Abstract:
The present invention discloses a photonic home area network for interfacing an external communications data network with a plurality of buildings, residential or commercial, in a neighborhood. The network includes an apparatus for a service node used in a multimedia network comprises a data distributor circuit; a data port adapted to couple with a data stream, said data distributor circuit having a relational code adapted to determine whether an address field of a data packet from said data stream is intended for local distribution by said distributor circuit, wherein said data port is operably coupled to said data distributor circuit; and a decoder in communication with said distributor circuit, said decoder having a virtual channel filter for filtering said address field to route said data packet to at least one data port.

Description:
[0001]    This application claims priority of U.S. application Ser. No. 09/435,657, filed on Nov. 8, 1999 entitled “Photonic Home Area Network,” the contents of which are incorporated by reference herein. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates to a photonic local or home area network for a residential or a business neighborhood for providing communications data services.  
         BACKGROUND OF THE INVENTION  
         [0003]    Neighborhood individuals are periodically charged expensive fees to have television, telephone and other future communications services provided to their homes. If these individuals could be formed into a network entity, then the resulting economic leverage of these networked individuals create a better negotiation position for reducing the charges of these services. That is, an organization representing five-hundred or more service subscribers has more negotiating leverage than one subscriber.  
           [0004]    As a result, the residential community would have the prerogative of selecting television channels that are consistent with the religious, moral and ethical standards of the community. However, if individual subscribers in the community insist on channels which would be offensive to the community, these channels can be encoded for the specific purchaser and the cost of service charged directly to the user. Products are in use which provide television, data and telephone service to the community.  
           [0005]    However, available neighborhood network technology has insufficient bandwidth to accommodate all the data associated with television, telephone and other communications services, making a neighborhood network impractical and expensive. Furthermore, such network systems do not accommodate varying data formats such as synchronous transmissions typical of television transmissions, and asynchronous transmission typical of computer data transmissions. For example, present network broadcasts of video are generally limited to uni-directional distribution. Ideally any next generation residential network not only must incorporate the bandwidth necessary for high definition television transmission but must allow those transmissions bi-directional to accommodate high definition video conferencing.  
           [0006]    An example of a product used for wireless communication is an OmniBeam available from Laser Communications, Inc. Such products are expensive and are limited in throughput bandwidth or data transfer rates. Furthermore, such systems rely on long range point-to-point transmissions using concentrating lenses, requiring precision alignment.  
           [0007]    U.S. Pat. No. 5,113,403 issued to Block et al., discloses a bi-directional free-space optical bus for electronics subsystems. A bi-directional optical link orients a beam with a polarizing beamsplitter such that the beam travels as a linearly polarized P-wave. The beam then travels through a quarter-wave plate which converts the polarization of the beam into a circular polarization mode. The beam travels through an amplitude beamsplitter to reflect the beam into two collinear axial beams along both directions of the axis of a single optical bus to interconnect computer subsystems.  
           [0008]    U.S. Pat. No. 4,183,054 issued to Patisaul et al., discloses a digital communication technique for a television communication system. The television channels are obtained and multiplexed, then transmitted through an LED to generate an encoded optical signal. The encoded signal is received by a photodetector which converts the optical signals into electrical signals. The signal is then demultiplexed into individual channels. A problem with such a device is that it is limited to distributing data and does not allow the addition of data by users. A further problem is that data is limited to synchronous transmissions.  
           [0009]    Thus, a need exists for a neighborhood network device that has a large data rate of at least 1.5 Giga-bits-per-second for accommodating video and audio synchronous and asynchronous data transmissions, which is also has unidirectional and bi-directional data transmission capability in a digital format for data distribution within and without the neighborhood community.  
         SUMMARY OF THE INVENTION  
         [0010]    The invention is a photonic home area network for distributing an external communications data network to a plurality of buildings, residential or commercial, in a neighborhood. The external communications network has a plurality of user data bandwidth segments with at least television programming data, audio programming data and telephony service data provided to the network. The photonic home area network has a photonic multiaccess channel, a head-end communications circuit, a plurality of set-top box circuits, and an executable program for demultiplexing and distributing the data segments in the set-top box circuits.  
           [0011]    In one embodiment, the head-end communications circuit has a bi-directional interface electrically connectable to the external communications data network. The head-end circuit formats the communications network data segments into a multiplexed data signal which is transmittable through the photonic multiaccess channel.  
