GB2615416A

GB2615416A - Wireless alarm system input devices

Info

Publication number: GB2615416A
Application number: GB2300470.8A
Authority: GB
Inventors: Galbraith Colin; O'connell Michael
Original assignee: Orisec Ltd
Current assignee: Orisec Ltd
Priority date: 2023-01-12
Filing date: 2023-01-12
Publication date: 2023-08-09
Anticipated expiration: 2043-01-12
Also published as: GB2615416B; GB202300470D0

Abstract

A wireless alarm system is provided which can work with input devices operating on different frequencies allowing for the use of devices from different manufacturers in the same system. The wireless alarm system comprises a central control panel 12 including a radio receiver listening continuously on a first frequency. A first alarm device, such as PIR sensor 14, transmits a signal on the first frequency to the radio receiver in response to being triggered. A second alarm device, such as smoke detector 16, transmits a signal on a second frequency in response to being triggered. The first alarm device, PIR sensor 14, listens periodically on the second frequency and relays a message from the second alarm device, smoke detector 16, to the control panel 12 radio receiver via the first frequency. Each of the control panel 12, the PIR sensor 14, and the smoke detector 16 only require a single radio.

Description

WIRELESS ALARM SYSTEM INPUT DEVICES

The present invention relates to alarm systems, for example intruder and/or fire alarm systems, in particular wireless alarm systems.

BACKGROUND TO THE INVENTION

Wireless alarm systems have become increasingly popular compared to wired alarm systems, because of the considerable labour savings involved in installing a wireless system, particularly in an existing building which has already been decorated and may already be occupied and in use.

Providing a wireless alarm avoids the need to run cables, and avoids all the drilling, chasing, and subsequent redecoration which is involved in doing that. It also avoids unsightly surface-mounted cables.

Furthermore, if a fault arises in a wired alarm due to a faulty cable, it may be problematic and time consuming to trace and repair the fault. In contrast, in a wireless alarm, repairing a fault will often involve simply replacing a single faulty sensor, which is battery powered and not physically connected to anything else.

Wireless alarms have proven to be generally very reliable, and wireless intruder alarm systems and wireless fire alarm systems are both currently installed. An alarm system typically includes an alarm "panel" (i.e. a central controller), and multiple inputs / sensors which connect to the central controller. In the case of a wireless system the communication is wireless, although controllers are available which can connect to both wired and wireless sensors. Some alarm systems are combined fire and intruder alarm systems, with both intruder inputs (e.g. PIRs, door sensors, panic buttons) and fire inputs (e.g. smoke sensors, heat sensors, manual call points). Alarm systems could also have other inputs, for example carbon monoxide sensors, flood sensors, and so on.

The wide range of sensors available in theory allows for very sophisticated bespoke systems in different applications. However, in practice, some of these types of sensors are rather low volume products. The range of sensors available from a particular manufacturer may therefore be limited. Typically, wireless sensors are designed to communicate at a particular frequency and with a particular modulation scheme, etc. One manufacturer's sensor is therefore unlikely to be directly compatible with another manufacturer's alarm panel! central controller. It may therefore not be possible to build a single system with a particular combination of types of specialist sensors.

Although there are similarities, slightly different considerations are in play for fire alarm systems compared with intruder alarm systems. A fire alarm system will normally be armed all of the time, whereas an intruder alarm system needs a reliable way for a user to easily arm the system when they leave the building unoccupied, and disarm the system when or before entering the building. In a combined intruder and fire system, the fire detection functions would remain armed at all times whereas the intruder detection functions will need to be armed! disarmed by the user.

