IES20090201A2

IES20090201A2 - An alarm system

Info

Publication number: IES20090201A2
Authority: IE
Inventors: Gerard Kelly
Original assignee: Gerard Kelly
Priority date: 2009-03-13
Filing date: 2009-03-13
Publication date: 2009-05-27
Also published as: GB2466335B; GB2466335A; GB0918657D0

Abstract

An alarm system comprises a central control unit (10) and a plurality of remote sensors (12,14,18,22) in intermittent two-way RF communication with the control unit. The sensors report to the control unit at greater intervals when enabled than when not enabled, and for each sensor, starting from a state in which the control unit is armed and the sensor is enabled, if the control unit is subsequently disarmed the sensor remains enabled until it is triggered whereupon it is disabled by the control unit. <Figure 1>

Description

An Alarm System This invention rel^WHTb^n^Tarm system of the kind comprising a central control unit and a plurality of remote sensors in two-way RF communication with the control unit.

According to the present invention there is provided an alarm system comprising a central control unit and a plurality of remote sensors in intermittent routine RF communication with the control unit, wherein the sensors routinely communicate with the control unit at greater intervals when enabled than when not enabled, and wherein for each sensor, starting from a state in which the control unit is armed and the sensor is enabled, if the control unit is subsequently disarmed the sensor remains enabled until it is triggered whereupon it is disabled by the control unit.

By routine communication we mean communication, initiated by the sensor, which occurs at pre-determined intervals for the purpose of informing the control unit that the sensor is present and working correctly and for allowing the control unit, if necessary, to respond to the sensor.

The invention provides the possibility of automatic smart inspection of an alarm system, by ascertaining the functionality of sensors which are relatively busy when the panel is disarmed relative to such sensors; and also identifying sensors which do not triqqer and so may need to be inspected or tested. $ j 1 Preferably, when a sensor is disabled it communicates routinely with the control panel at least every 20 seconds .

Preferably, when a sensor is enabled it communicates routinely with the control panel at a frequency of between 4 and 20 minutes.

Preferably, the sensor transmission circuitry is only enabled for long enough to transmit each routine signal and its receive circuitry is only enabled for long enough to detect a response from the control unit, if any.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an embodiment of an alarm system according to the invention.

Referring to Figure 1, an alarm system comprises a central control unit, or control panel, 10 and a plurality of remote sensors 12-22. The sensors may be of various types, such as passive infrared (PIR) sensors, ultrasonic sensors, movement detectors, window/door contact sensors, or any combination of these. Some of the sensors, such as the sensors 12, 14 18 and 22, communicate wirelessly with the control panel 10 by twoway RF communication, for example using packeted data. These sensors are typically battery-operated and, of course, power consumption is critical in terms of prolonging service life and reducing maintenance. Therefore, wireless sensors communicate with the panel by periodically sending a message to the panel and listening for a response. In the interim, their RX and TX antenna circuitry is switched off. Other sensors, such as the sensors 16, 20, may be connected by wires to the control panel 10 and are typically powered from the control panel . The system may also include one or more audible sounders, such as alarm bells or sounders 24, 26. Again, the alarm bells may be connected wirelessly to the control panel 10, e.g. alarm bell 26, or by wires, e.g. alarm bell 24. Wireless alarm bells are typically battery powered; wired bells, as well as wired sensors, usually include a back-up battery.

In operation, each sensor, if enabled, i.e., if its monitoring circuitry is switched on, monitors its environment according to the type of sensor it is, and sends a trigger signal to the control panel 10 if certain criteria are met indicative, for example, of an intruder. If the control unit 10 is armed with respect to that sensor, as explained below, when the control unit 10 receives the trigger signal it raises an alarm by, for example, sounding a local alarm bell 24, 26 and/or signalling a remote monitoring service and/or the police via a network 28. The network 28 may be a telephone network or the internet, for example. Not all sensors need be enabled all the time. For example, when a building is occupied at night it may be desired only to enable the sensors which monitor external doors and windows, while leaving internal sensors disabled (switched off) to allow for movement around the building.

During periods of unoccupancy, however, it might be desired to enable all the sensors. The individual sensors are enabled or disabled by a command sent from the control unit 10, either wirelessly or through wires, according to the connection of the sensor.

JE The principles of construction and operation of such systems are well-known.

As explained above, wireless peripheral devices such as sensors, bells, etc., communicate with the control panel based on a message/response protocol initiated from the peripheral device. Clearly, from a power consumption point of view, it is advantageous to minimize the amount of communication between the sensors and the control panel. At same time, it can also be useful for diagnostic purposes to be able to assess the functional state of a system including, for example, whether sensors are communicating properly with the panel.

The present invention concerns a particular European standard EN: 50131-5-3, R.F Interconnections governing the operation of wireless control panels in alarm systems. If a sensor is enabled, i.e. its monitoring circuitry is switched on, the control panel only has to detect that sensor's absence within 20 minutes, whereas if a sensor is disabled, i.e. its monitoring circuitry is switched off, the control panel must be able to enable the sensor within 20 seconds from the control panel arming. In this connection, the control panel is said to be armed with respect to a particular sensor if the control panel is in a state to raise an alarm upon receipt of a trigger signal from that sensor. Whether the control panel is armed or not is independent of the monitoring state of the sensor. The sensor may be enabled or disabled; if enabled, the control panel will just ignore any trigger signal sent by the sensor, or at least will not raise an alarm in response thereto.

The aforementioned regulation means that if a sensor is enabled, it only needs to report to the control panel relatively infrequently, typically between 4 and 20 minutes, whereas if a sensor is disabled, it must report to the control panel at least every 20 seconds.

