Audio/Video Signal Redistribution System

This invention relates to communications systems. In particular, this invention relates to an interactive audio/video telecommunications system which integrates and redistributes audio/video signals received in multiple formats to multiple users over existing telephone wires.

Modern society is heavily reliant upon many different kinds of audio/video telecommunications services affecting all aspects of daily life. Television is one of the most popular sources of information and entertainment. Other sources of information and entertainment include computer networks such as the Internet, which today offers interactive shopping, banking, gaming, venues for discussion and social intercourse and many other products and services, home video games, videotape movie rentals and the like. These types of services provide a virtually unlimited variety of information and entertainment to practically every corner of the world.

However, these services have evolved independently over many decades and as such are provided in different formats and through disparate channels of distribution. For example, television signals can be received by off-air antenna, cable redistribution networks (CATV) and satellite broadcasts, but access to each signal source is independent of the others and requires specialized equipment and/or service providers. A television set can be equipped to receive signals from all of these sources, but only one at a time so some form of switching equipment at the receiving end is required to change the television signal source. Further, each of these signals itself comprises many channels, which complicates attempts to pool the services into a single integrated system. The Internet is accessible by modem over CATV or telephone wires, but is typically connected to a computer which is a completely separate viewing system.

Prior to the invention there has never been a system available for integrating these types of services, which would allow a user to instantaneously access any channel provided by any telecommunications or broadcast service using a single system. Moreover, prior to the invention there has not been an inexpensive system available which is interactive, simple to use and delivers any desired telecommunications and broadcast service over a single network of wires.

The present invention overcomes these disadvantages by providing an interactive audio/video redistribution system which pools the various broadcast and telecommunications services available to a user, integrating these services in a single system which redistributes audio/video signals received in multiple formats to multiple users. The invention allows each user to remotely select and control the audio/video signal source desired to be viewed or accessed and provides access any available broadcast and telecommunications system through a single receiving unit, in the preferred embodiment a television receiver. Further, the invention provides an interactive system which is simple to operate and allows the user to utilize interactive services such as those available over the Internet. Still further, the invention can be implemented over existing telephone wires, which considerably reduces the cost of the system and renders installation of the system easy and inexpensive.

The invention accomplishes this by providing a redistributing device which is equipped to receive telecommunications signals in any desired format and redistribute a selected signals to a user's premises. The redistributing device is in interactive communication with an interface located in the user's premises which receives control signals from the user input using, in the preferred embodiment, a conventional infrared (IR) remote control device, and contains switching circuitry which routes the selected signal to the user's premises where it is received by the receiving unit, preferably a television receiver. A single redistributing device services an entire multi-user network from a common distribution point for conventional twisted-pair telephone wire, and services multiple users independently. Moreover, the system of the invention does not interfere with normal use of the telephone network, so users can be interactively access services provided by the system and use the telephone at the same time, or any existing off-air or CATV wiring, so users have the option of receiving services over these networks as well.

Each user may select access to a telecommunications system or program from a menu-driven user interface, which may provide many levels of sub-menus with options specific to the particular telecommunications service selected by the user. The users within the network thus can instantaneously and independently access any available telecommunications service regardless of the input signal format.

In the preferred embodiment the system of the invention is equipped with channel lockout for parental control, a signal processor which prevents videotaping of received programs, a magnetic card reader or other access control device, a system log which records all activities and services accessed by users within the network for billing purposes, a system override which allows the system operator to deny access to selected users of selected services, or redistribute selected programming (for example a message in an emergency situation), and other features which will become apparent from the description below.

The present invention thus provides a system for redistributing a plurality of audio/video signals to a plurality of communications interfaces over twisted-pair wiring, comprising a server, a redistributor for receiving a plurality of input signals, comprising for each input signal, a demodulator for demodulating the signal, the server controlling an output channel selection of the input signal responsive to one or more control signals input into the communications interface, for each communications interface, a switching device for routing the channel selection to an output of the redistributor, the switching device being controlled by the server responsive to one or more control signals input into the communications interface, and for each demodulated input signal, a processor for processing the signal for switching, wherein the communications interface receives the output of the redistributor for transmission to a receiving unit connected to the communications interface.

The present invention further provides a method of redistributing a plurality of audio/video signals to a plurality of communications interfaces over twisted-pair wiring, comprising the steps of receiving a plurality of input signals at a signal redistributor, demodulating each input signal, processing each input signal to a format suitable for switching, switching an output of the redistributor according to one or more control signals input into a communications interface, and routing the output of the redistributor to the communications interface, wherein the output of the redistributor is received by a communications interface for transmission to a receiving device.

