COMMUNICATION SYSTEM

Abstract: Voice frequency communication system in which communication is established between premises (10, 20, 30) and a service facility (19, 29, 101, 201, 202, 203, 208). A computer (18, 28), located at a telephone exchange (11, 21, 31) which is connected to the premises (10, 20, 30), can effect connection to at least one required service facility and is programmed to establish a voice frequency communication channel between the premises and the (or one of the) service facilities, on the basis of a pre-determined priority of connections. A terminal (14, 24) located at the premises (10, 20, 30) is used, in conjunction with the computer (18, 28) at the exchange (11, 21, 31), to establish the communication between the premises and the required service facility. The terminal (14, 24) may also be used to display information on a visual display unit (15, 25) located at the premises. Typical service facilities include police, fire and medical alerting facilities. Continuous monitoring (208) of a telephone line connection (22) between the premises (10, 20, 30) and the exchange (11, 21, 31) may also be provided.

Description: TITLE "COMMUNICATION SYSTEM" TECHNICAL FIELD This invention concerns communication 5 systems. More particularly it concerns communication systems operating at "voice frequency" frequencies (VF frequencies) , which utilise voice channels, such as telephone lines and radio channels that are reserved for voice communication. Within the term "telephone 10 lines" are included line concentrated telephone systems and telephone systems using time .division multiplex digitized transmission. The invention permits greater utilisation . of existing services, by the allocation of priorities !5 for use of systems that are currently reserved for one service use absolutely. BACKGROUND ART There is a growing recognition in both 20 developed and developing countries of the need to provide information about a myriad of events or circumstances. Among these are (a) the fact that a telephone call was made to a telephone subscriber when the subscriber was away from the telephone, ^ (b) the fact that an intruder has entered premises, and (c) that urgent medical attention is required. (These examples are not intended to be regarded as an exhaustive list.) State-of-the-art devices have been developed for most, if not all, of these 0 requirements. However, such devices represent additional telephone lines (or voice channels) and additional.equipment to that already installed. They are generally expensive, limited in their functi energy consuming and sometimes unavailable due to lac of the requisite communication facility or the impracticality of providing a necessary additional communication service. To illustrate this point, consider the syst which enable live telephone answering services to operate. Such systems require a second telephone lin to each subscriber who wishes to use the service. If the relevant telephone exchange has already used most of the lines available for subscribers, there may be insufficient lines available to subscribers who require the answering service in the locality service by the exchange. In such a situation, either the answering service will be available for only.a limite number of telephone subscribers., or the small number subscribers that could be connected to the service ma mean that the service has insufficient clients for a commercially viable operation, so that nobody in a particular district can have access to the service. DISCLOSURE OF THE INVENTION It is one of the objectives of the present invention to provide a communication system which can be used in most locations, without additional communication lines being provided, is economic in its provision and running, and is relatively simple. This objective is achieved by more efficien utilisation of a facility which is generally availabl particularly the telephone line connected to a house, office or other premises, and establishing voice frequency communication using the twin-cable telephon line and a computer installed at, or connected to, the telephone exchange and a terminal in the house, offic or other premises to which the telephone is connected. It is known that superimposition of signals on existing lines has been used, or proposed, previously. For example, ripple control of the operation of street lights, traffic lights, off-peak water heaters, and the like, using audio-frequency signals superimposed on the power cables to the devices being controlled, is a lo ' ng-established procedure. More recently, the British Post Office * has proposed an alarm system in which alarm signals are transmitted over a telephone line to receivers using a modulated carrier wave having a frequency which is outside the audio-frequency range (such a system is described in the specification of Australian patent application No. 33,771/78). Those skilled in this art, however, will recognise that the present invention is a different concept from ripple control systems and out-of-band superimposed signalling systems. Indeed, the present invention, instead of