           [0012]    In another embodiment, the plurality of set-top box circuits each have a multiplexer and a demultiplexer electrically connected to a set-top box microcontroller and an electronic memory device. Each of the set-top box circuits are electrically interconnectable in a ring network configuration to said photonic multiaccess channel and with the head-end communications circuit. A peripheral device interface is electrically connectable to a plurality of peripheral devices in the residence which can utilize the data segments.  
           [0013]    In a further embodiment, a program executable by the set-top box microcontroller routes a demultiplexed set of user data bandwidth segments according to a software subscription table stored in the electronic memory device to the plurality of peripheral devices. The program accumulates a multiplexed set of user data bandwidth segments to be transmitted to a subsequent set-top box circuit in the network.  
           [0014]    In yet another embodiment, a method of the invention interfaces an external communications source with a plurality of buildings in a neighborhood by accessing a plurality of user data segments with a head-end communications circuit, and combining the plurality of user data segments into a multiplexed data signal. The method continues by transmitting the user data bandwidth as photonic energy from an optical laser circuit to a first roof-top unit, receiving the multiplexed signal, demultiplexing the multiplexed signal into the user data bandwidth segments and routing the user data bandwidth segments to at least one peripheral device according to a software routing table, accepting bi-directional data from a bi-directional peripheral device and combining the bi-directional data with the unidirectional data into a subsequent multiplexed data signal, and transmitting the second multiplexed signal as photonic energy from an optical laser transmit circuit to a subsequent roof-top unit having an optical laser receive circuit.  
           [0015]    In yet a further embodiment, an apparatus for a service node used in a multimedia network comprises a data distributor circuit; a data port adapted to couple with a data stream, said data distributor circuit having a relational code adapted to determine whether an address field of a data packet from said data stream is intended for local distribution by said distributor circuit, wherein said data port is operably coupled to said data distributor circuit; and a decoder in communication with said distributor circuit, said decoder having a virtual channel filter for filtering said address field to route said data packet to at least one data port.  
           [0016]    In yet another embodiment, a multimedia network card comprises a deserializer coupled to a serial data stream, said deserializer adapted to convert said serial data stream to a parallel data stream representing a plurality of data of said serial data stream; a receiver coupled to said deserializer, said receiver having a relational code adapted to determine whether an address field of said parallel data stream designates local distribution; a decoder in communication with said receiver, said decoder having a virtual channel filter adapted to filter said address field to route said data packet to at least one data port; and a serializer coupled to said receiver, said serializer adapted to convert an output data stream from said receiver into an output serial data stream.  
           [0017]    In yet a further embodiment, a method of interfacing an multimedia communications data stream having a plurality of data packets, the method comprises (a) receiving a data packet of the plurality of data packets; (b) determining whether an address field of the data packet is intended for local distribution; (c) routing the data packet to a data port if the data packet is intended for local distribution; and (d) returning the data packet to the data stream if the data packet is not intended for local distribution or if other service nodes are also addressed or the packet is identified as a broadcast packet such as broadcast TV.  
           [0018]    These and other features, advantages, and objects of the present invention will be apparent to those skilled in the art upon reading the following detailed description of preferred embodiments and referring to the drawing.  
       
    
    
     DESCRIPTION OF THE DRAWING  
       [0019]    Drawings of a preferred embodiment of the invention are annexed hereto, so that the invention may be better and more fully understood, in which:  
         [0020]    [0020]FIG. 1 is an illustration of a photonic local area network set in a residential neighborhood;  
         [0021]    [0021]FIG. 2 is an illustration of a node station placed in a residence and interfaced with a television, telephone and personal computer;  
         [0022]    [0022]FIG. 3 is a detailed illustration of a node station with transmit optical lasers and receive detectors connected to a set-top box circuit;  
         [0023]    [0023]FIG. 4 is a schematic of a set-top box circuit;  
         [0024]    [0024]FIG. 5 is an illustration of a software subscription table;  
         [0025]    [0025]FIG. 6 is an illustration of a head-end communications circuit connected to a plurality of external data communications networks;  
         [0026]    [0026]FIG. 7 is an electrical schematic of a head-end communications circuit;  
         [0027]    [0027]FIG. 8 is a flow chart diagram of a program executed on the head-end communications circuit and the set-top box circuit; and  
         [0028]    [0028]FIG. 9 is an schematic illustration of a second embodiment having a transmission redundancy scheme. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    The present inventions will be described by referring to drawings showing and describing examples of how the inventions can be made and used. In these drawings the same reference characters are used throughout the several views to indicate like or corresponding parts.  
