WO2006085781A1

WO2006085781A1 - Network of wireless, stand-alone alarm units

Info

Publication number: WO2006085781A1
Application number: PCT/NZ2006/000020
Authority: WO
Inventors: Robert James Mitschak
Original assignee: Evacuation Alarms & Systems Nz Limited
Priority date: 2005-02-14
Filing date: 2006-02-14
Publication date: 2006-08-17
Also published as: NZ538232A; AU2006200598A1

Abstract

A plurality of battery-powered wireless-triggered evacuation alarm units is placed about an area to become protected. Each unit includes means to raise a range of audible (siren and spoken instructions) and visual alarm signals through high-intensity horns or flashers when triggered by a compatible wireless transmitter. Having no interconnecting or power wires, the units are suitable for use in building or demolition sites, or outdoors. The transmission range may be extended for outdoors use such as at a beach. The units would be suitable for tsunami evacuation alarms in response to satellite communications.

Description

TITLE NETWORK OF WIRELESS, STAND-ALONE ALARM UNITS.

FIELD This invention relates to an alarm device to warn people at risk of impending or actual disaster, particularly wherein each alarm device forms part of an integrated group, including wireless triggering means.

BACKGROUND

In many potential or actual emergencies there is some time available for raising an alarm and getting action before the actual disaster-causing event arrives. For example, tsunami waves may be in transit across the Pacific Ocean for up to 12 hours. The first, S-P ground waves of an earthquake take rather approximately 1 minute to travel 570 km along the ground (up to 5000 m/sec in granite); much slower than radio waves. Floods and cyclones can be predicted. Ski field operators could warn skiers of avalanches. There may be some time before the event spreads and overwhelms people, such as in a fire.

Taking civil defence (such as tornado or tsunami warnings) as an example, there does not appear to be a utilities-independent, public, warning system capable of effectively warning persons of an impending disaster, at least in the inventor's country, New Zealand. The New Zealand Ministry of Civil Defence must prepare an effective tsunami warning system in particular for areas such as Gisborne, Wellington, and Dunedin. Note that there are at-risk populations in many other countries, as shown up by the tsunami in the Indian Ocean of December 26, 2004. Japan has an earthquake warning system. Tsunami warnings could be triggered by cellphone type calls initiated at a national disaster centre, an international tsunami centre, or even automatically by a satellite in response to under-sea tsunami wave sensing equipment. The invention should therefore be compatible with international systems. Military or dedicated international communications links are advisable as a backup to the mains-dependent telephone network. In the event that international tsunami or earthquake sensing / recognition networks are not yet available or out of commission, a warning system of alarms may be triggered by the national or local Police or Civil Defence organisation.

Planners should not assume the continued availability of the utilities like telephones and electricity during an emergency. Many apparently reliable communications routes may have an unsuspected reliance on mains electricity. Recent current events (such as the July 2005 bombings in London subways) make it clear that cellular telephone structure cannot be relied upon; in that case it was switched off by the authorities in case bombers were using it to trigger further bombs. Furthermore, plans such as to send a text message to every cellphone user would fail because (a) the system would be overloaded, and (b) not every person is text-aware even if that person carries a working cellphone. The normal (landline) telephone system may crash (in the sense of a computer system failure) in the event of an earthquake elsewhere in the country. That would also halt internet-based communications. Many subscribers now use mains-driven local telephones (such as cordless phones) that stop working in the absence of a main supply. Transmission lines and dams may be switched off automatically or under manual control in the event of an earthquake and, even if only some transmission lines are affected, remaining lines may also be turned off to avoid overloading others. New Zealand's Amateur Radio Emergency Corps serves an emergency wireless communications function, and similar voluntary organisations exist in many other countries. Standard practice is to use batteries or stand-alone generators. They do not have the means or any particular authority to raise the alarm to the public at large.

Taking a school as another application example, ta public address system into classrooms from the principal's office usually exists, but this depends on a mains electricity supply and in-school message delivery by a person on the spot. Children in a school can be particularly vulnerable to a number of natural or man-made disasters. In the Napier earthquake of 1931, all but two of the primary school children were fortunately outside at play when the brick school buildings collapsed. 30 seconds warning should be enough to get the children to take cover or evacuate.

Taking a building site as the original application for this invention, it is common to have teams of workers on more than one floor or in many parts of a building being erected or demolished. From time to time, a fire for example may require evacuation of the workforce. Personnel movements between floors and out to a safe place may be dysfunctional (such as because of a lack of passenger lifts or safe stairs). There is a reasonably high risk that evacuation will be required during assembly of the building and its components and systems, before a finished, stable building configuration has been reached. It is useful to consider both the risk and the type of fire, (such as rate of spread, involvement of toxic materials, and amount of smoke) at a construction site. Smokers, welding sparks or stray oxyacetylene gas flames, paint stripper blowtorches, and sparks from angle grinders are examples of unusual fire hazards present only during construction. Sprinkler systems and fire fighting water supplies are unlikely to be available for use and ventilation may be poor. The usual safety regulations may not apply to a building under construction.

The New Zealand regulatory/legal situation is as follows: 1. NZ Standard 4512 embodies general requirements for fire alarm systems in buildings.

