WO2002077943A1

WO2002077943A1 - A closed user group alarm management system with a global distress search and rescue fallback facility

Info

Publication number: WO2002077943A1
Application number: PCT/SE2002/000514
Authority: WO
Inventors: Peter Gordon; Mark Button
Original assignee: Cm Hammar Utveckling Ab
Priority date: 2001-03-26
Filing date: 2002-03-19
Publication date: 2002-10-03
Also published as: GB0107522D0

Abstract

The invention refers to device and method for a rescue transceiver device, user unit (1), transmitting a digital, coded alarm and information signal, distress signal (4a). The invention is characterised in that the user unit (1) transmits the distress signal (4a) on a frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue Systems. The digital distress signal is based on an identify code unique for the user unit (1) and a continuously updated position. The user unit also receives a digital signal, rescue signal (6), from at least one master control unit, MCU (2), which rescue signal (6) comprises information. The user unit communicates the information in the rescue signal (6) to a user of the user unit (1). The transmitting means (3) also transmits an International distress signal (4b) on one or several predetermined frequencies for the International Distress and Search and Rescue systems when at least one predetermined condition is fulfilled. The invention also refers to a rescue transceiver device for alarm, search and rescue units, being master control unit, MCU (2), comprising means (13) for receiving ditigal distress signals (4a), preferably transmitted from one or more user units (1).

Description

TITLE

A Closed User Group Alarm Management System with a Global Distress

Search and Rescue Fallback Facility.

TECHNICAL FIELD

The present invention refers to a rescue transceiver device for a person or an object, user unit, in distress or hazardous situation or potentially causing a danger or hazard. The user unit further comprises means for transmitting a digital, coded alarm and information signal, distress signal. The invention also refers to a rescue transceiver device for alarm, search and rescue units, being a master control unit, MCU. The MCU further comprises means for receiving digital distress signals, preferably transmitted from one or more user units. The invention also refers to an inflatable bag/mast that may be illuminated, comprising the user unit and an aerial. The invention also refers to a method for using said devices.

BACKGROUND ART

In the field of search and rescue equipment for a distress situation at sea or on land, systems are known where a person or an object is equipped with a rescue device, user unit, that transmits a distress signal to a receiver in order to start a rescue operation. In most cases when a distress call is sent out, a person has fallen over board from a vessel, an oil rig or the like during severe conditions, for instance strong wind, large waves or cold water, where there is a need for a quick response. The rescue devices known are constructed in various ways for different purposes, but common for all is the need for a quick response to the distress signal.

One common way to achieve a quick response is to alert all receivers accessible in a certain region, which may be done by transmitting the distress signal on one of the International Distress and Search And Rescue, SAR, frequencies, 121.5/243/406 MHz. One advantage with transmitting the distress signal on one of the International Distress frequencies, is that the signal may be picked up by a number of receivers onboard boats, aircraft and rescue stations and/or one or more satellites that transmits the signal back over a large area on earth to co-ordination and control centres, enabling a large number of receivers to pick up the signal. A major disadvantage with this kind of system is that a full scale SAR operation is always initiated, regardless of the nature and/or the magnitude of the distress situation. For example, a person on a boat is equipped with a user unit that automatically transmits on at least one of the International Distress frequencies when the user unit hits the water or otherwise activated. If the person falls overboard, the user unit is activated and transmits a distress signal on at least one of the International Distress frequencies initiating a full-scale rescue operation resulting in redirection of ships and the launching of rescue helicopters etc. However, If the boat from which the person has fallen overboard then quickly rescues the person back onto the boat, the full-scale rescue operation may already be in progress. The rescue operation is then sufficiently advanced, that it is very hard to quickly abort the whole operation. Ships may have already deviated from their original course and have to be redirected and aircraft already in the air have to be aborted. This is an unnecessary and wasteful operation for such a localised distress situation.

A problem frequently occurring with systems that use the International Distress and Search And Rescue frequencies, 121.5/243/406 MHz, is the problem with false alarms. In some cases, a full scale SAR operation is initiated, which in view of the above mentioned example is very time consuming and wasteful. The dilemma is that to wait for further verification that this is not a false alarm may mean that rescue is then too late.

There have been several attempts to overcome the above mentioned problems by using a system for short ranges and thus a more local SAR area. WO 90/08060 discloses a system for locating a person utilising a personal transmitter attached to the person. When activated, manually or e.g. by contact with water, the transmitter is activated to emit an RF signal in the VHF range 800-1000 MHz, with a power of 50-400 mw. The system can comprise an omni-directional antenna to pick up a signal from the personal transmitter and raise an alarm, plus a directional portable antenna to be used in establishing the direction to the personal transmitter by variations of intensity of signal strength derived from a detector circuit of a receiver. In another embodiment of the system there may be at least two antennas connected to the base station, which antennas are fixed spaced apart in order to each receive the signal and with the aid of measuring and calculating means, calculate the difference in signal strength in order to establish the direction to the distressed. It is also suggested that an indication of the distance to the personal transmitter to be provided, by means of calculating the average signal as being a function of the distance to the man over-board. A major disadvantage with the system mentioned is obvious in the case of several people in distress, for instance from a sinking ship, since using radio direction finding for individually locating several people at the same time is unsatisfactory as the radio direction finding equipment cannot differentiate between them, when there is more than one transmission making place. The two antennas together with the measurement of the strength of the signal give only a crude estimation of the position of the distressed. One additional problem associated with the type of system mentioned is the need for a lot of devices, e.g. two antennas connected to the base station, a main unit connected to the antennas and a user unit. Yet another problem is that the system allows only one way communication, thus the distressed does not know if somebody has received the distress signal. A further disadvantage with the system is that there is no fallback possibility to transmit a distress signal on the International Distress and Search And Rescue, SAR, frequencies, 121.5/243/406 MHz in case of a need for a larger rescue operation. In order to launch such an operation a system that includes such an alert possibility has to be used as a complement. US 5461365 discloses a system for personal alarms utilising a personal remote unit and a base station. The system may be automatically activated via hazard sensors. The system uses a two-way communication to demonstrate that the system continues to be operational and is considered to be particularly applicable to monitoring of children, but may be used for other purposes. The system uses electronic hand shaking between the base station and one or more remote units and the remote unit may use a GPS receiver so that the base station can receive an indication of the transmitter's location. The system uses a numerous of additional options for initiating a distress signal for instance, either the remote unit or the base station measures the field strength of the received signal and initiates a distress signal if the measured field strength falls below a limit corresponding to a maximum distance. The distress signal from the remote unit may include both audible and visual beacons. The distress signal, sent by the remote unit, may also comprise a unit identification number in order to make it possible for the base station to separate different individuals from each other. One disadvantage with the system is that there is no fallback possibility to transmit a distress signal on the International Distress and Search and Rescue, SAR, frequencies, 121.5/243/406 MHz in case of a need for a larger rescue operation. In order to launch such an operation, a system that includes such an alert possibility has to be used as a complement. Another disadvantage with the system is the lack of information receiving capability for the user of the remote user unit, i.e. the user receiving information from the base station via the remote, for instance information that help is on its way. The information that help is on its way has a powerful effect on a person in distress. Yet another disadvantage is that the base station lacks a GPS module embodied in the base station in order to derive regularly updated range and bearing information to the distressed when the base station is moving. Nor does the system teach the management of user units' transmissions in order to prevent confusion when direction finding, nor does it teach the management of high populations by selective temporary vetoing of remote units' transmission capability.