Self-contained, often battery powered, smoke and/or heat alarms are common for protecting homes. These devices incorporate both a detector and a sounder and do not need to be connected to any other devices in order to function to alert and/or wake up an occupant in the event of a fire. Some devices interconnect with each other, either through wires or wirelessly, but will still function as standalone devices. When alarms are interconnected, when one alarm detects smoke or heat, all alarms in the building should sound, to be sure of waking up and/or alerting occupants to the potential danger as early as possible, maximising the chances of escape and/or successfully fighting the fire. Some sensors are neither strictly fire sensors nor intruder sensors, but they can be categorised based on the action which needs to be taken if the sensor is activated. For example, a carbon monoxide sensor would likely be considered part of the fire alarm function of a combined system because activation of the sensor indicates a safety risk which can be addressed by evacuating the building, and the carbon monoxide sensor, just like a smoke detector, should be monitored at all times and not only when the system is "armed".

In an intruder alarm system it is important to be able to detect when a sensor has lost communication with the panel. This could happen for a number of reasons, but one common cause of lost communication is a change in the environment. For example, moving or adding a large metal object such as a filing cabinet in an office can mean devices which could previously communicate with each other wirelessly can no longer do so. An intruder alarm which is graded Grade 2 or above according to British Standard PD6662 and European Standard EN50131 must be able to detect when a sensor has lost communication. To do this, detectors "poll" the alarm control panel regularly and a "lost" detector will show as a fault requiring investigation and fixing.

It would be possible in principle to make a "universal" wireless alarm panel, i.e. an alarm panel which can communicate with a range of different sensors at different frequencies. However, such a product would have to include multiple radios. This is because the panel needs to be listening on at least one "primary" channel at all times.

Most devices in the system will "poll" the alarm panel periodically, as it is important that the panel knows that all devices are still operating. Furthermore, some devices in a wireless alarm system which has an intruder alarm function may be user-operated devices for arming / disarming the alarm system, and the panel needs to be respond immediately to input on these devices. If a user is entering or leaving a building and wants to disarm or arm a system accordingly, it is no good if the wireless keyfob remote cannot contact the panel. "Trying again later", once the panel is listening on the primary channel, is not an option -the user entering the building who has failed to disarm the system because the panel is not listening will either not notice the failure, enter the building and cause a false alarm, or if the user notices the failure, may assume there is a fault or that the system was not armed in the first place, enter the building and cause a false alarm. Likewise, when leaving the building, if the panel is not listening on the primary channel when the user tries to arm the system with a remote keyfob, then the system will be likely to remain disarmed while the user is out.

In the UK there are at least twelve different channels specifically allocated to alarm use, and others which can be used by alarms but are also shared with other devices.

An alarm panel which could be used as part of a system including sensors from three different manufacturers would potentially need three radios, and this may still present a limitation when trying to build specialist systems. Providing multiple radios in the panel would increase the cost of the panel, and in many more straightforward applications the extra components would never be used. Larger systems have multiple receivers, to ensure coverage of a large building or even multiple buildings. To cover multiple channels, each receiver would need multiple radios, multiplying cost.

Use of channels allocated to alarms is regulated. In particular the transmission duty cycle on the channel is limited to either 0.1%, 1% or 10% (depending on the particular channel used). Systems need to comply with regulations by ensuring that transmissions do not exceed the allowed duty cycle.

It is an object of the present invention to reduce or substantially obviate these problems and to provide an alarm system, in particular an alarm system with an intruder alarm function, which may have a fire alarm function as well, which can work with input devices on different frequencies.

STATEMENT OF INVENTION

According to the present invention there is provided a wireless alarm system, the system comprising: an alarm system controller, a radio receiver connected to the controller, the receiver being adapted to listen continuously on a primary frequency, a first alarm input device adapted to communicate with the receiver on the primary frequency and to transmit a radio message on the primary frequency in the event of the first alarm input entering a triggered condition, and a second alarm input device adapted to communicate on a secondary frequency and to transmit a radio message on the secondary frequency in the event of the second alarm input entering a triggered condition, in which the first alarm input device is adapted to listen periodically on the secondary frequency and to relay a radio message from the second alarm input device, received on the secondary frequency, to the radio receiver, by transmitting a radio message to the receiver on the primary frequency.