2. Buildings under construction have no mandatory requirement for evacuation schemes under the Fire Safety and Evacuation of Buildings Regulations 1992, but

3. Employers are required to have emergency procedures in place according to the Health and Safety in Employment Act 1992 (S6(e)). If evacuation of the building by workers is required, it is important that as early and as effective a warning as possible be given. The common device used nowadays to raise warnings is an air horn with a can of propellant gas, held by the building warden. It will take time to get everyone out of a multi-storey building. Some types of work are extremely noisy and even a nearby acoustic alarm may be insufficient. It may be difficult to arrange a good warning system because the building in its present state probably lacks operating mains (utility) wiring and probably lacks any other kind of wired network. Such wiring is liable to be damaged by construction activity, and a warning from an alarm system cannot be compromised by the mains supply being off at the time. The mains supply may have been cut by the event that causes the requirement for evacuation.

In this document the term "siren" also includes any horn, hooter, klaxon, sound of a bell, or other non- spoken, preferably distinctive audible alarm signal.

PRIOR ART

Prior art must include the air raid sirens of World War II in London (circa 1941), for which different codes such as "take shelter" and "all clear" were transmitted by control of siren duration. More recent art includes use of designated radio channels but a selected channel is not accessible to all persons at substantially all times. Akira in JP2004056730 describes a disaster information network broadcasting to everyones' cellular telephones. Ito in JP61150444 describes an alarm system superimposed on a wired private telephone network (PABX). Also within defined premises, Hiroyuki et al JP 10148694 provide a two-way radio communications device for general use by workers in a factory, which can also be used for guiding evacuation. Jakubowski in US 2004203561 describes an evacuation control system that tracks persons in a building and informs a fire department of any discrepancies after evacuation. Hayman et al in GB 2343975 describe a non-wired system of roving devices (based on pagers) for summoning assistance or for raising a general alarm at a school, but do not use radio links for reaching the annunciators which are separate, existing, wired devices. Johnson et al in US 4176346 describe a plurality of smoke alarm stations, connected to a central controller capable of selectively operating the alarm in response to detected smoke. Thompson in US2003137415 describes a controller for a "homeland security emergency notification system" transmitting audible or visual displays to scattered notification devices.

OBJECT

It is an object of this invention to provide a reliable network of evacuation alarms, or at least to provide the public with a useful choice.

STATEMENT OF INVENTION

In a first broad aspect this invention provides an alarm unit, which may be used in conjunction with a plurality of like units, each capable of presenting a combined audible and visual alarm to one or more persons; wherein the alarm unit is capable of being activated by encoded, secure wireless signals from a dedicated alarm activating device; the alarm unit is capable, only when activated, of producing an alarm means including visual alarm means (a flashing light), and audible alarm means produced from at least one directional loudspeaker and, when waiting to be activated, relies on internal storage means for operating power over a long period so that it can be used without connection to any electric utility. In a first related aspect, the audible alarm means includes an electronically generated siren (including a horn, hooter, klaxon, sound of a bell, or other non-spoken audible alarm signal) , and relevant, pre-recorded 105 instructions in at least one spoken language.

Preferably the speech message is fully consistent with the purpose of the alarm unit, which in the first instance is to ensure that the premises or area is promptly evacuated of people; the speech message being repeated in at least one language in use by at least some of the people.

In a second related aspect, each unit contains a secondary cell storage means for holding electric power in 110 reserve for use when the alarm unit is activated.

Preferably each secondary cell storage means is capable of being recharged from locally environmental energy including daylight.

Preferably the number of alarm sounding units to be employed within the audible alarm system is determined by the extent to which effective coverage is required; having due regard to dimensions and 115 separation, ambient noise, noise generated by workers or work processes, duration of an evacuation, and the assessed risk of fire or other condition likely to require evacuation.

In a third related aspect, the dedicated, authorised alarm activating device is capable of transmitting a distinctive signal to a receiver within each alarm unit; the specific nature of the distinctive signal minimising the chance of inadvertent false alarms.

120 Optionally, the communication link includes an intermediate retransmission link.

Optionally, the intermediate retransmission link is also capable of being caused to transmit a distinctive signal by other authorised persons, or in response to a satellite transmission from an international tsunami warning system.

Optionally each alarm unit is also capable of re-transmitting the distinctive signal after becoming activated, 125 thereby increasing the chance that all alarm sounding units will be activated.

Optionally an automatic link to an emergency service such as a fire station is provided.

Optionally the alarm initiation means is a cellular telephone; at least some of the one or more alarm sounding units being equipped with receivers.

Preferably a different distinctive signal is used within the system as a de-activation signal so that the alarm 130 sounding units can be deactivated early such as after a test, a practice evacuation, or an inadvertent activation (false alarm), but alternatively the activation signal can be sent a second time.

In a fourth related aspect, each alarm sounding unit is provided with an internal battery capable of storing sufficient power to operate the audible and/or visual warning devices for the predetermined time. Preferably, a battery condition indicator is provided on each alarm sounding unit so that the battery can be 135 recharged or replaced if the stored power is insufficient.

In a second broad aspect, at least one of the self-powered alarm sounding units is itself provided with local alarm initiation means as well as (re) transmission means as previously described in this section, so that operation of an external alarm initiation means by a distant person is not a pre-requisite for activation.

Preferably the local alarm initiation means provided within the unit is selected from the range of: person- 140 activated controls (break-glass switches, knobs or handles), chemical (e.g. smoke or gas or radiation) detectors, or optical detectors (photocells, passive infra-red detectors, or cameras).

