IES930120A2 - Surveillance systems - Google Patents

Abstract

A surveillance system for detecting the presence of an intruder in a protected region or unauthorised interference with the protected region has a sound-detecting device (1) which provides inputs to an infrasonic circuit (2) and a frequency detection circuit (3). The listening device is responsive to signals in the frequency range from 0 to 20 KHz, while the infrasonic circuit (2) filters a narrow band of frequencies in the low frequency range 3 Hz to 25 Hz. The frequency detection circuit (3) monitors signals in the range 0 Hz to 10 KHz, that is a frequency range extending into and through the audio range. A secondary circuit (4) enables a background noise level to be identified. The three circuits (2, 3 and 4) provide inputs to a microcontroller (5), which establishes from the signals received from the three circuits (2, 3 and 4), the probable presence of an intruder within the protected region or interference with the region. On detecting an alarm situation, the microcontroller (5) activates one or more alarm devices including an internal siren (5), an external siren (7), and an autodial communication device (8). The system may communicate with an external network (9), and may also include further inputs (21a to 21n) and further outputs (31a to 3In). A control unit (11) enables the processor (5) to be programmed and also serves to arm and disarm the system in use.

Description

This invention relates to surveillance systems. In particular, the invention relates to a self-contained microprocessor-controlled alarm system.

It is an object of the invention to provide a stable self-contained microprocessor-controlled alarm system.

According to the invention, there is provided a surveillance system for detecting the presence of an intruder in a protected or monitored region or unauthorised interference with said region, comprising (a) means responsive to an input sound signal within a predetermined frequency range, (b) means for establishing in said input sound signal, the presence of 35 an infrasonic signal of low frequency, - 2 Ho (c) means for establishing in said input sound signal, the presence of a sound signal in a frequency range extending through the audio range, (d) means for differentiating between an intruder or interference-generated sound signal in said frequency range extending through the audio range and background noise, (e) means for establishing from said infrasonic signal and/or said sound signal in said frequency range extending through the audio range, the probable presence of an intruder or interference with said region, and (f) means for outputting an alarm signal on establishment of possible intruder presence or interference.

A surveillance system according to the invention for detecting the presence in a protected or monitored area of an intruder may include in combination, any two or more of the following features: means for reception of a naturally generated infrasonic low frequency signal, means for reception of an electronically generated signal frequency from a source either by radio transmission, via cable or sonically, means responsive to changes in the ambient or quiescent level of background noise, means responsive to the noise frequencies created by a person walking, talking, running, kicking, shouting and singing, means responsive to the noise frequencies created by gross attack on doors, windows, or walls, and '•»3, means responsive to the noise frequencies created by gross attack on furniture, fittings and contents within the protected or monitored area.

In a favoured embodiment, a surveillance system according to the invention comprises (a) means responsive to an input sound signal within a predetermined frequency range, (b) cooperating circuit means and processor means for (i) establishing in said input sound signal, the presence of an infrasonic signal of low frequency, (ii) establishing in said said input sound signal, the presence of a sound signal in a frequency range extending through the audio range, (iii) differentiating between an intruder or interferencegenerated sound signal in said frequency range extending through the audio range and background noise, (iv) establishing from said infrasonic signal and/or said sound signal in said frequency range extending through the audio range, the probable presence of an intruder or interference with said region, and (v) indicating an alarm condition on establishment of probable intruder presence or interference, and (c) means for outputting an alarm signal in response to said alarm condition of the circuit and processor means indicative of possible intruder presence or interference.

The system may comprise a plurality of further inputs to said processor means for association with respective further alarm condition initiating input means. The system may in addition comprise a plurality of further outputs from said processor means for association with respective further alarm condition indicating means. $930120! - 4 Said processor means is suitably programmable to effect said establishing of the probable presence of an intruder or interference with said region from said infrasonic signal and/or said sound signal in said frequency range extending through the audio range and/or also from input signals from other alarm condition initiating input means, where present. Said processor means is suitably a microprocessor.

