Alarm sensor for a window or a door and method of operating an alarm sensor

Abstract

The invention relates to an alarm sensor for a window or a door, comprising a detector arrangement for sensing a physical condition that is affected by opening and / or breach of the window (4) or door (3), a microphone and a memory for storing a recorded audio clip within the sensor, wherein the detector arrangement comprises a magnetic detector (32) and a shock and / or movement detector (34). The invention further relates to an alarm installation comprising at least one alarm sensor as defined above and a central unit, the central unit comprising a receiver. The invention finally relates to a method of operating an alarm sensor in an alarm installation, the alarm installation comprising a central unit, the central unit comprising a receiver, wherein the method comprises the step of sending a request signal to the alarm sensor and the step of the alarm sensor sending, in response to the request signal, information relating to the audio clip.

Description

[0001] Alarm sensor for a window or a door and method of operating an alarm sensor

[0002] The invention relates to an alarm sensor for a window or a door, an alarm installation including at least one such alarm sensor, and to a method of operating an alarm sensor of an alarm installation.

[0003] Alarm installations are used for monitoring premises / buildings and typically provide a means for detecting the presence and / or actions of people at the premises, and reacting to detected events. Commonly such alarm installations include alarm sensors to detect the opening and closing of doors and windows, movement detectors to monitor spaces for signs of movement, microphones to detect sounds such as breaking glass, and image sensors to capture still or moving images of monitored zones. Such alarm installations may be self- contained, with alarm indicators such as sirens and flashing lights that may be activated in the event of an alarm condition being detected. Such installations typically include a controller or “central unit” that is coupled to the sensors, detectors, cameras, etc. (“nodes”), and which processes received notifications and determines a response. The controller or central unit is typically linked to the various nodes wirelessly, rather than by wires, since this facilitates installation and provides some safeguards against sensors / detectors effectively being disabled by disconnecting them from the controller / central unit. Similarly, for ease of installation and to improve security, the nodes of such alarm installations are typically battery rather than mains powered.

[0004] Alternatively, an alarm installation may include an installation at a premises, domestic or commercial, that is linked to a remote monitoring centre where typically human operators manage the responses required by different alarm and notification types. In such centrally monitored alarm installations, a controller or central unit at the premises installation typically processes notifications received from the nodes in the installation, and notifies the remote monitoring centre of only some of these, depending upon the settings of the alarm installation and the nature of the detected events. In such a configuration, the central unit at the installation is effectively acting as a gateway between the nodes and the remote monitoring centre. Rather than providing a controller or central unit at the installation, the central unit may be provided remote from the installation, optionally communicating with the alarm sensors (also known as alarm peripherals) using, for example, an loT communication protocol such as NB-loT or LTE-M. Such an approach may also be adopted in aspects of the invention, and references to central unit should not be interpreted as referring only to a central unit that forms part of an installation at premises protected by a security monitoring system, but should also be interpreted to include systems, installations, and methods in which an installation controller is provided somewhere other than the protected premises - e.g. in the “cloud”.

[0005] In both centrally-managed and self-contained alarm installations one of the most important issues, from a practical perspective, is the battery life of the nodes of the installation - that is, the battery life of the various detectors, sensors, cameras, etc. Obviously, if a node’s battery loses sufficient power, the node may be unable to sense a change of state or to contact the central unit, and consequently the security installation may develop a weak spot where an intruder may gain access to the premises undetected. For monitored or centrally-managed alarm installations it is usually the responsibility of the company running the alarm installation, rather than the premises owner or occupier, to change batteries, and obviously the shorter the battery life in nodes, the more frequently site visits need to be made and the greater the administrative cost. Consequently, controlling power consumption in the nodes is a high priority.

[0006] Further, a very important issue for every alarm installation is a reduction of false alarms, or a means to distinguish between an incident and a false alarm when an event occurs which triggers one of the nodes.

[0007] The object of the invention is to provide means for reducing false alarms.

[0008] US2023 / 143806A1 describes premises monitoring using an acoustic model of the premises. A control device is configured to obtain a plurality of acoustic samples for the premises, detect a sound anomaly in at least one of the plurality of acoustic samples, obtain a verification that the sound anomaly is expected, generate an acoustic model for the premises based at least on the plurality of acoustic samples and the verification that the sound anomaly is expected, receive data representing a detected sound during monitoring of the premises, compare the detected sound with the acoustic model for the premises to determine that the detected sound is unexpected, and initiate a premises security system alert based at least on the detected sound being unexpected. So-called premises devices may include one or more types of sensors, control and / or image capture devices. For example, the types of sensors may include various safety related sensors such as motion sensors, fire sensors, carbon monoxide sensors, flooding sensors and contact sensors, sound sensors (e.g., sound detectors), among other sensor types. For example, the sound sensors may include glass break sensors for detecting the sound of breaking glass, break-in sensors for detecting sounds above a predefined threshold such as a door breach, etc.