In a third broad aspect, the entire system is provided with (a) means for modulating and demodulating the signals so that further information may be transmitted along with, or in support of the distinctive signal; (b) means for accepting information to be transmitted, and (c) means for applying the demodulated information, 145 including use of unique identifiers or callsigns for each self-powered alarm sounding unit,.

In a related aspect, each alarm sounding unit is capable of responding and reporting its internal status (such as battery condition) when polled from time to time by a controller, without activating the alarm; absence of any response being treated as an abnoπnal status.

150 PREFERRED EMBODIMENT

The description of the invention to be provided herein is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention. Throughout this specification and the claims which follow, unless the text requires otherwise, the word "comprise" and variations such as "comprising" or "comprises" will be understood to imply the inclusion of a stated integer or step or group of 155 integers or steps but not the exclusion of any other integer or step or group of integers or steps.

DRAWINGS

Fig 1 : is a diagram showing a typical alarm unit.

Fig 2: is a schematic diagram showing example internal functional blocks inside a typical alarm unit.

Fig 3: as Figs 3a, 3b and 3c shows a proposed network of alarm units, illustrating three complementary 160 modes of operation.

Fig 4: is a schematic diagram showing a prototype alarm unit. Fig 5: is a diagram showing a further proposed wireless network.

PRINCIPLES. For a group of people to be protected, this invention provides a plurality of strongly packaged, self- 165 powered, wireless-triggered alarm units each of which is placed about an area to be protected, and each of which includes means to raise one more audible and visual alarms when properly triggered by a central transmitter. Especially for governmental use, there is a requirement for well-standardised communications protocols and of course there is a requirement for protection against inadvertent triggering. In its simplest form the invention provides one or more alarm receivers and one or more triggering transmitters with no 170 return signals. More complex networks provide (a) one or more intermediate relay stations between the triggering transmitter and the alarm units, or (b) re-transmission of triggering signals from activated alarm units for a period of time thereby ensuring that a maximum number of alarm units are triggered. Two-way transmission facilities would increase the reliability and versatility of the system as described below.

The inventor is a construction site foreman and first developed this invention for use on construction sites 175 where preferably one would place alarm units all over a construction site, (as determined by sound coverage) so that an evacuation alarm status is adequately advised to all the workers. The Example IA type (see below) may be sold as sets of one unit, four units, ten units, etc with at least one remote controller. Other examples are also described below.

Wireless communications frequencies are chosen according to criteria well known to workers skilled in the 180 relevant arts; criteria including such factors as:

1. range through materials of a construction site (and perhaps throughout an underground mine), given realistic transmitter power levels,

2. range in the open air (perhaps an excessive range might inadvertently trigger distant alarm units),

3. availability of appropriate modules designed for use at specific frequencies,

185 4. subject always to allocation of frequency bands reserved for such purposes by the regulatory authorities, preferably free of interference from powerful signals such as harmonics of radio or television transmissions.

Factor 3 in particular has led to use during development at least of the citizen's band at about 27 MHz (including appropriate security) although factor 1 might dictate a very much lower frequency such as 27 190 kHz and factor 2 leads towards line-of-sight frequencies (VHF, UHF or microwave).

EXAMPLE 1

This prototype (see Figs 1 and 2, box 100) is a self-contained box holding at least one sounder unit including a loudspeaker, horn(s), or other audible alarm (101, 101') , an actuator (207, 204) to drive the warning alarm, and including adequate battery storage (209). The box is placed on a wall or the like near the 195 field of operations, near the working personnel. The actuator is set off by an external wireless signal transmitted to a receiver (202) within the unit, that enables (207) operation of the driver (204). Each sounder unit may also re-transmit (from transmitter block 201) the "raise alarm" signal to all other units so that even if a distant unit, or one in an area of poor reception did not pick up the original signal, it is likely to be triggered by intermediate units.

200 The "raise alarm" wireless signal is generated by a remote transmitter normally in the hands of the site foreman (or designated building warden, whoever is in charge) on realising that a situation involving risk is in place. A preferred range in the construction type application is typically 300 m line-of-sight and 50-200 m through a mass of buildings - walls and floors, obtained using 308 MHz RF modules. Activation of the audible alarm by a received plain continuous-wave (CW) signal or preferably a coded, site-specific signal

205 means compulsory immediate evacuation of the site by all personnel. The workers would gather and be counted at an assembly point until the site foreman or building warden has decided that the emergency is over, and transmits the "cease alarm" code signal. Practice evacuations are recommended.

Details of component parts selected...

1. Container 100: Each unit is built in a strong weatherproof and waterproof box (to ensure reliability and 210 durability) that may be placed in or on any convenient site, usually upon a wall, and, being wire-free, may be moved around such as when the wall is to be worked on. There is no need to have a qualified electrician available for installation and moving the box. After the site is finished, the network can be taken down and carted to another construction site. A typical box would be an about 250 x 200 x 100 mm cube. Metal boxes are generally preferred, except for low-frequency signals, though the aerial 215 should be external. The box may have eyes, attachment points, or other means (e.g. hanger lugs 104) for being tied on to a wall or hung on to a nail or nails in a prominent place. The lead-acid battery inside should be kept level.

