EP0229198A1

EP0229198A1 - Neighbourhood alarm

Info

Publication number: EP0229198A1
Application number: EP85308614A
Authority: EP
Inventors: Hansen Gerhard
Original assignee: HANSENS NEIGHBOURHOOD ALARMS Pty Ltd
Current assignee: HANSENS NEIGHBOURHOOD ALARMS Pty Ltd
Priority date: 1985-11-27
Filing date: 1985-11-27
Publication date: 1987-07-22

Abstract

A computer controlled radio network linked neighbourhood alram system in which a number of premises are each provided with detecting means (19) such as burglar alarms or fire detectors, a transmitter and a receiver under the control of a micro processor (10) whereby an alarm signal generated by the detector (19) is transmitted by the transmitter located at the premises at which the detector is located to the other premises in the network. The communication system used comprises a packet switching network in which the network is a token passing ring, the token passing ring may be configured as a topological ring or arranged in a linear configuration.

Description

This invention relates to a neighbourhood alarm system.
At the present time, there has been a great increase in the rate of burglaries and robberies and whilst, very often, persons living in a neighbourhood would be pleased to provide a general supervision of their neighbours' premises, this has been found to be impractical as it is generally very difficult, even if one sees a person entering onto an area, to know whether that person has any right to be there.
It would also be desirable for there to be a neighbourhood supervision system which provides a warning system in the case of fire or emergency situations, such as, for example, medical emergencies or intrusion by force or deception.
The object of the present invention is to provide a neighbourhood alarm system by which persons in a particular neighbourhood have selectively adopted to become a member of an alarm group, the member of which can readily ascertain if there is unauthorised entry, fire or other emergency situation in the premises of any other member of the group.
The invention, in its broadest sense provides a neighbourhood alarm system in which a number of premises are each provided with detecting means (as herein defined) and wherein means are provided whereby an alarm signal which is generated by any one of the detecting means is transmitted to each of the other premises.
Reference is made in the description and claims to detecting means. These detecting means may be means which are activated in response to physical or chemical stimuli, for example, smoke, movement, pressure and the like, or they may be activated by a person in the premises in response to an emergency situation.
Preferably each of the premises or station has a device whereby the status of the alarm in each of the other premises can be ascertained and which, on an alarm being received from any of the other premises, provides a warning signal in each of the other premises.
In order that the invention may be more readily understood, I shall describe a preferred embodiment of the invention together with possible modifications thereof, in reference to the accompanying drawings.
Block diagrams have been used as it is believed that these are all that is necessary for a competent electronic engineer to effect the invention. In these drawings:-

Fig. 1 shows the arrangement at a premises forming part of the neighbourhood alarm system of the present invention;
Fig. 2 shows an arrangement where the network used in the neighbourhood alarm system is configured as a topological ring;
Fig. 3 shows an arrangement where the network used in the neighbourhood alram system has a linear configuration.
Fig. 4 shows a schematic diagram of the radio communication system for receiving and transmitting packets of data between the stations in the system.