[0009] US2010 / 302025A1 describes a portable security alarm system comprising at least one movement detecting and signal transmitting means, including a retractable wire means, a receiver and a remote control. One movement detecting and signal transmitting means may be placed on each object whose movement it is desired to detect. For example, in a room with four windows and two doors, six movement detecting and signal transmitting means may be utilized, one on each window and one on each door. Each movement detecting and signal transmitting means is coupled to one object, such as a door, or window, whose movement is to be detected. In a preferred embodiment, the coupling means is a retractable wire which extends from movement detecting and signal transmitting means to the object whose movement is to be detected. One end of retractable wire is affixed to the object and the other is coupled to movable magnets located inside casing of movement detecting and signal transmitting means. The system may further comprise a separate information gathering device, which may be in the form of a video camera having a microphone and an RF transmitter. The information gathering device may be notified of a movement event by receiving, at the RF receiver, a predetermined signal from the movement detecting and signal transmitting means. The information gathering device then activates its camera to begin acquiring pictures. The camera is preferably aimed at the vicinity of the retractable wire affixing means, such that the cause of the movement will be viewable. The RF transmitter begins sending image information to a remote notification device. If the information gathering device also includes a microphone, the RF transmitter also sends audio information to the remote notification device. WO2020 / 187859A1 concerns a method of operating an alarm system having a central unit and a smart lock, the smart lock having an accelerometer and an RF module, the central unit having an evaluation module for evaluating acceleration signals provided via the RF module from the smart lock, the evaluation module being adapted for distinguishing between at least two of the following situations: a rotation of the smart lock about its central axis, a tilting of the smart lock about a horizontal axis which is perpendicular to the central axis, a rotation of the door to which the smart lock is mounted, vibrations resulting from an interaction with the smart lock, shocks resulting from an interaction with the door, stop of the door in an open position, closing of the door, and a predefined sequence of knocks on the door. If central unit detects that smart lock is rotated or tilted in a manner which should not occur during normal operation, an alarm can be triggered. The alarm can involve a notification sent to monitoring station, and / or involve activation of a siren, a loudspeaker and / or an alarm light. The alarm can also put the entire alarm installation into a state of higher alert - in which state, a microphone and / or a camera of the alarm system can be activated, and information captured by the camera or microphone can be transmitted either to operations control for a decision whether or not the police should be notified or a guard should be sent, and / or the user so that he / she can see e.g. on his / her smartphone what is going on. The information captured by the microphone and / orthe camera of the alarm system can also be evaluated by evaluation module in order to detect it there is an intrusion or not. This reduces the number of false alarms.

[0010] In order to solve the previously disclosed object, the invention provides an alarm sensor for a window or a door, comprising a detector arrangement for sensing a physical condition that is affected by opening and / or breach of the window or door, a microphone, digital processing circuitry for recording an audio clip from the microphone, and a memory for storing a recorded audio clip within the sensor, wherein the detector arrangement comprises a magnetic detector and a shock and / or movement detector.

[0011] The microphone allows capturing audio signals while the alarm sensor is being triggered by the magnetic detector (indicating that the door or window is being opened) or by the shock / movement detector (indicating mechanical impact on the glass, the window orthe door). The audio signal may thus provide “context information” which allows an easier distinction between a false alarm and a critical situation. The audio clip can be stored locally in the alarm sensor for processing there, or for transmission to a central unit or other controller.

[0012] The magnetic detector may comprise, for example, a magnetometer and / or one or more Hall sensors. The magnetic detector may also include one or more reed switches or other binary detectors. The magnetic detector may enable detection of magnetic tampering - e.g. where a villain attempts to conceal an attempt to open a window or door, or increase the size of an existing opening, by introducing one or more powerful magnets to compensate for a reduction in the strength of a magnetic field from one or more magnets that form part of the installation and that cooperate with a magnetic detector of the installation. For example, a magnetometer may sense an increase in magnetic field as an additional magnet is brought near to the window or door.

[0013] The use of both a magnetic detector and a shock and / or movement detector may enable the alarm sensor to determine both whether a closure (window or door) is open or closed, but also if it is open the extent to which it is open. Such an alarm sensor mounted to a window may enable the extent to which a window is open, so that it may be possible to allow a security monitoring installation to be armed even though a window is determined to be open - provided that the extent of the window’s opening is such that it does not constitute a security hazard. For example, there may be minimal increased risk of illicit entry into protected premises when e.g. a casement, tilt or sliding window, which can be locked in a partly open state, is left open with an opening too small to allow entry of a human (even of a small child). The magnet detector may be used to detect the extent to which a closure is open - for example, a magnetometer may be used to provide this functionality, while an accelerometer or other shock or vibration sensor may be used to detect any change in the extent of opening and / or vibration and / or shock from an attempt to force open the closure. The ability to permit the arming of a security monitoring installation, even though one or more windows has been opened to be provide ventilation, without substantially increasing the risk of an undetected intrusion into the protected premises, would make such security monitoring systems much more attractive to customers / users, particularly in territories which experience high ambient temperatures but where the use of air conditioning is not common. The shock and / or movement detector may comprise at least one of a piezo shock / vibration detector and an accelerometer.

[0014] If the audio clip is to be sent to a central unit, the alarm sensor includes a wireless transmitter such as an RF transmitter.

[0015] Should it be desired that the alarm sensor “processes” the audio clip differently in response to requests received from the central unit and / or a remote monitoring centre, the alarm sensor includes a wireless receiver (e.g. an RF receiver) so that an upload signal, a deletion command signal etc. can be received by the alarm sensor. If both a transmitter and a receiver are provided, they may exist in the form of one or more transceivers (e.g. one or more RF transceivers).

[0016] In one embodiment, the alarm sensor includes a classification device for classifying the audio signal of the audio clip. Classifying the audio signal is advantageous in that only the classification data have to be sent to the central unit in the first place, thereby saving transmission time and battery life. Should there be the need for a user of the alarm installation or an operator at the remote monitoring centre to listen to the entire audio clip, it can be uploaded by the alarm sensor upon receiving a specific request.