superimposing a signal on an existing line, requires that the line is used for transmission of a single signal which is selected, on the basis of a pre-deter ined priority, from a plurality of signals. According to the present invention, a voice frequency co munication system between premises and at least one service facility is characterised in that it comprises: (a) a voice frequency channel between a telephone exchange and the premises; (b) a computer located at or connected to the exchange, to which computer a plurality of voice channels at the exchange may be connected; said computer being adapted to be connected to at least one service facility; (c) a terminal located at the premises and connected to the voice channel at the premises; said system being further characterised in that the computer is adapted to establish communication between (i) the terminal and said, one or a plurality of said service facilities, and/or (ii) the or one of the service facilities and the terminal, in response to predetermined signals. In most built-up areas, the voice frequency channel will be the two-wire telephone line which connects the premises to the telephone exchange, and the plurality of voice channels at the exchange will be the telephone lines, or some of the telephone lines, entering the exchange (including, of course, the telephone line from the premises) . , „ It should be noted that the word "premises" in this specification has a connotation which is wide than simply a building. (In fact, in this specificat "premises" is as wide in its meaning as the term "hou which is defined in the Health Act 1958 of the State Victoria, Australia. That Act defines "house" as including "... dwellings of any kind, schools, ... factories, work-rooms, shops, boarding houses, tents and other buildings or structures (whether temporary permanent) ; and also includes any vessel lying in any river, harbour or other water ...".) This is important to note, for in remote ar where communication between camps, boats, drilling ri and the like is often by single side band radio transmission in radio channels in the 200 to 3,400 kH region, reserved for a "telephone" service use, the voice channel of the present invention will be such a radio channel. _ 5 - In the "built up" environment, the service facility or one of the service facilities will usually be a live telephone answering service, which is actuated by a signal from the terminal, established when an incoming telephone call is received in the premises and either (a) the incoming call is not answered within a predetermined time or (b) the terminal has been manually set to indicate the absence of the occupier of the premises. The terminal of the present invention may include connections to a television set or other form of visual display unit, and/or connections to sound- • producing or visual alarm indicators. These and other features of the present invention will be more clearly appreciated from the following description of embodiments of the present invention, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of a simple system, established in accordance with the present invention. Figure 2 is a block diagram of a system established in accordance with the present invention, which utilises additional service facilities an display units to those of the embodiment illustrated in Figure 1. Figure 3 is a circuit diagram of a system which uses impulse signalling which may be used * in establishing the system of Figures 1 and 2. DESCRIPTION OF ILLUSTRATED EMBODIMENTS • Referring first to Figure 1 , there is shown, schematically, premises 10 connected to a telephone exchange 11 by a two-wire telephone line 12. In the absence of the system of the present invention, the telephone line 12 would be connected directly to a telephone 13 in the premises 10. In the arrangement shown in Figure 1, however, the telephone line 12 is connected, in the premises, to a computer terminal 14 which is also connected to telephone 13. When the occupier of the premises is within ' the premises, the terminal 14 will usually be set to connect the telephone 13 directly to telephone line 12, thus enabling incoming calls to be received normally. If the occupier of the premises is absent, the terminal 14 will be set to enable incoming telephone calls to be directed to a telephone answering service 19 (through an arrangement to be described below) . As indicated earlier in this specification, terminal 14 will normally be set to direct incoming telephone cal to the telephone answering service if the telephone 1 is not answered within a pre-determined time,period. This will ensure that an -inadvertent omission to set terminal 14 to the "answering service" mode on leavin the premises will not result in the incoming call bei an abortive attempt at communication. Also connected to the terminal 14 is a visu display unit 15. This unit is adapted to display an indication that an incoming telephone call has been directed to the answering service facility 19. In a more extensive system, the visual display unit will usually be adapted to display a range of