Fig. 1 shows generally the arrangement at each station in the neighbourhood alarm system of the present invention.
It can be seen that each station 1 in the neighbourhood alarm system is provided with a microprocessor 10, radio communication system 30, display board 20 and one or more detecting means 19.
It is not necessary for each station to have the same type of detecting means 19, the means being selected on the particular requirements at each station 1. In the preferred system, the neighbourhood alarm system comprises a packet data network of not more than sixteen and not fewer than two stations 1, each equipped with a transceiver operated under the control of a micro-computer 10.
The network is a token passing ring which may be configured as a topological ring or a line which is traversed in both the forward and reverse directions alternatively.
Fig. 2 is a schematic representation of the network configured as a topological ring. Thus in the proper ring configuration, station N receives a packet from station N-1 and passes a packet onto station N+1. This proceeds until the packet arrives at the last station M from where it proceeds to station 1 to complete the ring.
Fig. 3 illustrates a network having a linear configuration. In the linear configuration the packet is received at the last station M from the last-but-one station, M-1, and the packet is then transmitted from M back to M-1 then M-2 etc., until the packet is passed to station 2, which passes it to station 1 which then passes it back to station 2 and so on.
Ring or linear configurations may incorporate linear spurs in situation where the distance between stations N and N-1 is within transmitter range, but the distance between N and N+1 is not, although the distance between N-1 and N+1 is within range. Thus the packet would follow the route N-1 to N to N-1 to N+1.
The packet duration is 0.1 seconds, and each packet is 32 bytes long. Each station 1 in the network transmits for 0.1 seconds at intervals of 1.6 seconds.
Each packet contains a code word which is a function of the packet number, cycle number and station number. The station and cycle numbers are transmitted as part of the data in the packet and these are used by the receiving station to establish the veracity of the packet.
Each packet contains error correcting information to permit reconstruction of partial errors due to interference.
Persistent failure to receive a packet from a particular station is communicated to all accessable stations in the network, which then actuate audible and/or visual alarms identifying the station at risk.
The transmitter used in the system preferably uses a 150.5 MHz carrier with FSK modulation. The intermediate frequency signal is 455 KHz derived by variable division of a 20.7 MHz crystal AT cut with a 7 ppm tolerance. Suppression of spurious signals preferably exceeds 30 decibels. The DC power of the unit is preferably less than one watt, and the range of transmission is preferably less than one kilometer.
The schematics for the communication system located at each station is generally shown in Fig. 4.
Data from the microprocessor are input to a FSK generator 35 which impresses a modulating signal on the carrier wave.
Synchronisation of the system is provided by a 20.7 MHz oscillator 36. The communication system utilizes a standard transceiver comprising a Single Side Band (SSB) up/down Converter 37, power amplifier 38, receiver amplifier 39, PIN switch 40 for switching either the receiver circuit or the transmitter circuit to the aerial 41.
The PIN switch 40 is under the control of the microprocessor and can be switched from transmit to receive mode depending on the data received from the microprocessor.
As indicated above, the system preferably uses a 150.5 MHz carrier which is provided by the oscillator 38a
The Intermediate Frequency (IF) Board shown in Fig. 4 includes the FSK generator 35 already referred to, an IF amplifier 42 and an FSK demodulator 43.
The system also includes filters 44 for filtering the signal received from the demodulator 43. The output from the filters is input to the microprocessor as well as to means for diagnosing the data 45. The data from the diagnostic unit 45 is also fed to the microprocessor 10.
In operation the PIN switch 40 is normally switched to the receiving mode. When a signal is received from another station in the network via antenna 41, the signal is amplified in amplifier 39 and converted by converter 37. The intermediate frequency output from the converter 37 is fed to an amplifier 42 and the signal demodulated by FSK demodulator 43.
The signal is then filtered and passed to the microprocessor directly and via the diagnostic unit 45.
In the transmitting mode, the pulsed train from the microprocessor is impressed on the carrier wave through the FSK generator 35. The carrier wave with the signal impressed thereon is power amplified 38 and transmitted by the aerial 41.
In the normal mode each station waits until it receives a packet from the station ahead before transmitting. If there is an alarm situation, the microprocessor switches the switch 40 to transmit mode and inputs data into the communication system 30 for transmitting the appropriate signal to other stations in the network.
Power to the system is provided by batteries connected to the main power supply 50. The mains, in normal circumstances are also connected through a battery charger which maintain the battery charge. The power supply to the microprocessor 10 includes means for diagnosing and failsafe unit 52 to prevent unauthorised tampering with the system.
The microprocessor 10 is programmed with the system for controlling the transmission and reception of packets of data within the token passing ring.
In the preferred form the packet used is 32 bytes long. Each of the 32x8 data bits in a packet is encoded as a sequence of 7 modulation bits. The modulation bits for a data zero and a data one are unique to a particular network and arranged to ensure maximum separation of data bits by virtue of the low correlation between ones and zeroes. This coding system is intended primarily to provide symmetric power distribution about the carrier.
The system synchronisation is derived from this coding and software is used to register an alarm condition if there is a persistent failure to synchronise which condition indicates a frequency drift.
The above described alarm actuation system may be used for domestic, commercial or industrial application. Preferably, to make the system tamper-proof, an alarm is signalled when a message packet incorporating a time dependent code fails to arrive from a station.
Furthermore, the system is protected from unauthorised interference, and is thus pirate-proof as the code transmitted by a particular station is difficult to predict without continuous monitoring over many months. Hence the system is inviolate against a pirate station taking over from a genuine disabled station. The code generation process may be modified at regular intervals if necessary in high security applications.
Because the communication system is a token passing ring and the range of the transmitters is limited to an output power of 1 watt, it is necessary for all of the transmitters to be operable at all times. Hence if the distance between stations N, N+1 and N+2 is 0.6 kilometers and they are arranged in a straight line thus: N ----0.6----N+1----0.6----N+2
and N+1 is taken off the air then N will be out of range of N+2.
The use of a token passing ring communication system protects the alarm group against attacks on the network itself. As stated above, each station waits until it receives the packet from the station ahead of it before transmitting. This ensures that the communication proceeds in an orderly way without stations jamming each other. Should a packet fail to arrive within the requisite time interval the receiver signals this failure in the packet it then forwards to the next station. Persistent failure of a transmitter to send a packet indicates that the transmitter in question has been disabled by an intruder or other means warranting investigation.