There is also previously known systems for other close range Search and Rescue operations, for instance GB 21220048 which discloses a system comprising at least one radar that receives the distress signal in order to establish the position of the person in distress. Such a system requires a radar which is an expensive device requiring expert knowledge to handle. It would of course be an improvement to use a system that is cheaper and more easy to handle.

Thus, there are some problems with previously known techniques in that the systems that transmit distress signals directly on International Distress and SAR frequencies only are time consuming and wasteful in cases of false alarms or minor distress events that are locally resolved. Additionally any close range systems lack the possibility to automatically expand the SAR area from being local to being a full-scale operation via the International Distress and SAR frequencies. Also, there is a need for an improved rescue system that reduces the costs caused by false alarms or unnecessary alerts during a small local rescue operation, by not initially alerting on the International Distress and Search And Rescue frequencies, and that is small, safe, cheap and easy to handle. Preferably, the system should be able to handle a distress situation first locally with the possibility to automatically expand to a full-scale operation, and easily manage a distress situation with several distressed, with the possibility to assist the distressed in a suitable priority order as well as giving the distressed information during the rescue operation.

Another problem with radio transmitting devices, such as described in the foregoing examples and art, is that to achieve a strong and reliable transmission. An aerial of sufficient height is then needed to be fitted to the transmitter. However, the nature of such transmitters is that they need to be small and compact so that they easily can be worn or carried by a person. Known art in this field shows aerials that can be extended once the transmitter is switched on, or in one case a flexible wire aerial can be used as a "necklace" to suspend the transmitter around the neck. Aerial height on transmitters operating close to the water surface is extremely critical. If an aerial is not high enough above the water surface, it can be obscured by waves in "line of sight" and can suffer from loss of signal strength because of "multi-path", a phenomenon caused by transmissions at a glancing angle to the water surface. A problem exists therefore to achieve an aerial that can extend from a small compact form to an appreciable height above the transmitting device. Another problem that exists, particularly with locating transmitters at sea, is that it is important that the aerial is not only as elevated above the water surface as is possible, but that it is maintained in a vertical orientation. If the person is unconscious then this may not be achieved with known devices, and the aerial may be oriented flat or nearly flat on the water surface, where it is of little use. The problem is this, that an aerial must therefore always be vertically elevated for best signal propagation.

Another problem that exists with Search and Rescue systems, is that the survivor may be unconscious or severely incapacitated. They may not be able to signal or make themselves known to the their rescuers. In the field of

Search and Rescue systems, devices are known which transmit radio distress signals to bring rescuers to an area of search and we have described these. Some of these described devices are automatically activated e.g. if a person falls into the water unconscious, they will automatically switch on. However this will only bring the rescuers into an area of search and these rescuers must then begin a visual method in order to achieve the final rescue of the person in the water. Known prior art shows a number of methods of improving visual location in water and particularly if it is dark. A problem with such methods is that it is difficult to see an object such as a light if such light is close to the water surface. This is because it is obscured by waves or part of the person, for example the head. A problem with all such known technology is that the visual location device is not elevated sufficiently above the water surface and therefore is difficult to see.

DISCLOSURE OF INVENTION A main object of the present invention is to remedy the above mentioned problems, providing a system that first enables a closed local search area, with a fallback possibility to expand the search area into a full scale International search and rescue operation. The system uses personal transceiver devices, user units, transmitting- and receiving signals to- and from a master control unit, MCU outside predetermined International Search and Rescue frequencies, and which user units transmitting signals on the predetermined International Search and Rescue frequencies after predetermined conditions have been fulfilled. The user unit is preferably fitted inside an inflatable bag that comprises an aerial, connected to the user unit, which aerial extends in a vertical orientation when the bag is inflated. The inflatable bag is advantageously made of a waterproof semi transparent material and equipped with a light inside the bag, which light lights up the bag when inflated, such as the bag sends out a light.

The present invention uses a digital coded signal, which enhances the system performance, as well as remedies the problem with false alarms. Because, a lot of false alarms on the 121.5 MHz are caused by spurious radiation from various sources, but the present invention remedies this because a digital code message cannot be spurious electromagnetic radiation and therefore false alarms are reduced.