2. Input / output parts : a) Horn 101 (and 101') for sound output. The standard device is a weatherproof device capable of 220 sounds of 110 dB at 1 meter distance. Because speakers configured as horns are directional, more than one horn may optionally be used, as in Fig 1. b) Breakglass type activator switch (103) labelled accordingly, for local triggering of the evacuation system by a person. (Glass is no longer used, a frangible plastics material is preferred). c) Smoke and other types of fire detector (105, for instance an ionisation detector and a photosensitive 225 resistor or passive-infra-red detector) may be included; useful for fires that occur out of working hours. Other detectors such as movement sensors (passive-infra-red detectors or microwave field detectors) may aid site security. d) Aerial (102). This may protrude or may be on or within the box surface, depending on the technology available within the electronics arts for the frequency of choice, whether directional

230 reception with aerial gain or whether transmission is required, the box material, and in relation to the desired range. The aerial may be tuned or untuned; a simple wire or a directional device such as a Yagi antenna. e) Function indicators.

• One version (109) is a low-power lamp device such as a winking green light to indicate normal 235 function - all systems enabled and ready to emit an alarm. This "normal function" could include making a repeated test for sufficient radio field strength.

• Another type is a light-emitting diode (LED) indicator (110) to separately indicate battery status - such as slow charging (green), fast charging (red), or faulty (red). If battery swapping is practised the yellow light could indicate dropping voltage and the red light could indicate a need

240 for an immediate change of battery. It will be appreciated by a person skilled in the art that a variety of coded indications can be used. If bidirectional communications exist, the system in the box may transmit its status to a central site. Alternatively the central site may repeatedly poll each box separately using a unique box code, in order to check its status, and warn personnel of any box that cannot be interrogated.

245 f) Optional visual alarm devices; a flashing xenon lamp or rotating beacon light warning (not drawn) for noisy sites, to support the audible alarm. A flashing strobe may be emulated by a bright flashing LED array. g) Lockable door access (108) to the interior for battery servicing, and an optional connector for fast charging of the internal battery.

250 h) An optional key-operated on-off power switch (not shown) that would be used for example if the box goes into storage. i) Optional window (106) on the box surface admitting light for the optional solar panel (107) trickle charger for the battery. j) Handles, eyes, hooks and related supporting hardware 104.

255 3. Battery (209) - principally to avoid having each unit wired to and dependent on a reliable power line (which may be standard AC mains or a low-voltage line). a) Each 12-volt unit should always includes adequate battery power for sounding for at least 20 minutes. A gel-type lead-acid battery may be preferred because it can be tipped over without electrolyte loss. The auto-discharge rate should be low.

260 b) Battery Servicing

• One option is for a maintenance person to patrol the site with a set of fully charged batteries from time to time (expecting a normal life of 3 months or so between swaps), and after each actual alarm, and replace all those for which the battery (voltage) status light (110) as described in 2(e) above is yellow or red. The depleted batteries are taken back to a base for recharging. A similar

265 approach could replace non-rechargeable batteries (primary cells) with new batteries if economics merit that approach.

Another option is to trickle charge each battery within its alarm unit, using a source such as solar panels (107); preferably concealed under a plastic window (106) against theft or any other appropriate energy source. Again the battery voltage status light is preferably retained as an external 270 check of "fϊt-for-purpose". This has the advantage that there is no reliance on periodic patrols of devices. Battery life would probably be three to five years.

• A further option is to rely on polling through the list of "callsigns" or unique codes by a base station to detect low batteries or lack of response, and to send a person to visit each specific box that gave either an abnormal response or none at all.

275 4. Aerial (102). The preferred system uses radio-frequency waves of some definite frequency as the communications medium.

• The actual aerial type and dimensions depend on the operating frequency. Omnidirectional aerials are preferred for use on building sites. The selected frequency depends on which band is available for this application under the laws and regulations of a particular country. A very low frequency (16 kHz to 530

280 kHz) may be advised for use in ferroconcrete buildings or inside mines. 27 MHz is freely available. A range of frequencies in the high VHF to UHF range (304-430 MHz) is a general-purpose solution although an installer has to beware of localised "dead spots" where reflected incoming signals cancel out the direct incoming signal. Use of signals in a specially allocated low-frequency band under about 300 kHz may assist in the reliable penetration of thick layers of damp concrete and the like. (An aerial for

285 this band may comprise a resonant coil concealed just under the exterior of a non-conductive box)

Signals in the microwave (such as around 2.4 Ghz) or in a selected cellular telephone band are also likely to be used because a cellular telephone interface may be one triggering means. Any aerial is preferably compact and of low profile in order that it does not receive inadvertent damage either when on the site or during re-placement at a new location.

290 5. Any form of carrier modulation (as is known in the art) may be used to send messages to and from a particular unit, such as frequency, tone, or phase modulation. a) The simplest control system as shown in Fig 3a would be "transmit a plain carrier at frequency A for time T (where A and T are distinctive) to all receivers (202) in order to set off all the alarms in range, each of which has a built-in timer (203) to switch off at 20 minutes". In this drawing the dedicated

295 remote control 300 is shown transmitting a unidirectional signal (302) to all the alarm units, 304a,

305a, 307a but in the event cannot reach 306a. Fortunately 305a (as do 304a and 307a) re-transmits the alarm and so reaches 306a to trigger it as well. The numeric keypad on the remote control is for entering a PIN or other code so that inadvertent or malicious triggering of module 300 is rendered difficult. If as in Fig 3b, the breakglass switch (as 103 in Figs 1 and 2) on any one unit (305b,

300 shown here as a black circle (meaning activated) is to be capable of setting off the rest of the system, then each unit is provided with a transmitter (201) also able to transmit that carrier at frequency A for time T. 305b originates a signal that triggers 304b, 306b, and 307b. Also, each unit, just after being triggered, may re-transmit the carrier at frequency A for time T in order to set off all possible units as in Fig 3a . Because of the increased number of initiatiors, such a simple system is possibly 305 prone to false alarms, for which a tolerable number over 3 months is zero to at most, one. Each unit would then have a relatively simple yet reliable, selective receiver module 202 capable starting a timer 203 to enable a power switch 207. Hence power is provided to the horn driver for a period of time (such as 20 minutes) when a carrier at frequency A for time T has been received.