         [0030]    Referring to FIG. 1, shown is a photonic home area network (“HAN”) generally designated with the numeral  10 . The photonic HAN  10  distributes an external communications data network  12  having a plurality of asynchronous and synchronous user data bandwidth segments or channels. These channels contain television programming data, audio programming data and telephony service data from backhaul service providers or world wide communications networks. The photonic HAN has a plurality of node stations  18  and a head-end communications circuit  20  arranged in a ring network. The data network  12  is distributed to a plurality of residential buildings  14  in a residential neighborhood  16  through a multiplexed data signal path  58 . It should be understood that the multiplexed data signal path  58  refers to a signal which contains the data provided by the communications data network  12  and that the signal path  58  can be either in a photonic infrared (“IR”) form or a radio frequency (“RF”) form. Preferably the signal path  58  is in photonic IR form due to low distortion characteristics.  
         [0031]    The photonic HAN  10  provides a time multiplexed two-way communications service at optical frequencies. Optical frequencies provide wide signal bandwidths greater than or equal to 1 GHz. Such bandwidth capacity, for example, allows distribution of at least two-hundred television channels to residential buildings  14  in the HAN  10 . The bandwidth simultaneously allows telephony and personal computer transmissions, compressed video conferencing and other data transmission from the residential buildings  14  to the data network  12 . An intelligent head-end station  20  can “accumulate” outbound data from the homes delivered through signal path  58 . The head-end station  20  delivers the accumulated outbound data in a cost effective manner in wide-bandwidth asynchronous transmissions, including, asynchronous transmissions mode (“ATM”), Internet Protocol (IP), and synchronous transmission mode formats. Use of these formats create a flexible interconnect of the HAN with the data network  12  by allowing variable transmission bandwidth rate structures. The HAN system is composed of a plurality of node stations  18  and the head-end communications circuit  20  arranged in a ring network. The digital time division multiplexed (“TDM”) data signal path  58  is distributed to a plurality of buildings  14  throughout the neighborhood  16  using an infrared (“IR”) transmission medium between node stations  18 . Where necessary, passive repeaters  17  can be positioned in the HAN  10  to complete a circuit or multiple optical transmitter and receivers can be included at a node station  18  for crossing signal paths.  
         [0032]    The intelligent head-end station  20  can accommodate incoming data from the various data networks  12 . The incoming data is time multiplexed data on the digital transmission carrier and modulated onto the optical signal path  58 . Neighborhood selectable TV signals are selected from various optional network sources shown in FIG. 6, such as: free space local transmissions, cable company signals  108 , and direct space TV sources  102  (Ka Band) and  104  (C and S Band). Neighborhood incoming data flow includes incoming telephony  110  from the local public service telephone network (PSTN), local cellular providers, local Personal Communications Service Providers (“PCS”) Networks or specialized service providers, including data transmissions from various telephony, backhaul or direct space network sources  106 .  
         [0033]    Referring to FIG. 2, a node station  18  placed on a residential building  14  is shown. The node station  18  has a roof-top unit  22  connected to a set-top box circuit  24  connected through a receive wire  26 , a transmit wire  28  and a low-voltage power wire  30 . A suitable wire is a coaxial cable having suitable radio frequency transmission characteristics. An example of such a coaxial cable is RG-75. The roof-top unit  22  transmits and receives multiplexed digital data signal path  58  in an IR signal carrier. The signals are converted into a digital TDM signal and delivered to the set-top box circuit  24  through the receive wire  26 . The set-top box circuit  24  can interface with a television  32 , a telephone  34  and a personal computer  36  through interface cables  33 ,  35  and  37 , accordingly.  
         [0034]    In another aspect of the invention shown in FIGS. 1 and 3, fiber optic cable  200  can be used to complete a direct-transmission connection between set-top boxes  24  to replace the roof-top units  22 . Such fiber optic cables can be either single-mode or multi-mode depending on the transmission media. The photonic waveform can be generated in the set-top box  24  by installing a laser diode and photonic detector in this enclosure for signal transmission over the fiber optic cable  200 . Otherwise, the set-top box electrical components, described later in detail, remain the same. Referring to FIG. 3, a node station  18  is shown in detail. The roof-top unit  22  forms a photonic free space interface using a photonic signal path  58  between the other node stations  18  shown in FIG. 1 for a high-speed digital network. The roof-top unit  22  has a receive optical detector  38  connected to a downlink power amplifier circuit  40  through a coaxial cable  41 . A transmit optical laser  42  is connected to an uplink power amplifier circuit  44  through a coaxial cable  45 . Multiplexed data path signals are transmitted and received in optical wavelength format by the transmit optical laser  42  and the receive optical detector  38 , respectively. The uplink and downlink amplifier circuits  40  and  44 , respectively, compensate for conversion losses and optical coupling losses. Conversion losses are generated by converting the optical signals into an electrical form and vice versa which can be from about 20 dB to about 30 dB. The coupling losses are generated by imprecise alignment of the node stations  18  which can be as high as 10 dB.  