The invention refers to a rescue transceiver device for a person or an object, user unit, in distress, or hazardous situation or potentially causing a danger or hazard. The user unit comprises transmitting means for transmitting a digital, coded alarm and information signal, distress signal. The invention is characterised in that the transmitting means of the user unit comprises means for transmitting the distress signal on a frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue systems. The user unit then comprises means for transmitting in a local search area, thereby allowing a closed local rescue operation to take place. The digital distress signal is based on an identity code unique for the user unit and a continuously updated position. The user unit also comprises receiving means for receiving a digital signal, rescue signal, from at least one master control unit, MCU, which rescue signal comprises information, for example command, progress, warning, alerting and advisory information. The user unit also comprises means for communicating the information in the rescue signal to a user of the user unit, and the means for communicating the rescue information in the rescue signal to the user may comprise audible means and/or a light emitting object. For a person in distress it is very encouraging to receive information from a rescuer.

The transmitting means also comprises means for transmitting an International distress signal on one or several predetermined frequencies for the International Distress and Search and Rescue systems, when at least one predetermined condition is fulfilled, which predetermined conditions may be; after a predetermined time limit, if the user unit is out of range from the MCU, or if the user unit is initiated by the MCU. The transmitting means may also comprise means for commanding a separate transmitter to transmit on such frequencies, when at least one predetermined condition is fulfilled. The means for transmitting an International distress signal on one or several predetermined frequencies for the International Distress and search and rescue systems, transmits on any or all of the predetermined frequencies for the International Distress and Search and Rescue systems currently being 121.5/243/406 MHz.

In order to establish position for the user unit, the user unit comprises means for receiving GPS signals. The GPS signals are signals for global positioning preferably sent out by one or more satellites. The user unit may comprise a high-energy light emitting object for close range detection.

The user unit may also comprise means for communicating with a second user unit.

The system according to the invention advantageously uses an aerial device for use with a rescue transceiver device and that an aerial, connected to the rescue transceiver device, is fitted into an inflatable bag, which aerial being raised in a vertical orientation when the inflatable bag is inflated. The aerial is advantageously made of a flexible material, or has a construction that admits being folded together. The rescue transceiver device fitted inside the inflatable bag is a user unit according to the invention. The bag is filled with a gas from an inflating means, for example a gas container, and the discharge of gas, filling the bag, vertically extends a hollow tubular structure, in which structure the aerial is fitted, thereby extending the flexible aerial to its maximum length in a vertical orientation. The extended aerial ensures the maximum transmission strength for the distress signals from the user unit.

The inflatable bag may be in the form of a lifejacket, so that when the bag is inflated, it can be used as a lifejacket. The lifejacket is then shaped in such way that a part of the life jacket constitute a mast when inflated, in which mast the aerial is fitted and extended in a vertical orientation.

The inflatable bag may also be mounted on a lifejacket, with the same purpose as the previously described embodiments of the bag.

The invention also refers to a rescue transceiver device for alarm, search and rescue units, being master control unit, MCU. The MCU comprises means for receiving digital distress signals, preferably transmitted from one or more user units. The MCU is characterised in that the MCU further comprises means for identifying unique identity codes and means for identifying a regularly updated position. The regularly updated position, is in the form of global coordinates, e.g. GPS coordinates.

The MCU also comprises means for transmitting a digital rescue signal comprising rescue information, which may be in the form of command, progress, warning, alerting and advisory information, to the user unit. The MCU also comprises means for continuously calculating range, bearing and direction to the user unit. The MCU further comprises means to temporarily cause a temporary halt to or lengthen the period between transmissions from selected user units thereby managing the user units transmissions preventing radio channel congestion.

The MCU comprises means to command at least one user unit to transmit signals for direction finding purposes, via transmitting means, on a suitable frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue systems.

The MCU comprises means to command at least one user unit to transmit an International distress signal via means for transmitting on the International Distress and SAR systems of 121.5/243/406 MHz. The MCU also comprises means to command at least one user unit to transmit signals for direction finding purposes, via transmitting means, on a one or several predetermined frequencies for the International Distress and Search and Rescue systems.

The MCU may also comprise means to command a separate dedicated transmitter to transmit an International distress signal on the International Distress and SAR systems of 121.5/243/406 MHz.

The MCU comprises means to indicate course for SAR personnel in order to direct themselves to a certain point. The MCU comprises control relay means enabling external actions, such as indicating visually and audibly alarm, control an engine or helm steer.

The MCU comprises means to command a high-energy light emitting object on the user unit to be activated for close range detection.

The MCU comprises means for receiving GPS signals.

The MCU may comprise a MCU display for displaying the information in and derived from the distress signal from each user unit.

The rescue information in the rescue signal comprises information about distance and bearing, but may of course comprise other suitable information.

The MCU comprises means for communication with another MCU. For example, one or several mobile MCUs may relay information from user units among each other and to a stationary MCU. The possibility to relay information enhances the performance of the system by securing communication between the user units and at the MCUs, as well as expanding the size of the local search area. The information being shared between the different MCUs also regularly updates every user of a MCU, thereby securing that the information given to all the users of the MCUs is updated and the same.

The invention also refers to the use of the devices for tracing an object, and determining the position of the object.

The invention also refers to methods for using the mentioned devices, according to the appended method claims. Some examples will be drawn hereupon, and the reference 121.5/243 MHz denotes the predetermined International Search and Rescue frequencies mentioned above: A. User unit within its "closed" local search area: -The user unit is switched off until emergency,

-A user unit is activated and sends a distress signal and indicates unique identity and GPS coordinates, -The MCU replies to the user unit (s) confirming receipt of information,

-The user unit communicates confirmation of receipt of the distress signal to the distressed, via the communicating means, e.g. LCD display or LED display.

B. User unit used for ongoing information communication or "search only" location:

-The user unit is always in "listening" mode,

-MCU interrogates the user unit and if necessary communicates information via the communication means, -The user unit replies confirming safe receipt of message and confirms its identity and GPS coordinates (if required),

-The user unit can be returned to "listening" mode by the MCU, or continue to transmit identity and GPS coordinates.

