible portion  14 . The subscriber portion cover may also include a locking mechanism (not shown) to prevent unauthorized access to the components inside the subscriber accessible portion  14 . 
     The service modules  22  are selected based upon the desired communications services that the utility is providing to the subscriber. The modular configuration of the universal demarcation point  10  allows the universal demarcation point  10  to receive either analog or digital signals from the utility distribution network and to transmit either analog or digital signals to the subscriber&#39;s dwelling for use on the subscriber owned equipment. 
     The modular configuration of the universal demarcation point  10  also allows the utility to modify the universal demarcation point  10  to deliver the communications services over different types of cables. For example, the video signal can be transmitted from the universal demarcation point  10  to the subscriber owned equipment using coaxial cable or fiber optic cable. 
     Preferably, the service modules  22  include an optical receiver service module  22 a. The optical receiver service module  22 a converts information transmitted as a light signal on the fiber optic cable into an electrical signal that is transmitted on a copper cable. 
     To convert the light signal into the electrical signal, the optical receiver service module  22 a preferably includes a conventional PIN-FET (positive intrinsic negative-field effect transistor) photodetector (not shown). The PIN-FET photodetector produces an electrical signal that varies based upon the intensity and wavelength of light that strikes the photodetector. The PIN-FET photodetector preferably possesses the characteristics set forth in Table 1. A preferred PIN-FET photodetector can be obtained from Epitaxx Inc. (Trenton, N.J.) under the designation ETX700. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
            
               
                   
                 Optical Input Range 
                 −10 to −1 dBm 
               
               
                   
                 Optical Wavelength 
                 1300 to 1550 nm ± 20 nm 
               
               
                   
                 Optical Return Loss 
                 40 dB 
               
               
                   
                 Impedance 
                 75 Ohms 
               
               
                   
                 Return Loss 
                 −15 dB 
               
               
                   
                 Bandwidth 
                 50 to 550 Mhz (min) 
               
               
                   
                 Frequency Response 
                 ±1 dB 
               
               
                   
                 Input Voltage 
                 12 Volts DC 
               
               
                   
                 Current 
                 100 Milliamps 
               
               
                   
                 Operating Temperatures 
                 −40 to +80° C. 
               
               
                   
                   
               
            
           
         
       