[0017] Classification may be performed (in the alarm sensor and / or in the central unit or other controller) using a pre-trained machine-learning algorithm. The pre-trained machine-learning algorithm(s) may at least be trained with a plurality of audio signals or audio clips corresponding to different events related to an alarm installation.

[0018] In an alternative embodiment, classification of the audio signal is not performed locally in the alarm sensor but at the central unit (at the installation or elsewhere) which comprises for this purpose a classification device for classifying the audio clip. In the central unit, more sophisticated classification algorithms requiring more computing power can be used than in the alarm sensors which tend to be battery powered and which may include less powerful processors such as MCUs.

[0019] The processor that performs the classification may be operable to classify the audio clip according to one or more of: contains human voices; contains animal noise; contains raised voices; contains sounds of breakage; contains sounds of glass breakage; contains mechanical tampering sounds; contains nothing but silence. For example, the processor may be programmed to perform an initial classification or “triage” in which audio clips are classified as belonging to one of three categories: sound, no sound, and glass break. Such a triage classification may permit very rapid verification either by an automated system or by personnel at a remote monitoring centre. Events where an audio clip is classified as “glass break” may be fast tracked for intervention, while “no sound” events may be treated as false alarms - at least initially: if there are repeated event reports then the remote monitoring centre may request video captures or other data from the installation. Whereas events classified as “sound” may be subject to follow up from the remote monitoring centre, perhaps initially requesting that the audio clip (or clips) be shared with the monitoring centre, possibly for human review. Additionally, or alternatively, events classified as “sound” may be subject to a further stage of classification, for example in which the presence of human voices results in a first classification, and in which sounds which do not include glass-break noises but which are suggestive of a break in or other destruction of property result in another classification, and optionally where the presence of both sound types results in yet a further classification.

[0020] In order to solve the above object, according to a further aspect the invention provides a method of operating an alarm sensor as defined above in an alarm installation, the alarm installation optionally comprising a central unit, the central unit comprising a receiver, wherein the method comprises the step of sending a request signal to the alarm sensor and the step of the alarm sensor sending, in response to the request signal, information relating to the audio clip. The trigger signal ensures that the audio signal is recorded only if there is “a need” such as suspicious activity which is detected by the alarm sensor or possibly by any other node of the alarm installation (such as a camera or a motion sensor such as a PIR), thereby increasing the battery lifetime.

[0021] In one embodiment, the alarm sensor sends the entire audio clip so that it is available for a user of the alarm installation or an operator at the remote monitoring centre.

[0022] In another embodiment, the alarm sensor sends the result of the classification process, rather than the entire audio clip, which may be advantageous regarding the transmission speed and minimising power consumption.

[0023] Should an operator feel that listening to the entire audio clip provides helpful context information for better assessing the situation, he / she can send an upload request so that the entire audio clip is sent to the remote monitoring centre. In combination with the result of the classification process, it is possible for an operator at the remote monitoring centre to quickly assess which of a plurality of recorded audio clips might be the most relevant one.

[0024] It is also possible that a deletion command signal is transmitted to the alarm sensor so that the audio clip is deleted after an alarm situation has been cleared.

[0025] In a related aspect, the invention provides an alarm sensor for a window or a door, having a detector arrangement for sensing a physical condition that is affected by opening and / or breach of the window or door, a microphone and a memory for storing a recorded audio clip within the sensor, wherein the detector arrangement comprises a magnetic detector and a shock and / or movement detector. The alarm sensor may include any one or more of the following features, which are all optional:

[0026] (a) the alarm sensor may include a transmitter.

[0027] (b) the alarm sensor may include a receiver.

[0028] (c) the alarm sensor may include a classification device for classifying the audio clip.

[0029] In a related aspect, the invention provides an alarm installation comprising at least one alarm sensor as defined above and a central unit, the central unit comprising a receiver, e.g. an RF transceiver. Optionally, the central unit comprises a classification device for classifying the audio clip.

[0030] In a related aspect, the invention provides a method of operating a sensor as defined above in an alarm installation (optionally also as defined above), the alarm installation optionally comprising a central unit, the central unit comprising a receiver, wherein the method comprises the step of sending a request signal to the alarm sensor and the step of the alarm sensor sending, in response to the request signal, information relating to the audio clip. The method may further comprise any one or more of the following steps, which are all optional: (a) the alarm sensor may send the entire audio clip.

[0031] (b) the alarm sensor sends the result of a classification process.

[0032] (c) information relating to the audio clip is forwarded to a remote monitoring centre.

[0033] (d) transmitting the entire audio clip in response to a request sent from the remote monitoring centre.

[0034] (e) a step of deletion of the audio clip is performed.

[0035] In a related aspect, the invention provides an alarm sensor for a window or a door, comprising a detector arrangement for sensing a physical condition that is affected by opening and / or breach of the window or door, a microphone, digital processing circuitry for recording an audio clip from the microphone, and memory for storing a recorded audio clip within the sensor, wherein the detector arrangement comprises a magnetic detector and a shock and / or movement detector.

[0036] The alarm sensor may be configured to record the audio clip in response to an event selected from at least one, optionally at least two, optionally all of:

[0037] (a) a trigger signal generated by the detector arrangement;

[0038] (b) a recording command signal received via a wireless receiver of the sensor;

[0039] (c) a tamper signal generated by a tamper detector of the alarm sensor.

