GB2275356A

GB2275356A - Alarm system

Info

Publication number: GB2275356A
Application number: GB9303610A
Authority: GB
Inventors: Michael John Wild
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-23
Filing date: 1993-02-23
Publication date: 1994-08-24
Anticipated expiration: 2013-02-23
Also published as: GB2275356B; GB9303610D0

Abstract

An alarm system 10 comprises a plurality of local stations 12, each associated with respective premises 14. Each station 12 can respond to an alarm condition, such as burglary, in the associated premises. Links 16 allow each station 12 to communicate with at least one other station. The existence of an alarm condition in one of the premises 14 can thereby be detected by the corresponding local station 12, and also at least one other station 12. Preferably, each station normally sends a first signal to at least one other station, and the absence of reception of this first signal by a receiving station being indicative of an alarm condition in the transmitting station. A second signal may be transmitted upon detection of an alarm condition, this second signal containing information as to station identity, type of alarm condition etc. <IMAGE>

Description

Alarm System The present invention relates to alarm systems and particularly but not exclusively to domestic burglar alarm systems.

Conventional domestic burglar alarm systems can be broadly classified into two types. One type is a self contained unit monitoring the premises and including a siren, light or other audible or visible device.

Alternatively, the unit may be arranged to monitor the premises until an alarm condition has been detected, and then to send the signal, usually by a telephone line connection, to a monitoring centre at which a monitoring service can alert emergency services after carrying out checks intended to eliminate false alarms.

It is found that the alarm signals generated by the first type of device are often ignored. People have a tendency to assume that any alarm is in fact a false alarm. The second type of device can be disabled by severing the communication link to the monitoring centre.

It is an object of the present invention to obviate or mitigate these and other disadvantages.

According to the invention there is provided an alarm system comprising a plurality of local stations operable to respond to the existence of an alarm condition in respective associated premises, and further comprising communication link means operable to allow each local station to communicate with at least. one other local station, whereby the existence of an alarm condition in the premises corresponding to one of the local stations can be detected by that local station and at least one other.

Preferably substantially all of the local stations can communicate with at least two other local stations.

Substantially all of the local stations can preferably communicate with local stations associated with neighbouring properties. Substantially all of the local stations can preferably communicate with local stations associated with immediately neighbouring properties.

Each local station may be operable in the absence of an alarm condition to send a first signal repeatedly to at least one other local station. Each local station may be operable to send a second signal when an alarm condition is detected. Each local station may be operable to detect when first signals are not being received from another local station, and to interpret the absence of first signals as an alarm condition. A second signal sent by local stations may contain information which identifies the premises in relation to which the alarm condition has been detected. Substantially every local station may be operable in response to a second signal being received from a second local station to pass the second signal to a third local station. Each second signal may contain information which identifies the number of times the second signal has been passed on by local stations.Each local station may be operable to detect the number of times a received second signal has already been passed on, and to refrain from passing the signal to another local station if the said number is in excess of a pre-determined number.

Each second signal preferably contains information which identifies the nature of the alarm condition which has been detected.

The or each communication link means is preferably bi-directional.

Each local station may comprise alarm detecting means, or may be operable to receive signals from an alarm detecting means. The alarm system may respond to alarm conditions consisting of the detection of intruders, fire or smoke or the detection of a signal generated manually to request assistance. Each local station may incorporate display means operable to display information relating to the associated premises and/or signals received from other local stations. The or each communication link means may comprise optical, acoustic or ultrasonic links, telephone or other electrical cable or radio transmission means. One or more local stations may comprise means operable automatically to transmit a signal to alert the emergency services.

The invention also provides a local station for use in the alarm system defined in any of the preceding definitions.

In a second aspect, the invention provides an alarm system comprising a local station operable to respond to the existence of an alarm condition in associated premises, communication link means operable to allow the local station to communicate with a remote location, and monitoring means associated with the remote location and in communication with the local station through the communication link means, the local station being operable to send a first signal repeatedly to the monitoring means in the absence of an alarm condition, and the monitoring means being operable to detect when first signals are not being received from the local station, and to interpret the absence of first signals as an alarm condition.

The local station may have the features of any of the preceding definitions.

Embodiments of the present invention will now be described in more detail, by way of example only and with reference to the accompanying drawings, in which: Fig. 1 is a simple schematic diagram of part of an alarm system according to the invention; Fig. 2 is a more detailed schematic diagram of a local station forming part of the system of Fig. 1; and Fig. 3 shows an alternative layout for part of the system of Fig. 1.

Fig. 1 shows a section of an alarm system 10 which comprises a plurality of local stations 12, each associated with respective premises 14, such as domestic houses. Each local station 12 is operable to respond to the existence of an alarm condition, such as a burglary, in the associated premises 14. Communication links at 16 allow each local station 12 to communicate with at least one other local station. As will be described below, this allows the existence of an alarm condition in the premises 14 corresponding to one of the local stations 12 to be detected by that local station and at least one other.

In more detail, each local station 12 has a bi-directional communication link 16 to two neighbouring stations 12. Fig. 1 shows only three stations 12. It is envisaged that there will be a greater number of stations in the system and consequently, communication links 16 are shown for connection to further local stations which are not themselves shown.