The invention is particularly intended for use in a domestic environment where a single unit device will give a house or apartment resident an economic method of protection. In a network format, it may be used in larger buildings or be grouped together with other like and unlike units to cover an entire apartment building complex. Because the unit is preferably microprocessor controlled, a large number of additions may be added to it to enhance its functions and capabilities.

When an attempt is made to enter a property there are typically seven occurrences. One is a very small temperature change at the point of entry. The other six are sonic; sounds of various frequencies, strengths and amplitudes are created. It has not so far proved possible to develop for the marketplace an economically viable, self-contained and centrally positionable device to measure the temperature changes that occur. Hence, attention has focussed on sonic detectors and the sounds created by intruders. These have been identified as: 1. Breaking glass to effect entry into or exit out of the property and to move around within it. 2. Gross attack on doors or walls to effect entry into or exit out of the property and to move around within it. 3. Human voice during the intrusion, e.g.. shouting, talking, singing. 4. Human action sounds such as walking, running or kicking during the intrusion. Μ*ϊο 2 Ο - 5 5. Noise created from gross attack on or rifling of drawers, cupboards, cabinets or furniture. 6. Infrasonic shock occurring as a result of forced entries through doors, windows or walls into the property or within it.

There are also background noises or sounds present in nearly every building, such as the hum associated with refrigerators, microwave ovens, clocks, cookers and other utility instruments. What is called mains hum is very prevalent in the domestic environment.

The unit of the invention has a sonic sensor (a microphone) which listens to all the frequencies generated. When it hears a combination of intrusive noise types, it will activate initially an internal siren and, if it has connected to it ancillary output devices, they will also be activated. Battery back-up supports the unit in the event of mains power failure or should it be accidentally switched off at the mains power or be specifically unplugged from the power source by an intruder. The device may be wall-mounted as an additional protection against the possibility of an intruder attempting to disarm it or committing a gross attack on it.

In addition to its own functions, the unit may either by way of radio transmission or fixed wire connection or using its own sonic capabilities have connected to it or associated with it several additional sensors such as; 1. Passive infra-red detectors. 2. Microwave detectors. 3. Smoke and flame detectors. 4. Door and window contacts. - 6 S93O12O . Pressure sensitive mats. 6. Another similar unit. 7. Personal attack button. 8. Medical emergency wrist button or neck pendant.

Signalling methods of connection noted are additional circuitry to the unit's own circuits.

On the output side the unit may link up with a series of devices to alert further equipment such as: 1. Additional internal siren or bell. 2. External siren, klaxon, or bell, with or without strobing light. 3. Digidialler for connection to a monitoring station or connecting via the telephone system to a bleeper or a neighbour's phone or other designated signal recipient. When connected via standard communication systems available today, it may signal the designated recipient by satellite. 4. Another similar unit in a network.

The connection capability to the first three would normally be by a fixed wire, although the first two may also be via radio transmission and the last can be either radio, fixed wire or sonic.

The software contained in the unit may signal not only the existence of a problem but also the type of problem that exists, e.g.. smoke, fire, intrusion or emergency.

The actual operation of the core unit is based on a Μ J Mi»j -7- ^8930120 microprocessor. The device is constantly sampling the frequencies of signal information fed to it by the sensing microphone. The microprocessor determines what the sound is and acts accordingly. It needs two clear signals to activate the intrusion alarm, from the following possibilities. Thus: EITHER 1. An infrasonic shock signal, i.e. a very low frequency signal caused by the forced opening of a window or door. This signal is also present in the breaking of a window.

AND/OR 2. Sudden increase in the ambient or quiescent background noise.

AND/OR 3. Noise created by running, talking, walking, kicking, shouting, gross attack on doors, windows or walls.

OR 4. Any two of the above three occurrences in themselves.

In addition to the combinations above, the unit may, on receiving a signal from say, a smoke detector, also be activated accordingly.