information. Another feature included in the system illustrated in Figure 1 is a heat and/or smoke sensin device 16. This is connected to the terminal 14 and arranged to sound an audible alarm 17 and provide a signal to the fire brigade's monitoring service 101. Such an arrangement will be connected to terminal 14 such a manner that if sensor 16 responds to heat and/ smoke, the connection of an alarm signal to monitor 1 will take priority over normal telephone calls being made using line 12, and any recordal of calls by the telephone answering service 19. At the exchange 11, the normal path of line 12 is interrupted and the line is connected via jumpers 104 and 105 to a computer 18. Computer 18 may be located within the exchange or in a separate location. In the illustrated embodiment, only line 12 is shown connected to computer- 18 but in practice, ~ - plurality of lines will be connected to computer 18. The computer 18 is designed and operated to allow normal telephone communication through line 12 to premises 10 unless terminal 14 indicates (a) a signal from the heat and/or smoke sensor 16, or (b) unoccupied premises requiring telephone answering service connection. In the presence of a signal from the terminal 14 indicating actuation of sensor 16, a connection is made to the fire brigade monitoring service 101, and details ' (usually by code) are provided to the fire brigade of the location of the premises 10 where a fire must be presumed to have broken out.. The presence of the "unoccupied premises" signal. ' from terminal 14, either by manual selection of that mode for terminal 14 or the failure to answer an incoming call to telephone 13, will cause line 12 to be redirected to the answering service 19. As indicated above, the signal from the terminal 14 in response to actuation of sensor 16 will have priority. At this point of the description, it may be ' noted that the operation of the system illustrated in Figure 1 departs in one major way from established procedures. This departure is the failure to give telephone line 12 absolute priority as a telephone line at all times. Notwithstanding that telephone lines are generally used for telephone communication for only a small fraction of a day, no existing or proposed system that is within the present inventor 's knowledge attempts to use the telephone line for a plurality of purposes, with the selection of a particular use being on the basis of a predetermined priority . The system illustrated in Figure 1 is a relatively simple system, illustrating the present inventive concept. Those skilled in the art will appreciate that this system can readily be adapted to include a large number of monitoring and information providing facilities. Among these are: (a) Security monitoring (detecting the presence of an intruder and providing a signal to the police station with silent and/or audible alarm and/or television camera or photographic monitoring) ; (b) calling required tradesman (plumber, electrician, motor mechanic, washing machine serviceman, refrigerator serviceman, and the like) , with remote security entry control of the tradesman if required (remote security entry contro could utilise a magnetically codable card which is coded by the computer when it is used, after identification, to enter the premises and is decoded again when the service call has been completed and the tradesman leaves the premises) ; (c) health emergency call (to nurse, in the case of patient requiring occasional emergency treatment of known type, -using a monitor or signalling device carried by the patient-, or to doctor or ambulance service) ; (d) taxi required; (e) visitor monitoring with message recording; (f) "appliance on" monitors; 5 (g) provision of a display of time, latest weather data, sports results, and the like on a visual display unit; and (h) shopping list transmission to a selected store. 10 This list is not an exhaustive list. Figure 2 illustrates (schematically) another example of the system of the present invention in use. In Figure 2, the premises 20 are provided 15 with a terminal 24 connected to telephone line 22. The terminal 24 has a plurality of input signals derived from monitors -26A, 26B and 26C, which may be, for example, a heat/smoke sensor,, an "intruder present" indicator and sensors adapted to signal that 20 "the oven is switched on" or "the power to the freezer is disconnected" . Terminal 24 also has an intercom connection from the front door of the premises, the connection being shown as intercom input 206. Terminal 24 is also provided with a visual display 25 unit 25, a voice recorder 25A (for use with intercom service 206) , a telephone 23, a plurality of specific services signal transmission selectors 207 (for example, taxi-call, clock or other information required on visual display unit 24, call to doctor 30 or tradesman, and the like) , a visual and audible alarm 27, and loudspeaker system 27A. For use with such an arrangement in premises 20, the computer 28 at, or connected to, telephone exchange 21, which is connected to 35. telephone line 22 by jumpers 204 and 205, is / CJ c:.:?