The frequency A is preferably unique to any one one network of alarm boxes, so that for example 310 activation at one site does not also trigger alarms at independent construction facilities at other sites. It may be sufficient to have about 20 different channels available for the manufacturer to use and sell to different buyers. 128 high- VHF channels are available under one allocation scheme. b) A first enhancement would be a facility to disable the horn driver as soon as a carrier at frequency B 315 for time T has been received - the "all clear" signal - which over-rides or resets the internal 20- minute timer. This would be useful for tests, exercises, and false alarms. c) In a further enhancement, indicated in Fig 3c, each box includes a unique identification code (UIC or callsign); likely to be held within optional microprocessor module 206. The RF signal can be modulated and demodulated and is bidirectional (303). Each box can read and decode data such as

320 frequency or phase modulation of a signal in digital form at a rate of perhaps 1200 Baud, or faster, or slower for increased reliability. A control box (which may be contained within a hand-held device 300 or resemble a computer 301) is capable of interrogating each device specifically, as described below. Systems including UICs would be more reliable and useful than the simple one described previously, such as ...

325 • by allowing polling of all units by a master unit from time to time in order to check battery status and/or other functions, including absence of an expected response, or

• to identify which particular one of the units had its breakglass sensor set off or had sensed smoke. 6. Electronics card(s) to provide facilities including at least some of: a) Status e.g. battery voltage monitoring and optionally RF signal field strength monitoring (useful at 330 the time of installation), and battery charging such as to manage the solar panel trickle charging.

Block 208 is provided for charger and power control. b) Receiver unit (202) connected to interface items and aerial, c) Optional transmitter unit (201), power probably 1-3 watts, d) Optional digital control section (206) probably implemented within a microprocessor, to provide 335 unique identification codes (see 5c above) especially on transmitted signals, and to interpret incoming commands; also optionally to time and control (as by providing audio-modulated signals when required) to the section driving the horn. Non-legal commands such as from a different site nearby or malicious calls can be detected and rejected. A procedure to check functions and place sections into predetermined modes of operation on first powering up the box would be useful. 340 Digitally driven sounds generation may be included in this or a separate memory block (205). e) Driver/actuator module (204) to drive the high-intensity horn; this may be a simple audio power amplifier with adequate heat sinking, that may also have internal sound and/or speech generator chips that generate an audio signal if there is no microprocessor unit present. There is a first requirement in most versions to generate siren or like noises and a preferred second requirement to

345 emulate human speech, probably in several languages e.g. English, Maori, Samoan, Tongan, and

Cantonese in New Zealand or Spanish, English, Hindu in the USA, depending on the makeup of the population of workers actually likely to be present. Such speech can be contained in a low-cost type of read-only memory chip because the messages such as "Everybody Out" or "Evacuate Now" would be short. A service to load dedicated messages into plug-in non-volatile memory chips may be

350 provided and new messages may be installed easily, particularly if block 205 is physically separate. f) Optionally, the particular voice message to be broadcast could be digitally selected by a transmitted code. It is also possible, but may detract from the special status of an alarm system to emulate a public-address device broadcasting signals made up from time to time at the control centre and sent to a selected one or many units for broadcasting.

355 g) Timing circuit. A simple 20-minute timer may provide power to the audio power amplifier through a relay or the like, so that inactive- state power consumption is as low as possible. Alternatively the system runs until an internal battery has run down. A transmitted signal may turn the device off. This function may also be provided by the microprocessor module. h) Another optional part of the circuit or plug-in module emulates a cellular telephone (duplicate of the

360 transmitter and receiver modules 201, 202), and consider the remote controller 300 to actually be a cellular telephone, so that a person can ring up the unit and either read statuses of parts of the system, or send commands to the units from a cell phone anywhere. "Nokia" (Finland) is one source of compatible devices or cards. If the units are set up to rebroadcast the distinctive triggering signal to each other, then at least one, or only a few would require a cellphone interface. Of course one

365 must be aware that in a national emergency rather than an on-site emergency, the cellular telephone network may be unavailable. i) Some or all of the above circuit modules may be put into effect within an integrated electronics module or integrated circuit (chip) if the economic benefit warrants it. 7. There is a remote control transmitter (in the simplest version) for setting off the alarm from outside the

370 building. This may include a keypad for an authorised person to enter a code to enable the machine, and a transmitter to transmit a carrier at frequency A for time T to set off the alarms. Given that the person in charge of the transmitter may be out of the actual site and in a supervisor's building this transmitter should have extra power capability to reach the units. A more complex version may be set off by a cellular telephone link, probably involving text messaging to transmit a password and instruction

375 (assuming that text messaging is passed on immediately by the network provider). Otherwise, because lives are at stake, ringing a separate identified number for each function would be a more reliable option with immediate confirmation to the responsible person.