     
     The optical receiver service module  22 a also includes a monolithic microwave integrated circuit (MMIC) amplifier (not shown) that amplifies the electrical signal to a radio frequency output of approximately +6 dBmV. A preferred MMIC amplifier can be obtained from Hewlett Packard Company of (San Jose. Calif.) under the designation MAV-11. As one of ordinary skill in the art will appreciate, the optical receiver service module  22 a may also use a conventional amplifier to amplify the electrical signal. 
     The optical receiver service module  22 a preferably includes a removable physical contact optical connector  72  to connect the PIN-FET photodetector to the fiber optic cable. The physical contact optical connector  72  is preferable because it provides a low return loss while allowing the optical receiver service module  22 a to be quickly disconnected from the fiber optic cable. A preferable physical contact optical connector  72  can be obtained from Siecor Corporation (Orlando, Fla.) under the designation FC-PC. 
     Once the optical receiver service module  22 a converts the communications services into the electrical signal, the electrical signal is separated into the individual communications services. Preferably, the communications services are transmitted in discrete wavelength regions so that the individual communications services can be separated by filtering based upon wavelength. Other conventionally known techniques can be used when the communications services are transmitted in a digital format. 
     The optical receiver service module  22 a also includes separate modular connectors  64  that provide a connection for cables that carry the individual communications services from the utility accessible portion  12  to the test ports  44 ,  46  in the subscriber accessible portion  14 . For example, when the optical receiver service module  22 a delivers video signals, the optical receiver service module  22 c preferably includes an SMB connector that provides a connection to a coaxial cable. 
     To assist in monitoring the status of the incoming light signal on the fiber optic cable, the optical receiver service module  22 a includes an input signal LED  66  that illuminates to indicate when the light signal drops below a threshold value. Preferably, the input signal LED  66  illuminates when the light signal drops below −10 dBm. 
     The optical receiver service module  22 a also includes a receiver power LED  68  that indicates the power supply is providing electric power within a desired range to power the operation of the PIN-FET photodetector and the MMIC amplifier. Preferably, the receiver power LED illuminates when the electric power is approximately −12 volts. 
     The optical receiver service module  22 a is preferably encased in an outer layer of sheet metal  70 . The sheet metal layer  70  protects the components in the optical receiver service module  22 a from damage and shields the other components in the universal demarcation point  10  from interference by radio frequency radiation emissions. 
     The service modules  22  also preferably include an optical transmitter  22 b for converting electrical signals into light signals that are transmitted from the universal demarcation point  10  to the utility over fiber optic cables. The electrical signals are preferably converted into light signals using a Fabry-Perot laser (not shown). Variations in the electrical signals cause the laser to vary the current through a light source. The laser is preferably a Fujitsu Lightwave semiconductor, which can be obtained from Fujitsu America, Inc. (Lake Bluff, Ill.) under the designation FLD130C2PL. 
     The optical transmitter service module  22 b has modular connectors  78  that provide a connection to the cables that transmit the communications services from the subscriber. For example, when the optical transmitter service module  22 b delivers video signals, the optical transmitter service module  22 b preferably includes an SMB connector that provides a connection to a coaxial cable. 
     The optical transmitter service module  22 b preferably includes the capability to transmit several communications services from the subscriber to the utility distribution network over a single fiber optic cable. To facilitate transmitting more than one communications service on the fiber optic cable, the communications services are preferably transmitted at different wavelengths. 
     Similar to the optical receiver service module  22 a, the optical transmitter service module  22 b preferably includes a transmitter power LED  74  that indicates the power supply is providing electric power within a desired range to power the operation of the components in the optical transmitter service module  22 b. Preferably, the transmitter power LED  74  illuminates when the electric power is approximately −12 volts. 
     The laser is preferably connected to the fiber optic cable with a removable physical contact optical connector  76 . The physical contact optical connector  76  is preferable because it provides a low return loss while allowing the optical transmitter service module  22 b to be quickly disconnected from the fiber optic cable. A preferable physical contact optical connector  76  can be obtained from Siecor Corporation (Orlando, Fla.) under the designation FC-PC. 
     The utility preferably connects the utility distribution network to the universal demarcation point  10  with a hybrid cable  60 . The hybrid cable  60  contains a plurality of fiber optic cables and a plurality of copper cables. The number of fiber optic and copper cables is selected based upon the type of communications services that the utility is providing to the subscriber and the number and type of service modules  22  in the universal demarcation point  10 . When the universal demarcation point  10  is being used with a residential dwelling, the hybrid cable  60  preferably includes four single-mode fiber optic cables and four 16 gauge braided copper cables. 
     The hybrid cable  60  has a protective coating  86  to protect fiber optic and copper cables from damage. The protective coating  86  is selected based upon where the hybrid cable  60  is installed. For example, a double layer polyethylene jacket with a single armor layer is suitable for protecting the fiber optic and copper cables when the hybrid cable  60  is installed underground. A hybrid cable  60  having the above characteristics can be obtained from AT&amp;T Fitel (Carrollton, Ga.). 
     When the hybrid cable  60  contains four fiber optic cables, a first fiber optic cable is preferably used to transmit the audio, video, and computer data signals to the subscriber and a second fiber optic cable is preferably used to transmit the audio, video, and computer data signals from the subscriber. A third fiber optic cable and a fourth fiber optic cable are spares that can be used to replace a defective fiber optic cable. In the alternative, the third fiber optic cable can be used to provide a high speed computer data link (greater than 1.5 Mbps) between the subscriber and the utility. 