[0040] Additionally or alternatively, the sensor may be configured to delete a recorded audio clip in response to an event selected from at least one, optionally both, of:

[0041] (a) expiry of a predetermined time period after recording of the audio clip;

[0042] (b) a deletion command signal received via a wireless receiver of the alarm sensor.

[0043] Additionally or alternatively to any of the above, the alarm sensor may be configured to transmit the audio clip via a wireless transmitter of the alarm sensor, in response to an upload command received via a wireless receiver of the alarm sensor.

[0044] In some embodiments, the digital processing circuitry is configured to classify the audio clip, optionally with a pre-trained machine-learning algorithm, and to generate a classification result, optionally wherein the processor is operable to classify the audio clip according to one or more of: contains human voices; contains animal noise; contains raised voices; contains sounds of breakage; contains sounds of glass breakage; contains mechanical tampering sounds; contains nothing but silence. Optionally, the pre-trained machinelearning algorithm is at least trained with a plurality of audio signals or audio clips corresponding to different events related to an alarm installation.

[0045] The alarm sensor of any preceding aspect may be configured to be surface mounted to a movable or fixed part of a door or a window, optionally independently of a locking mechanism of the door or window.

[0046] In the alarm sensor of any preceding aspect the shock and / or movement detector may comprise at least one of a piezo shock / vibration detector and an accelerometer.

[0047] In a related aspect, the invention provides an alarm installation comprising at least one alarm sensor, optionally as defined in any one of the preceding aspects, and a central unit, the central unit comprising a wireless transmitter for transmitting a signal to the alarm sensor, and a wireless receiver for receiving a signal from the alarm sensor, the central unit being configured to:

[0048] (a) receive an alarm trigger signal from the alarm sensor; and

[0049] (b) transmit to the sensor a recording command signal to command the alarm sensor to record an audio clip; optionally wherein the central unit is further configured to:

[0050] (c) transmit to the alarm sensor an audio information command signal in respect of an audio clip recorded by the alarm sensor; and

[0051] (d) receive an audio information signal from the alarm sensor, the audio information signal comprising at least one selected from: the recorded audio clip; and a classification result relating to the audio clip

[0052] Where the installation may comprise a plurality of alarm sensors, the central unit may be configured to transmit to at least a group of said alarm sensors one or more recording command signals for commanding those sensors to record respective audio clips.

[0053] The central unit may optionally comprise a classification device for classifying the audio clip. A classification device at the central unit may avoid some power consumption constraints compared to implementation at the sensor. In a related aspect, the invention provides an alarm installation comprising at least one alarm sensor, the alarm sensor and / or the installation optionally as defined in any of the preceding aspects, the installation having a disarmed state and at least one armed state, wherein:

[0054] - in the disarmed state, the alarm sensor is operable to transmit alarm trigger signals without recording audio clips; and

[0055] - in at least one of the armed states, the alarm sensor is operable to transmit alarm trigger signals and to record audio clips, optionally selectively.

[0056] In a related aspect, the invention provides a method of operation of an alarm sensor, optionally as defined in any of the preceding aspects, the method comprising the steps of:

[0057] (a) receiving wirelessly a command signal at the alarm sensor; and

[0058] (b) in response to the command signal, an execution step selected from at least one of the sub-steps:

[0059] (b)(i) recording an audio clip, and storing the audio clip in the alarm sensor;

[0060] (b)(ii) transmitting wirelessly a recorded audio clip to another device;

[0061] (b)(iii) performing a classification of an audio signal captured by the microphone, optionally by applying a pre-trained machine-learning algorithm to classify the audio signal;

[0062] (b) (iv) transmitting wirelessly to another device a result of classification of a recorded audio clip;

[0063] (b)(v) deleting a recorded audio clip at the alarm sensor.

[0064] Step (b) may optionally comprise selectively performing a sub-step from a group of said sub-steps in dependence on a function commanded by the command signal.

[0065] In a related aspect, the invention provides a method of operating an alarm sensor, the alarm sensor and / or the method optionally as defined in any of the preceding aspects, the alarm installation having a disarmed state and at least one armed state, the method comprising:

[0066] - in the disarmed state, controlling the alarm sensor to transmit alarm trigger signals without recording audio clips; and

[0067] - in at least one of the armed states, controlling the alarm sensor to transmit alarm trigger signals and to record audio clips, optionally selectively. In a related aspect, the invention provides a method of operating an alarm sensor, the alarm sensor and / or the method optionally as defined in any of the preceding aspects, the method comprising:

[0068] (a) transmitting to the alarm sensor a recording command signal to command the alarm sensor to record an audio clip, optionally in response to receiving or having received an alarm trigger signal from the alarm sensor;

[0069] (b) transmitting to the sensor an audio information command signal in respect of an audio clip recorded by the alarm sensor, to command the alarm sensor to transmit to the central unit an audio information signal comprising at least one selected from: the recorded audio clip; and a classification result relating to the audio clip;

[0070] (c) an optional step of transmitting to the alarm sensor a deletion command signal to command the alarm sensor to delete the audio clip stored at the alarm sensor.

[0071] Where the alarm installation may comprise a plurality of said alarm sensors, step (a) may optionally comprise transmitting a signal for commanding at least a group of said plurality of sensors to record an audio clip.

[0072] The invention will now be described with reference to the enclosed drawings. In the drawings,

[0073] - Figure 1 schematically shows an alarm installation,

[0074] - Figure 2 schematically shows an alarm sensor used in the alarm installation of Figure 1 , and

[0075] - Figure 3 is a schematic flow diagram illustrating various functions and information flows during operation of the alarm installation, for example, at an alarm sensor of Fig. 2, a central unit, and a remote monitoring centre.