Advantageously, each of the radio receiver, the first alarm input device and the second alarm input device needs to be provided with only a single radio. The second alarm input device may be an "off-the-shelf" device from substantially any manufacturer.

Alarm devices in the UK and Europe will use one of several channels in different sub-bands in the 863-870MHz range. A suitable radio could transmit and receive on any channel in that range, but the "off-the-shelf' second alarm input device is likely to be hard-wired / hard-coded to a single frequency. The alarm system controller / radio receiver may also be a standard component designed to operate on a single frequency.

On the other hand the first alarm input device may be programmable to specify a secondary frequency to match the hard-coded frequency of the second alarm input device. In some embodiments, the first alarm input device may be programmable to specify the primary frequency as well, to match different controllers / receivers from different manufacturers.

Examples of alarm input devices include, in an intruder alarm system, PIR motion detectors, door sensors (commonly reed switches or proximity sensors), shock detectors, panic buttons, break-beam detectors, etc. Examples of alarm input devices in a fire alarm system include smoke detectors, heat detectors, carbon monoxide detectors, and alarm call points. Alarm input devices, generally speaking, are any devices which can cause an alarm condition in the alarm system.

In one embodiment, the alarm system is a combined fire and intruder alarm system, in which the first input device is an intruder alarm input device and in which the second input device is a fire alarm input device.

The second alarm input device preferably includes an internal alerting means, for example a sounder, strobe, or both. Thus, in the case that the second alarm input device enters a triggered condition, it will sound an alarm at the place where the detector is located. This is a particularly useful feature in the case that the second input device is a fire alarm input device (for example a smoke detector). If smoke is detected in, for example, a bedroom, the smoke detector will sound an intemal sounder straight away, alerting anybody who may be in the room or nearby without any delay at all. The smoke detector will also work to alert an occupant even if the alarm panel is not working, or if a message for some reason cannot get to the alarm panel, for example because the transceiver on the first alarm input device is faulty. The second alarm input device may be a household smoke or heat alarm with a wireless interconnect function.

Systems according to the invention may be suitable for use in a dwelling, which would usually be protected with self-contained smoke and/or heat alarms, each smoke and/or heat alarm having both a smoke / heat sensor and its own internal sounder or other alerting means. In addition to alerting locally, smoke/heat alarms can be obtained which transmit a wireless signal. Typically this is used to interconnect with other smoke / heat alarms in the same building. Such smoke / heat alarms operate entirely normally when used as the second detector in embodiments of the invention. In particular, the smoke / heat alarm will still sound its own internal sounder, and the wireless message transmitted when the alarm is activated can be received by other similar smoke / heat alarms so that they can produce the alarm sound / alert as well. The wireless message is also received by the radio of the first alarm input device and hence the receiver in the alarm system of the invention.

The alarm system controller, in many embodiments, is primarily an intruder alarm system controller. The fire alarm functions perfectly well as a plurality of standalone but interconnected smoke / heat alarms. However, the advantage of receiving the signal from the fire alarm at the alarm system controller is often that an alarm receiving centre (ARC) could be notified of the fire alarm condition, or, increasingly, a householder or another person could be notified directly of a fire alarm condition for example by text message or mobile app. This is very valuable, for example if a householder has left for work but left the grill on. It also has applications where vulnerable people, for example the elderly, are living alone.

The radio receiver connected to the controller listens continuously on the primary frequency. Therefore, the radio receiver will receive any messages from any devices which are part of the alarm system. This may include multiple alarm input devices, for example intruder alarm input devices (PIRs, door sensors, etc.) and fire alarm input devices (smoke detectors, call points, etc.). Alarm input devices may periodically send a polling message to the radio receiver to indicate that they are present on the system and working properly. This is a requirement of intruder alarms graded Grade 2 or above on the relevant British and European standards.