     When the hybrid cable  60  contains four 16 gauge braided copper cables, two of the braided copper cables provide electric power for the operation of the components in the universal demarcation point  10 . The other two the braided copper cables are preferably used to provide conventional telephone service to the subscriber. 
     The service modules  22  may also include a control service module  22 c. The control service module can be programmed using conventional techniques to perform a variety of tasks in the universal demarcation point  10 . For example, the control service module  22 c can monitor the operational status of the other service modules  22  and notify the utility if a problem arises. When the control service module  22 c is used to modify the other service modules  22 , a data path  80  is provided between the service modules. 
     The control service module  22 c can also be programmed to actively control the operation of the other service modules or other utility meters. For example, the control service module  22 c can be assigned an identification number, similar to “caller id”, that is unique to each subscriber. The identification number allows the utility to remotely monitor each subscriber&#39;s usage of utility services, such as natural gas, water, and electricity and then transmit the readings to the utility. By remotely monitoring each subscriber&#39;s use of utility services, the utility reduces the costs associated with manually reading the utility meters at the subscriber&#39;s dwelling. Remote monitoring systems having the above characteristics are described in Brennan. Jr. et al., U.S. Pat. No. 5,243,338, and Venkataraman et al., U.S. Pat. No. 4,862,493. The identification number also enables the utility to shut off power to the building in the event of a fire or if the subscriber is delinquent in paying for the communications services. 
     The control service module  22 c also preferably includes the ability to monitor when there is unauthorized access to the utility accessible portion  12 . The control service module  22 c not only notifies the utility that there has been unauthorized access to the utility accessible portion  12  but also preferably stops all transmission of communications services to and from the subscriber until the utility resets the universal demarcation point  10 . By stopping all transmission of communications services, the control service module  22 c deters subscribers from tampering with the components inside the utility accessible portion  12 . 
     Because the universal demarcation point  10  provides a source for the entry of all or substantially all of the utilities to the building, it provides a central bonding location from which all of the utilities can be grounded. Thus, the possibility of electrical problems resulting from an improper ground are minimized. 
     The modular construction of the universal demarcation point  10  allows the universal demarcation point  10  to operate in a variety of configurations. Once the universal demarcation point  10  is mounted to the subscriber&#39;s dwelling, the universal demarcation point  10  allows the utility to later offer the subscriber additional communications services that would not be feasible without already having access to the subscriber&#39;s dwelling. 
     In the following flow diagrams, each of the components is generally identified as being within the boundaries of the universal demarcation point  10 . One of ordinary skill in the art would appreciate that the placement of the components in particular service modules  22  is a design choice based upon the size of the service modules  22  and the desired features of the service modules  22 . 
     The universal demarcation point  10  allows the audio, video, and data signals to be transmitted from the utility distribution network on a fiber optic cable and to the utility distribution network on another single fiber optic cable, as illustrated in FIG.  2 . 
     The incoming light signal is transformed into an electrical signal with an optical receiver. After being converted into an electrical signal, the electrical signal is separated audio, video, and computer data signals based upon differences in the wavelengths that the signals are transmitted at. The separate audio, video, and computer data signals are then transmitted to an audio, video, or computer data output processor, respectively. The audio, video, and computer data output processors convert the signals into a form that can be utilized by the subscriber. For example, the audio signal is preferably transmitted into the subscriber&#39;s dwelling using a twisted pair copper cable having RJ-11 connectors and the computer data signal is preferably transmitted into the subscriber&#39;s dwelling using either the RS 232 or RS 485 protocols. 
     This preferred embodiment of the universal demarcation point also includes the capability for transmitting audio, video, and computer data signals from the subscriber. The separate incoming audio, video, and computer data electrical signals are first multiplexed onto a single copper cable based upon the different wavelengths that the signals are transmitted at. The electrical signals are then transmitted using copper cable to an optical transmitter where the electrical signals are converted into light signals that are transmitted through the utility distribution network on a fiber optic cable. 
     With this preferred embodiment, the operation of each of the components is preferably monitored by a control service module. When the control service module senses that there is an error with one of the components, the control transmits an error message to the utility. The error message is multiplexed with the audio, video, and computer data signals for transmission through the utility distribution network on a fiber optic cable. 
     The universal demarcation point of the present invention also enables the incoming and outgoing audio, video, and computer data signals to be transmitted on a single fiber optic cable as illustrated in FIG.  3 . With this embodiment, the light signal from the utility distribution network is preferably separated from the light signal being transmitted to the utility distribution network using a conventional multiplexer. The conventional multiplexer is preferably obtained from JDS Fitel (Ottawa, Ontario, Canada) under the designation WD-1315X. Then, the incoming light signal is processed similar to the procedure described with reference to the embodiment illustrated in FIG.  2 . 
     After the outgoing audio, video, and computer data signals are converted into light signals as described above with reference to the embodiment illustrated in FIG. 2, the light signals are then transmitted to the utility distribution network by combining the outgoing light signals with the incoming light signals using a conventional multiplexer. Also similar to the embodiment illustrated in FIG. 2, the operation of each of the components in this embodiment is monitored by a control service module. 