[0076] In Figure 1 , reference numeral 1 designates an example building to be protected with an alarm installation. The building 1 can, for example, be a house, an apartment in the house, or a small business building.

[0077] The building 1 comprises a door 3 and a plurality of windows 4. Associated with the door 3 and one or more (for example, each) of the windows 4 is an alarm sensor 10 which is part of an alarm installation. The alarm installation is adapted for detecting an unauthorized intrusion or an attempt of unauthorized intrusion. The alarm sensor 10 is mounted on at least one of the movable parts or fixed parts of the door or window, for example, a door leaf or door frame or on a window leaf, casement, or a window sash or a window frame. A magnet 12 may be mounted on the other of the movable or fixed parts.

[0078] The alarm installation comprises a controller or central unit 14 which can communicate (typically via a wireless communication such as power-efficient transceivers in the frequency band between 862 MHz and 870 MHz, or LTE cat M) with each of the alarm sensors 10. To this end, central unit 14 comprises an RF transceiver 16. Dashed lines symbolize the wireless communication.

[0079] The alarm installation can further comprise at least one camera 18 which also communicates with the central unit 14. Although not shown, the alarm installation may also include other peripherals, for example, a motion detector (e.g. a passive infra-red detector), a keypad, a video-doorbell, and / or an obfuscation cloud generator (e.g. for hindering visibility and thus urging an intruder to leave).

[0080] The central unit 14 is connected to a remote monitoring centre 20 (remote that is from the location of the installation at the home or premises) also via a wireless and / or wired communication means. An internet connection or, as a fall-back means, a cellular or other wireless connection, may be used. The term “remote monitoring centre” may include one or more centres manned by human operators responsible for reacting to alarms, and / or one or more data processing centres, whether or not such centres are located on the same site as one another.

[0081] In an alternative embodiment, the central unit 14 may be omitted at the installation, and the or each alarm sensor 10 (and optionally the camera 18) may communicate independently with a remote monitoring centre 20, for example, via cellular wireless data communication, for example, LTE cat M communication.

[0082] In Figure 2, details of the alarm sensors 10 are shown. The alarm sensor 10 comprises a microcontroller 30, and a power supply 42. The sensor 10 includes a detector arrangement comprising at least one detector for sensing a physical condition that is affected by opening and / or breach of the window or door. The at least one detector may include a magnetic detector 32, and a shock / movement detector 34. Additionally, the sensor 10 comprises a microphone 36 and a memory 38.

[0083] Further, the alarm sensor 10 comprises a tamper detector 40. Still further, the alarm sensor 10 comprises indicator lights 44 (preferably LEDs), and a wireless transceiver 46 (e.g. comprising a wireless transmitter and / or a wireless receiver).

[0084] The microcontroller 30 controls functionality of the alarm sensor 10. The magnetic detector 32 is adapted to generate a signal when its position with respect to the magnet 12 changes, in particular to indicate that the door 3 or the window 4 is being opened. To this end, the magnetic detector 32 can comprise a hall sensor, a reed switch, or a magnetometer, e.g. multi-axis (e.g. 3-axis) magnetometer.

[0085] The shock / movement detector 34 is adapted to generate a signal when there is a movement of the door or window, and / or when there are vibrations in the door / window. To this end, shock / movement detector 34 can comprises a piezo shock / vibration detector, or an accelerometer.

[0086] The microphone 36 is adapted to capture audio signals which are then recorded / stored as an audio clip in the memory 38. Memory 38 can in particular be a flash memory.

[0087] The tamper detector 40 is adapted for detecting an attempt to manipulate, remove or otherwise make the alarm sensor 10 inoperable. It can comprise electric contacts which are arranged so as to change state (for example, be interrupted) when a housing of the alarm sensor 10 is opened or when there is an unauthorized attempt to cut off the power supply of the alarm sensor 10. The power supply 42 comprises a battery or a plurality of batteries which can be replaced when necessary.

[0088] The indicator lights 44 can provide an indication to the user that the alarm sensor 10 operates properly, e.g. by flashing a green light at specific intervals, or can provide an indication that there is a malfunction, e.g. by flashing a red light at specific intervals.

[0089] The transceiver 46 provides for bi-directional communication with the central unit 14.

[0090] The alarm sensor 10 is housed within a case that is configured for surface mounting to the window or door, for example, by adhesive or by one or more fixings, for example, screws. The alarm sensor 10 can be configured for mounting to the window or door independently of a locking mechanism for the window or door. Such an example is distinct from the locking mechanism, which may provide a degree of sensor independence sensitive to intrusion attempts whether or not the intrusion attempts focus on the locking mechanism or other regions of the door or window.

[0091] Referring to Figures 2 and 3, the alarm installation and the alarm sensor 10 can be operated as follows:

[0092] Upon receipt of an audio capture trigger signal (S1 ; S2; S3), also referred to below as merely a trigger signal, the microphone 36 captures (S4) audio signals for a predetermined period of time. As the lifetime of the power supply 42 is an important aspect of the alarm sensor 10, the audio signals are captured for a short period of time only. As examples, the audio signal is captured for five or ten seconds.

[0093] The audio signal is stored (S4) as an audio clip in the memory 38. The audio data may be compressed during recording for storage, and / or compressed for uploading. The trigger signal can be of one or more, optionally any, of the following different origins.