In drawings which illustrate by way of example only a preferred embodiment of the invention,

FIG. 1 is a block diagram of a redistributor according to the invention,

FIG. 2 is a block diagram of a communications interface for the redistributor of FIG. 1, and

FIG. 3 is a diagrammatic illustration of a user interface.

As illustrated in FIG. 1, the invention comprises a redistributing device 8 and communications interface 100. The redistributor 8 serves as a telecommunications signal receiver and router/distributor, receiving a plurality of audio/video input signals and redistributing user-selected signals to multiple users from the common distribution point of the telephone wiring at the multi-user site. The communications interface 100 is located in each individual unit and delivers the selected input signal from the redistributor to the receiving device 2, in the preferred embodiment a conventional television receiver, and receives control signals input by the user for transmission to the redistributor 8 to select the input signal and communicate interactively where the selected input permits. As used herein "audio/video signals" refers to all telecommunications and broadcast signals containing audio information or video information or both.

The redistributor 8 receives signals in multiple formats, processes the signals and, based on commands transmitted through the communications interface 100, redistributes the selected signal to the user. The command signals are transmitted to the redistributor 8, and the signals are distributed to the users, over existing twisted-pair telephone wire 1. In rare cases where existing telephone wiring is unsuitable, being for example a single pair cable, suitable twisted pair cabling can be installed for the system of the invention. In new buildings where the system of the invention is contemplated in the building plans, eight pair cabling may be installed (ie. instead of two or four pair cabling) to maximize the advantages provided by the invention, including the servicing of multiple television receivers 2 in a single unit as described below.

The redistributor 8 is installed at a multi-user site, which may for example be an apartment or condominium, commercial high rise, hospital, school, a local loop in a neighbourhood telephone system, etc. The multi-user site may be any site or network which provides a common distribution point for conventional twisted-pair telephone wire, for example PSTN, network category five copper cable or any other local area network cabling, distributed to individual units within the site. Existing wiring in such multi-user sites is almost invariably, as a minimum, four-conductor twisted-pair copper wire distributed from a common distribution point to individual units. Examples of multi-user sites are apartments buildings, office towers, hospitals, a block of detached houses networked in a local loop, schools (through intercom wiring to individual classrooms), etc.

Each input comprises a demodulator and processor for the particular format of the input signal. The preferred embodiment illustrated in FIG. 1 incorporates various types of signal inputs by way of example only. The system of the invention may be equipped to receive and redistribute any video or audio/video signal in any format, including all remote audio/video signals and local audio/video signals (such as a signal from a closed-circuit security camera), and the invention is not intended to be limited to the specific types of signals illustrated and described below.

Off-air input 20 is adapted to receive off-air television signals through an antenna 22 configured to receive VHF and UHF frequency bands, including FM broadcast bands. The off-air signal is received by a frequency-agile off-air demodulator 24 with a tuner preferably compatible with at least NTSC, PAL, and SECAM video formats, which processes the separate audio and video signals to baseband for injection into off-air processor 26, which in turn processes the signals for switching, as described below. The input frequency selection is controlled by commands transmitted by the user with a conventional remote control through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

CATV input 30 is adapted to receive CATV signals through conventional coaxial cable 32. The CATV signal is received by a frequency-agile CATV demodulator 34 with a tuner adapted to receive CATV signals throughout sub, low, mid, hyper and super bands in both inter-harmonically related carriers (IRC) and harmonically related carriers (HRC). The demodulator 34 processes the separate audio and video signals to baseband for injection into CATV processor 36 which processes the signals for switching. The input frequency selection is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

DSS input 40 is adapted to receive DSS (direct satellite) signals received by satellite dish 42 through a frequency agile DSS demodulator 44, which processes the separate audio and video signals to baseband for injection into the DSS processor 46. The demodulator 44 is preferably adapted to receive the DSS signal in both C and KU bands, independent of protocol and format, with a tuner compatible with NTSC, PAL, and SECAM and a receiver bandwidth of approximately 0.900 to 21.8 GHz. The demodulator 44 processes the separate audio and video signals to baseband for injection into DSS processor 46 which processes the signals for switching. The input frequency selection is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher through data buss A.