C. User unit within its "closed" local search area, but SAR resources (Aircraft,

Helicopters, Ships, etc.) are also being used in that area:

-The user unit is either switched off or in "listening" mode,

-The user unit is activated,

-The MCU indicates unique identity and GPS coordinates, -The MCU replies to the user unit, but the SAR protocol shows that certain user units are to be recovered by 121.5/243 MHz direction finding capability on incoming SAR platforms,

-The MCU commands the user units, one at a time, to transmit on 121.5/243

MHz frequencies, i.e. the user unit begins to transmit the modulated tone signal for direction finding.

D. The user unit is outside its "closed" local search area: -The user unit is either in listening mode or switched off until emergency, -The user unit is activated and sends a distress signal, -The user unit does not receive any reply from the MCU, -The user unit automatically switches to start sending on the 121.5/243 MHz frequencies and also transmits to at least one satellite,

-The user unit returns to "listening" mode at pre-determined intervals.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in the following by way of examples only and with reference to the attached drawings, in which:

Fig. 1 schematically shows a user unit and a MCU according to the invention

Fig. 2 schematically shows a system including several user units and several MCUs.

Fig. 3 shows a flowchart over events for the example mentioned in the following text.

Fig. 4a shows a user unit fitted inside a deflated inflatable waterproof bag according to one embodiment of the invention.

Fig. 4b shows a user unit fitted inside an inflated inflatable waterproof bag, during use at sea, according to one embodiment of the invention.

Fig. 4c shows a user unit fitted inside an inflated inflatable waterproof bag connected to a user, during use at sea, according to one embodiment of the invention.

Fig. 5a shows a user unit fitted inside an inflated inflatable waterproof bag used as a lifejacket, during use at sea, according to one embodiment of the invention. Fig. 5b shows a user unit fitted inside an inflated inflatable waterproof bag mounted onto a lifejacket, during use at sea, according to one embodiment of the invention.

MODES FOR CARRYING OUT THE INVENTION

The rescue system according to different embodiments of the invention are shown in Fig. 1-5 and will be described hereupon. The embodiments presented shall not be seen as limiting for the invention, but merely as descriptions for facilitating the understanding of the invention.

Fig 1 shows the rescue system according to the invention, which system comprises at least one rescue transceiver device for a person or an object, user unit 1 , and a rescue transceiver device for alarm being a master control unit, MCU 2. To simplify the explanation of the invention, the invention according to the first embodiment is described with only one user unit 1 and one MCU 2, but the system may include several user units and MCUs. Not all parts included in the devices will be described, but only those necessary for describing the invention.

The user unit 1 is a rescue transceiver device for a person or an object in distress, or hazardous situation or potentially causing a danger or hazard. The user unit is attached on a user by a method suitable for the purpose, for example the user unit may be held in a pocket of the user, or fitted on a rescue suit or fitted onto a lifejacket worn by the user, or strapped on to the user by strapping means, or in an alternative suitable manner. The user unit 1 may also be attached to lifesaving devices such as Dan-Buoys, man- overboard rings and buoys or other man-overboard recovery devices or life saving equipment such as life rafts etc. The user unit 1 is advantageously watertight and robust for being able to be used during very rough conditions, e.g. in cold water, snow, storm, etc. The user unit may advantageously be fitted inside a waterproof inflatable bag, which will be describe as one embodiment in the following text. The user unit 1 can be fitted with alternative batteries, e.g. sealed for life or a rechargeable type battery or may be fitted to an external source of energy. The different devices in the user unit may also have their own battery sources. The user unit comprises first transmitting means 3 for transmitting a digital, coded alarm and information signal, distress signal 4a, on a frequency outside the predetermined frequencies of the \ntemat\ona\ Distress and Search and Rescue, SAR, systems, currently being 121.5/243/406 MHz. The first transmitting means transmits in a local search area. One advantage with transmitting the distress signal 4a locally and outside the International Distress and SAR systems of 121.5/243/406 MHz, is that it reduces the costs for the rescue operation by launching only a small rescue operation force in the local area of the distress situation. This is of course especially advantageous if the distress situation is of a minor nature or in the case of false alarm. The user unit 1 may also comprise means for transmitting on a licence-exempt frequency. The user unit may further comprise means for communicating with a second user unit, i.e. each user unit 1 may include means for transmitting a signal to another user unit 1 as well as means for receiving a signal from another user unit 1.

The range for the user unit 1 varies on the environmental and other conditions, but typically with a MCU aerial at 12m height above water and a user unit at water surface the range is about 10 km, therefore giving a local search area of approximately 400 km². If the MCU is operated at a lower level, the range for the user is approximately 8 km, and if the MCU is operated from an aircraft the range is considerably greater than 10 km.

The digital alarm and distress signal 4a is based on an identity code unique for the user unit 1 and a continuously updated position. The identity code may be of any combination of digital numbers or figures, and length, that separates one user unit from other user units. The continuously updated position may be provided to the user unit 1 in the form of global coordinates, via any commercially known or unknown devices, advantageously the user unit 1 may comprise first GPS-receiving means 8 for receiving a first GPS- signal 9 from a suitable system for global positioning, for example the Global Positioning System, GPS.

The user unit 1 also comprises first receiving means 5 for receiving a digital signal, rescue signal 6, from at least one MCU 2, which rescue signal 6 comprises information, for example command, progress, warning, alerting and advisory information. The user unit 1 also comprises communicating means 7 for communicating the information in the rescue signal 6 to the user. The communicating means 7 may advantageously comprise an audible means 10, e.g. a loudspeaker, and/or a light emitting object 11 , for instance an indicator LED panel comprising a number of LEDs (Light Emitting Diodes), and/or another suitable device for communicating the information to the user.