ι programmed to direct, on a priority of needs basis, original signals at voice frequency from terminal 24 to telephone answering service 29, to clock, weather, sport or other information transmitters 29A, 29B, 29C ..., and to fire brigade, police station, nurse, and the like at 201, 202, 203, ... A telex service 209 may also be included in the system. The system of Figure 2 is also provided with an external visual display unit 208 which is under 24 hour surveillance. The computer 28 is programmed to ensure that a visual and audible signal is provided by visual display unit 208 in the event that the line 22 is disconnected (.for example, by accidental fracture or by sabotage of the line 22) . Such a signal will then be treated as a general alarm and all appropriate emergency services will be alerted. * Society is prepared tσ tolerate a reasonable level of false alarms. Preferably, with such a system, the computer 28 will also be programmed to analyse the occurrence of general alarms, and to advise (by an appropriate signal), the likelihood of a general failure in a particular region when a predetermined plurality of general alarms occurs simultaneously. The operation of the system of Figure 2 should be clear from the description, above, of the operation of the system of Figure 1. Xt will be appreciated by communications • engineers that in those circumstances where a telephone service must be inviolate, two alternatives exist. The first is for the top priority to be given to telephone calls at all times. The second, and preferable, arrangement is to ensure that an indication is provided, at all times, when a telephone call is made to premises equipped with the terminal of the present invention. O For example, in the system illustrated in Figure 2, the visual display unit 25 may be a television screen, which is adapted to display, at all times, the occurrence of an incoming telephone call. Such a display might be the flashing of a message such as "telephone ringing" on the screen of unit 25, which is superimposed on the information that is then being displayed on the screen. . he user of the system, in the premises 20, then has the option to decide (in the same way as any person in a house or office equipped with a telephone has this option) to answer the telephone 23, or not to answer the telephone. By answering the telephone, the user of the system effectively determines that top priority is to be given to the telephone call, and on lifting the receiver of the telephone 23,. the previously displayed information on the screen of the visual display unit 25 is automatically removed. By way of example, one form of circuit for adapting an existing telephone line to operation in accordance with, the present invention is shown in Figure 3. This circuit uses two optically coupled isolators 33 and 34 located in one of the wires constituting the telephone line in, respectively, premises 30 and telephone exchange 31. This circuit, which, uses readily .available components, may be used with a primitive form of information signalling, known as "impulse signalling", which uses a mechanical make-break contact. As shown in Figure 3, a DC voltage E is established across the pair of wires, so that a current flows through the wires. Resistors Rl and R2 control the level of the constant DC current through the wires. In a typical telephone system, the constant current will be of the order of 0.5 milliamp, which is sufficient to keep light emitting diodes Dl of the optically coupled isolators 33 and 34 in their light emitting mode, but insufficient to ring the bell of a telephone. Usually, a current in excess of 5 milliamps, and often about 20 to 30 milliamps is required to operate a telephone line. Such a high level of current will not affect the operation of the optically coupled isolators,, but if a current of greater than about 200 milliamps is likely on the lines, current protectors should be fitted to the optically coupled isolators. With the light emitting diodes continually operating, an indication is provided at both the premises 30 and the exchange 31 that the telephone li is operating satisfactorily. It is thus unnecessary interrupt the operation of the system to test that it is operational. Each light emitting diode is located alongside a photo-sensitive diode PI, which conducts when light is incident upon it. Failure to conduct can be readily monitored. This feature is used in the system illustrated in Figure 3, where the presence of any alarm or "function required" signal opens switch SI. The current through diodes Dl is no removed and diodes Dl no longer emit light. Photo- sensitive diodes PI then no longer conduct and an --. j - y -m GI-.l? "alert" signal is generated at the computer(not shown in Figure 3) . An "alert" indication may also be provided in the premises 30 and in exchange 31. The computer then sends an interrogation signal to the terminal (not shown in Figure, 3) in the premises 30, which indicates the alarm or service required. The computer then activates the auto-dial make-break system 35, to provide the connection to the appropriate