[0094] In one embodiment, the trigger signal (S1) originates from the alarm sensor 10. In particular, the trigger signal (S1) can be the result of the magnetic detector 32 and / or the shock / movement detector 34 generating a signal which indicates that the door 3 or window 4 is being opened, or can be the result of the shock / movement detector 34 generating a signal which indicates that there is a vibration in the door / window, or that somebody is banging on the door / window. The trigger signal can also be the result of the tamper detector 40 generating a signal which indicates that there is an attempt to tamper with the alarm sensor 10.

[0095] Additionally or alternatively, the trigger signal (S2) originates from the central unit 14. The trigger signal can be sent in response to one of the plurality of alarm sensors 10 sending an alarm signal (S5) (as an indication that there is activity which is at least suspicious), or in response to a signal sent from the camera 18, indicating that there is movement somewhere within the building at a place where movement is not expected. Additionally or alternatively to either of the above, the trigger signal (S3) originates from the remote monitoring centre 20. The trigger signal can be sent by personnel of the remote monitoring centre 20 in a situation in which the personnel notices suspicious activity in the building 1 because of an alarm notification signal (S6) sent from the central unit 14, and commands or requests an audio clip to be recorded by one particular alarm sensor 10 or by a plurality of alarm sensors 10, to provide additional context for helping clarify if there is a false alarm or if there is a true alarm situation.

[0096] The alarm installation may have, or be set in, a disarmed state, or at least one armed state. For the current embodiments, the trigger signal is preferably generated only when the alarm installation is in an armed state. This is advantageous in order to reduce the power consumption of the alarm sensors 10 (and thus to increase the lifetime of the batteries) and with respect to privacy laws and occupant privacy.

[0097] The armed state of the alarm installation can be one of an “armed-away” state (which is the state when no occupants are in the building so that there is a level of maximum protection), and an “armed at home” state (which is the state when occupants are in the building but have defined areas which are unoccupied so that these areas and the perimeter of the building are monitored by the alarm installation). In the “armed-away” state, potentially each and every of the alarm sensors 10 can be used for recording an audio clip, while in the “armed at home” state, only those alarm sensors 10 which are in areas supposedly unoccupied can be used for recording an audio clip.

[0098] In other words, the alarm sensors 10 are authorized to record an audio clip only in an armed state. In a disarmed state, there is no recording of an audio clip.

[0099] In one embodiment, the central unit 14 transmits (S7) the arm state (or changes to the arm state) to the alarm sensors 10. The sensors are authorised to self-record when in an armed state.

[0100] In another embodiment, the alarm sensors 10 behave the same way whether the alarm installation is armed or disarmed, and always transmit basic alarm triggers (S5) to the central unit 14 whether armed or disarmed. However, the alarm sensors 10 will only record audio when the central unit 14 (which knows the arm / disarmed state) authorises or commands (S8) audio recording. This requires a two-way exchange of information between the alarm sensors 10 and the central unit 14 for each trigger event. The sensor 10 is responsive to a command signal (S2) received via the transceiver, to record an audio clip. In the current examples, an audio signal itself is not a trigger, as continuously monitoring and processing audio may consume battery power excessively. Instead, a low power trigger is used, which can be a movement signal (S1 ; S4) detected by the magnetic sensor or by the vibration / movement sensor, or a vibration signal (S1 ; S4) detected by a piezo shock detector, or a specific recording command signal (S2) sent by the central unit 14.

[0101] Should an audio clip be recorded, the alarm sensor 10 can upload (S9) it to the central unit 14 automatically (from where it can be sent to the remote monitoring centre 20 either automatically or upon request), or the audio clip can be uploaded to the central unit 14 only if there is a specific command or request (S10) (sent from the central unit 14 or by an operator in the remote monitoring centre 20 where alarms of alarm installations are monitored).

[0102] A user can, in some embodiments, replay the audio clip (either at the central unit 14 directly or remotely via a mobile device) to obtain additional context on the event which triggered the recording of the audio clip and the associated alarm.

[0103] The audio clip can be analysed in the remote monitoring centre 20 by an operator so that additional context on the alarm is made available to the personnel there, to help verify a true alarm or to help cancel or de-escalate a false alarm.

[0104] In some embodiments, an audio clip is recorded by the alarm sensor 10 which has detected a trigger. In other embodiments of the invention, a recording command signal (S2; S3) is sent to an alarm sensor 10 which has not (e.g. not yet) detected a trigger, by either the central unit 14 or the remote monitoring centre 20. A recording command signal (S2) can be sent from the central unit 14 automatically in response to some other trigger occurring at the premises and processed by the central unit 14. In addition or alternatively, a recording command signal (S3) can be sent from an operator at the remote monitoring centre 20 in order to make available additional context information.

[0105] As an example, an alarm installation is considered which comprises in the building several audio-equipped window / door alarm sensors 10, and perhaps other sensors (PIR motion detectors, or PIR-cameras). In response to an initial alarm trigger somewhere in the alarm installation, transmitted via the installation’s central unit 14 to the remote monitoring centre 20, either the central unit 14 (automatically) or the operator at the remote monitoring centre 20 (acting via the central unit 14) may generate a recording command signal (S2; S3) to command all of the window / door alarm sensors to record an audio clip, even if the individual alarm sensors have not been triggered locally.

[0106] This gives the operator at the remote monitoring centre 20 access to audio from several different sources, to provide additional context information.