A basic electronic device as described above may be configured into an advanced device having one or more of a host of relatively more sophisticated functions such as using an incorporated microprocessor 380 board, permitting larger amounts of transmitted or received information, more alarm patterns, and in conjunction with more complex input and output devices.

1. While turned on, maintain functional condition by...

(a) maintaining battery power reserves using trickle charge if available, such as from a solar cell mounted in the external skin.

385 (b) Provide local indication, such as by coloured or flashing lights, of internal status

(c) Report by RF transmission to a base station the call-sign of the box and the state of the battery either from time to time or when the base station requests a report that is received by that specific box. A polling process would confirm the status of each box in turn.

(d) Report to a base station the received signal strength of the base station at the callsign-identified box 390 when the base station requests a report from that specific box, thereby ensuring adequacy of signal strength even though installations may have modified the RF environment since placement .

(e) Log, in internal non-deletable memory, any interference with the box such as its opening or unsealing by personnel for any purpose.

2. Receive a general, system-wide or a box-specific "raise-alarm signal, then over an extended period... 395 (a) Emit loud sounds that are a pre-arranged signal that evacuation shall be carried out.

(b) Emit loud speech (in one or a series of appropriate languages likely to be held as sound files in internal memory or as and when received from the base station) instructing those in earshot to carry out certain actions, such as that evacuation shall be carried out.

(c) Make visual signals (such as strobe lights or flashing lights) - another prearranged signal that 400 evacuation shall be carried out.

(d) Return an acknowledgement that the box has reacted to the alarm.

(e) In an option, the base station or any one or more boxes may be provided with means to receive cellular telephone calls and act on an embedded code within, to allow alarm triggering of a special type.

405 (f) Boxes should also be able to recognise a "de-activation signal" in the event of a false alarm or a test so that the noise does not continue,

3. Be capable of transmitting to the base station any local events of predetermined significance including:

(a) A person closing a clearly obvious alarm switch which is mounted on and forms part of the box. This alarm is assumed to be that which sets off the full evacuation either without question or via an

410 evaluation step - whether by a site foreman or otherwise.

(b) A person closing an optional alert switch which also forms part of the box, having the effect of informing the base that action should be taken in relation to the call sign-identified box. Specific actions would depend on the site but this may serve as a type of intercom function, or be used to signify that an accident has occurred near the box yet wholesale evacuation is not appropriate.

415 (c) Fire or smoke detector activation (which may be directly converted into a general evacuation alarm).

(d) Gas sensor activation. (For toxic or lethal gases: may be particularly relevant in subterranean sites).

(e) Optical (light as from flames) or passive infra-red sensor inputs if activated.

(f) Camera images, as a continuous or interrupted stream, or on demand.

(g) Failure of a nearby worker to periodically confirm being in "good health" by pressing the alert 420 switch - a "dead-man's handle" function such as for use in subterranean sites where the worker may be overcome by gas, or in any sites when the worker is working alone in a risky environment, (h) Nearby worker identity information - using the machine in conjunction with RFID badges carried by the workers to maintain a list of workers so that on evacuation a list of persons not present at the assembly point (whose RFID badges have also been scanned on arrival) can be prepared automati- 425 cally. For this, each box might be close to a entry point for the work area or more preferably would function within the work area.

4. Base-station responses to local events of predetermined significance may be modified by an attendant supervising person, or may be automatically converted into appropriate action. The base station may have a capability to automatically dial a fire brigade service and report the address of the site as part of

430 the evacuation alarm procedure. This may save valuable time. The base station may be used as an intercom device, working with an identified alarm box that had been triggered.

5. For a given set of base station and alarm-raising boxes as described above, a single channel at a common radio frequency may be sufficient for both directions of transmission, where each box has a unique call sign and is normally

435 (a) polled in turn for non-emergency status enquiries and the like, or

(b) called as one of a group when an emergency warning is to be emitted,

(c) Box-to-box co-operation to ensure that an emergency warning is acted on may be at a separate frequency or may be done by re-transmission on the same frequency, regardless of possible collisions. Given that a total warning period of for example 20 minutes is required, it may be sufficient

440 for activated boxes to re-transmit for the first minute of activation only so that the alarm eventually stops. EXAMPLE 2

Another alarm unit 400 is shown in Fig 4. Attributes of this unit include:-

445 1. Commercial modules are bought in and connected together. Some are intended for secure activation of functions at a distance. Those use a 27 MHz working frequency and have means for selecting one of 4095 possible activation codes. That should provide adequate proof against being inadvertently triggered, but the same units are also sold as garage door openers and it may be preferable to use a reserved transmission frequency.

450 2. Use of relay switching with no relays activated when "listening" so, when in the "listening" but inactivated mode the current demand is about 15 mA.

3 No battery replenishment circuitry is included in this prototype. The life of the specified battery exceeds 2.5 months. (At this time, regular replacement with a recharged battery is assumed, although addition of solar powered charging is not difficult).

455 4. In the form described, the alarm unit, when in an activated state, repeatedly reproduces one recorded speech message of up to 20 seconds duration, alternated with a siren noise, meanwhile flashing an xenon lamp as a visual correlate of the alarm.

Referring to Fig 4, the electronic components used in Example 2 are:

460 401 is a type LA 5265 voice-coil speaker unit, 20 watt rating; capable of 110 dBA (siren) and 80 dBA voice) at 1 metre. (Jaycar Electronics Ltd, PO Box 9667 Newmarket Auckland).