The user unit also comprises second transmitting means 12 for transmitting an International distress signal 4b on the International Distress and SAR systems of 121.5/243/406 MHz when at least one predetermined condition is fulfilled. The second transmitting means 12 may be a separate part of the user unit 1 , for instance a separate dedicated transmitter, or may be a part of the first transmitting means 3. The predetermined conditions may be fulfilled after a predetermined time limit, if one or more user units 1 are out of range from the MCU 2, if the MCU 2 initiates the user unit 1 or if another condition is fulfilled suitable for the purpose. Thus, the user unit 1 may comprise means for transmitting on the International Distress and SAR systems of 121.5/243/406 MHz, for example after a predetermined time limit, if the user unit 1 is out of range from the MCU 2 or if initiated by the MCU. The user unit 1 may also use the second transmitting means 12 for transmitting the International distress signal 4b on any of the 121.5/243/406 frequencies for direction finding, in order to enable a SAR unit, not equipped with a MCU 2 or user unit, to search and find the distressed with conventional methods. When the user unit transmits on the International Distress and SAR systems of 121.5/243/406 MHz, it may also transmit to at least one satellite. The user unit 1 may also comprise a distress sensor 21 for sensing various types of distress situations, for example, water, wind, snow, G-forces etc. The distress sensor 21 is used to set the user unit 1 into a distress mode, which means that the user unit 1 starts transmitting the distress signal 4a. The user unit 1 may also comprise a health detector system for monitoring the distressed, and thereby may initiate the user unit 1 to start transmitting, and may also provide a rescue leader with information on the status of the distressed for priority judgement use. The user unit may also be activated manually.

The MCU 2 comprises second receiving means 13 for receiving digital distress signals 4a, preferably transmitted from one or more user units 1. The MCU 2 further comprises identifying means 14 for identifying the unique identity codes, and position means 15 for identifying the regularly updated position transmitted by the user unit. The MCU 2 further comprises third transmitting means 16 for transmitting a digital rescue signal 6 comprising rescue information, which may be in the form of command, progress, warning, alerting and advisory information, to the user units. The rescue information that is sent to the user unit 1 from the MCU 2, is that the distress signal has been received and that help is on the way, but may also comprise information about distance and bearing or other useful information. The information may be communicated to the user of the user unit via the audible means 10 and/or the light emitting object 11 of the user unit 1, or the user unit 1 may additionally be equipped with a LCD display 24 in order to display the information to the user as a text message. The MCU 2 also comprises calculating means 22 for continuously calculating range, bearing and direction to the user units 1. For this purpose The MCU 2 comprises second GPS means 17 for receiving second GPS signals 18 giving a regularly updated position in the form of global coordinates from, for example, the Global Positioning System, GPS, i.e. GPS coordinates. The position of the user unit 1 is then compared to the position of the MCU 2. The MCU 2 is capable of receiving signals from a number of user units 1 and may therefore comprise managing means 19 to temporarily cause a halt to transmissions from selected user units in order to manage the user unit transmissions preventing radio channel congestion.

The MCU 2 may further comprise a MCU display 20 for displaying the information obtained from the distress signal 4a from each user unit 1 The MCU 2 has the capability to handle thousands of user units 1 and the MCU display 20 screen may be scrolled up and down in order to monitor the user units 1 one by one. The information may be used in making rescue priorities, i.e. decide which of the distressed that is going to be rescued first etc. The MCU 2 may additionally be equipped with a Palm PC, a laptop computer, a panel PC or any other device suitable for the purpose, on which "radar like" positions of the user units 1 can be displayed. Also a chart plotter can be utilised, onto which the positions of the user units 1 can be displayed. The MCU 2 may also be equipped with a number of light emitting objects 38, for instance LEDs (Light Emitting Diodes) for steering indication, for example a left, a centre 39 and a right light emitting object in different colours indicating steering port, straight on, or starboard respectively. This is evidently useful when using a mobile MCU 2. At a distance where the MCU 2 becomes close to the user unit 1 , the straight ahead direction light 39 begins to flash or another warning indicator may be activated to warn the rescue vehicle, and to avoid that the distressed person is hit by the rescue vehicle. The MCU may also be equipped with an additional light emitting object indicating that the rescue vehicle is closer to the user unit than a predetermined distance, suitably about 100m and/or 50 m.

In order to manage the rescue system, the MCU 2 comprises means to command at least one user unit 1 to transmit a continuous signal for direction finding purposes on a frequency used for transmitting data, for example 121.5 MHz on the International Distress and SAR frequency. When the MCU 2 is within a predetermined distance from the chosen user unit 1 , the MCU may command the user unit to start transmitting high powered audible and/or visible signals, for example high intensity light.

In one embodiment of the invention the user unit comprises a high energy light emitting object 36 for close range detection. The high energy light emitting object may be switched on when a SAR unit is close enough, for instance by request from the MCU, or manually by the user of the user unit.

If the distress situation is of such nature that a local SAR operation is not enough, the MCU comprises command means 23 in order to command at least one user unit 1 to transmit the International distress signal 4b, via the second transmitter means, on the International Distress and SAR systems of 121.5/243/406 MHz, thereby launching a full scale SAR operation. The command means 23 may also command a separate user unit 1 to transmit signals on the International Distress and SAR systems of 121.5/243/406 MHz, in order to be used conventionally for direction finding purposes by a SAR unit. The command means 23 may also command a separate dedicated transmitter to transmit the International distress signal 4b on the International Distress and SAR systems of 121.5/243/406 MHz.

The MCU 2 may also be connected to a satellite telephone, Internet, fax, landline or cellular, in order to either manually or automatically launch a rescue operation of desired dimension via existing public or private telecommunication infrastructure. The MCU 2 then access the infrastructure and transmits a message, giving the recipient on the other end of the line indication that it is an MCU 2 activated and may also communicate a position, number of persons or objects in distress, and other information that might be of help for the SAR units. Thus the MCU 2 may be used at an unmanned location. The MCU may also be connected to a radio that transmits on the Digital Selective Calling, DSC which is the VHF Marine channel nr 70, which channel is dedicated to digital distress signalling. When the MCU 2 is activated by a user unit 1 , for example in the case where a lone sailor falls overboard, the MCU 2 activates the DSC-radio, which then transmits the distress signal and information on the DSC. The information may comprise user identification and position, and other suitable information.