Further, user control input devices may be provided which communicate with the radio receiver on the primary frequency. User control input devices may include for example a keyfob remote with buttons for arming or disarming the intruder alarm system (or the intruder alarm function of a combined intruder and fire alarm system). Because the radio receiver is constantly listening on the primary channel, the alarm system controller can respond quickly and reliably to a user command to arm or disarm the system.

The first alarm input device listens on the secondary frequency periodically. For example, in one embodiment the first alarm input device listens on the secondary frequency for 10ms every eight seconds. A period of between about one second and twenty seconds may be acceptable. The first alarm input device turns on the radio at the secondary frequency and listens to see if there is a carrier / any signal at all on the secondary frequency. If a carrier is detected, the first alarm input device will continue to listen to see if it is a signal from a transmitter it recognises -i.e., a second alarm input device forming part of the alarm system. If so, the first alarm input device will continue to listen to receive a message, and then relay that message to the radio receiver by switching the radio of the first alarm input device to the primary frequency and transmitting a message to the radio receiver on the primary frequency.

In an alternative embodiment, the first alarm input device will relay all messages received on the secondary frequency to the alarm system controller on the primary frequency. It is then for the alarm system controller to identify whether the transmission is from a second alarm input device forming part of the alarm system and either take action (i.e. cause a fire alarm condition in the system) if the signal is from a second alarm input device forming part of the alarm system or ignore the transmission Cif it is from a device not forming part of the system, for example it is a signal picked up from a neighbouring building). Leaving it to the alarm system controller to distinguish messages from inside and outside the system has the advantage that it is not necessary to provide storage on the first alarm input device for the IDs / addresses of each second alarm input device which forms part of the system. This is at the slight cost of potentially reduced battery life if the first alarm input device is forwarding messages unnecessarily, but it is found that in practice, because the channels are regulated and are quiet, these non-system messages are not received often. Even if many nearby buildings have the same kind of smoke alarm, they should not transmit often because the devices are designed to transmit only when smoke is detected, which should be a rare event.

The second alarm input device is preferably adapted to transmit only infrequently, or preferably not at all, unless the alarm enters a triggered condition (i.e., when the second alarm input device detects smoke, heat, or when a manual call point has been pressed). The second alarm input device may ensure that messages are repeated over a continuous period which is longer than the period for which the first alarm input device is switched off, between periodically listening to the secondary frequency.

It will be understood that although the primary function of the "radio receiver' is to receive messages from other devices in the system, it may in fact be a transceiver since a bidirectional communication protocol may be implemented, at least for example to acknowledge receipt of messages. Listening continuously is to be understood in this context. The radio receiver is always listening on the primary frequency but when a message is received, an exchange of messages between devices may then take place which means that the radio receiver is for short periods of time transmitting, rather than receiving. Suitable protocols are already known to manage communication between multiple devices and the radio receiver, and to handle situations such as two devices trying to send messages to the radio receiver at once, or a device trying to send a message to the radio receiver while the radio receiver is transmitting.

According to a second aspect of the invention, there is provided an alarm input device for use in a system according to the first aspect of the invention. The alarm input device comprises: a sensor or user input means; a radio transceiver, the transceiver being switchable for operation on at least two different frequencies, the alarm input device being adapted to monitor the sensor or user input means, and to transmit a radio message on a primary frequency in the event that the sensor or user input means enter a triggered condition, and the alarm input device being further adapted to periodically activate the transceiver to monitor a secondary frequency for a transmission, and on receipt of a radio message from a second alarm input device on the secondary frequency, to relay the message by making a transmission on the primary frequency.

The alarm input device is preferably an intruder alarm input device. As such the sensor may be for example a PIR motion sensor, a door contact sensor, a shock sensor, or any other type of sensor which may be used to detect a possible intrusion and enter the triggered condition. In an intruder alarm system an example of an input device with a user input means is a "panic button", which usually has two separate buttons which must be pressed simultaneously to enter the triggered condition.

The alarm input device is preferably battery powered, for example by a CR123 lithium cell. Devices may be produced in which ordinary good quality CR123 cells can last over two years.