         [0035]    Transmit laser  42  and receive optical detector  38  are mounted to a large diameter collimation Fresnel lens or reflector  46  to create a low power density photonic radiation pattern which is less susceptible to propagation and vibration disturbances. A suitable Fresnel lens is available from Edmund Scientific Company, New Jersey under the part number E43,011.  
         [0036]    Focusing lens  48  is mounted on detector  38  and laser  42  to improve the angular radiation pattern match of detector  38  and laser.  42  with the large diameter collimation Fresnel lens  46 . Fresnel lens  46  provides a wide-beam diameter pattern for greater optical misalignment robustness and is less susceptible to propagation disturbances caused by, for example, insects or tree leaves crossing data path  58 . Collimation lens  46  generates a photonic beam having a diameter of about three-inches which has the additional benefit of aligning the station nodes  18  when installing the HAN.  
         [0037]    Reflectors  46  are connected to azimuthal- and elevational-beam pointing adjustments  50 . The adjustments  50  have a reflector member  52  and a bracket member  54  pivotally connected through a bolt  55 . The adjustments allow adjustment of the plurality of node stations  18 , shown in FIG. 1, to establish a photonic ring network. Adjustments  50  are mounted around a column  56  and secured in place by tightening bolt  55 .  
         [0038]    Surrounding and enclosing the optical detector  38  and laser  42  is an optical window  54  having a bottom edge and a top edge. The optical window is transparent to operational photonic wavelengths. The optical window  54  prevents the buildup of snow and ice and also protects the internal optical detector  38  and laser  42  and amplifiers  40  and  44  from rain, dust or other such foreign objects. On top of the optical window  54  is a roof-top enclosure  60  to prevent the buildup of snow or dust on the optics of the transmit and receiver devices. The bottom plate  62  of the roof-top unit  22  completes the enclosure of the optical laser and detector devices.  
         [0039]    Referring to FIG. 4, a schematic illustration of node station  18  is shown. The set-top box circuit  24  has a demultiplexer  70 , a multiplexer  72 , and a microcontroller  74  which has an on-board electronic memory. The set-top box circuit  24  converts the digital multiplexed data signal  58  into a demultiplexed signal having a set of user data bandwidth segments and common one-way data segments which constitutes the television data segments. The television data segments, consisting of over about 100 to about 200 television channels, are transmitted to the home and then re-transmitted to the next home and so on until the TV signal format returns to the head-end equipment  20  where it is disregarded. To optimize bandwidth on the multi-access channel,  200  or  58 , switched television channel equipment could be located at the Head-End  20  so as to provide specific television signals on customer demand.  
         [0040]    After demultiplexing the television signals in the home set-top box demultiplexer circuit  70 , the television signals are sent through a switch/demultiplexer assembly  88  for in home use of the television signals while the identical signal is forwarded by the switched/demultiplexer assembly  88  to multiplexer  72  to be recombined in a multiplexed format, such as time division multiplexed (“TDM”) or frequency domain multiplexed (“FDM”) and retransmitted to the next home or node. If switched television methodologies are employed signals or data segments for such channels would have unique addressing for specific home ports or groupings of homes and ports.  
         [0041]    A particular channel output of the switch/demux assembly  76  is selected by a home remote tuning selector furnished with the set-top box  24 . The television channels selected through the remote are passed to the digital decoder  78 . If the television channel program is not in the standard distribution category that is distributed free of charge to all subscriber homes, such as premium viewing programs, the data of the television channel is decoded for viewing by the user. Special program or premium program content channels must have a digital code resident in the electronic memory of the set-top microcontroller memory  74  for distribution to that residence. Encoding algorithms are generated in the head-end equipment microcontroller  126  and are passed to each subscriber set-top box having authorized access to the premium channel. This encoding is automated with an update rate which is programmable by the user organization at the head-end station  20 . After passing through the decoder the premium channel signal is displayed on the home television  32 . Uncoded TV channels are not affected by the decoder  78 .  