Novel and unique aspects of the unit of the invention include: 1. The frequency sensing of all sounds and assessing them accordingly. 2. Programming the unit to activate on receipt of audible sound signals from a smoke detector or other device that creates its own sounds.

I20j| - 8 3. Combining a multiple choice of sounds to activate. 4. Totally self-contained as much as possible. Standard electrical power is the only external wiring to the unit when it is operating without additional external devices.

. Utilising modern microprocessing technology.

An embodiment of the invention will now be described having regard to the accompanying drawing in which: Figure 1 is a block-diagram of a surveillance system in accordance with the invention.

As shown in Figure 1, a surveillance system in accordance with the invention uses a single source listening signal provided by sound detecting device 1 to provide inputs to three separate monitoring circuits. Suitably the sound listening device is responsive to signals in the frequency range from 0 to 20 KHz. The three monitoring circuits comprise an infrasonic sound circuit 2, a frequency detection circuit 3 and a background noise detector or noise level circuit 4.

The infrasonic circuit 2 filters a narrow band of frequencies in the low frequency range 3 Hz to 25 Hz using a band pass filter. Any noise signal detected within this band having an amplitude in excess of a predetermined level triggers a logic pulse for a predetermined period. The predetermined amplitude level above which the logic pulse is triggered is suitably adjustable, for example by a potentiometer.

The duration of the logic pulse is also preferably adjustable, again suitably by a potentiometer. This logic pulse, when generated, provides an input signal to a microcontroller 5 of the system of the invention, indicating that a relevant event has taken place. The logic level is applied to the microprocessor by way of a latch. the state of the latch is monitored at predetermined intervals by the processor. When the latch is found to be set, this is noted by the 88120 I - 9 processor as indicative of possible intrusion, and the latch is reset. A succession of latch set conditions encountered on successive monitoring operations carried out by the microprocessor thus indicates a high level of probability of intruder presence.

The frequency detection circuit 3 comprises a wide band filter effective in the range from 0 Hz to 10 KHz, i.e. a frequency range extending into and through the audio range or audio frequencies.

There is initial amplification of the input signal to circuit 3 from listening device 1, and any signal in the specified frequency range having an amplitude above a predetermined value then triggers a logic pulse. This logic pulse is in turn used to set a latch. Inspection of the latch by the microcontroller 5 determines whether or not the latch has been set. If the latch is found to have been set, the microcontroller then resets the latch in preparation for the next inspection. The frequency of latch reset, i.e. the number of times the latch is found to have been set and is reset by the microcontroller, then provides an indication of the presence of a relevant sound signal input to the surveillance system of the invention, as well as a measure of the frequency of the signal, by virtue of the latch monitoring and reset frequency being sufficient to encompass the upper end of the frequency range to which circuit 3 is responsive. Thus the frequency of latch monitoring is suitably 10,000 inspections per second.

The output of circuit 3 is thus a digitised frequency detect signal derived from the initial sound input signal. This digitised output in addition to serving as an input to the microcontroller is also fed to a secondary circuit 4, defining a noise level or background noise detector circuit, through a one-way arrangement, such as a diode, to charge a capacitor of circuit 4 which has a continuous drain facility by way of a resistor. The voltage level of this capacitor is fed to an analog to digital converter and the output of this converter provides a further input to the microcontroller as a signal indicative of the background noise level.

The microcontroller of the system, designated by reference 5 in Figure 1, is suitably a Motorola MC 68 HC 705 C8 or a related or equivalent such device. The input signals provided to the microcontroller 5 by the monitoring circuits 2, 3 and 4 are compared in accordance with preprogrammed criteria defined in the microcontroller and the probability or otherwise of an intruder situation is established in accordance with predetermined criteria already programmed into the microcontroller. This pre-programmed data may include background noise profiles appropriate to the protected premises or region. Thus by comparisonofthe signal from the frequency detect circuit 3 with contemporary signals input by the infrasonic shock circuit 2 and a level of background noise received by way of the circuit 4, the surveillance system is enabled to distinguish between signals coming from, for example, draughts, refrigerators and the like, and real or genuine intruder signals resulting in shock inputs to circuit 2 and sound inputs to circuit 3. This distinction between inputs is facilitated by appropriate programming of the processor.