The alarm input device may send a polling signal periodically on the primary frequency.

The purpose of the polling signal is to inform an alarm controller that the device is present and operating normally.

The alarm input device may in some embodiments be a fire alarm input device. In such a device the sensor may be for example a smoke sensor or a heat sensor. An example of a fire alarm input device with user input means is a manual call point, which is usually activated by breaking a glass or plastic component which then causes the device to enter the triggered condition.

The alarm input device preferably includes only a single radio and a single antenna. The radio transceiver may be switchable to operate on more than one frequency, preferably any frequency within a range, for example any frequency between around 863 and 870Mhz, although it will be understood that frequency allocations vary in different jurisdictions and may be changed at times by regulatory authorities. At a minimum, the radio transceiver must be capable of operating at at least two different frequencies -the primary frequency and the secondary frequency.

The alarm input device for most of the time will operate in a standby mode. In the standby mode, the sensor or user input means is monitored, but as long as the sensor or user input means does not enter a triggered condition, nothing will happen. In the standby mode the radio will remain switched off for most of the time. This reduces power consumption and hence ensures that a battery powering the device will last a long time. It is preferable for a device to have minimal power consumption so that it can be powered by, for example, a lithium CR123 cell which does not need to be changed for at least two years.

The alarm input device may switch on the radio periodically, for a short period of time, to send a polling message on the primary frequency.

The alarm input device also switches on the radio periodically, for a short period of time, to listen on the secondary frequency. In an example embodiment, this is done every eight seconds. When the radio is switched on, to the secondary frequency, the device listens (for example for about 10ms) to see if there is a carrier or any signal at all on the secondary frequency. If not, then the radio is switched off again straight away, and remains switched off for another eight seconds (for example) until the process is repeated. If a transmission is detected, then the radio will remain switched on to receive and identify the transmission. The radio is then switched to the primary frequency to transmit the message to the main system controller.

In practice, it is expected that most of the time when the radio is switched on to listen to the secondary frequency, there will be nothing there. Transmissions when the second alarm input device is in a triggered condition, e.g. because it has detected smoke, may be repeated for quite a long time, for example for at least 24 seconds, but it should be reasonably rare for the second alarm input device to be in a triggered condition at all On the case of a smoke or heat detector this will only happen if potentially dangerous heat or smoke is detected). Regulations applicable to use of the alarm channels limit the time a device may transmit on the channel to 0.1%, 1% or 10% (depending on the channel chosen) of a time window. The channel is expected therefore to be generally very quiet, and so the alarm input device will usually switch on the radio to the secondary frequency, find nothing there, and switch it off again quickly. This means that little power is used.

The alarm input device of the second aspect of the invention uses only the same hardware as a known wireless alarm input device, e.g. the same hardware as an existing wireless PIR, wireless door sensor, or wireless shock sensor. There is no additional hardware cost associated with the device, and the power requirements are also kept within what is required to ensure that an ordinary lithium CR123 cell will last at least two years. In principle a diligent installer! service engineer should change all batteries in a system on an annual service. However in case a device is missed, then the battery should last until the next annual service.

The first alarm input device may be configurable to operate in either one of two modes, the first alarm input device in the first mode being adapted to listen periodically on the secondary frequency and to relay a radio message from the second alarm input device, received on the secondary frequency, to the radio receiver, by transmitting a radio message to the receiver on the primary frequency, and the first alarm input device in the second mode being adapted to communicate on the primary frequency, and not to listen on the secondary frequency, the mode of the first alarm input device being settable by means of a signal sent by the alarm system controller to the first alarm input device on the primary frequency.

In other words, the first alarm input device may be configurable to act as a relay for second alarm input devices, as described in detail above, or not. If the system does not require devices on a secondary frequency, then there is no need for the first alarm input device to monitor the secondary frequency. Accordingly, this function can be turned off, and conveniently this can be done by a signal from the controller on the primary frequency.