         [0042]    The user data segment of the demultiplexed spectrum  89  contains a plurality of video, audio and telephony information designated for different homes in the LAN  10  community. The user data segments have home codes attached that allows the microcontroller to distinguish which data is addressed for the particular home it resides in. Data addressed to the particular home is interpreted by the set-top box microcontroller  74  and distributed to the applicable output port  31 ,  37  or  35 . Set-top boxes could be configured for multiple telephone, fax, personal computer or auxiliary lines, as necessary. Analog-to-digital (“A/D”) and digital-to-analog (“D/A”) conversion devices  80  are resident in the set-top box for connection to analog equipment still in service in the home. Digital waveforms can interface directly with digital equipment.  
         [0043]    Demultiplexer  70  and multiplexer  72  are high speed integrated circuits capable of at least a 1.5 Giga-bits-per-second data rate time-division multiplexing. A suitable demultiplexer is a HDMP1014 and a suitable multiplexer is a HDMP1012, both available from Hewlett-Packard. The demultiplexer  70  separates the high speed serial data link from the receiver wire  26  into low-speed parallel data paths. Microcontroller  74  coordinates the data flow of the demultiplexer  70  and multiplexer  72  with the other set-top box circuits  24  in the network.  
         [0044]    The demultiplexed data is delivered to various units or ports such as a television, telephone or the like. Communications data is conveyed to a television through a television switch select circuit  76 . The switch select circuit  76  selects one of the TV channel outputs from the  100  or so transmitted from the head-end  20  for viewing on the home television monitor. A user selects the channel with conventional television remote control devices. Digital-to-analog converters (“D/A”) devices  80  are implemented to provide analog outputs for analog television sets as needed. Similarly, digital television outputs or high definition television outputs are also available.  
         [0045]    The microcontroller  74 , shown in FIG. 4, controls the flow of user data from and to its respective residential building  14  in the HAN neighborhood  16  by removing data from the user data segment or segments of the multiplexed data stream addressed to a node station  18  and synchronizing data from the residential building  14  back into the user data stream. A suitable microcontroller is an 80286 microprocessor available from Intel, Inc.  
         [0046]    The user data stream is a 62.5 Mega-bits-per-second (Mbps) channel  89 , but can be increased to two or three similar channels as the demands of the users increases. The user data bit stream is dynamically allocated by the head-end microcontroller  126 . As an example, about 2 Mbps to about 5 Mbps of the data frame can be allocated toward telephone conversations. Specific telephone conversations starting will be allocated to a position in the data frame at the start of the telephone call by the head-end microcontroller  126  and that position in the data frame would remain allocated until that telephone call is terminated. User data would consist of telephony, personal computer data, auxiliary data for home maintenance and control, fire and intrusion alarm, etc. Futuristic home video conferencing equipment allowing total office immersion of stay-at-home workers could be supported. The bandwidth availability can readily accommodate data transmissions common today. For example, telephone service can be accomplished to about 500 homes with less than 3 Mbps. However, bandwidth hungry technologies such as real-time video conferencing, can require throughputs approaching a magnitude of Giga-bits-per-second. An initial allocation of 125 Mbps for the residences in the HAN  10  is sufficient for future bandwidth needs in the near future.  
         [0047]    The head-end equipment  20  records in an electronic memory the devices located in each residence or business node  18  to which it is furnishing information to the HAN. Also recorded is the type of specialized service provided to the residence or business nodes  18 . FIG. 5 shows a software table of node information that is typical of the information contained in the head-end equipment for system control.  
         [0048]    Connected to demultiplexer  70  through receive wire  26  is downlink power amplifier circuit  40 . The receive optical detector  38  is connected to the downlink power amplifier circuit  40  through coaxial cable  41 . Direct current (“DC”) blocking capacitors C decouple the alternating current (“AC”) signal path from the DC path such that it amplifier  82  and receive optical detector  38  can be individually electrically-biased. The amplifier  82  is sufficiently linear in operation across the operational bandwidth of the system which is initially selected at about 1 GHz. A suitable amplifier is a VNA-25 available from Mini-Circuits. A suitable receive optical detector is a C30616E available from EG&amp;G of Canada. The electrical current generated in the receiver optical detector  38  results in an output voltage across the resistor R 1 . Resistor R 1  also matches the receiver optical detector  38  to the amplifier  82  input impedance. The RF choke  86  reverse biases the receiver optical detector  38 .  