402 is a type 126 xenon flasher device, which flashes repeatedly when supplied with 12 V DC. It can be seen for 0.4 km. (Seco-Larm USA Inc, Irvine California).

403 is a 12 volt lead-acid storage battery with about a 7 ampere hour rating.

465 404 is a power switch that places the unit in the "listening" but inactivated mode when on. (A demonstration unit may have various disabling switches to interrupt power to the speaker and the xenon flasher).

405 is an adapted type XC0276 digital voice recorder (including a non-volatile memory) which is capable of holding 20 seconds of sound. (Jaycar).

406 is an electronic siren kit such as Jaycar KA-1813 or equivalent or modification, so long as it is capable 470 of driving the speaker at full power when connected by the relay of 407.

407 is a type KA1732 "Flexi Timer" kit from Jaycar which when activated causes its relay contacts to alternate between ON and OFF states at a pre-set period to cause either siren or voice sounds to be broadcast by the speaker 401.

408 is an ELSEMA Pty Ltd (Smithfield, Australia) type FMR-212 receiver capable of responding to an 475 appropriately coded message received at 27.145 MHz by causing its 5 ampere rated relay contacts to connect C (common) to NO (normally open) and thereby energise other blocks, thereby making the alarm unit enter the "activated" mode. Further details are given at the manufacturer's web site http://www.elsema.com/fmr-212.htm (available on 12 February 2005). The flip-flop setting ensures that the alarm unit stays in the "activated" mode until the same code signal is received again. (The other optional 480 setting requires that the energising signal be constantly broadcast. A latching-ON mode is also available in which case resetting by battery exhaustion or personal intervention is required). Antenna requirements are not critical for short range applications and a wire placed in conjunction with the metal sheet, inside the non-conducting box may be sufficient.

409 is a 12 volt SPDT (single pole double throw) relay used to put the voice recorder into replay mode, so 485 that the voice recorder is reset to the beginning of the message during each siren mode. (In this circuit, recording must be carried out for each alarm unit 400).

410 is a 12 volt 4 pole double throw relay used to switch either the amplifier 412 output or the siren 406 output to the speaker 401.

411 is a conventional three-terminal voltage regulator (such as type 78L06) to supply a 6 volts output to the 490 adapted voice recorder 405. (Bypass capacitors are not shown)

412 is a 12 watt audio amplifier type KEMO M32, (Kemo, Germany) . The single speaker output is returned through the 12 volt line hence two poles of the relay 410 are required to switch this output into the speaker 401. (Jaycar).

All wiring is shown in Fig 4, with positive supply lines, whether switched or not, marked by a (+) sign. C

495 (common) NC (normally closed and NO (normally open) refer to relay contacts. Signal lines are shown with short dashes and control lines are shown as long dashes.

The components except the battery are preferably assembled upon a sheet of aluminium which serves as a heat sink and as a ground plane for a short wire antenna, and mounted inside a robust, weathertight sealed box made of polycarbonate, ABS, (acetyl butyl styrene) or other plastics material. The flasher and speaker

500 (401 and 402) are of course external. Diodes adjacent to relays 409 and 410 are for example type 1N4001, used to minimise inductive switching transients.

An example corresponding hand-held transmitter for activating this receiver is Elsema hand-held transmitter GLT 2700 or similar, designed primarily for carriage about the person but having a range of only about 150 metres. This device on its own may suffice for activating alarm units about a construction or demolition site,

505 although it would be preferable to boost the transmission with a more powerful device such as the Elsema FMT-401 hand-held device, or to use a device such as the compatible Elsema 1 watt hand-held transmitter FMT-312 E which, with an efficient aerial, provides a range of several kilometres and also transmits an encoded signal compatible with the receiver 408. A network including a relay transmitter can be constructed, as in Fig 5. In one mode, an alarm is instigated

510 at 501 by a hand-held, battery-powered transmitter as above, the signal from which is encoded in a first code capable of causing receiver 502 (for example Elsema model FMR 212 ) to become activated. This is wired to an adjacent also battery-powered Elsema 1 watt transmitter FMT-312 E (503), the signal from which is encoded in a second code capable of causing all the array of alarm units 504 (five units are shown here) each according to Fig 4 in which the corresponding receiver 408 is set up to respond to the code

515 transmitted by transmitter 503. Preferably transmitter 503 which is preferably at a fixed location, is connected to an efficient aerial at the frequency in use, in order to increase the reliability of the signal path between 503 and any one of the array 504. The wiring between modules 502 and 503 which may comprise a 12 volt supply 505 (such as from a battery with good shelf life and at least a 1 ampere output) to transmitter 503 as turned on by the relay within the receiver 502, could be extended to a number of kilometres of cable if appropriate, and, also if appropriate, the wiring could pass a number of actuator stations so that authorised persons could set off the array of alarm units by applying an activating voltage from supply 505A to the wiring by pressing the suitably protected switch 506.

VARIATIONS Receiver 502 may include satellite signal receiving equipment for use with global tsunami (or earthquake) warning satellite 507. Satellite signals would be most appropriate for a global tsunami detection and warning system as currently proposed for the Indian Ocean, or as in use in the Pacific Ocean. They would be independent of local cellular telephone services. Satellite signals might first be received by module 502 (fig 5) which allows some monitoring of the local appropriateness of a warning by a local person, or might be received by each individual alarm unit - which solves problems of local network range.