The system may include a plurality of similar first alarm input devices, for example multiple PIRs, multiple shock detectors. Each of the first alarm input devices may be operable in either the first mode or the second mode, and the mode of all of the first alarm input devices may be settable by means of a signal sent by the alarm system controller on the primary frequency.

Hence, each primary frequency input device on the system does not need to be configured individually. By providing devices which are configurable in this way, it is easy, for example, to add a smoke detector into an existing intruder alarm system which already has multiple PIRs. The PIRs do not need to be individually reprogrammed, or jumpers set, to put them into the mode where they listen for smoke alarm signals on the secondary frequency. Instead, the configuration is simply input into the controller (for example, by a keypad on the controller, or an external keypad, or via a mobile phone app or other interface). The controller then sends a configuration signal to all the capable devices in the system, and puts them into the mode where they listen periodically on the secondary frequency.

Advantageously, the alarm system controller may include storage means for storing identifiers associated with second alarm input devices (e.g. smoke alarms). Typically wirelessly interconnectable smoke alarms are pre-programmed with a unique identifier.

This identifier can then be "learned" into the alarm system controller so that the alarm system controller will recognise a message from that second alarm input device as a message from a device which is part of its system, as opposed to for example a message picked up from a similar alarm in a neighbouring building.Accordingly, the alarm system controller may have a "learn" mode in which the controller in response to receiving a message from a second alarm input device (the message having been relayed by a first alarm input device) stores an identifier associated with the second alarm input device in its storage means. The controller may be placed in "learn" mode in response to user input. The alarm system controller when not in "learn" mode is in "operating" mode, in which the controller in response to receiving a message from a second alarm input device (the message having been relayed by a first alarm input device), checks whether the identifier of the sending second alarm input device matches an identifier in the storage means. If the received identifier matches a stored identifier then the controller enters an alarm condition, otherwise, the message is ignored.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawing, in which: Figure 1 shows an alarm system according to the first aspect of the invention, including a PIR alarm input device according to the second aspect of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figure 1, a wireless alarm system is shown. The system illustrated is a combined intruder and fire alarm system. The intruder alarm system may be a Grade 2 or above intruder alarm according to the relevant standards mentioned above. As a fire alarm, it may be of the type suitable for use in a dwelling, in which standalone smoke alarms! heat alarms, preferably interconnected but which will function alone, are acceptable. For clarity, only one intruder alarm input is shown and only one fire alarm input is shown, but it will be understood that in practice multiple intruder inputs, for example PIRs, shock detectors, door sensors, panic buttons, and multiple fire inputs, for example smoke detectors, heat detectors, manual call points, may be provided.

In particular where multiple fire inputs are provided they may be wirelessly interconnected smoke! heat alarms which receive signals from each other, in addition to signals from the smoke! heat alarms being received by the PIP motion detector 14 as described below.

Also, although the invention relates particularly to wireless systems, it is possible for some other inputs and/or outputs to be connected to the alarm system by wires.

In particular the alarm system includes a central controller or alarm panel 12, a PIP motion detector 14 which forms a first alarm input device, and a smoke detector 16 which forms a second alarm input device. A keyfob remote control 18 is provided for allowing a user to arm or disarm the intruder alarm function of the alarm system (the fire alarm function would normally remain constantly armed).

In this embodiment, the alarm panel 12 includes a keypad for allowing configuration of the system and for allowing the user to arm or disarm the intruder alarm function using a PIN (as an alternative to using the keyfob remote control 18). However, in some embodiments no keypad may be provided, and in some embodiments the keypad is an external device not physically present on the same device as the alarm panel 12. In this embodiment, the alarm panel 12 includes a radio receiver, although again in other embodiments the radio receiver may be an external device, connected by wires to the alarm panel 12.