         [0049]    Connected to the multiplexer  72  through transmit wire  28  is the uplink power amplifier circuit  44 . The transmit optical laser  42  is connected to the uplink power amplifier circuit  44  through coaxial cable  45 . DC blocking capacitors C decouple the AC signal path from the DC path such that the amplifier  84  and transmit optical laser  42  can be individually biased. Resistor R 2  is a matching resistor to raise the impedance of the laser to the amplifier  84  output impedance. The amplifier  84  is sufficiently linear in operation across the operational bandwidth of the system, which is about 1 GHz. A suitable laser is a HL1326MF available from Hitachi. The laser  44  is biased through the RF choke  90 . The multiplexed data stream is transformed into an on-off keying (“OOK”) modulated optical carrier signal for transmission. The modulated data stream is then converted into light energy through the transmit optical laser  42  into the multiplexed data signal  58 . If fiber optic cable  200  is used in place of free space IR transmission  58  items  40 ,  26 ,  42 , and  28  are replaced with an optical transceiver.  
         [0050]    The multiplexed data signals  58  can contain television, telephone, and computer data. The multiplexed data carrier signals  58  can take other binary waveforms encoded in digital formats such as On-Off-Keying (“OOK”), Frequency-Shift-Keying (“FSK”), Quadrature-Phase-Shift Keying (“QPSK”), or Quadrature-Amplitude-Modulation (“QAM”). OOK format is preferred for the present embodiment due to its relatively low complexity.  
         [0051]    Shown in FIG. 4, synchronous telephony and fax data line  35  is provided. Demultiplexer  70  routes the telephony data to the user in the same manner as the video data. If analog phones and faxes are used in the residence, the lines are connected to A/D converter  80  for signal conversion, accordingly. A/D converter  80  has bi-directional conversion capability for digitization of analog signals from analog equipment before the signals are sent to the microcontroller  74  for synchronization with the television data and computer data communications. Data from the user is routed through the microcontroller  74  to the multiplexer  72  for incorporation into the multiplexed data signal  58 .  
         [0052]    The node station  18  also supports asynchronous data transfers associated with personal computers  36 , referring briefly to FIG. 2. The personal computer interface  37  for the HAN can be in asynchronous transfer mode (“ATM”), frame transmission or Ethernet interface or other such formats. An auxiliary interface is available through coaxial cable  31  for a universal and software programmable peripheral options. Such options can include, for example, a fire alert, a security monitoring function, a remote access to home maintenance functions, or medical alert.  
         [0053]    Similarly, as stated in previous paragraphs fiber optic path  200  interconnections can replace the interconnections between the set-top box and the roof-top unit. This embodiment removes the electronics bandwidth limitation of the coaxial cable from the HAN  10 . This embodiment allows the HAN  10  to be upgraded to higher bi-directional bandwidths with minimal system changes. That is, as multiplexer and demultiplexer integrated circuit technology development continues, the limitation of 1.5 Gigabits-per-second will be removed. Referring to FIG. 6, a head-end communications circuit  20  is shown. The head-end circuit is the interface between the photonic HAN  10  shown in FIG. 1 and external communications data sources  12  such as local cable, local free space UHF and VHF television transmissions, direct space television, and direct space wide bandwidth data transfer.  
         [0054]    The head-end communications circuit  20  has an interface connectable to external communications data sources  12 . For example, data is provided by a DBS television dish  102 , a S &amp; C Band satellite dish  104 , a Ka Band LED Direct Space Communications link antenna  106  which feeds through a terminal box  107 , a telephone cable  108  and a cable television cable  110 . These sources are routed to the head-end communications circuit  20 . The head-end circuit  20  converts these data sources into a high-speed digital data signal. This signal is conveyed through a transmit cable  26  and broadcast from a roof-top unit  22 .  
         [0055]    Referring to FIG. 7, shown is the head-end circuit  20  with a signal formatting circuit  120  for formatting the communications data sources into a multiplexed data signal  58 . The signal formatting switch  120  takes the digitized television channels from numerous raw sources of single-way television such as DBS television  102  and S&amp;C band satellite television  104  and selects a cross-section of channels and synchronizes their carriers for combination. The channels selected are a result of negotiations with communications service providers and the users of the photonic HAN  10 . The synchronization switch  120  includes A/D devices internally where necessary to digitize an analog television channel.  
         [0056]    The channel selection register  120  designates the core television channel selection for the photonic HAN. The channel selection register  120  is controlled by a head-end personal computer (“PC”)  122  having an executable program. Head-end PC  122  can be programmed on a weekly, monthly or longer basis as needed. Control of the selection register  120  can be dynamic in that a specific program on a specific television network can be allocated at a designated programming time in the register, such as scheduling of “pay-per-view” boxing matches or similar sporting events.  
         [0057]    When premium television channels or requested channels are placed on the network the microcontroller  126  creates a digital encoding key and initiates encoding of the channels through digital encoder or enabling register  121 . Users verified to view these services that are recorded on the control station  122  and are sent a software key through the user data stream to their residence. Network connections  112 ,  113  and  114  are interfaces with microcontroller  126  for routing accordingly.  