The MCU 2 may comprise means for transmitting on the International Distress and SAR systems of 121.5/243/406 MHz, for example after a predetermined time limit, for instance a time limit during which the user unit has been out of contact with the MCU, or if the user unit 1 is out or goes out of range from the MCU 2.

The MCU 2 may comprise a MCU 2 distress sensor for sensing various types of distress situations, for example, water, wind, snow, G-forces etc. The MCU distress sensor may then be used to set the MCU 2 into a distress mode, which means that MCU may command the user unit 1 to start transmitting the International distress signal 4b, or may itself transmit the International distress signal 4b.

In order to direct the SAR personnel to a certain point, the MCU may comprise means to indicate course for the SAR personnel, for example directing a helicopter or a boat to a certain point. This may be done by using the position of the SAR personnel, for instance using another MCU, and the position for the MCU 2 in order to calculate a proper course. The means for calculating the course may be either a separate unit or the calculating means 22 in the MCU 2.

The MCU 2 may also be capable of sounding an audible and/or visual signal to alert personnel that a first distress signal has been received from a user unit 1. The audible and/or visible means may, for example, be a klaxon, siren and/or a flashing light.

The MCU 2 may comprise control relay means enabling external actions, such as indicating visually and audibly alarm, control an engine or helm steer. For example, when a person equipped with a user unit 1 falls into the water from a boat, the user unit 1 transmits a distress signal to the MCU 2, the MCU then transmits a signal via the control relay means to a device that may execute the desired task, for instance switching an engine off.or steering the boat towards the user unit 1.

The MCU 2 may also comprise means for communication with another MCU, to permit exchange of command, control tasking, progress, warning and other useful information.

In a further embodiment of the invention, shown in Fig. 2, the system comprises a number of MCUs 2 which interact via inter communication 37, for example one stationary MCU 2 and several mobile MCUs 2. One of the MCUs may then be designated as the rescue co-ordinator that makes priority judgements and directs the mobile MCU/SAR units to the next distressed in priority as part of an overall rescue plan. The mobile MCUs can display the priority list made by the rescue leader and also display the position, bearing and identity of the user unit. The overall rescue plan with the priority listing may be done on the co-ordinator MCU by selecting one of the distressed displayed on the MCU 2, or simply by letting the MCU 2 automatically make the priority, for example based on distance, health status or another suitable variable. The co-ordinator MCU 2 may also command one of the MCUs 2 to rescue a certain individual by transmitting the information to the designated MCU 2 that presents the information in a suitable way to the MCU operator, for instance by high lighting the distressed in the list. Each MCU 2 in the rescue operation may update the list, and via communication with the other MCUs 2 update all MCUs involved. This enhances the possibility to detect and relay a rescue signal from a user unit. For example, if there are a lot of distressed over a large area, at least the MCU 2 closest to a user unit 1 detects the signal and forwards the information to the other MCUs 2, and most important, to the co-ordinator MCU 2. This action of relaying MCU 2 information, ensures that the SAR operation has the widest area possible. The inter-communication between the different MCUs 2 thus extends the range of the system and if, for instance, a MCU 2 is fixed mounted in high position, e.g. on an oil rig, mast, etc. the operating range of the system is further expanded. Since all the MCUs 2 continuously transmits and receives updated information about the distressed, the system becomes very robust. The management of the different MCUs 2 according to the above is a great improvement compared to previously known rescue devices which uses audible or visible systems, for example telephones or walkie-talkies, which are cumbersome and error- prone communication methods.

The system may also include different MCUs 2 with different features, for instance a co-ordinating MCU 2 (rescue leader) responsible for the managing of the rescue operation, may be equipped with all features accessible and mobile MCUs 2 equipped with only some of the features. The co-ordinating MCU 2 may be equipped with different appearances on the display, for example a radar type display, a list of the distressed showing distance, bearing and additional information that can be of help for the rescue leader. The user of the MCU 2 also has the possibility to zoom in on the display in order to get a better resolution, enabling the rescue leader to separate distressed individuals in a cluster of distressed.

All devices for communication are dependent on a strong and reliable transmission between the devices. Off course this is true also when using the invention, why it is of the utmost importance that the user unit 1 is equipped with a suitable transmission means with a suitable aerial arrangement. Previous known rescue transceiver devices for a person or an object in a local search area have got problems with range and reliable transmissions, especially those devices used at sea. The height of the aerial above the surface determines the transceiving performance of the transceiver. So, in order to achieve a user unit 1 , according to the embodiment, with sufficient performance to cover a large enough local search area when communicating with a MCU 2, a vertical extended aerial is used together with the user unit 1. Thus, in a further embodiment of the invention, an aerial device comprising an inflatable bag 26, which can be in the form of a mast 34, is used to extend an aerial 25, connected to and used together with a rescue transceiver device, user unit 1 , in order to achieve a strong and reliable transmission between the user unit 1 and the MCU 2.

Fig. 4a, 4b and 4c show one possible embodiment for the user unit combined with the inflatable bag 26. The user unit 1 and the aerial 25 are preferably contained within the sealed bag 26 such that upon the bag 26 being inflated with gas into an elongated shape, the aerial 25 is extended. If the surrounding medium has greater density than the inflated structure, then the user unit 1 within the inflated bag will be buoyant. Such surrounding medium could be, for example, either water or snow or air. The unit is attached by a line such as a cord 27 to the user themselves. To give examples, in Fig. 4c is shown a diver in distress that might deploy the unit under water such that it floats to the surface attached to a line which is attached to the diver thereby signalling his distress to the people on the surface. Alternatively, the unit may be attached to a person who falls overboard so that it floats directly alongside him. The unit may also be carried by a snow skier who might be in danger of being covered by an avalanche. In this case he activates the inflator before he is overrun by the avalanche and the unit tends to "float" towards the avalanche surface so that he can be found more easily, in which case the inflatable structure would be spherical in shape.