MMDS input 50 is adapted to receive MMDS (multi-point multi-distribution system) signals received MMDS antenna 52 through a frequency agile MMDS demodulator 54, which processes the separate audio and video signals to baseband for injection into the MMDS processor 56. The demodulator 54 is preferably adapted to receive the MMDS signal in 2.4 GHz and 22 GHz bands, independent of protocol and format, with a tuner compatible with NTSC, PAL, and SECAM. The demodulator 54 processes the separate audio and video signals to baseband for injection into DSS processor 56 which processes the signals for switching. The input frequency selection is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

MPEG input 60 is adapted to receive MPEG signals through MPEG decoder for processing by demodulator 64, which processes the separate audio and video signals to baseband for injection into the MPEG processor 66. The demodulator 64 is preferably adapted to receive the MPEG signal in 1, 2 or 4, for example from a video server or video library. The demodulator 64 is independent of protocol and format, and has a tuner compatible with NTSC, PAL, and SECAM. The demodulator 64 processes the separate audio and video signals to baseband for injection into MPEG processor 66 which processes the signals for switching. The input selection is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

Graphics input 70 is adapted to receive component video signals from a video source such as a video game server 72 for processing by demodulator 74, which serves as a VGA or computer generated video and audio signal to composite converter. Text, graphical user interfaces navigation screens and video games and are separated into audio and video baseband signals for injection into the graphics processor 76which processes the signals for switching. The input selection is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

Internet input 80 is adapted to receive component video signals from a computer 82 for processing by demodulator 84, which serves as a VGA or computer generated video and audio signal to composite converter. Internet browser and communications is not limited by protocol or architecture. Internet processor 86 processes the signals for switching. Navigation is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

Closed-circuit input 90 is adapted to receive component video signals from a closed-circuit camera 92, for example a security camera, for processing by demodulator 94, which serves as a VGA or computer generated video and audio signal to composite converter. Closed-circuit processor 96 processes the signals for switching. Switching between different cameras is controlled by commands transmitted by the user through communications interface 100 to the server 6, which controls the cross point matrix switcher 7 through data buss A.

The server 6 is preferably an open architecture, platform independent and scalable computer having as a minimum a 486 microprocessor. The server 6 controls the upstream data from the communications interface 100 and all demodulated inputs, and manages the database as described below to provide accounting, billing, audit trails and programme history. The server 6 provides communications ports for ISDN, fibre, satellite, PSTN, analog and digital input-output devices and/or any other desired accessory. The server 6 also functions as a router to control and route information through the data busses A, B and C.

The demodulator data bus B interconnects all demodulators and decoders and interfaces to the server 6. The buss B is not limited to protocol, speed, frequency, form factor or format.

The processors 16, 26, 36, 46, 56, 66, 76, 86 and 96 process their respective incoming signals into a format that is able to be switched by the cross point matrix switcher 7 and sent to the communications interface 100 over unshielded twisted pair copper cable. The processors 16, 26, 36, 46, 56, 66, 76, 86 and 96 each match the impedance of the signal to the output impedance; raise the baseband of the demodulated signal (for example to 300 kHz); equalize the high frequency components (for example at 3 dB) and increase the level of chroma; and increase the peak-to-peak voltage (vpp) of the demodulated signal. The processors 16, 26, 36, 46, 56, 66, 76, 86 and 96 also convert and translate upstream control signals received by the cross point matrix switcher 7 from the communications interface 100 and route the control signals to the server 6 via data buss B.

The cross point matrix switcher 7 is a non-blocking, many to one switch, which is not limited by size, bandwidth, speed, form factor, protocol, architecture or format. Control signals received by and output from the processors 16, 26, 36, 46, 56, 66, 76, 86 and 96 are transmitted to the server 6, which controls the cross point matrix switcher 7 and routes the selected input to the output of the cross point matrix switcher 7 for transmission back to the communications interface 100. A separate cross point matrix switcher 7 is provided for and dedicated to each communications interface 100 installed in the individual units within the multi-user site.

The processor data buss C interconnects all processors 16, 26, 36, 46, 56, 66, 76, 86 and 96 and interfaces to the server/router 6. The buss C is not limited to protocol, speed, frequency, form factor or format.

Data buss A interconnects each cross point matrix switcher 7 with the server/router 6. The buss A is not limited to protocol, speed, frequency, form factor or format. The output of cross point matrix switcher 7 is connected to a standard or custom telephone or twisted copper splice block 5. Type Bix and no. 66 are typically used, however the configuration of the splice block 5 does not effect the operation of the invention. The splice block 5 conveys the output of the cross point matrix switcher 7 to the copper pair (red-green) of the existing telephone system or PSTN. The splice block 5 may also be used for category five or 10baseT cabling.