For outdoors use such as at a beach for rip current, shark or tsunami evacuation warnings, directional aerials may be used so that a row of alarm units can cover an entire beach, mounted on poles or trees with their speakers directed generally at the beach area where people gather. Because tsunami responses involve running to far above the water level, whereas shark sightings mean just getting out of the water, a facility to vary the messages according to type of danger is useful. Example 2 which is a "proof of concept" device should be able to broadcast several different messages. The description of Example 3 provided for only one message such as "Everybody out of the water". The manufacturer Elsema produces a two-channel receiver which can be used in conjunction with their two-channel transmitter type FMT31202E. It would be trivial to adapt Example 3 to select one or another voice recorder according to the selected channel, or to have Elsema develop a four (or more) channel receiver. Clearly, the invention is amenable to further development yet still retaining its novel attributes.

Alternative sources of triggering signals to set off the alarm units include: cellular telephones (using a specific code), wireless signals from a previously accredited source such as the police, surf lifesaving club, Civil Defence organisation, or AREC. Example 2 is a simple, one-direction communications network. It is desirable to be able to

(a) identify each alarm unit electronically, and

(b) include a transmitter function in each alarm unit and so have a bidirectional communications network,

(c) automatically poll all known units from time to time in order to determine which ones are not capable of action and identify those in need of repair.. (d) The alarm unit could be mounted on wheels if a group of workers moves about a lot. A backpack version can be used.

(e) For alarm units that are frequently shifted around a construction site, it would be useful to include a signal strength meter function in each unit so that it is not set up in a "dead" site or one affected by multiple paths.

555 Further improvements may be based on a design based for example on one or more of the "Zigbee" standard chipsets developed for wireless control. There is an open global standard communications protocol (www.zigbee.org) (available on 12 February 2005). This version would use a purpose-designed and programmed microprocessor board which employs a standard set of chips already developed for wireless remote control purposes, with range enhancement as required for specific applications. Advanced power

560 management is one aspect of this chip set. This design would not be limited to the frequency used by the bought-in radio module of Example 2.

A mains-powered variation is a possibility especially where emergency backup generators are provided.

A scaled-up unit would be suitable in an outdoors environment such as a quarry or open-cast mine, to cover a much larger volume with effective sound. This could also be used to warn of planned explosions as well 565 as of other hazards, instead of or as well as the existing sirens.

INDUSTRIAL APPLICABILITY and ADVANTAGES

The alarm system is simple, has low maintenance and low cost, and is independent of local utilities and services for example not needing an external mains supply at each alarm unit. An alarm unit can be set 570 down wherever workers are currently engaged. The units are reliable, by always raising an alarm when properly triggered and never if not properly triggered, so that it can be used in areas where technical expertise is lacking. Battery replacement (in the absence of solar-based recharging) is the main attention required.

The particular risks relating to a construction (or demolition) site have been mentioned; the invention takes 575 care of some of the risks experienced by workers. An installed system can be dismantled in order to follow a contractor from site to site. There is no cost of wiring, nor a need for particular personnel (such as electricians) at installation time which comprises simply placing the units about a site.

Finally, it will be understood that the scope of this invention as described and/or illustrated herein is not limited to the specified embodiments described. Those of skill will appreciate that various modifications, 580 additions, known equivalents, and substitutions are possible without departing from the scope and spirit of the invention as set forth in the following claims.

Claims

We Claim:

1. A wireless-driven alarm unit which may be used alone or in conjunction with a network of like units, 585 each capable of presenting a combined audible and visual alarm to one or more persons; characterised in that the alarm unit is capable of being activated by secure wireless signals from a dedicated alarm activating device; the alarm unit is capable, only when activated, of producing an alarm means including visual alarm means (a flashing light), and audible alarm means produced from at least one directional loudspeaker and, when waiting to be activated, the alarm unit relies on internal storage means for 590 operating power over a long period so that the alarm unit can be used without connection to any electric utility.

2. An alarm unit as claimed in claim 1, characterised in that the audible alarm means includes an electronically generated siren signal (including a horn, hooter, klaxon, sound of a bell, or other non- spoken audible alarm signal) , and pre-recorded evacuation instructions spoken in at least one language.

595 3. An alarm unit as claimed in claim 2, characterised in that each unit contains a secondary cell storage means for holding electric power in reserve for use before and during activation of the alarm unit .

4. An alarm unit as claimed in claim 3, characterised in that each secondary cell storage means is capable of being recharged from local environmental energy including daylight.

5. An alarm unit as claimed in claim 3, characterised in that the alarm unit or units are capable of being 600 activated by a wireless communication including unique coded data from an authorised transmitter held in the possession of an authorised person.

6. An alarm system including at least one alarm unit as claimed in claim 5, characterised in that the communication by wireless to the or each alarm unit includes an intermediate relay or retransmission link.

605 7. An alarm system including at least one alarm unit as claimed in claim 6, characterised in that the intermediate relay or retransmission link is also capable of being triggered by other authorised persons.

8. An alarm system including at least one alarm unit as claimed in claim 6, characterised in that the intermediate relay or retransmission link is also capable of being triggered from a received external transmission, including a satellite transmission.

610 9. An alarm system including at least one alarm unit as claimed in claim 5 or in claim 6 or in claim 7 or in claim 8, characterised in that the communication by wireless may be initiated between alarm units by a person actuating any one alarm unit; the alarm unit including actuation means and transmission means capable of activating other alarm units within the group.