Protection against an attempt by a potential intruder to circumvent this protocol by disabling the transmitter and sending a packet using his own pirate transmitter is provided by the time dependent code incorporated in each packet. The pirate would need the microcomputer memory contents in order to determine the code to send. To prevent false alarm situations, the alarm conditions may be monitored, when they occur, over several network cycles before they are accepted as real alarms as opposed to effects due to radio interference. This provides stability and hence a low probability of false alarms.
The system may also be adapted such that if a station signal disappears altogether, all remaining stations are altered so as to listen for the missing station to establish that it is not merely an individual receiver which cannot pick up the signal due to local radio interference blocking one link.
The invention is particularly applicable for use, say, in a suburban street where there are a number of detached houses each standing on its own block and which houses can be effectively more or less isolated one from the other.
For the operation of the invention, a number of the residents can decide to be associated in the neighbourhood system and each of these residents must provide means 19 whereby intrusion into his premises can be ascertained.
These means 19 may be any of the normal means of detecting break-ins, such as switches, which cause actuation of a signal when a door or window opens, pressure mats or the like which provide a signal when weight is applied thereto or radar or infra red type systems whereby movement can be detected.
Insofar as the means relates to fire detection any suitable means 19 may be used, for example, a smoke detector or heat detector systems.
The detection device 19 may be so designed that it can be activated by the occupant(s) of the premises; for example a press button switch located in an accessible position or on a portable unit. This form of detection means is particularly useful for elderly persons or persons suffering from life-threatening medical conditions. Thus a system is provided whereby an occupant may activate the alarm means in an emergency situation such as heart attack, injury or forced entry into the premises.
As stated above, is not necessary for each of the members of the group to have the same detection equipment.
Each member must have the radio communication system 50 under the control of a microprocessor 10 which, together, provides a required output and a means of detecting such output from other member's equipment.
Although a particular form of system has been described above, the detector and receiver may be of any known form, for example, they could comprise a radio transmitter and receiver with the transmitter being adapted to use a carrier of a pre-determined frequency which can be modulated in any way, for example, by modulation in a way to permit the receiver ascertaining from which transmitter the signal has come.
In another form of the invention, not illustrated, the signals could be discriminated by using different frequencies, but for reasons which will be described hereinafter, I prefer to use a single frequency for a particular neighbourhood.
In a second form of device the power mains could be frequency modulated and each transmitter and receiver would only need to be connected to power mains which are common to each member of the neighbourhood and the frequency modulated signals impressed upon the normal fifty cycle power signal could be detected and demodulated by individual receivers.
A display board 20 may be associated with each receiver which may comprise two lights, or a single light which can adopt several functions, preferably LEDs, associated with each member of the neighbourhood. In particular, the board 20 may have three 7 segment LEDs
When a person is leaving his/her premises and the intruder detecting means and/or fire detection means is activated, then a first light is illuminated on the board of each of the neighbours. This may well be a green light.
When there is an intrusion into the premises of any of the neighbours, which intrusion causes actuation of the intruding detecting means 19, then a second form of signal is transmitted and this causes actuation of a second light, possibly a red light or, if the first light is operable in two different colour modes, can cause this to change colour. A similar scheme can be used for the fire detection system.
At the same time an audible alarm such as a bell or a buzzer can be initiated in the premises of each of the neighbours, so that the neighbours can be warned of the fact that there has been a status change, can check their display boards 20 to see in which the intrusion has been effected, and can telephone the police and notify them of the intrusion.
It will be appreciated that under normal circumstances, provided the neighbourhood, as far as this invention is concerned, consists of say ten or more premises, it is highly likely that at no time shall all the premises be empty and as such an alarm will be noted by at least one of the neighbours, and notification of the intrusion be able to be transmitted to the police, or in the case of fire, the fire brigade.
It may be preferred to provide a second alarm situation, which could also be a default situation, and that is where, when a signal is being transmitted to indicate that the protection device is operative, and the signal ceases otherwise than by a recognised shut down then an alarm condition is indicated.
Such a system could be useful both for places where an intruder deliberately damages or destroys the transmitter in a particular premises or where there is a power failure associated with the transmitter, either because of failure of the batteries from which the transmitter runs, or, alternatively, a break in mains power if the transmitter is operated from the main, or, of course, if the receiver and transmitter received and transmits signals along the power mains. In these cases, it will be appreciated that whilst the fault signal may not necessarily indicate an alarm condition, there is certainly a presumption that there would be an alarm and prudence would suggest that this be checked.
Earlier in relation to the second form of the invention, I indicated that I believed it preferable that a particular neighbourhood run on a particular frequency and it will be appreciated that the main reason for this is that a number of systems can operate in closely adjacent areas, and will be appreciated that if each neighbourhood, for the purposes of the invention consists of, say, ten premises, there can, in a small locality, be a number of such neighbourhoods and, provided each of these operates at a different frequency, there will be no feed-back between the neighbourhoods when an alarm signal is transmitted.
The type of transmitter to be used is one which operates only over a small radius and even with a relatively small total number of frequencies the same frequency need only be used at spacings which are such as to ensure lack of cross talk.
Whilst in this specification I have only mentioned two possible forms of transmitter, it will be appreciated that the invention is not restricted to either of these but can use any form of transmission and reception which is available, the requirement of the invention is that each member of the neighbourhood have a receiver which can comprise or have associated therewith an indicator board 20 to provide an indication of which premises has intruders therein and, preferably, an indication as to in which the alarm system is operative. Alternatively, as described above, the receiver may be a transceiver operated under the control of a micro-computer.
The system of the invention may be used for domestic, commercial or industrial applications.