The redistributor 8 may also include an HDTV processor 144 for processing HDTV signals received at HDTV input 140 by an antenna, satellite dish or other suitable receiver 142. The HDTV processor 144 is connected directly to the server 6, which controls the channel selection and routes the HDTV signal through a high speed data router or hub 150 that distributes HDTV signals from the server 6 over coaxial cable or category five or six cable (10BaseT) network within the multi-user site. The PSTN wiring does not have the capacity to also transmit an HDTV signal, and thus requires coaxial cable or category five or six cable to couple the HDTV output from the server 6 directly to the receiver 2. If category five or six cable (which typically has 4 pairs) is used, the HDTV signal requires only two pairs and the two unused pairs of the category five or six cable may be coupled to the PSTN splicer block 5, as shown in FIG. 1, to effectively merge the telephone wiring (red/green and yellow/black) with the unused pairs in the category five or six cable.

Additionally, a movie storage database 146 may be connected directly to the server 6, which controls the movie selection responsive to control signals input by the user based on a directory accessed by the user through a movie sub-menu.

The audio/video signal output by the redistributor 8 is transmitted to the communications interfaces 100 in the individual units over the unused wires in the PSTN, which are typically black/yellow. The PSTN is not limited by voltage or frequency, and can transmit the full bandwidth of the audio/video signal over a considerable distance with minimal signal loss.

At the communications interface 100, illustrated in FIG. 3, the modified combination of the signals are received from redistributor 8 and separated into individual audio and video signals by separator 102. In the preferred embodiment the video signal ranges from DC to 4.5 MHz NTSC, PAL or SECAM, and the audio is a sub-carrier ranging between (but not limited to) 4.6 to 5.0 MHz, preferably around 4.7 MHz.

The output of the separator 102 is fed into the audio and video demodulators 104, 106, respectively. The video output of the separator 102 is preferably at impedance of 100 to 600 ohms, depending on line conditions and the setting of the video modulator in the redistributor 8. The video signal may be reshaped to clip the H sync and colour burst peaks using a horizontal synchronization attenuator and amplifier that is controlled by the redistributor 8, to regulate the sync level to the receiver 2 so that illegal recording of video is prevented (a typical television receiver is able to lock to the video signal with as little as 15 units of sync, whereas videotape recorders generally require a minimum of 25 units of sync to lock effectively to the input signal).

Optionally a signal-to-noise detector can be provided in the communications interface 100, which signals the redistributor 8 to boost the audio/video signal output level if the signal-to-noise ratio decreases below a threshold level. This would allow the redistributor 8 to compensate for the disparate length of telephone cable between the splicer block 5 and the communications interfaces 100 in the various individual units (for example, a penthouse apartment will experience less attenuation from a roof-mounted redistributor 8 than a basement apartment located within the same multi-user site). It is also contemplated that a system analyzer for testing the various signals used by the system would plug directly into the RJ11 port in the communications interface 100, and could communicate directly with the server 6 for recording system analysis results.

The video demodulator 104 then converts the reshaped video into a standard composite video signal at 1 vpp for injection to the modulator 110. The demodulator 104 also filters common mode rejection and other radio frequency and electromagnetic interference. The modulator 110 modulates the video signal to a selected channel such as channel 3 using conventional NTSC, PAL, and SECAM modulation techniques. The modulator 110 is preferably phase lock looped with saw filtering, and frequency agile within the 1 GHz bandwidth spectrum. The communications interface 100 may be provided with a user-operated switch (not shown) for selection of channel 3 or 4, which is standard for domestic video receivers.

The output of the modulator 110 is connected directly to the receiving device 2. In the preferred embodiment the receiving device 2 is a television set, however it may be a videotape recorder, stereo receiver, or any other device capable of receiving an audio/video signal.

The audio sub-carrier signal is received from the output of the separator 102 and demodulated (stereo on monaural) by audio demodulator 104 to a common audio base band signal of approximately (but not limited to) a 20 Hz to 20 kHz frequency range with an impedance which can vary from 75 to 600 ohms, for injection to the modulator 110 and optionally directly to an audio output. The demodulator 104 also filters out radio frequency and electromagnetic interference.