Regular background noises will occur in any volumetric space being monitored. For example, a refrigerator switching on and off generates background noise. In the surveillance system of the invention, there is compensation for the presence of such background noises, and these are effectively eliminated from the monitoring operations of the surveillance system, so that background noises of the kind previously identified do not activate the system. Effectively, the microcontroller is programmed to interpret background noise as a base level of noise, and intruder activity is then denoted by inappropriate departures from this base level. Background noise input is provided to the microcontroller 5 by way of circuit 4, which processes information originating at listening or sensing device 1 and reaching circuit 4 by way of circuit 3.

Various alarm condition signalling devices are then driven by the microcontroller 5 to provide suitable indications of the existence of an intruder situation. Typically, these alarm indicating devices may 8® J0 f20| include an internal siren or bell 5, an external siren, klaxon or bell 7, and an autodialling communication device 8, for reporting the existence of an intruder situation to a surveillance system control room or the police. The system may further comprise an interface with a processor unit 9 of a networked surveillance system, the link being established by sonic or serial data transmission interface, using either a wired connection or radio transmission. Unit 9 may have further interfaces with still further systems or units by way of lines or communication facilities designated by references 41a to 41n in Figure 1.

A controlling keypad or other like input feature is indicated in Figure 1 by reference 11, and may be used to program the processor and to arm and disarm the system during use. The microcontroller 5 may also be provided with a multiplicity of additional inputs designated by references 21a to 21n from auxiliary or accessory devices, including inter alia any one or more of the following: Passive infrared (PIR), Microwave, Smoke and flame, Door contacts, Pressure sensitive mats, A link to a similiar surveillance system microprocessor, A personal attack/panic feature, Medical emergency radio telephone, A tamper-detecting feature to indicate interference with the system itself, and A timer.

Further external outputs designated by references 31a to 31n may also be provided, depending on the necessities of the situation.

In operation of the unit, following initial programming of the microprocessor to effect the required probabilistic assessment of the Sfi30lag - 12 nature of noise signals received by the system, the unit may be armed by appropriate operation of the keypad or other control feature dsignated by reference 11, which may include one or more light-emitting diode indicators for reporting system status to the user. The system of the invention may be programmed for operation in any one of a diversity of modes, in each of which it is responsive to certain selected inputs either from control unit or keypad 11, the detecting circuits 2, 3 and 4, or the further inputs 21a to 21n, or combinations of inputs from either of the two latter groups. These modes may include, for example an emergency mode, in which the system will be responsive to fire or flame input, personal attack or medical emergency to provide an appropriate output indication. In a normal or system mode of operation, which is the basic and preferred mode of the invention, the microprocessor is responsive to inputs from circuits 2, and 4 to output either a brief test signal in response to suitable input at keypad 11 or an appropriate alarm signal, when the system is put in an operative condition by further appropriate action at keypad 11.

The system may also operate in an accessories mode, when it is responsive to input from any one or more of selected ones or all of the accessory inputs 21a to 21n, again to produce suitable test outputs and, in an operating configuration, an alarm signal in the event of being triggered by an alarm condition at one or more of the accessories. A still further possibility is network mode, in which the system is responsive to a signal coming from a like unit, to report an emergency condition at that other like unit.

Various alarm sequences are also programmed into the microcontroller 5. These include sequences usual in such systems, including, for example, an emergency sequence, an armed exit sequence, enabling a user to set the alarm and then exit from the premises or region to be protected without an emergency signal being generated, a reset sequence, a test entry sequence, and an armed entry sequence, again so that the authorised user of the system may enter the premises 180 Jotggj - 13 or region protected without initially triggering the system, a brief period being provided for the authorised user to disarm the system following entry.