Claims

1. A neighbourhood alarm system in which a number of premises are each provided with detecting means (19) (as herein described) wherein means are provided whereby an alarm signal, which is generated by any one of the detecting means is transmitted to each of the premises.

2. The alarm system of claim 1 wherein each of the premises has a device whereby the status of the alarm in each of the other premises can be ascertained and which, on an alarm being received from any of the other premises, provides a warning signal in each of the other premises.

3. The alarm system according to claims 1 or 2 in which the system comprises a packet switching network.

4. The alarm system according to claim 3 in which the packet switching network is a token passing ring.

5. The alarm system according to claim 3 wherein the token passing ring is configured as a topological ring.

6. The alarm system according to claim 3 wherein the token passing ring has a linear configuration.

7. The alarm system according to any one of the preceding claims in which the premises are equipped with a transceiver operated under the control of a microcomputer (10).

8. The system according to claims 4, 5 or 6 in which the ring incorporates a linear spur(s).

9. The system according to any one of the preceding claims in which the packet switching network employs packets having a sequence of modulation bits.

10. The system according to claim 9 in which the packet also incorporates a time dependent code.

11. The system according to any one of the preceding claims wherein the system provides for prevention of false alarm situations.

12. The system according to any one of the preceding claims wherein the system is adapted to be tamper proof and pirate proof.

13. The system according to any one of the preceding claims wherein the detecting means (19) is an intruder detecting means.

14. The system according to any one of the preceding claims wherein the detecting means (19) is a fire detecting means.

15. The system according to any one of the preceding claims wherein the detecting means (19) may be activated by an occupant in any one of the premises in response to an emergency situation.

16. The system according to claims 1 or 2 in which the means for transmitting to each of the premises comprises a transmitter and receiver, the transmitter and receiver being connected to a power source having frequency modulated signals impressed thereon.

17. A neighbourhood alarm system substantiall as herein described with reference to the examples.