The data modulator 120 sends instructions from the interfaces upstream to the redistributor 8, receiving a varying data stream from one of a plurality of interfaces, which preferably includes an optical interface such as an infrared receiver 122 comprising a photoreceptor that receives signal from a common hand held IR remote control device 123. The remote control 123 is used to input numeric information which controls the signal input selection, and the channel selection where the input signal includes multiple channels (for example a CATV television signal). The IR receiver 122 may be built into the communications interface 100, or may be wired to the communications interface 100 remotely and mounted at a convenient position such as on the television receiver 2. In the preferred embodiment the remote control device 123 will control the power, mute and volume, and picture/sound settings of the television receiver 2 directly through the television receiver's IR remote system. All other selections are controlled by the redistributor 8 based on control signals input by the user into the infrared receiver 122 using the remote control device 123, and transmitted to the redistributor over live (ring and tip) PSTN wiring.

The communications interface 100 may also include a data port 124 for interfacing with other types of data entry devices, for example a keyboard, a mouse, track pad and/or joystick, a bar code and/or swipe card reader, and any other data input device which facilitates the input of alphanumeric information for purposes of interactivity. The data port 124 is not limited by protocol, standards, speed, clock or voltage.

The data modulator 120 is preferably also inductively coupled, or direct capacitively coupled, to the PSTN telephone connection as at 132. The common PSTN is passed directly onto the user without compromise so that telephone, facsimile and Internet functions all operate normally. The modulation scheme is selected according to the upstream data requirements. FSK has been found to work favourably. The frequency bandwidth is variable and the frequency allocation is agile. A frequency in the range of 160 to 190 kHz has proven effective and does not interfere with telephone signals (which are typically in the range of 300 Hz to 1.5 kHz). The data modulator 120 incorporates high and low pass filters, and may operate at data rates ranging from 300 to 30,000 bps or as otherwise desired. The circuitry of the communications interface 100 may be programmed into an ASIC or like hardware.

The network card 132 is able to interface with any unused twisted pair wire, whether included in the telephone cable bundle or a separate category five cable. The network card is not limited to IEEE 10baseT standards although this protocol is preferred. The network card 132 provides an optional interface for connecting client or server computers to the system of the invention. Any microprocessor-based computer 134 may be connected to the network card 132 and may include peripherals such as printers, scanners, modems etc. The network card 132 may be advantageously employed in newer multi-user sites, where existing telephone wiring typically provides at least three twisted pairs (often between 4 and 8 pairs) in the PSTN cable.

Information input into the communications interface 100 using these upstream devices is transmitted to the redistributor 8 over the red/green pair of the telephone cable, which are used for the ring and tip lines of the telephone service. These control signals are preferably transmitted in a data carrier having a frequency of approximately 150 kHz. The content of the control signals is sufficiently sparse as to require very little bandwidth, and the signal is preferably filtered so as not to interfere with the telephone service. The ring/tip twisted pair may be used to provide the power supply for the communications interface 100, or if insufficient power is available from the telephone service the communications interface 100 may be powered directly from a transformer (not shown) in the redistributor 8 outputting a DC signal along with the video signal over the yellow/black twisted pair.

Interactivity using the remote control 123 permits the user to utilize such services as shopping, banking and electronic commerce, gaming etc. which are presently available over the Internet. It should also be possible to transmit audio/video signals over the yellow/black PSTN without interfering with the incoming video signal. This would increase the level of interactivity and permit such complex data exchange functions as video conferencing. Spread spectrum transmission methods conventionally used on AC power lines can be used to provide signals for extra voice and data lines, a printer port, pay-per-use software etc.

To install the system of the invention, the redistributor 8 is located at a multi-user site in the vicinity of the common distribution point for the telephone wiring at the site. This may for example be a master telephone panel in a commercial office tower, apartment building or hospital, a local loop distribution box in a residential neighbourhood, etc. The output of the cross point matrix switcher 7 is connected to the PSTN yellow/black pair, or any other unused twisted pair in the PSTN cable, for transmitting the selected input signal to the communications interfaces 100. The input to the cross point matrix switcher 7 is connected to the red/green pair (or equivalent ring and tip conductors) in the PSTN cable, for transmitting control signals from the communications interface 100 to the redistributor 8.

One or more communications interfaces 100 are installed in the individual units within the site. Each communications interface 100 provides at least a remote control interface such as an optical interface 122 connected to the red/green PSTN, and an output for connection to the receiving device 2, such as a conventional 75 ohm coaxial connector, connected to the yellow/black PSTN. A network card 132 is optionally connected to a second unused pair in the PSTN cable for interfacing with a personal computer, microcomputer or computer network 134.