[0107] According to one possible embodiment, the audio clip or more precisely the audio signal is classified (S11 ; S12) by a classification device. Classification can be performed by a classification device incorporated into the microcontroller 30, incorporated into the central unit 14, or provided at the remote monitoring centre 20. The classification device may be implemented by software running on a processor of the sensor 10, or of the central unit 14, or at the monitoring centre.

[0108] Classification (S11 ; S12) is performed by a pre-trained machine-learning algorithm. As an example, input data is classified by a machine-learning model comprising a convolutional neural network (CNN) to produce a classification result, wherein the input data is based at least in part on an audio signal provided by the microphone 36 of the alarm sensor 10. The classification result indicates a correspondence of the input data with alarm installation related events such as glass-break, door-break, window-break, dog barking, humans, speaking, shouting, and screaming. For example, the machine-learning algorithm may at least be trained with a plurality of audio signals or audio clips corresponding to different situations, i.e., events, related to an alarm installation; the training preferably includes an indication of the situations corresponding to some or all audio signals or audio clips used in the training so as to associate audio (e.g., features in the audio signals or audio clips) with the situations. By way of example, audio signals or audio clips of situations like, e.g., glass-break, dog barking, shouting, etc.

[0109] Classification result data are generated based on the classification. The classification result data can be a code word which indicates the nature of the identified incident which was recorded in the audio clip (e.g. a code word indicating “glass breaking”).

[0110] If classification (S11) is performed by the alarm sensor 10, an embodiment of the invention provides that in a first step, not the entire audio clip is sent from the alarm sensor 10 to the central unit 14 but only the classification result data. This saves battery life as sending the classification result data requires less energy than sending the entire audio clip. Further, in view of the limited bandwidth of the transmission between the alarm sensor 10 and the central unit 14, sending classification result data is faster than sending an entire audio clip. Classification result data may be transmitted automatically, or it may be transmitted in response to an upload command (S10).

[0111] Should a user of the alarm installation or personnel in the remote monitoring centre want to listen to the entire audio clip, an upload request (S10) is sent to the alarm sensor, and the entire audio clip is sent to the central unit 14 from where it can be sent to the remote monitoring centre 20.

[0112] An advantage of making available to the personnel in the remote monitoring centre 20 the classification result data is that a decision on the nature of the alarm can be taken faster as compared to a scenario in which a couple of audio clips are being sent which an operator in the remote monitoring station 20 has to listen to, possibly a few times until he / she understands what sound has been recorded. Instead, the operator can either take a decision immediately based on the classification result data (indicating e.g. “glass breaking”) or replay only the audio clip which appears to be, based on the classification result data, the most relevant one.

[0113] The audio clip is preferably deleted at some point (S13), both with a view to memory constraints in the alarm sensor 10 and with a view to data privacy. Like camera images, audio is subject to data privacy considerations. This is potentially even more relevant than camera images as audio capture may be less directional compared to a camera. For example, if a window or door is open, it may record audio from outside the premises.

[0114] Deletion (S13) can be done in response to reception at the sensor 10 of a deletion command signal (S14) or automatically after a predefined time period has lapsed. A deletion command signal (S14) can be sent from the remote monitoring centre 20 or the control unit 14 after an alarm situation has been cleared.

[0115] Should an audio clip have been recorded without there being a subsequent upload request from the control unit 14 or the remote monitoring centre 20, the audio clip can be automatically deleted (S14) when enough time has lapsed so that it is clear that the audio clip will no longer be used. Examples of such time periods are 24 hours, 12 hours, or 1-2 hours, 30 minutes, 20 minutes, 10 minutes, or less.

[0116] In an embodiment of the invention, the audio clip is automatically deleted after a predetermined time has lapsed, and also in a situation in which the audio clip has been uploaded to the central unit 14. Such automatic-delete ensures, with a view to data privacy, that the audio clip is deleted even if there is no explicit deletion command signal.

[0117] The clip might be over-written anyway by a subsequent audio clip recording, but using explicit automatic-deletion would ensure that no clip is retained on-device for longer than is justifiable.

[0118] Deletion of an audio clip can be performed by actual erasure, by overwriting with other data, or by erasing a pointer to the recording in memory, or by destroying an access or encryption key to the recording.

[0119] In the foregoing example, communication with the alarm sensor 10 is generally via the central unit 14. For example, in Figure 3, communications to and from the remote monitoring centre 20 generally pass via the central unit 14. However, as mentioned above, in some embodiments, the central unit 14 of the installation may be omitted. In such case, where the functionality of the central unit 14 is not implemented at the installation itself (e.g. in another sensor, camera, keypad, doorbell, etc), the sensors 10 may communicate independently with the remote monitoring centre. Communications to and from the central unit 14, described above, will then be understood to be with the remote monitoring centre 20. In Figure 3, the functionalities represented in the central unit 14 would be merged into the functionalities at the remote monitoring centre 20.

Claims

Claims1 . An alarm sensor (10) for a window (4) or a door (3), comprising a detector arrangement for sensing a physical condition that is affected by opening and / or breach of the window (4) or door (3), a microphone (36), digital processing circuitry for recording an audio clip from the microphone (36), and a memory (38) for storing a recorded audio clip within the sensor (10), wherein the detector arrangement comprises a magnetic detector (32) and a shock and / or movement detector (34).

2. The alarm sensor of claim 1 , wherein the sensor (10) is configured to record the audio clip in response to an event selected from at least one, optionally at least two, optionally all of:(a) a trigger signal generated by the detector arrangement;(b) a recording command signal received via a wireless receiver (46) of the alarm sensor (10);(c) a tamper signal generated by a tamper detector (40) of the alarm sensor (10).