         [0058]    The head-end PC  122  creates and maintains a master program scheduling plan. The scheduling plan tracks premium monthly channel service for monthly billing  124 . Special single event programming can be purchased by users through the set-top box  24  with interactive requests by users. These interactive requests are tracked by the head-end PC  122  and billed accordingly. Head-end PC  122  also executes a program which controls the synchronization switch  120  and works interactively with microcontroller  126  via multiple conductors  123  to control premium channel access and special event programming.  
         [0059]    An aspect of the photonic HAN  10  is that bidirectional user data is combined with the multiplexed data signal path  58 . Referring to FIG. 4, user data is provided to the set-top box circuit  24  through personal computer line  37  and telephone line  35  routed by the microcontroller  74  to multiplexer  72 . Multiplexer  72  incorporates digitized voice transmissions and data transmissions from the residential customers into the multiplexed data signal  58 . Referring to FIG. 6, the head-end microcontroller  126  synchronizes the user data transmitted to and received from the node stations  18 .  
         [0060]    The head-end microcontroller  126  program performs node station code field monitoring. That is, node station code monitoring tracks voice and data transmissions originating from users and routes this data to other users or external networks  12  in the HAN  10  as required. Node station codes are allocated as shown in FIG. 5, which illustrates a computer screen display indicating the communications services available to each node in the HAN. The head-end microcontroller  126  separates voice transmissions from data transmissions. The voice transmissions are time sequenced onto a local telephone transmission line  108  of the external communications network  12 . The data transmission has an address data format designating whether the data is synchronous or asynchronous. The address data format contains the node station field  140 , a device field  141  which indicates the services at a node such as telephone, computer, and the like. A device field  142  contains information regarding particular electronic communications devices at the node. A subroutine field  143  contains peripheral device address information such as telephone numbers and the like. A special-instruction field  144  contains information that is acted upon in the occurrence of certain events. For example, with respect to auxiliary devices listed in the device field  141 , if a fire alarm is triggered, then the fire alarm will notify the fire department and designated neighbors. If a burglar alarm is sounded, the police department designated neighbors are notified.  
         [0061]    The head-end microcontroller  126  also performs system failure monitoring of all homes on the photonic HAN. A break in the ring network formed by the plurality of node stations  18  is indicated by the loss of the homes or residences preceding the break and the loss of the common carriers in the return link. Therefore, head-end microcontroller  126  can determine which link of potentially several hundred node stations has failed. A software algorithm initiates the microcontroller  126  to notify maintenance personnel accordingly for repair.  
         [0062]    Software decoding keys are loaded on individual set-top box circuits  24  periodically through the multiplexed data path  58  and the set-top box microcontrollers  74 , with respect to the device field  141  contents. Decoding keys are randomly generated for security purposes and can be updated periodically so as to preclude unauthorized access to services. For example, the microcontroller  126  encodes premium television channels, controls access to special “Pay-Per-View” programs and reports to the head-end PC  122  user purchases of these programs.  
         [0063]    As shown in FIG. 7, the head-end microcontroller  126  is connected to the head-end demultiplexer  128  and the head-end multiplexer  130 . The demultiplexer  128  decodes the multiplexed data path  58  from the photonic HAN arriving through receive wire  26 . The signal contains user data which requires further processing and transmission to the external data communications network  12 . The demultiplexer  128  removes the user data stream from the multiplexed data signal  58  while disregarding the real-time television channel portion. The microcontroller  126  processes the extracted user data which is identified by node station code  140  and form of data such as synchronous telephony data, asynchronous user requests or otherwise.  
         [0064]    The system discussed in this patent application as it relates to telephony service lends itself to providing its own dial tone service. This will be an option for the purchasing authority. They can use existing terrestrial service providers, direct space service providers or be their own service provider and purchase backhaul service from one of the above companies. The business relationship will be fluid and subject to regulatory options available to the community.  
         [0065]    Referring to FIG. 8, a flow chart of the program executed on the set-top box circuit microcontroller  74  and the head-end microcontroller  126  is shown. The program applies to the user data stream having bi-directional data such as telephony or computer data since the video and audio channels  88 , shown in FIG. 4, are merely passed through the set-top box circuit  24  and are continuously multiplexed onto the data stream through the head-end circuit  20 .  