The system is managed by a service provider, who can either pay the various input signal providers (where the input signal is a fee-based service) and chargethe individual units a fee for use of the system, or bill the individual units for payment directly to the signal providers. The server 6 maintains a database through which all input signal and channel selections input by users in the multi-user site are tracked and recorded for billing purposes. This information can also be used by signal providers to produce viewership and other statistical and related information. The service provider may insert or substitute programming into any outgoing signal at any time, for example commercial messages, emergency broadcasts or the like, through a signal override resident in the server 6.

The service provider may also bundle the telephone service with other services, for example to resell long distance telephone services through a dedicated port. A single twisted pair telephone cable is capable of carrying multiple voice and data lines, and could service many lines and extensions in the unit. The reselling scheme could include pay-per-use telephone services and any other telephone reselling scheme.

In the preferred embodiment the cover plate for the communications interface 100 provides contact switches which disconnect when the cover plate is removed, providing an immediate indication that the system is being tampered with to prevent attempts to pirate signal services.

In use, the receiving device 2, preferably a conventional television receiver, is maintained on channel 3 or 4 as optionally set by the user. When the television receiver 2 is turned on the redistributor defaults either to a main menu or to the last input signal selected by the particular user. An example of a main menu for the preferred embodiment is illustrated in FIG. 4. Each menu option provides a corresponding numerical selection parameter which is selected by the user via the remote control 23. The user selects their choice of input signal by entering the corresponding numeric selection into the remote control 123. The numeric selection is received by the optical interface 122 and a corresponding control signal is transmitted to the redistributor 8 over the red/green PSTN and transmitted to the server 6 via cross point matrix switcher 7.

The selected menu option may provide any number of levels of sub-menus. For example, if the "television" option is selected by entering the number "1" the server 6 may switch to a submenu offering the options "1--Off-Air", "2--CATV", "3--HDTV" and "4--DSS". Using the same remote control 123 the user selects the numeric value corresponding to the desired selection, and is prompted to enter the channel number. The main menu, sub-menus and prompt messages are generated by conventional browser software resident on the server 6. Selectable options may also be embedded in the vertical blanking interval of an incoming video signal, accessible by depressing a "hot key" on the remote control 123 when information (for example a web site URL) is displayed on the television receiver 2.

The server 6 signals the cross point matrix switcher 7 via data buss A to connect the selected input signal to the output of the matrix switch 90, and the input signal is transmitted to the communications interface over the yellow/black (or other unused) PSTN. If the input signal contains multiple channels, for example in the case of a television signal, the server 6 controls a tuner in the corresponding demodulator 14, 24 or 34 to pass the selected channel. The selected input signal may modulated to channel 3 or 4 and transmitted to the individual unit to be received on the user's television receiver 2 through a conventional coaxial or other two-conductor cable 3. Alternatively, a port can be provided for direct connection of the component video and audio to the television receiver, to be viewed in a "video" mode, which would eliminate the need for an output modulator 110 in the communications interface 100.

The capacity of the server 6 is selected having regard to the number of individual units within the multi-user site. The server 6 provides a separate cross point matrix switcher 7 for each individual unit, and can thus independently transmit an input signal to each unit irrespective of input signals selected by users in other units. The possible selection of input signals is limited only by the capacity of the redistributor 8 to receive signals in any particular format. Where an individual unit has more than one television receiver 2, where the telephone cabling contains extra twisted pairs the redistributor 8 may be equipped with a separate matrix switcher 7 for each television receiver 2 within the unit. Thus, an eight pair twisted cable can support up to four separate television receivers 2 in a unit, each television receiver using one pair for incoming and outgoing audio/video signals and another pair for transmitting control signals to the redistributor 8. This capacity can be increased even further by assigning an identifier number to each communications interface 100 within a unit, and using the ring/tip telephone pair to transmit control signals to the redistributor 8 for all television receivers 2 in the unit; the redistributor 8 receives the identifier number and routes the audio/video signal along the twisted pair associated with the particular communications interface 100 so identified.

Because the telephone wiring in an individual unit acts as a common distribution point for that particular unit, a scaled-down embodiment of the invention could be used to allow for controlling signals received by a television receiver 2 in the unit. For example, the redistributor 8 might receive off-air, closed-circuit and CATV signals transmitted to the unit by coaxial cable and 300 ohm wires, and when coupled to the telephone wiring in the manner indicated above a television receiver 8 can be switched remotely from one signal input to another.

The invention having been thus described by way of example of the preferred embodiments, it will be apparent to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention, as set out in the appended claims.