The links 16 may be provided by optical, acoustic or ultrasonic links, telephone or other electrical cables, radio links or any other technology capable of providing the necessary communication.

In addition to the links 16, each station 12 has an input 18 for receiving a signal indicative of an alarm condition. This signal may come from a separate burglar alarm system, such as a conventional burglar alarm. The input 18 may also carry signals indicating other types of alarm condition, such as fire, smoke or the manual activation of a panic button. As an alternative to receiving an input at 18 from discreet alarm sensing apparatus, appropriate alarm detecting apparatus could be incorporated in the local station 12.

The internal construction of the local stations 12 is shown schematically in more detail in Fig. 2. Each station 12 includes e -transmitting/receiving device 20.

A control device 22, which may be microprocessor controlled, is operable to interpret signals received by the device 20, and to instruct the device 20 to send signals of various types. Any signal sent by the device 20 is transmitted to all other local stations to which the transmitting station is connected by the links 16.

Operator controls 23, for instance a keypad, are provided for the user to control the apparatus.

The input 18 is received by the control device 22.

A display 24 is provided for reasons explained below.

The control device 22 can also control an optional automatic telephone dialling apparatus 26 connected by a telephone line 28 to a telephone exchange or direct to a monitoring service or emergency services etc.

During normal conditions, in the absence of any alarm conditions in any of the premises associated with the local stations 12, the control device 22 in each station 12 will be instructing the corresponding device 20 to send periodically a first signal to the other stations to which it is connected. This first signal indicates that no alarm condition exists in the associated premises. In addition to sending this first signal, the control device 22 will be monitoring signals received from neighbouring stations 12, to ensure that first signals are being received. If the device 22 knows that first signals are being correctly sent and received, the display 24 will be operated to indicate that conditions are normal.

If the device 22 senses that first signals have not been received, the device 22 interprets this as an alarm condition. First signals may cease to be received because of a fault in a link 16 or a neighbouring station 12, or because of tampering. Thus, if a burglar attempts to tamper with the link 16 of neighbouring premises, in order to attempt to disable the alarm system associated with those premises, this tampering will be detected by the station 12 in the neighbouring premises. The station 12 detecting the alarm condition in this way can display an appropriate message at 24, operate a local visible or audible device to alert occupants of the premises, or use the dialling apparatus 26 to alert emergency services or a monitoring service.

In addition to first signals ceasing in the event of a fault or tampering, a simple embodiment of the invention would allow the stations 12 to cease sending first signals when an alarm condition was detected in the associated premises. Thus, in the event of burglary, fire etc., a station 12 would cease to transmit.

Neighbouring stations would therefore detect this and act as described above.

However, it is preferable to provide more information to neighbouring premises by arranging that each station 12 begins to transmit a second signal in the event that an alarm condition is detected in the associated premises. The second signal would preferably be a digital signal containing data arranged in fields, as follows: Field Meaning 1 Synchronization signals etc. to establish communication between stations 2 Data identifying the premises associated with the local station initiating the signal 3 Additional data identifying premises, if required 4 Data identifying the type of alarm condition, i.e. fire, burglary etc.

5 A flag indicating that the premises giving rise to the alarm condition are not in the same road or street as the station receiving the signal 6 Data indicating the number of times the message has been relayed from station to station.

It can be seen from this that the second signal contains "absolute" address data in fields 2 and 3, and also "relative" address data in field 6. The absolute data in field 2 will usually be the street address.

Field 3 may be used to identify part of a property, e.g.

where a group of flats are numbered 29A,29B etc., or where two stations are provided in different parts of one property. The relative address data in field 6 indicates the number of times the signal has been relayed and therefore indicates where the originating station is in the system in relation to the receiving station. The absolute address data can be decoded by the control device 22 and displayed at 24, to allow occupants of premises corresponding to the receiving station to identify the premises in which the alarm conditions have been detected. This allows them to take appropriate action. It will usually be appropriate to display the absolute address data, but in some circumstances, such as where every neighbouring property is connected to the system, it may be adequate to display relative address data.For instance, a user who knows that a signal has passed through two other premises in order to reach the user's premises will thereby be able to identify the premises from which the signal originated. However, this presupposes that the user knows which premises are connected to the system and which are not.

The main purpose of transmitting relative address data is to prevent second signals propagating through the system without limit. In a large system, this could cause second signals to pass through the system to premises separated by a long distance from the originating local station until a point is reached at which the second signal becomes meaningless, because the receiving station may be too far away from the originating station to allow any useful action to be taken by a user. Accordingly, when a second signal is received by a station 12, the control device 22 checks field 6 to see how many times the signal has already been relayed.If it has been relayed less than a pre-determined number of times, the device 22 will increment the contents of field 6 before transmitting the second signal on to any other stations to which it is connected (but not back to the station from which the signal was received). The numbers to be compared with field 6 can be set to ensure that signals are sent to premises close to the originating premises, but are not passed further down the system. It is envisaged that a signal may be passed on only about four times.