         [0066]    The program begins (step  1 ) and checks for an input interrupt (step  2 ). If there is not an input interrupt then the program proceeds to decode the address of the user data (step  4 ). The decode address user data in the signal is compared to the local address at the node station  18  or the head-end communication circuit, accordingly (step  5 ). If the two addresses are the same, then the data delivery routine is invoked (step  7 ). Then the node station is addressed (step  7 ) and the data is delivered (step  8 ) and the program returns to the start of the main program (step  9 ).  
         [0067]    If the address in the signal and the local address are not the same (step  6 ), then the program seeks to acquire user data (step  14 ) if there is open space in the transmission signal (step  15 ). If there is no open space, the program returns attempts again to acquire user data (step  14 ) and continues to do so until a space in the transmission signal opens in which user data is added to the signal (step  16 ). The program returns to the main program (step  17 ).  
         [0068]    When an interrupt is received (step  3 ) an interrupt service routine is called (step  10 ). The source of the interrupt is searched (step  11 ). If the interrupt source is a hand-held television remote control then the television channel is changed (step  12 ) and the program returns to the start of the main program (step  9 ). If the interrupt source is not a hand-held television remote control then the address of the data input source is acquired (step  18 ). The accompanying data is retrieved (step  19 ) and the destination address is added to the signal for multiplexing (step  20 ). The destination address is another node station in the photonic HAN or external network, which allows local telephone communications without the necessity to go outside the HAN to call, for example, a next-door neighbor. The program then returns to the main program (step  21 ).  
       SECOND EMBODIMENT  
       [0069]    Redundancy can be designed into the HAN  10  with a bi-directional path. For example, when a node station  18  in the HAN  10  is interrupted, data flow can be re-routed such that each side of the photonic network interruption is self-contained. Hardware redundancy in the set-top box and in the transmit optical laser  42  and the receive optical detector  38  can be installed using the same principles as disclosed above. Similar redundancy is accomplished through the use of dual counter rotating fiber optic cable  200 . Because of the nature of knowledge inherent in the edge network access system Head End it is possible to effectively utilize the entire dual circuit bandwidth simultaneously (the system knows the low priority customer data segments). This negates the necessity for the 100% backup as utilized in classical SONET networks.  
         [0070]    A redundant-path roof-top unit  300  is illustrated in FIG. 9. For clarity, one receive and transmit configuration is shown. Another such configuration is mounted substantially opposite the illustrated unit so that the network ring can be completed. Redundant-path roof-top unit  300  of would require the position of the laser  42  and the detector  38  to be complementary arranged for the laser at one location to optically couple to the detector at the other location and vice versa. If a link or photonic path  58  is blocked, the information can be looped back to the head-end  20  or next roof-top unit  18  (shown in FIG. 1).  
         [0071]    The transmit optical laser  42  generates optical radiation from a direct injection, diode heterojunction laser. Such radiation is highly polarized in a direction parallel to the semiconductor junction of the device. This polarization characteristic of the laser  42  allows the addition of a polarization beamsplitter  302  to separate and route the incoming and outgoing light or information path of the optical carrier  58 . A suitable beamsplitter is available from Newport Corporation under the part number 05FC16PB.9 or 10FC16PB.9. For further clarity, the optical carrier  58  is split, or polarized, into a receive wave and a transmit wave. The receive wave is the P-component of the optical carrier  58 . The transmit wave is the S-component of the optical carrier  58 . The S-component is deviated through a 90-degree angle while the P-component passes undeviated through the beamsplitter  302 . This opposite polarization does not interfere with the detector nor the optical carrier  58 .  
         [0072]    Fresnel lens  46  can be used to focus and gather the receive wave A and the transmit wave B, respectively. An optical filter  306  reduces the external random light frequencies injected into the system by ambient light from the sun, street lights or the like. Optical filter  306  preferably has a wavelength cutoff position of about 1000 microns. A suitable optical filter is available from Edmund Scientific Company, New Jersey, under the part number E32,770 or E32,760. Reducing the background radiation generated from these sources makes the system more sensitive.  
         [0073]    The embodiments shown and described above is only exemplary. Many details which are omitted are well known in the art such as descriptions of the inner workings of multiplexers, demultiplexers, laser transmitters and detectors, and the like. Therefore, many such details are neither shown or described. It is not claimed that all the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present inventions have been set forth in the foregoing description, together with the details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in the detail, especially in the matters of shape, size, and arrangement of the parts within the principles of the inventions to the full extent indicated by the broad general meaning of the terms used in the attached claims. The restrictive description and drawings of the specific examples do not point out what an infringement of this patent would be, but are to provide at least one explanation how to make and use the inventions. The limits of the inventions and the bounds of the patent protection are measured by and defined by the following claims.