The operation of the microcontroller in all modes of the system is essentially similar. The microcontroller continually scans all of the relevant inputs, depending on the particular mode, and establishes from the conditions detected at each of these inputs, the likelihood or otherwise of an intruder situation prevailing. The particular range or series or selection of inputs which are relevant at any given time depends on the mode or regime under which the system is currently operating. In certain instances, especially where accessory input is in question, no probabilistic assessment is required. The presence of a signal emanating from a particular accessory merely triggers an alarm condition in the system by virtue of its presence. In the case of signals originating through the circuits 2, 3 and 4, the controller is programmed to distinguish between background noise and an intrudergenerated signal, which may be induced by the infrasonic or shock detector 2 or by way of the frequency detector 3. The relative balance between inputs from these sources enables the system of the invention to establish with a high degree of precision and accuracy, intruder presence in the space protected, or interference with the protected region.

The surveillance system of the invention provides therefore comprehensive monitoring of the noise level in the region protected, for example a house, and detects any increase in sound levels due to an unpredicted activity. The surveillance system is also able to establish the source of such increase in noise. The surveillance system of the invention provides therefore a high quality and reliable intruder detection system without the necessity to install auxiliary features such as contact detectors and the like, and thereby offers considerable economies in installation and operation and by way also of savings in maintenance. Nonetheless, should the situation demand, the surveillance system of the invention may also function in cooperation 893012(, with such other known input features, to provide an intruder monitoring system of the very highest quality and reliability.

Claims (5)

1. A surveillance system for detecting the presence of an intruder in a protected or monitored region or unauthorised interference with said region, comprising (a) means responsive to an input sound signal within a predetermined frequency range, (b) means for establishing in said input sound signal, the presence of an infrasonic signal of low frequency, (c) means for establishing in said input sound signal, the presence of a sound signal in a frequency range extending through the audio range, (d) means for differentiating between an intruder or interference-generated sound signal in said frequency range extending through the audio range and background noise, (e) means for establishing from said infrasonic and/or sound signal in said frequency range extending through the audio range, the probable presence of an intruder or interference with said region, and (f) means for outputting an alarm signal on establishment of intruder presence or interference.

2. A surveillance system according to Claim 1, comprising, in combination, any two or more of the following features: means for reception of a naturally generated infrasonic low frequency signal, means for reception of an electronically generated signal frequency from a source either by radio transmission, via cable or sonically, - 16 means responsive to changes in the ambient or quiescent level of background noise, means responsive to the noise frequencies created by a person walking, talking, running, kicking, shouting and singing, means responsive to the noise frequencies created by gross attack on doors, windows, or walls, and means responsive to the noise frequencies created by gross attack on furniture, fittings and contents within the protected or monitored area.

3. A surveillance system for detecting the presence of an intruder in a protected or monitored region or unauthorised interference with said region, comprising (a) means responsive to an input sound signal within a predetermined frequency range, (b) cooperating circuit means and processor means for (i) establishing in said input sound signal, the presence of an infrasonic signal of low frequency, (ii) establishing in said said input sound signal, the presence of a sound signal in a frequency range extending through the audio range, (iii) differentiating between an intruder or interferencegenerated sound signal in said frequency range extending through the audio range and background noise, (iv) establishing from said infrasonic signal and/or said sound signal in said frequency range extending through the audio range, the probable presence of an intruder or interference with said region, and (v) indicating an alarm condition on establishment of probable intruder presence or interference, and S03O 1 - 17 (c) means for outputting an alarm signal in response to said alarm condition of the circuit and processor means indicative of possible intruder presence or interference.

4. A surveillance system according to Claim 3, wherein said processor means is programmable to effect said establishing of the probable presence of of an intruder or interference with said region from said infrasonic signal and/or said sound signal in said frequency range extending through the audio range and/or also from input signals from other alarm condition initiattrrg input meanST

5. A surveillance system substantially as described herein with reference to and as shown in the accompanying drawing.