     In yet another embodiment of the universal demarcation point of the present invention illustrated in FIG. 4, incoming audio and video signals are transmitted from the utility distribution network on a first fiber optic cable. This embodiment includes a decoder to decode the communications services from a digital signal. Outgoing audio and video signals are transmitted from the subscriber on a second fiber optic cable. This embodiment also includes an encoder to encode the communications services into a digital signal. 
     This embodiment also illustrates that both the outgoing and incoming computer data signals are transmitted and received on a third fiber optic cable. By using a separate fiber optic cable to transmit and receive only computer data signals, this embodiment enables the computer data transfer to occur at greater rates than when the computer data signals are combined on a single fiber optic cable with audio or video signals. 
     Still another embodiment of the universal demarcation point of the present invention is illustrated in FIG.  5 . This embodiment illustrates the universal demarcation point as receiving video and data signals on a fiber optic cable. The optical receiver converts the light signals into an electrical signal. The electrical signal is then separated into individual video and data signals that can be transmitted into the subscriber&#39;s dwelling using conventional cables such as twisted pair copper conductors or coaxial cable. 
     To reduce the cost of manufacturing the universal demarcation point with an optical transmitter as well as an optical receiver, the universal demarcation point accepts audio signals on a twisted pair copper cable. However, it is noted that the modular construction of the universal demarcation point allows the utility to later upgrade the universal demarcation point to include the incoming and outgoing audio signals on the fiber optic cables. 
     The operational status of the components in the universal demarcation point are monitored with the control service module, illustrated at  22 c in FIG.  1 . The logic followed in one embodiment of the control service module is set forth in FIG.  6 . The control service module begins each cycle by sensing whether the power supply is providing electric power within a specified operating range. If the electric power is not within the operating range, the control service module sends an error message to the utility indicating the error. The control service module then monitors the operation of the optical receiver, the decoder, the video output unit, the data output unit, and the audio transmission level. If any of these values are not satisfactory, the control service module transmits a corresponding error message to the utility. The monitoring process is continually repeated while the universal demarcation point remains connected to the utility distribution network. 
     The universal demarcation point may also include a filter module, such as is illustrated in FIG.  7 . The filter module enables the utility to control the channels that the subscriber is able to view. The filter module enables the utility to transmit unscrambled video signals through the utility distribution network. By transmitting unscrambled video signals through the utility distribution network, the utility is able to provide higher quality video signals to the subscribers. Because the video signals are transmitted from the utility distribution network on fiber optic cable, which is difficult for unauthorized users to tap into, it is not necessary for the utility to transmit scrambled video signals. 
     Prior to entering the filter module, the video signal is preferably split into two lines (lines  1 ,  2 ). Line  1  is directed through filter  1  where the video signal is filtered so that only the off-air video signals remain on line  1 . Alternatively, the off-air video signals can be obtained from a separate source such as an antenna or a satellite dish. 
     Line  2  is directed into the filter module where the video signal is filtered to produce video signals that the utility restricts access to based upon the services that the subscriber pays for. By restricting access to certain services, the utility is able to charge the subscriber additional fees to receive the services. 
     Line  2  is preferably split into a plurality of lines. Each of the lines is filtered so that only a desired portion of the video signal remains on the lines. After each video signal is filtered, each video signal passes through a controller. The controller either allows the video signal to pass through or blocks the video signal based upon whether the subscriber has paid for the desired channel. For example, the video signals can be divided into basic cable television services, premium channels, and pay per view channels. 
     The operation of each of the controllers is controlled by a control signal (line  4 ) from the control service module. The control signal passes through the master controller where the control signal is directed to the appropriate controller. 
     The master controller may also transmit a signal to a controller in the off-air video signals lines (not shown) so that a portion of the off-air video signals are blocked when the subscriber is receiving a premium channel or a pay per view channel. By transmitting more than one video signal on each channel the utility is able to increase its ability to offer subscribers a greater variety of programming within a given bandwidth. 
     The filter module also preferably include system services video and audio signals (line  6 ). While line  6  indicates that the system services are brought in on a single cable, one of skill in the art will appreciate that separate cables can be used to transmit audio and video signals. When the audio and video signals are transmitted on separate cables, a conventional multiplexer is preferably included in the cable to enable each of the signals to be transmitted to the RF modulator. As indicated in FIG. 7, the RF modulator preferably produces a signal that can be viewed by the subscriber on channel  3 . 
     After the system services signal passes through the RF modulator, the system services signal passes through a controller. Similar to the other controllers, the controller is controlled by a signal from the control service module that is transmitted to the controller through the master controller. 
     Prior to being transmitted out of the filter module, each of the video signals are preferably joined onto a single cable. After being joined onto the single cable, the video signals are preferably amplified using a conventional amplifier. The conventional amplifier returns the video signals to a level that is needed for use by the subscriber. 
     After the video signals exit the filter module, the video signals are joined with the off-air video signals onto a single cable (line  8 ). Placing all of the video signals on the single cable allows the subscriber to plug the single cable into the subscriber owned equipment and obtain all of the video services. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.