The sealed bag 26 ensures the user unit to be watertight even to depths of at least 200m and is therefore always protected from water. It also means that the unit is protected from other environmental hazards such as snow etc. The bag may incorporate a device for detecting whether the bag is sealed. This might, for example, be a humidity indicator that indicates that the inside of the bag is sealed from the environment. The user unit is preferably fitted with a location light 28 and the material 35 of the bag 26 is preferably of a transparent or partially transparentfhigh visibility" colour, such that the light from the location light 28 illuminates the full surface of the inflated bag from the inside, making it readily visible to rescuers. The aerial 25 is made of a flexible metallic material such as a wire, so when the bag is not inflated it is folded down within the bag, but upon inflation of the bag it is extended to its full length. The medium used to inflate the bag is typically a compressed gas, typically contained within an inflating means 29, for example a gas container. A mechanism exists to release the gas which is usually a means of puncturing the container. The mechanism is either manual and requires the user to activate its release, or it may be activated "automatically" for example, by water in the case of a person falling overboard. The action of the gas inflating the bag may also be the action to switch on the user unit 1. The reverse action is also possible, i.e. the user unit 1 activates the inflating process. If the bag is not transparent, then a transparent "window" may be incorporated to allow the user to see the light emitting objects, for example signal LEDs 30, on the user unit, which light emitting objects may be used for communicating information from the MCU to the distressed. It is important that the bag 26, once inflated, floats in the correct orientation for the aerial 25 - so the heavier items within the structure i.e. a transmitter battery 31 and the inflating means 29, are lower in position when floating such that they tend to hold the aerial 25 in the correct vertical orientation.

An additional embodiment, shown in Fig. 5a, is such that the sealed bag 26 referred to in the previous embodiment of the invention, is an inflatable lifejacket 32. Here the user unit 1 and location light 28 are contained within the sealed lifejacket 32 made of material and comprising inflating means 33 such that the aerial 25 is supported vertically above the water surface. The inflating means 33 may be used to inflate the entire lifejacket 32, thereby inflating a vertical projecting inflatable mast 34, which is part of the life jacket, i.e. the bag. The aerial is placed within the inflatable mast. In yet another embodiment, shown in Fig. 5b, the inflatable mast 34 is mounted on the lifejacket and has got the same features as the inflatable bag 26 in Fig. 4a-4c.

The shape of the bag 26/mast 34 when inflated may be cone shaped, with the base of the cone towards the water surface and the aerial fitted essentially concentric inside the bag/mast, from the top of the cone to the centre of the base. The shape of the bag/mast may of course be in any shape suitable for extending the aerial vertical from the surface, and keeping the bag/mast in an upraised vertical orientation in relation to the surface.

In order to facilitate the understanding of how the system works, some examples will be described in the following text:

The flow chart described is not strictly chronological, but some of the steps may occur simultaneously. The examples shall not be seen as limiting the invention, but merely as an example of how the system may work. The item numbers i -i5. with subsections will be shown in the flowchart in Fig. 3. As before, the non-item numbers refer to figures 1 and 2.

The following example shall be read as follows: The headline for a head event is denoted with the letter i followed by a number, e.g. i1 , and the headlines for events that follow under each head event is denoted with the letter i followed by a number and an additional letter, e.g. i1a. Under each headline there is a text that illustrates the event in question.

i A user unit is activated, go to i1a or i1 b:

- A user unit 1 is activated;

- The inflating means 29 inflates the bag/mast 26/34, thereby extending the aerial 25 into a vertical orientation; - The user unit receives the first GPS signals 9 via the first GPS receiving means 8; - The user unit transmits a distress signal 4a via the first transmitting means 3, go to i1a or Mb;

i1a. Normal activity: - A MCU 2 receives the distress signal 4a via the second receiving means 13;

- The MCU 2 activates an audio/visual alarm on receipt of such distress signal 4al;

- The MCU 2 replies to the user unit 1 by transmitting a rescue signal 6 to the user unit 1 via the third transmitting means 16, confirming receipt of distress signal 4a;

- The user unit receives the rescue signal 6 via the first receiving means 5;

- The user unit communicates the information in the rescue signal 6 via the communicating means 7. - The MCU 2 receives the second GPS signals 18 via the second GPS receiving means 17;

- The calculating means 22 in the MCU 2 uses the information in the distress signal 4a and the information otherwise collected by the MCU 2 to calculate bearing to, distance to and relative position from the user unit; - The MCU 2 display 20 displays information regarding the user unit 1 to a rescue leader;

- The rescue leader makes a priority judgement in the case where several user units 1 are transmitting, and also decides whether the rescue operation is large enough or if it has to be expanded. If it is large enough, go to i2, and if it has to be expanded, go to i3;

M b. No contact between user unit 1 and MCU 2:

- The user unit 1 does not establish contact with the MCU 2, therefore transmits the International distress signal 4b via the second transmitter 12 thereby launching a full scale SAR operation, go to i5.

i2. Local SAR operation, go to i2a or i2b: i2a. Normal local search and rescue operation:

- The rescue leader directs the SAR units to the user unit 1 via the MCU 2;

- The MCU 2 may command a separate user unit 1 to transmit signals on the International Distress and SAR systems of 121.5/243/406 MHz, which signals may be used conventionally for direction finding purposes by a SAR unit;

- When the distressed is rescued, the rescuer resets the user unit 1 or shuts it off and redirects a mobile MCU 2 to another distressed, or aborts the operation if the last distressed is rescued;

i2b. No contact between user unit 1 and MCU 2 during local operation:

- If the User unit drifts out of range, or loses contact with the MCU in another way, go to Mb.