In this system, the smoke detector 16 is an off-the-shelf wireless smoke detector. This may be for example a household smoke alarm with a wireless interconnect function. It may be manufactured by a different manufacturer, in particular from the alarm panel 12. The smoke detector may be hard-coded to operate at a particular radio frequency, which is not the same as the frequency of the other devices in the system. In particular, the PIR 14 and the wireless remote keyfob 18 both operate on a primary frequency, and the smoke detector 16 operates on a secondary frequency which is different from the primary frequency.

The alarm panel 12 must be configured to listen at all times on the primary frequency.

A particular reason for this is to guarantee that a user input to arm or disarm the system via the remote keyfob 18 can be immediately processed.

The alarm panel 12 includes a single radio, and since the alarm panel 12 is always listening on the primary frequency, the alarm panel 12 cannot receive communications directly from the smoke detector 16, which transmits on the secondary frequency.

The PIR 14 also includes a single radio. However, the PIR 14 is configured to periodically switch the radio to the secondary frequency and listen for any transmissions. In this embodiment, the radio in the PIR is switched on every 8 seconds, and listens for 10ms. Usually, nothing will be heard and the radio of the PIR is immediately switched off again. However, if the smoke detector 16 is transmitting a message, then the PIR will receive the message, then switch its radio to the primary frequency, and then transmit the message to the control panel 12.

In the case that the smoke detector 16 detects smoke, it will enter a triggered state and begin transmitting a message, indicating that the detector has detected smoke and therefore the system should enter into a fire alarm state. In the triggered state, the smoke detector 16 transmits a message on the secondary channel, and keeps repeating the message for at least 24 seconds. The smoke detector 16 will also activate its internal sounder to alert occupants who are close by, even before the radio message has been transmitted to the controller. Although the PIR 14 only switches on the radio every eight seconds, in the triggered state the smoke detector will continuously transmit for at least 24 seconds, and therefore will be heard the next time the radio in the PIR is switched on. The PIR will then receive the message and retransmit it to the alarm control panel 12, activating the fire alarm.

Other similar smoke detectors in the building will be listening on the secondary channel and will also hear the radio message from the smoke detector which has detected smoke. All smoke detectors in the building which hear the message will sound their own internal sounders, alerting all occupants of the building to the potential danger.