Field 5 can be used to provide a flag which indicates either that the source of the signal is in the same street as the receiving station or is in another street.

Field 4 allows the device 22 to display the type of alarm condition which has been detected. Thus, the user at a local station receiving a second signal is provided with adequate information, through the display 24, to decide what action is appropriate. Any or all of this information can also be sent through the dialling apparatus 26 to a remote location.

The choice of the type and amount of data to be transmitted can be varied in many ways, according to the situation in which the system is installed, but it is to be expected that a common protocol would be desirable to facilitate the inclusion of new stations in the system.

The above description in relation to Fig. 1 assumes that each station is connected only to two other local stations, preferably neighbouring properties. It is envisaged that in some circumstances, it may not be possible to link local stations in this way, or it may be simpler to link them in other ways. One alternative arrangement is shown in Fig. 3. The local station 12 marked A is connected to station B as shown in Fig. 1, and also to a third station C which forms a branch from the system. The internal capacity of the station A may need to be increased to accommodate this addition but in other respects, the system and its operation remain essentially unaltered. That is, in normal conditions, each local station will send first signals to every other station to which it is connected, which may be one, two or three or more. An alarm condition will be detected if first signals are not received or if second signals are received as described above. If the station A receives a second signal from one of the three stations to which it is connected, it will send a signal on to the two other stations to which it is connected (having incremented field 6). This will result in more than one second signal propagating through the system but each will stop when the contents of field 6 reach the pre-determined value. If several branches are present in the system, loops could be formed which could cause duplicate signals to be received by a single station. The control device 22 will be configured to take account of this by ignoring any duplicated signals.

It may be appropriate in some circumstances to connect local stations together in a closed loop, particularly if the total number of local stations is small. This ensures that every local station is in communication with at least two other stations, even if it is geographically located at the end of a line of premises.

It will be apparent from the above description that many variations and modifications can be made to the apparatus described, without departing from the scope of the present invention. Furthermore, many alternative forms of conventional techniques can be used to implement the various components of the system.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. An alarm system comprising a plurality of local stations operable to respond to the existence of an alarm condition in respective associated premises, and further comprising communication link means operable to allow each local station to communicate with at least one other local station, whereby the existence of an alarm condition in the premises corresponding to one of the local stations can be detected by that local station and at least one other.

2. A system according to claim 1, wherein substantially all of the local stations can communicate with at least two other local stations.

3. A system according to claim 1 or 2, wherein substantially all of the local stations can communicate with local stations associated with neighbouring properties.

4. A system according to claim 3, wherein substantially all of the local stations can communicate with local stations associated with immediately neighbouring properties.

5. A system according to any preceding claim, wherein each local station is operable in the absence of an alarm condition to send a first signal repeatedly to at least one other local station.

6. A system according to claim 5, wherein each local station is operable to detect when first signals are not being received from another local station, and to interpret the absence of first signals as an alarm condition.

7. A system according to any preceding claim, wherein each local station is operable to send a second signal when an alarm condition is detected.

8. A system according to claim 7, wherein a second signal sent by local stations may contain information which identifies the premises in relation to which the alarm condition has been detected.

9. A system according to claim 7 or 8, wherein substantially every local station is operable when in receipt of a second signal to pass the second signal to another local station.

10. A system according to any of claims 7 to 9, wherein each second signal contains information which identifies the number of times the second signal has been passed on by local stations.

11. A system according to claim 10, wherein each local station is operable to detect the number of times a received second signal has already been passed on, and to refrain from passing the signal to another local station if the said number is in excess of a pre-determined number.

12. A system according to any preceding claim, wherein each second signal contains information which identifies the nature of the alarm condition which has been detected.

13. A system according to any preceding claim, wherein the or each communication link means is bi-directional.

14. A system according to claim 13, wherein the or each communication link means comprise optical, acoustic or ultrasonic links, telephone or other electrical cable or radio transmission means.

15. A system according to any preceding claim, wherein one or more local stations comprise means operable automatically to transmit a signal to alert the emergency services.

16. A system according to any preceding claim, wherein each local station comprises alarm detecting means, or is operable to receive signals from an alarm detecting means.

17. A system according to claim 16, wherein the alarm system is responsive to alarm conditions consisting of the detection of intruders, fire or smoke or the detection of a signal generated manually to request assistance.

18. A system according to any preceding claim, wherein each local station incorporates display means operable to display information relating to the associated premises and/or signals received from other local stations.

19. An alarm system substantially as described above.

with reference to the accompanying drawings.

20. A local station for use in an alarm system according to any preceding claim.

21. An alarm system comprising a local station operable to respond to the existence of an alarm condition in associated premises, communication link means operable to allow the local station to communicate with a remote location, and monitoring means associated with the remote location and in communication with the local station through the communication link means, the local station being operable to send a first signal repeatedly to the monitoring, means in the absence of an alarm condition, and the monitoring means being operable to detect when first signals are not being received from the local station, and to interpret the absence of first signals as an alarm condition.

22. A system according to claim 21, wherein the local station has the features set out in any of claims 1 to 20.

23. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.