Abstract:
A system for the connection of any standard analog terminal subscriber telephone equipment, e.g. analog telephone, facsimile, and analog computer modem devices, to be utilized concurrently at a location interior to the building that is serviced by the single conventional two conductor telephone wire. The simple installation of the present invention&#39;s Master Subscriber Line Multiplexer Unit at the nearest interior or exterior location of the attachment of the telephone service provider&#39;s two conductor analog subscriber lines and the premise owned interior conventional two conductor analog telephone subscriber wire. The Master units input are two of the telephone service provider&#39;s two conductor analog subscriber lines. The control and voice and data signals are then multiplexed and transmitted over an interior conventional two conductor analog telephone subscriber wire to a remote location service by the wire. The present invention&#39;s Slave Subscriber Line Demultiplexer Unit provides demultiplexion, detection, and properly reproduces the control, data, and voice signals for each separate analog two conductor telephone subscriber lines.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates generally to a telephony multiplexed communications device for buildings with preexisting interior conventional two conductor wiring. More particularly, the invention relates to a multiplexor device that enables two, or more, line telephone service provided on two conductor analog subscriber telephony lines to be multiplexed over a single existing interior conventional two conductor wire and demultiplexed at the terminal subscriber location to two, or more, analog two conductor subscriber lines. 
     The problem with existing wired buildings with conventional two conductor telephony wiring is that there are often only single subscriber lines wired to specific locations in the buildings. Modern communications commonly require multiple analog terminal subscriber devices, e.g. analog telephone, facsimile, and analog computer modem devices, to be utilized concurrently at a single location interior to the building. Many older buildings were constructed at a time when a single telephone line comprised of a conventional two conductor wire was installed in only a few specific areas of the interior of the building. The modern communications user who needs two analog communications devices which can be used concurrently, is faced with the choice of installing another conventional two conductor analog telephone subscriber line through the existing interior building structure which can be both costly and possibly damaging to the interior building physical appearance. The modern communications user can also face stringent or prohibitive building codes or prohibitive historic codes if the building is categorized as a historic structure or limited alterations if enacted by community building associations regulations. 
     2. Discussion of Prior Art 
     In order to provide background information so that the invention may be completely understood and appreciated in its proper context, reference may be made to a number of prior art patents as follows: 
     U.S. Pat. No. 5,363,432, issued to Martin et al. is concerned with using shielded cable as opposed to, the single pair of conventional twisted unshielded two conductor wire, and broadband signals, e.g. television type signals. This patent proposes that if the telephone analog subscriber line uses a shielded cable consisting of more than one pair of wires, then one of these pair of wires and the shield element can be used to transmit a broadband type of signal into the subscriber&#39;s unit without having to add a separate coaxial type of cable commonly used in conventional broadband transmission systems. 
     U.S. Pat. No. 5,090,052, issued to Nakajima et. al. (Tandy Corp.) provides for a telephone system with multiple analog subscriber terminal equipment for use interior to the subscribers&#39;s building which allows multiple simultaneous calls on a single telephone line. A plurality of carrier frequencies are chosen to allow for simultaneous calls incorporating frequency modulating channels for each telephone extension. The present invention distinguishes itself therefrom by using the reducing technique of multiplexing so that two, or more, analog subscriber two conductor telephone lines supplied by the telephone service provider is transmitted over existing conventional two conductor telephone wire interior to the building and using an expanding technique of demultiplexing to provide the two, or more, separate analog two conductor subscriber lines to be connected to two unaltered standard analog subscriber terminal equipments. 
     U.S. Pat. No. 4,821,319, issued to Middleton et. al. and U.S. Pat. No. 4,996,709 to Heep et al. disclose devices solely concerned with intercommunications (intercom) service inside the subscriber&#39;s terminal unit, using one conventional analog two conductors subscriber line connected to the telephone service provider owned central office telephone switch. The present invention distinguishes itself by multiplexing two analog two conductor lines over one pair of conventional two conductor telephone wire preexisting and interior to the building. 