service facility. ' The auto-dial system 35 can also be used to provide the terminal at the premises 30 with an acknowledgement that an alarm (or other) signal has been received from the premises by the required facility. Optically coupled isolators suitable for use in a circuit of the type shown in Figure 3 are already available on the market. For example, they are produced by Fairchild Corporation, as catalogue component No. 4N33. Note that for a telephone answering service, the arrangement shown in Figure 3 will not be used. Ring-detectors for such purpose, which are already well developed, standard components., will be located in the exchange 31 and selected as required. Existing independent alert systems are normally provided with an automatic monitoring system, which tests each connection to the system at least once a day. While such a test is being carried out, the system itself will be inoperable. A- feature of the present invention is that it readily includes a continuous monitoring of the system and, as noted above, a malfunction signal can easily be established, thus ensuring that, apart from a breakdown (which is treated as an alert) , the system is operable.throughout the entire 24 hour period. INDUSTRIAL APPLICABILITY It has been shown above that the present invention is well suited for use with the conventional two-wires telephone connection to "premises". The invention is also applicable to the other types of voice channel communication, particularly to systems using line concentrators, carrier signal communication systems and time division multiplex digitization systems. With line concentrators, a plurality of telephone connections (for example, the individual flats in a block of flats) are connected to a telephone exchange by a single two-wire telephone line. A line concentrator joins the plurality of connections to the single telephone line and a concentrator operating in reverse, located at the input to the exchange, separates the connections into a plurality of exchange lines. With this system, each individual connection retains its own identity at the block of flats and at the telephone exchange. Thus the present invention could be used in a single flat which is connected to the telephone exchange only through a line concentrator. Carrier systems also use a single two-wire telephone line to form a connection from a plurality of telephones and an exchange. In such systems, each telephone connection is provided with an oscillator, producing a carrier signal, which is modulated by the audio-frequency message to be conveyed over the telephone system. As the oscillators in -a given system- all produce a carrier signal at a frequency that is different from all the other carrier signals, a number of carrier signals can be simultaneously transmitted, without interference between signals, over a single two-wire telephone line, provided that there is a filter system and decoding arrangement for the signals at the exchange. Again, each telephone connection retains its own identity at the "premises" and at the exchange, and so the system of the present invention may be used. Voice frequency communication systems which use time division multiplexing also transmit a plurality of messages simultaneously over a single two-wire telephone line. In ' these- systems, the individual messages from a plurality of telephone connections are divided into a number of time segments, and the corresponding segments of the plurality of messages are converted into digital form and transmitted sequentially over a single line. The fractions of the voice signals that have been transmitted in this way are combined, in a decoder which is synchronised with the "codex" equipment which chops the message signals into the required time segments and converts the signals into digital form, to re-ass-emble each complete message and then put it on to its respective telephone line at the exchange. Yet again, there is no loss of identity of the individual premises as messages are transmitted to the exchange, so again the present invention is * applicable. As already indicated earlier in this specification, the present invention may also be used when telephone communication is effected by radio transmission, at frequencies reserved for telephone communication. Finally, it is noted again that in all systems that include the present invention, the system can include means to ensure that, at all times, the presence of an incoming telephone call is indicated at the premises. Thus, whilst the telephone line is shared - l 6 - by a number of facilities, the actual telephone servic can remain inviolate. This is an important feature where local legislation, or- government or company policy, requires an inviolate telephone service. The telephone service is not interrupted; what is achieved with the present invention is an increased usage of the telephone line with (a) economical provision of a plurality of additional alert or service facilities for premises equipped with a telephone, and (b) line monitoring provisions which are superior to existing line monitoring systems.

