Note: Descriptions are shown in the official language in which they were submitted.
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TITLE:
"COMMUNICATION SYSTEM"
TECHNICAL FIELD
This invention concerns communication systems. More
5 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 lines" are
10 included line concentrated telephone systems and
telephone systems using time division multiplex
digitized transmission.
The invention permits greater utilisation of
telephone lines while ensuring the inviolate nature of
15 the telephone service in systems that are currently
reserved for one service use absolutely.
BACKGROUND ART
There is a growing recognition by socially aware
people of the need to be able to provide information
20 about a myriad of events or circumstances. Among these
events 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
25 is required. (These examples are not intended to be
regarded as an exhaustive list.) Devices which provide
information about a single event have been developed for
most, if not all, of these requirements. However, such
devices, when they use a telephone line to convey the
30 information, require the installation of additional
telephone lines (or voice channels) and additional
equipment to that already installed. They are generally
expensive, limited in their function, energy consuming
and sometimes unavailable due to lack of the requisite
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communication facility or the impracticality of
providing necessary additional telephone lines or
channels.
To illustrate this point, consider the systems which
5 enable live telephone answering services to operate.
Such systems require a second telephone line to each
subscriber who wishes to use the service. If the
relevant telephone exchange has already used most of the
lines available to subscribers, there may be
10 insufficient lines available to subscribers who require
the answering service in the locality serviced by the
exchange. In such a situation, either the answering
service will be available for only a limited number of
telephone subscribers, or the small number of
15 subscribers that could be connected to the service may
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.
In an attempt to overcome this problem, E.H.B.
20 Bartelink has proposed a remote supervisory system in
which a plurality of sensors are adapted to provide an
alarm signal on the occurrence of, for example, a fire
or an intruder. When the alarm is generated, auxiliary
equipment in the premises where the sensors are located,
25 which monitors the sensors, causes the normal telephone
service to the premises to be disconnected for a short
time. During that short "off hook" period, the auxiliary
equipment causes a signal to be transmitted along the
telephone line to the premises, and this signal is acted
30 upon in the telephone company's central office or in the
telephone exchange, where a
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computer initiates appropriate signal transmission to
the agency to be alerted ~for example, the fire brigade
or the police station).
A disadvantage with Bartelink's system, which is
5 sufficient to prevent its adoption in many countries
(including Australia) where, for policy reasons, the
telephone service must at all times have priority, is
that during the transmission of the alarm signal, the
telephone line is "busied ou*" - that is, it is not
10 available for telephone calls to and from the premises
containing the alarm sensors.
DISCLOSURE OF THE INVENTIO~
One of the objectives of the present invention is to
provide a communication system which can be used in most
15 locations, without additional communication lines being
provided, which is economic in its provision and
running, which is relatively simple, and which leaves
the telephone line intact at all times.
This objective is achieved by providing an
20 improvement on the Bartelink system which has been
discussed above. The improvement consists of
a) providing a visual display unit (VDU) in the
premises in which the alarm sensors have been
installed, with each monitored function
(including an incoming telephone call) having a
respective display on the VDU; and
b) at the telephone exchange or its equivalent, the
telephone line from the premises is connected by
jumpers to a computer which reacts to alarm
signals (and other signals) from the sensors or
other equipment installed in the premises, but
which permits, at all times, a telephone call to
be transmitted to the premises.
In this arrangement, both alarm or other signals and
35 telephone conversations will be transmittable, in the
voice frequency band, simultaneously, using the one
voice frequency channel. Usually the presence of an
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alarm or other function signal will be noted during a
telephone call by the presence of a tone - perhaps a
modulated tone - additional to the conversation.
It is known that superimposition of signals on
5 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
10 long-established procedure. More recently, the ~ritish
Post Office has proposed an alarm system in which out-
of-band 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.
15 Those skilled in this art, however, will recognise the
distinction between in-band multiple slgnal transmission
of the present invention and the out-of-band
superimposed signal concepts of ripple control systems
and the aforementioned Post Office signalling systems.
According to the present invention, a voice
frequency communication system between premises and at
least one service facility 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 are
connected; said computer being adapted to be
connected to at least one service facility;
c) at least one sensor located in or adjacent
to the premises; and
d) a terminal located at the premises and
connected to the voice channel at the
premises and also to the or each said
sensor;
said system being characterised in that:
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e) a visual display unit is also located in
said premises and is adapted to have a
display thereon when a telephone call is
made to the premises and whenever a signal
is generated by the sensor or sensors;
f) the computer is adapted to establish
communication between the terminal and said,
one or a plurality of said facilities in
response to signals from the or each sensor;
and
g) the connection between the voice frequency
channel to the premises and the computer is
by jumpers.
In most built-up areas, the voice frequency channel
15 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 other
telephone lines, or some of the other telephone lines,
entering the exchange (including, of course, the
20 telephone line from the premises).
It should be noted that the word "premises" in this
specification has a connotation which is wider than
simply a building. (In fact, in this specification,
"premises" includes dwellings of any kind, schools,
25 factories, work-rooms, shops, boarding houses, tents and
other buildings or structures (whether temporary or
permanent); it also includes any vessel lying in any
river, harbour or other water; this list is not
exhaustive.)