     U.S. Pat. No. 4,706,244, issued to Watson et al. discloses a frequency multiplexed system which couples a plurality of individual telephone sets to one analog two conductor telephone subscriber line, in which the system provides for intercommunications (intercom) calls between the telephone sets which have been designed specifically to decode the frequency multiplexed signal. This system also provides additional two conductor telephone subscriber lines and requires additional conventional two conductor telephone wiring interior to the building. The present invention distinguishes itself by multiplexing two, or more, analog two conductor lines provide by the telephone service company to the outside of the building over one pair of conventional two conductor telephone wire preexisting and interior to the building and allows subscriber&#39;s to install standard analog subscriber terminal equipment to the output two conductor terminal analog subscriber telephone lines. 
     U.S. Pat. No. 4,807,225, issued to Fitch discloses a frequency multiplexed system which couples a plurality of individual telephone stations to one analog two conductor telephone subscriber line, in which the system provides for telephone stations that create additional communications channels and a data channel at frequencies that do not interfere with standard analog telephone extension equipment already present. These telephone stations have been designed specifically to decode the frequency multiplexed signals. The present invention distinguishes itself by multiplexing two, or more, analog two conductor lines provided by the telephone service company to the outside of the building over one pair of conventional two conductor telephone wire preexisting and interior to the building and allows subscriber&#39;s to install standard analog subscriber terminal equipment to the output two conductor terminal analog subscriber telephone lines. 
     A commercially available digital two telephone line carrier system, manufactured by PairGain Technologies, Inc., provides equipment located at the central office telephone switch and typically at the subscriber terminal building telephone wire entrance to provide two analog two conductor subscriber lines over a single pair of two conductor analog telephone subscriber lines supplied by the telephone service provider exterior to the building. The present invention distinguishes itself by multiplexing two, or more, analog two conductor lines provided by the telephone service company to the outside of the building over one pair of conventional two conductor telephone wire preexisting and interior to the building and allows subscriber&#39;s to install standard analog subscriber terminal equipment to output two conductor terminal analog subscriber telephone lines. The present invention further distinguishes itself by not requiring any equipment at the telephone service provider central office switch location. 
     Whatever the precise merits, features, and advantages of the above cited references, none of them achieves or fulfills the purposes of the telephone subscriber line multiplexer system of the present invention. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to achieve the fully functional two conductor analog telephone subscriber lines multiplexing over a single conventional two conductor telephone wire that preexists in the interior of the building&#39;s structure and demultiplexing the signal into the original fully functional two, or more, analog two conductor telephone subscriber lines. 
     It is a further object of the present invention to allow for the connection of any standard analog terminal subscriber telephone equipment, e.g. analog telephone, facsimile, and analog computer modem devices, to be utilized concurrently at a location interior to the building that is serviced by the single conventional two conductor telephone wire that preexists in the interior of the building&#39;s structure. 
     The Multiple Line Telephone Multiplexed Communications System of the present invention overcomes the problems and limitations of adding additional analog two conductor telephone subscriber lines to the interior of buildings with existing interior single conventional two conductor analog telephone wire that by virtue of the building, historic, or community regulations prohibit additional interior telephone wiring or the economics become prohibitively costly for the installation and restored to original physical condition. The simple installation of the present invention&#39;s Master Subscriber Line Multiplexer Unit at the nearest interior, or exterior, location of the attachment of the telephone service provider&#39;s two conductor analog subscriber lines and the premise owned interior conventional two conductor analog telephone subscriber wire. The Master units inputs are two, or more, of the telephone service provider&#39;s two conductor analog subscriber lines. The control and voice and data signals are then multiplexed and transmitted over an interior conventional two conductor analog telephone subscriber wire to a remote location service by the wire. The present invention&#39;s Slave Subscriber Line Demultiplexer Unit provides demultiplexion, detection, and properly reproduces the control, data, and voice signals for each separate analog two conductor telephone subscriber lines. The present invention allows for the connection of any standard analog terminal subscriber telephone equipment, e.g. analog telephone, facsimile, and analog computer modem devices, to be utilized concurrently at a location interior to the building that is serviced by the single conventional two conductor telephone wire. 