For a busy sensor, e.g. a movement sensor in a shopping mall lobby, which would be regularly triggered if enabled when the panel 10 is disarmed for that sensor, the triggering would involve a high power consumption, higher, in fact, than reporting every 20 seconds as would occur if the sensor were disabled. For a non-busy sensor e.g. an attic movement sensor, frequent reporting (i.e. every 20 seconds) when disabled would be wasteful.

In the present embodiment, for any given sensor, assuming initially that the control panel 10 is armed with respect to that sensor and the sensor is enabled, if the panel is subsequently disarmed for that sensor the sensor remains enabled so that it reports to the control panel every 4 to 20 minutes (or other relatively long period set by the control panel). However, if the sensor is triggered after the panel is disarmed with respect to that sensor, receipt of the corresponding trigger signal by the control panel causes the latter to return a disable command to the sensor, switching off its monitoring circuitry. The sensor remains disabled until the control panel 10 re-arms with respect to that sensor. While disabled the sensor reports to the control panel with a frequency of no less than every 20 seconds to see if the panel has re-armed with respect to that sensor and, if so, it switches on its monitoring circuitry. The reporting period (typically 4 to 20 minutes) when the sensor is enabled can be set when the panel responds.

The benefits of this arrangement are seen in, for example, a shopping mall where there are oeriods of high activity (during shopping hours) alternating with periods of inactivity (at night). During the night it is assumed that all the sensors are enabled and the control panel is armed. Thus all sensors are reporting at, e.g., 20 minute intervals. At the start of shopping hours the control panel is disarmed, but all sensors remain enabled and thus continue to report to the control panel at 20 minute intervals. However, relatively busy sensors (e.g. those which monitor zones frequented by shoppers) will soon be triggered, and when each sensor is first triggered it is disabled by the control panel to avoid the power drain associated with subsequent repeated triggering. On the other hand, relatively non-busy sensors located in areas where no triggering is normally expected, e.g. attic areas, remain enabled and therefore continue to report to the control panel at 20 minute intervals.

This means that when the control panel arms, it can assume that non-busy sensors are enabled and reporting; and it will expect a trigger signal from busy sensors soon after arming, to which the panel can respond with a disable signal. Non-functioning non-busy sensors would be discovered lost within the regulation 20 minutes.

As well as saving on power consumption for non-busy sensors by minimizing their reporting when the panel is armed, the panel is also provided with information on whether relatively busy sensors are working.

« So, sensors are essentially classed as busy or non-busy if they trigger or not after a panel is disarmed i.e. any sensor which has triggered when the panel is disarmed is classified as a busy sensor.

If there is a problem with the system, a customer can check non-busy sensors with the panel disarmed by triggering the sensor but not causing an alarm and this can be logged. Logs can be accessed remotely either to produce periodic reports and perhaps service calls, or to help in diagnosing problems.

So on the one hand the invention provides an automatic inspection system and at the same time the system has the side effect of power saving on wireless systems.

In a further refinement, the log for the automatic inspection system is maintained separately from the normal alarm log maintained by an alarm system. A reporting period for the log may extend over a number of arm/disarm cycles e.g. a number of days or weeks. Over the reporting period, sensors which trigger each time or most often when the panel is disarmed in respect of those sensors can be categorised as most busy; sensors which do not trigger over the course of the reporting period can be categorised as least busy; with intermediate categorisations being applied to other sensors.

This enables the least busy sensors to be identified as needing to be checked for the functionality of their monitoring circuitry.

Also mapping the busyness of sensors to the layout of a building can give an installer or engineer a better idea IE of how an installation is operating and may indicate a need to re-configure aspects of the system for example by adding extra sensors or alternative sensors or even removing sensors.

Preferably, an installer or engineer can select a time cycle for the reporting period e.g. 1 day or 31 days or more, either at the panel or remotely, to have the inspection system transmit the log from the control panel to the monitoring service across the network 28.

Alternatively, the log can just be re-cycled so that it is available for inspection at the control panel 10 as required.

By comparison to the twice yearly physical inspection which is typically is carried out of a monitored alarm system, using the present system, a report would be sent automatically to the monitoring company who could either forward it on to the client as part of the service contract or use the information to flag to the client that a sensor should be tested for functionality - for example, by having the customer go into the attic when the alarm is disarmed for the attic and triggering the attic movement sensor. When a system is being remotely monitored, the panel 10 can be arranged to report such movement immediately to the monitoring company so that this activity can be viewed live and the customer advised immediately if there is a problem and if maintenance is required. As such, there are large savings to the monitoring company such as transport costs and labour as well as the possibility of adding value to their service.

Also, during the reporting period, the sounder 24,26 could also be tested (at a barely audible tone) as would all communications.

The invention is not limited to the embodiment described herein which may be modified cr varied without departing from the scope of the invention.

Claims

1. An alarm system comprising a central control unit and a plurality of remote sensors in intermittent routine 5 RF communication with the control unit, wherein the sensors routinely communicate with the control unit at greater intervals when enabled than when not enabled, and wherein for each sensor, starting from a state in which the control unit is armed and the sensor is enabled, if 10 the control unit is subsequently disarmed the sensor remains enabled until it is triggered whereupon it is disabled by the control unit.

2. An alarm system as claimed in claim 1, wherein when 15 a sensor is enabled, each time it is triggered it sends a signal to the control unit.

3. An alarm system as claimed in claim 1 or 2, wherein the system maintains a log indicating sensors which have 20 triggered when the panel is disarmed.

4. An alarm system as claimed in claim 3, wherein the log has a period extending over a plurality of arm/disarm cycles .

5. An alarm system as claimed in claim 3 or 4, wherein the log is transmitted across a network to a monitoring station.