This is important to note, for in remote areas,
where communication between camps, boats, drilling rigs
and the like is often by single side band radio
transmission in radio channels in which the voice
channel band of from 200 to 3,400 Hz is reserved for a
35 "telephone" service use, the voice channel of the
present invention will be such a radio channel.
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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, establishéd when an incoming
5 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 absense of the occupier of the
premises.
The terminal of the present invention may also
include connections to sound-producing or visual alarm
indicators.
These and other features of the present invention
will be more clearly appreciated from the following
15 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 and display units to those
of the embodiment illustrated in Figure 1.
Figure 3 is a circuit diagram of a system which uses
25 impulse signalling which may be used in establishing a
system of Figures 1 and 2.
DESCRIPTION OF ILL~STRATED EMBODIMENTS
_
Referring first to Figure 1, there is shown,
schematically, premises 10 connected to a telephone
30 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
35 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
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13 directly to telephone line 12, thus enabling incoming
calls to be received normally. If the occupier of the
premises is absent, the terminal 1~ will be set to
enable incoming telephone calls to be directed to a
5 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 calls to the telephone
answering service if the telephone 13 is not answered
10 within a pre-determined time period. This will ensure
that an inadvertent omission to set terminal 14 to the
"answering service" mode on leaving the premises will
not result in the incoming call being an abortive
attempt at communication.
Also connected to the terminal 14 is a visual
display unit 15. This unit is adapted to display an
indication that an incoming telephone call is being
made, even when the system is transmitting an alarm
signal or when the incoming call has been directed to
20 the answering service facility 19. In a more extensive
system, the visual display unit, which may also function
as the family television set, will usually be adapted to
display a wide range of information.
Another feature included in the system illustrated
25 in Figure 1 is a heat and/or smoke sensing device 16.
This is connected to the terminal 14 and is 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 in such a
30 manner that if sensor 16 responds to heat and/or smoke,
the connection of an alarm signal to monitor 101 will
take place while normal telephone calls are being made
using line 12, and during 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
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illustrated embodiment, only line 12 is shown connected
to computer 18 but in practice, a plurality of lines
will be connected to computer 18.
The computer 18 is designed and operated to allow
5 normal telephone communication through line 12 to
premises 10 but to be responsive to signals from
terminal 14 which indicate that (a) there has been
actuation of the heat and/or smoke sensor 16, or ~b) the
unoccupied premises require incoming telephone calls to
10 be directed to the answering service 19. 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
15 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
20 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.
The system illustrated in Figure 1 is a relatively
simple system, illustrating the present inventive
25 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 phGtographic 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 control could
utilise a magnetically codable card, which is
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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 re~uired;
e) visitor monitoring with message recording;
f) "appliance on" monitors;
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.
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 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
25 sensors adapted to signal that "the oven is switched on"
or "the power to the freezer is disconnected". Terminal
24 also has an intercom connected from the front door of
the premises, the connection being shown as intercom
input 206. Terminal 24 is also provided with a visual
30 display 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 in~ormation required
on visual display unit 24, call to doctor or tradesman,
35 and the like), a visual and audible alarm 27, a
loudspeaker system 27A.
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For use with such an arrangement in premises 20, the
computer 28 at, or connected to, telephone exchange 21,
which is connected to telephone line 22 by jumpers 204
and 205, is programmed to direct, on a priority of needs
5 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
15 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
20 services will be alerted. Society is prepared to
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
25 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
30 the system of Figure 1. It should be noted, however,
that because the telephone service to the premises is
inviolate, it will be usual practice for the visual
display unit 25 to be adapted to display, at all times,
the occurrence of an incoming telephone call. Such a
35 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. The user of the system, in the
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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
5 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 te?ephone 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
15 line in, respectively, premises 30 and telephone
exchange 31. This circuit, which uses readily available
components,
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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 line
is operating satisfactorily. It is thus unnecessary to
interrupt the operation of the system to test that it
is operational.
Each light emitting diode is located
alongside a photo-sensitive diode Pl, 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 Sl. The current through diodes Dl is now
removed and diodes Dl no longer emit light. Photo-
sensitive diodes Pl then no longer conduct and an
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"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.
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INDUSTRI~L 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 r.lultiplex
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
concentratox 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
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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 sc the
system of the present invention may be used.
Voice frequency communication systems
which use time divi~ion multiplexing also transmit
a plurality of messages ~imultaneously over a ~ingle
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 transmltted 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 r~-assemble each cn,mplete 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 exch~nge, so again the present inventivn is
applicable.
As already indicated earlier in this
specification! the present invention may also be used
when te~ephone communication is effected by radio
transmission, at frequencies reserved for telephone
3~ communication.
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Finally, it is noted again that in all systems that
include the present invention, there-are means to ensure
that, at all times, the presence of an incoming
telephone call is indicated at the premises. Thus,
5 whilst the telephone line is shared by a number of
facilities, the actual telephone service remains
inviolate. This is an important feature where local
legislation, or government or company policy, requires
an inviolate telephone service. The telephone service is
10 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
15 provisions which are superior to existing line
monitoring systems.