     The Master Subscriber Line Multiplexer Unit contains electronic circuitry that interacts with the telephone service provider&#39;s central office telephone switch for dialing, ring detection, and communications for the two, or more, telephone service providers analog two wire telephone subscriber lines. The Master Unit then multiplexes the incoming telephone line calls and sends control signals for the lines on to the existing interior conventional two conductor telephone wire-pair. The Master Unit also demultiplexes the outgoing terminal subscriber line calls and signals the appropriate line to the central office switch and communicates the voice or data and terminates the call when transmission is signaled complete by the terminal subscriber equipment. 
     Slave Subscriber Line Demultiplexer Unit (Slave Unit) contains electronic circuitry that interacts with the Master Subscriber Line Multiplexer Unit to demultiplex the incoming calls and generate the appropriate line ringing signal, supervisory signals from the central office switch, on hook and off hook detection, and data and voice communications for the two telephone service providers analog two wire subscriber lines. The Slave Subscriber Line Unit for outgoing subscriber terminal calls will detect and encode for each subscriber terminal line both rotary pulse dial codes and Dual Tone Multifrequency (DTMF) dial tones, detect on and off hook status and transmit those signals to the Master Unit over the existing interior conventional two conductor telephone wire-pair. The Slave Unit will multiplex the two telephone terminals equipment&#39;s voice and data requirements concurrently and terminate the transmission with appropriate control signals when the terminal equipment indicates completion of the assigned communications task. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a symbolic pictorial drawing showing two through n telephone subscriber line multiplexed telephony system of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 provides the overall Telephony Multiplexed Communications System and is composed of a Master Multiplexer Subscriber Line Unit (Master),  18 , and Slave Subscriber Line Units (Slave),  34 , that are interconnected to each other by a single conventional two conductor telephone wire,  24  and  26 , interior to the building. The two through n analog telephone subscriber lines supplied by the telephone service provider,  14 - 16 , are connected to the Master Unit at the telephone service entrance to the building in close proximity to existing country alternating current line power and also houses one terminal end of the interior preexisting conventional two conductor telephone wire,  24  and  26 . The Master is then connected to a single interior two conductor pair wire  24  and  26  that is preexisting and is run to a single terminal location within the building. The Slave Unit is then connected to the terminal location of the preexisting conventional two conductor telephone wire  24  and  26  at a point in close proximity to existing alternating current line power outlet. The Slave Unit can accommodate any standard two wire analog terminal subscriber equipment on the female RJ11 two, or more, wire analog telephone subscriber ports  36 ,  37  and  38 . 
     Master Subscriber Line Unit 
     The Master Unit  18  functions as an interface between the outside provided two, or more, analog telephone subscriber lines supplied by the telephone service provider,  14 ,  15  and  16 , which originates at the dial central office telephone switching equipment and the digital multiplexing and signal control scheme provided to connect to the preexisting conventional two conductor telephone wire,  24  and  26 . The Master Unit  18  is powered by a direct current that has been transformed by a switch selectable alternating current to direct current power supply designated  20 ,  22 . The power supply  20  has a switch selectable input alternating current source range to support various countries&#39; alternating current power sources as necessary, e.g. nominal 115 volts at 60 hertz frequency for the U.S., nominal 220 volts at 50 hertz frequency for Europe. It is envisioned that the power may be alternately supplied from the existing telephone lines. The Master Unit  18  provides dialing, ring detection, and data and voice communications for the two, or more, telephone service providers analog two wire subscriber lines,  14 ,  15  and  16 , which are connected via analog signal and communications telephony techniques to the telephone service provider&#39;s dial central office telephone switch. The Master Unit then uses digital and analog techniques to provide the control signals such as ring, busy line, and progress tones and voice and data signals and place those on the Tip conductor  24  and Ring conductor  26 . The Tip conductor  24  and Ring conductor  26  provide the conduit for the two way digital multiplexion of both incoming and outgoing telephone calls for the two, or more, analog telephone subscriber lines supplied by the telephone service provider  14 ,  15  and  16 . The details and methods for handling incoming and outgoing telephone calls are discussed in a separate section below. 