The system of the invention allows for an alarm system made up of multiple different devices, from different manufacturers, with only one device (the PIR in this case) having to be specially configured to use two frequencies. This is done without any additional hardware and therefore cost is kept low. Importantly, the alarm control panel continues to operate on a single primary frequency, which means that messages from, for example, the remote control keyfob will always be heard. Furthermore, because the radio in the FIR is only turned on for a short period of time every eight seconds, a long battery life is preserved.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS1. A wireless alarm system, the system comprising: an alarm system controller, a radio receiver connected to the controller, the receiver being adapted to listen continuously on a primary frequency, a first alarm input device adapted to communicate with the receiver on the primary frequency and to transmit a radio message on the primary frequency in the event of the first alarm input entering a triggered condition, and a second alarm input device adapted to communicate on a secondary frequency and to transmit a radio message on the secondary frequency in the event of the second alarm input entering a triggered condition, in which the first alarm input device is adapted to listen periodically on the secondary frequency and to relay a radio message from the second alarm input device, received on the secondary frequency, to the radio receiver, by transmitting a radio message to the receiver on the primary frequency.
2. A wireless alarm system as claimed in claim 1, in which each of the radio receiver, the first alarm input device and the second alarm input device is provided with only a single radio.
3. A wireless alarm system as claimed in claim 1 or claim 2, in which the first alarm input device is programmable to select a secondary frequency from a plurality of alternative secondary frequencies.
4. A wireless alarm system as claimed in any of the preceding claims, in which the first alarm input device is programmable to select a primary frequency from a plurality of alternative primary frequencies.
5. A wireless alarm system as claimed in any of the preceding claims, in which the first alarm input device is an intruder alarm input device.
6. A wireless alarm system as claimed in any of the preceding claims, in which the second alarm input device is a fire alarm input device.
7. A wireless alarm system as claimed in any of the preceding claims, in which the first alarm input device periodically sends a polling message to the radio receiver on the primary frequency.
8. A wireless alarm system as claimed in any of the preceding claims, in which a user control input device is provided for arming and/or disarming an intruder alarm function of the alarm system, the user control input device being adapted to communicate with the radio receiver on the primary frequency.
9. A wireless alarm system as claimed in any of the preceding claims, in which a standby time period in which the first alarm input device is not listening on the secondary frequency is at least one second.
10. A wireless alarm system as claimed in claim 9, in which the second alarm input device is configured to transmit a message for at least as long as the standby time period when the second alarm input device enters the triggered condition.
11. An alarm input device for use as the first alarm input device in a system according to any of the preceding claims, the alarm input device comprising: a sensor or user input means; a radio transceiver, the transceiver being switchable for operation on at least two different frequencies, the alarm input device being adapted to monitor the sensor or user input means, and to transmit a radio message on a primary frequency in the event that the sensor or user input means enter a triggered condition, and the alarm input device being further adapted to periodically activate the transceiver to monitor a secondary frequency for a transmission, and on receipt of a radio message from a second alarm input device on the secondary frequency, to relay the message by making a transmission on the primary frequency.
12. An alarm input device as claimed in claim 11, which is an intruder alarm input device.
13. An alarm input device as claimed in claim 12, which is a PIR (passive infra-red) motion sensor), a shock sensor, or a door contact.
14. An alarm input device as claimed in any of claims 11 to 13, in which the device is adapted to send a polling signal periodically on the primary frequency.
15. An alarm input device as claimed in any of claims 11 to 14, in which the device includes only a single radio.
16. An alarm input device as claimed in any of claims 11 to 15, in which the device operates in a standby mode for at least 90% of the time when not in a triggered condition, the radio transceiver in the standby mode being switched off.
17. An alarm input device as claimed in claim 16, in which the device operates in the standby mode for at least 99% of the time when not in a triggered condition.
18. An alarm input device as claimed in any of claims 11 to 17, in which the period of time between activations of the transceiver to monitor the secondary frequency is at least one second.
19. An alarm input device as claimed in claim 18, in which the period of time between activations of the transceiver to monitor the secondary frequency is at least 5 seconds.
20. A wireless alarm system as claimed in any of claims 1 to 10, in which: the first alarm input device is configurable to operate in either one of two modes, the first alarm input device in the first mode being adapted to listen periodically on the secondary frequency and to relay a radio message from the second alarm input device, received on the secondary frequency, to the radio receiver, by transmitting a radio message to the receiver on the primary frequency, and the first alarm input device in the second mode being adapted to communicate on the primary frequency, and not to listen on the secondary frequency, the mode of the first alarm input device being settable by means of a signal sent by the alarm system controller to the first alarm input device on the primary frequency.
21. A wireless alarm system as claimed in claim 20, in which a plurality of first alarm input devices are provided, each of the first alarm input devices being operable in either the first mode or the second mode, and the mode of all of the first alarm input devices being settable by means of a signal sent by the alarm system controller on the primary frequency.
22. An alarm system controller suitable for use in a wireless alarm system as claimed in claim 20 or claim 21, the alarm system controller including input means for receiving a configuration value from a user, and the alarm system controller being adapted to transmit a signal on the primary frequency for setting the mode of associated first alarm input devices, in response to the inputted configuration value.
23. An alarm system controller as claimed in claim 22, in which the controller includes storage means for storing identifiers associated with second alarm input devices.
24. An alarm system controller as claimed in claim 23, in which the controller is configurable in a learn mode or in an operating mode, the controller in the learn mode, in response to receiving a message from a second alarm input device, stores a received identifier associated with that second alarm input device in the storage means, and the controller in the operating mode, in response to receiving a message from a second alarm input device, compares a received identifier associated with that second alarm input device to stored identifiers, and causes an alarm condition only if the received identifier matches a stored identifier.