3. The alarm sensor of claim 1 or 2, wherein the alarm sensor (10) is configured to delete a recorded audio clip in response to an event selected from at least one, optionally both, of:(a) expiry of a predetermined time period after recording of the audio clip;(b) a deletion command signal received via a wireless receiver (46) of the sensor (10).

4. The alarm sensor of claim 1 , 2 or 3, wherein the alarm sensor (10) is configured to transmit the audio clip via a wireless transmitter (46) of the alarm sensor (10), in response to an upload command received via a wireless receiver (46) of the alarm sensor.

5. The alarm sensor of claim 1 , 2, 3 or 4, wherein the digital processing circuitry is configured to classify the audio clip optionally with a pre-trained machine-learning algorithm and to generate a classification result, optionallywherein the processor is operable to classify the audio clip according to one or more of: contains human voices; contains animal noise; contains raised voices; contains sounds of breakage; contains sounds of glass breakage; contains mechanical tampering sounds; contains nothing but silence.

6. The alarm sensor of claim 5, wherein the pre-trained machinelearning algorithm is at least trained with a plurality of audio signals or audio clips corresponding to different events related to an alarm installation.

7. The alarm sensor of any preceding claim, configured to be surface mounted to a movable or fixed part of a door or a window independently of a locking mechanism of the door (3) or window (4).

8. The alarm sensor of any one of the preceding claims, wherein the shock and / or movement detector (34) comprises at least one of a piezo shock / vibration detector and an accelerometer.

9. An alarm installation comprising at least one alarm sensor (10) as defined in any one of the preceding claims and a central unit (14), the central unit (14) comprising a wireless transmitter for transmitting a signal to the alarm sensor (10), and a wireless receiver for receiving a signal from the alarm sensor (10), the central unit (14) being configured to:(a) receive an alarm trigger signal from the alarm sensor (10); and(b) transmit to the sensor (10) a recording command signal to command the alarm sensor (10) to record an audio clip; optionally wherein the central unit (14) is further configured to:(c) transmit to the alarm sensor (10) an audio information command signal in respect of an audio clip recorded by the sensor (10); and(d) receive an audio information signal from the alarm sensor (10), the audio information signal comprising at least one selected from: the recorded audio clip; and a classification result relating to the audio clip.

10. An alarm installation of claim 9, comprising a plurality of said alarm sensors (10), wherein the central unit (14) is configured to transmit to at leasta group of said alarm sensors (10) one or more recording command signals for commanding those alarm sensors (10) to record respective audio clips.11 . The alarm installation of claim 9 or 10, wherein the central unit (14) comprises a classification device for classifying the audio clip.

12. An alarm installation comprising at least one sensor (10) according to any of claims 1 to 8, the installation optionally according to any of claims 9 to 11 , the installation having a disarmed state and at least one armed state, wherein:- in the disarmed state, the alarm sensor (10) is operable to transmit alarm trigger signals without recording audio clips; and- in at least one of the armed states, the alarm sensor (10) is operable to transmit alarm trigger signals and to record audio clips, optionally selectively.

13. A method of operating an alarm sensor (10) as defined in any one of claims 1 to 8 in an alarm installation, wherein the method comprises the steps of:(a) receiving wirelessly a command signal at the alarm sensor (10); and(b) in response to the command signal, an execution step selected from at least one of the sub-steps:(b)(i) recording an audio clip, and storing the audio clip in the alarm sensor (10);(b)(ii) transmitting wirelessly a recorded audio clip to another device;(b)(iii) performing a classification of an audio signal captured by the microphone, optionally by applying a pre-trained machine-learning algorithm to classify the audio signal;(b)(iv) transmitting wirelessly to another device a result of classification of a recorded audio clip;(b)(v) deleting a recorded audio clip at the alarm sensor (10).

14. The method of claim 13, wherein step (b) comprises selectively performing a sub-step from a group of said sub-steps in dependence on a function commanded by the command signal.

15. A method of operating an alarm sensor (10) as defined in any one of claims 1 to 8 in an alarm installation, the method optionally according to claim 13 or 14, the alarm installation having a disarmed state and at least one armed state, the method comprising:- in the disarmed state, controlling the alarm sensor (10) to transmit alarm trigger signals without recording audio clips; and- in at least one of the armed states, controlling the alarm sensor (10) to transmit alarm trigger signals and to record audio clips, optionally selectively.

16. A method of operating a sensor (10) as defined in any one of claims 1 to 8 in an alarm installation, the method comprising:(a) transmitting to the alarm sensor (10) a recording command signal to command the alarm sensor (10) to record an audio clip, optionally in response to receiving an alarm trigger signal from the alarm sensor (10);(b) transmitting to the sensor (10) an audio information command signal in respect of an audio clip recorded by the alarm sensor (10), to command the sensor (10) to transmit to the central unit (14) an audio information signal comprising at least one selected from: the recorded audio clip; and a classification result relating to the audio clip;(c) an optional step of transmitting to the alarm sensor (10) a deletion command signal to command the alarm sensor (10) to delete the audio clip stored at the alarm sensor (10).

17. The method of claim 16, wherein the alarm installation comprises a plurality of said alarm sensors (10), and wherein step (a) comprises transmitting a signal for commanding at least a group of said plurality of alarm sensors (10) to record an audio clip.

Images