     The Master Unit  18  provides for the detection of power failures and an Automatic reset mechanism for any power failures. The Master Unit  18  also provides both opto-coupled protection and UL 1459 protection for U.S. or the foreign equivalent certified protection at the frontend connection to the two analog telephone subscriber lines supplied by the telephone service provider  14 ,  15  and  16 . 
     Slave Demultiplexer Subscriber Line Unit 
     The Slave Unit  34  functions as an interface between the Master Unit  18  and the analog terminal subscriber equipment, e.g. analog telephone  40 , facsimile  42 , analog computer data modem  44 , facsimile or analog telephone detection switch  46 , which are connected to the Slave Unit&#39;s  34  two conductor telephone line ports  36 ,  37  and  38 . These two, or more, telephone lines,  36 ,  37  and  38 , are composed of a TIP and Ring conductor configured in the standard female RJ11 connector thereby mating the connection of standard analog terminal subscriber equipment,  40 ,  42 ,  44 ,  46 , having a male RJ11 telephone connector. The Slave Unit  34  is powered by a direct current that has been transformed by a switch selectable alternating current to direct current power supply designated  20 . The power supply  20  has a switch selectable input alternating current source range to support various countries&#39; alternating current power sources as necessary, e.g. nominal 115 volts at 60 hertz frequency for the U.S., nominal 220 volts at 50 hertz frequency for Europe. 
     The Slave Unit  34  interacts with the Master Unit  18  to demultiplex the incoming calls and generate the appropriate line ringing signal, supervisory signals from the central office switch, on hook and off hook detection, and data and voice communications for the analog two wire subscriber lines  36 ,  37  and  38 . The Slave Unit  34  detects and processes outgoing subscriber terminal calls. The Slave Unit  34  will detect and encode for each subscriber terminal line both rotary pulse dial codes and Dual Tone Multifrequency (DTMF) dial tones, detect on and off hook status and transmit those signals to the Master Unit  18  over the single existing interior conventional two conductor telephone wire-pair  24  and  26 . The Slave Unit  34  will multiplex the two, or more, telephone terminals equipments voice and data requirements concurrently and terminate the transmission with appropriate control signals when the terminal equipment  40 ,  42 ,  44 ,  46 , indicates completion of the assigned communications task. The Slave Unit  34  provides the detection of power failures and an Automatic reset mechanism for any power failures. 
     Incoming Calls Functional Description 
     This paragraph provides a functional description of the process of the present invention as it handles the two, or more, analog two conductor telephone subscriber lines  14 ,  15 , and  16  for incoming telephone calls. The incoming telephone call first generates a ring signal at the telephone service providers dial central office telephone switch on one of the two through n analog two wire telephone subscriber lines  14 ,  15  or  16 . The Master Unit  18  detects the ring signal from the dial central office and then signals the Slave Unit  34  to detect if the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , attached to the two conductor analog subscriber line of the Slave Unit  36 ,  37  or  38  is on hook or off hook. If the designated telephone line terminal subscriber equipment  40 ,  42 ,  44 ,  46 , is off hook and therefore busy the Slave Unit  34  then signals the Master Unit  18  not to seize the line  14 ,  15  or  16  thereby signaling the dial central office that the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , is busy. If the Slave Unit  34  detects that the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , is on hook and thereby not busy then the Slave Unit  34  signals the Master Unit  18  to seize the telephone line. Upon the Master Unit  18  seizing the line to establish communication with the dial central office telephone switch the Slave Unit  34  will generate a ring signal to the appropriate terminal subscriber equipment  40 ,  42 ,  44 ,  46 . At any time, if the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , goes on hook, the Slave Unit  34  will signal the Master Unit  18  which will release the line signaling to the dial central office switch that the terminal end has disconnected the telephone call. Conversely if the dial central office signals that the originating end has gone on hook and terminated the telephone call then the Master Unit  18  will release the line and signal the Slave Unit  34  that the originating end has disconnected the telephone call. Once the Master Unit  18  has seized the line acknowledging that the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , is off hook the two way data or voice communications can ensue. The Master Unit  18  will multiplex the originating callers data or voice over the preexisting conventional two conductor telephone wire,  24  and  26  to the Slave Unit  34  which will demultiplex the data and voice and generate the analog signal to the appropriate analog two wire subscriber lines  36 ,  37  and  38 . The incoming telephone call will be terminated by either the originator or terminal subscriber going on hook as functionally described above. 