Claims: CLAIMS A voice frequency communication system between premises (10, 20, 30) and at least one service facility (19, 29, 101, 201, 202, 203, 208) characterised in that it comprises: (a) a voice frequency channel (12, 22) between a telephone-exchange (11, 21) and the premises (10, 20, 30) ; (b) a computer (18, 28) located at or connected to the exchange (11, 21) , to which computer a plurality of voice channels (204, 205) at the exchange may be connected; said computer being adapted to be connected to at least one service facility; and (c) a terminal (14, 24) located at the premises (10, 20, 30) and connected to the voice channel (12, 22) at the premises: said system being further characterised in that the computer is adapted to establish communication between (i) the terminal (14, 24) and said, one or a plurality of said service facilities (19, 29, 101, 201, 202, 203, 208) , and/or (ii) the or one of the service facilities and the terminal, in response to predetermined signals. A system as defined in Claim 1, in which the voice frequency channel (12, 22) is a two-wire telephone line, and the voice channels at the exchange (11, 21) are the, or some of the, telephone lines entering the exchange. A system as defined in Claim 2, -in which the OMPI telephone line includes, between the premises and the exchange, a line concentrator system, a carrier signal system, a time division multiplex digitization system-, or a radio- signal link. 4. A system as defined in any preceding claim, in which: (a) at least one monitor (16, 17, 26A, 26B, 26C) is located at the premises (10, 20, 30) and 'connected to the terminal (14, 24); and (b) communication is established with the or a service facility in response to a signal to the terminal (14, 24) from the monitor or a respective one of the monitors. 5. A system as defined in Claim 4, including a visual display unit (15, 25) in said premises (10, 20), connected to the terminal ' (14, 24) and adapted to display information when signals from the or each monitor are received by the terminal. 6. A system as defined in Claim 4 or Claim 5, in which a plurality of monitors are located at the premises and connected to the terminal, further characterised in that a signal produced by at least one of the monitors is effective to cause the terminal to provide an indication in the premises of the operation of the respective monitor, without establish¬ ing communication with the or a service facility. 7. - A system as defined in any preceding claim, including alarm means (208) connected to said O computer (28) , adapted' to provide a visual and/or audible alarm signal if the voice- frequency channel is -dis-established. A system as defined in Claim 2, Claim 3, or any one of Claims 4 to 7 when appended directly or indirectly to Claim 2 or Claim 3, further characterised in .that: (a) a voltage source (Ξ is connected across the two-wire telephone line (22) at the exchange (31) .and a resistance circuit including a switch (SI) is connected across the two-wire telephone line at the premises (30) to establish, when the switch is closed, a low level current in the telephone line which is insufficient to ring a telephone bell; (b) an optically coupled isolator (34) is included in one of the two wires of the telephone line at the exchange (31) , the optical isolator being adapted to produce an output signal when the low level current is established in the telephone line; (c) the computer (18, 28) is responsive to the output of the optical isolator (34) ; and (d) the switch (SI) άs adapted to be opened, to thereby dis-establish the low level current, in response to a signal from the terminal. A system as defined in Claim 8, including a second optical isolator (35) connected in one of the two wires of the telephone line (22) at the premises (30), and adapted to produce an output signal at premises, when the low t j URE-A * * level current is established in the telephone line (22) , to thereby provide an indication at the premises (30) that the line is established between the premises (30) and the exchange (31) . 10. A system as defined in Claim 8 or Claim 9, in which the or each optical- isolator (34, 35) comprises, in combination, a " light-emitting diode (Dl) connected in a wire of the telephone line and a photo-sensitive diode (PI) responsive to the output of the light emitting diode (Dl) . 11. A system as defined in any preceding claim, in which the service facility or one of the service facilities is an alerting facility for police, fire or medical services. 12. A system as defined in claim 11, including a telex service (209). c:-.:

Inventors: MORGAN D
Applicants: MORGAN D
Application year: 1981
Main classification: H04M11
IPC codes: H04M11