     Outgoing Calls Functional Description 
     This paragraph provides a functional description of the process of the present invention as it handles the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , for outgoing telephone calls. The terminal subscriber equipment  40 ,  42 ,  44 ,  46 , will initiate the outgoing telephone call procedure. The Slave Unit  34  detects the terminal subscriber telephone equipment  40 ,  42 ,  44 ,  46 , going from the on hook condition to the off hook condition signifying that the analog terminal subscriber telephone equipment  40 ,  42 ,  44 ,  46 , is ready to communicate. The Slave Unit  34  will signal the Master Unit  18  that the outgoing call is necessary on the appropriate two conductor analog terminal subscriber line port  36 ,  37  or  38  on the Slave Unit  34 . The Master Unit  18  will then seize the telephone line. Upon the Master Unit  18  seizing the line to establish communication with the dial central office telephone switch the Master Unit  18  will signal the Slave Unit  34  that the line has been seized and dialing procedures may begin. The Slave Unit  34  will detect and encode for each subscriber terminal line both rotary pulse dial codes and Dual Tone Multifrequency (DTMF) dial tones and multiplex the control signals to the Master Unit  18  which will detect the dial control signals and generate them on the appropriate two analog telephone subscriber lines  14 ,  15  and  16  supplied by the telephone service provider. Once dialing control signals have completed the Master Unit  18  will wait for any progress control signals to be generated by the dial office central telephone switch or the distant end terminal subscriber equipment going off hook and thereby ready to communicate. Once the distant end is off hook signifying a complete connection on the telephone system the Master Unit  18  will signal the Slave Unit  34  that data or voice communication can begin. The Slave Unit  34  will multiplex the voice or data from the terminal subscriber telephone equipment  40 ,  42 ,  44 ,  46 , and transmit the multiplexed signal over the single existing interior conventional two conductor telephone wire-pair  24  and  26 . The Master Unit will demultiplex the signal and generate and transmit the voice or data signal over the appropriate one of the two through n analog telephone subscriber lines supplied by the telephone service provider  14 ,  15  or  16  to the dial central office. The Master Unit  18  will conversely detect the incoming data voice or control signals for the communications session and Multiplex that analog signal for transmission to the Slave Unit  34  over the existing interior conventional two conductor telephone wire-pair  24  and  26 . The Slave Unit  34  will then demultiplex the data or voice signal from the Master Unit  18  and generate the analog signals on the appropriate two conductor terminal subscriber lines  36 ,  37  or  38  At any time if the terminal subscriber equipment  40 ,  42 ,  44 ,  46 , goes on hook the Slave Unit  34  will signal the Master Unit  18  which will release the line signaling to the dial central office switch that the terminal end has disconnect the telephone call. If at any time the central office telephone switch signals to the Master Unit  18  that the distant end terminal subscriber equipment has gone on hook and thereby terminated the telephone call prematurely the Master Unit  18  will detect the signal and transmit a signal to the Slave Unit  34  that call has been terminated. The Slave Unit  34  will generate a dial tone to the terminal subscriber equipment designating a terminated call and line available for outgoing or incoming call. At the same time the Master Unit  18  will drop the line signaling to the central office switch the line is free for incoming or outgoing calls. 
     CONCLUSION 
     A system and method has been shown in the above embodiments for the effective implementation of a Subscriber Line Multiplexer. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.