i3. Local SAR operation is not enough:

-The rescue leader decides to expand the search operation to a full scale SAR operation, go to i3a or i3b;

i3a. MCU 2 commands user unit 1 to transmit the International distress signal 4b:

- The MCU 2 transmits a rescue signal 6 to the user unit 1 , via the command means 23 and the third transmitting means 16, which rescue signal 6 contains information commanding the user unit 1 to transmit the International distress signal 4b, go to ι^'5;

i3b. The MCU 2 additionally transmits the International distress signal 4b: -The MCU 2 may additionally transmit the International distress signal 4b (go to i4a) thereby launching a full scale SAR operation;

i4. The MCU 2 transmits the International distress signal 4b, go to i4a or i4b: i4a. The MCU 2 transmits the International distress signal 4b via the third transmitting means 16 or via a specially dedicated transmitter, go to i5:

ι^'4b. In case of an unmanned MCU 2: -The MCU 2 may be connected to and use any telecommunication infrastructure for automatically dialling and playing a message containing distress information thereby launching a local or fully scale SAR operation, go to i2a or i5

i5. Full Scale SAR operation after a distress signal has been sent on the predetermined International Distress and SAR systems of 121.5/243/406 MHz:

- The MCU 2 display 20 displays information regarding the user units 1 to a rescuer; - The rescue leader makes a priority judgement in the case where several user units are transmitting;

- The rescue leader directs the SAR units to the user unit 1 , for example by radio or via communication with a mobile MCU 2;

- When the distressed is rescued, the rescue leader redirects the SAR units.

The invention is not restricted to the embodiments described above and shown in the drawings, but may be modified within the scope of the appended claims. For example, the mentioned GPS in the user unit as well as in the MCU, may be any system for global positioning.

If the frequencies for the International Distress and Search and Rescue signals are changed, the invention may of course be changed in order to keep out of these frequencies in order to uphold the mentioned advantages with the invention correctly utilising the frequencies. The inflatable bag/mast may also be used to support only the aerial and or/ the location light 28, wherein an electrical cord connects the user unit and the aerial, and a weight is placed in a low position in order to keep the aerial above the surface. Also, the visual location device described above may be used. The mast is then allowed to drift of a bit from the user unit, while the distressed has the possibility to manage the user unit.

Claims

1. A rescue transceiver device for a person or an object, user unit (1), in distress, or hazardous situation or potentially causing a danger or hazard, comprising transmitting means (3) for transmitting a digital, coded alarm and information signal, distress signal (4a), characterized in that the transmitting means (3) of the user unit (1) comprises means for transmitting the distress signal (4a) on a frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue systems, the digital distress signal being based on an identity code unique for the user unit (1) and a continuously updated position, the user unit also comprises receiving means (5) for receiving a digital signal, rescue signal (6), from at least one master control unit, MCU (2), which rescue signal (6) comprises information, for example command, progress, warning, alerting and advisory information, the user unit also comprises means (7) for communicating the information in the rescue signal (6) to a user of the user unit (1), the transmitting means (3) also comprises means (12) for transmitting an International distress signal (4b) on one or several predetermined frequencies for the International Distress and Search and Rescue systems or means for commanding a separate transmitter to transmit on such frequencies, when at least one predetermined condition is fulfilled.

2. A rescue transceiver device according to claim 1 characterized in that the user unit (1) comprises means for transmitting in a local search area.

3. A rescue transceiver device according to claim 2 characterized in that the means (12) for transmitting an International distress signal (4b) on one or several predetermined frequencies for the International Distress and search and rescue systems, transmits on any or all of the predetermined frequencies for the International Distress and Search and Rescue systems, currently being 121.5/243/406 MHz.

4. A rescue transceiver device according to according to claim 3, characterized in that the user unit comprises means (8) for receiving GPS signals (9).

5. A rescue transceiver device according to claim 4, characterized in that the means (7) for communicating the rescue information in the rescue signal (6) to the user comprises audible means (10).

6. A rescue transceiver device according to claim 5, characterized in that the means (7) for communicating the rescue information in the rescue signal (6) to the user comprises a light emitting object (11, 30).

7. A rescue transceiver device according to claim 6, characterized in that the user unit comprises a high energy light emitting object (36) for close range detection.

8. A rescue transceiver device according to claim 7, characterized in that the user unit (1) comprises means for communicating with a second user unit.

9. A rescue transceiver device according to claim 8, characterized in that the user unit (1) comprises means (12) for transmitting the International distress signal on the International Distress and SAR systems of 121.5/243/406 MHz after a predetermined time limit.

10. A rescue transceiver device according to claim 9, characterized in that the user unit (1) comprises means (12) for transmitting the International distress signal on the International Distress and SAR systems of 121.5/243/406 MHz if the user unit (1) is out of range from the MCU (2).

11. A rescue transceiver device according to claim 10, characterized in that the user unit (1) comprises means (12) for transmitting the International distress signal on the International Distress and SAR systems of 121.5/243/406 MHz if initiated by the MCU.

12. A rescue transceiver device according to any of the preceding claims, characterized in that the user unit (1) is fitted into an inflatable bag (26), which bag comprises an aerial (25) raised in a vertical orientation by the inflatable bag (26) when inflated, which aerial (25) is connected to the user unit (1).

13. A rescue transceiver device for alarm, search and rescue units, being master control unit, MCU (2), comprising means (13) for receiving digital distress signals (4a), preferably transmitted from one or more user units (1) according to claim 1, characterized in that the MCU (2) further comprises means (14) for identifying unique identity codes and means (15) for identifying a regularly updated position, the MCU (2) also comprises means (16) for transmitting a digital rescue signal (6) comprising rescue information, which may be in the form of command, progress, warning, alerting and advisory information, to the user unit, the MCU (2) also comprises means (22) for continuously calculating range, bearing and direction to the user unit, the MCU (2) further comprises means (19) to temporarily cause a temporary halt to or lengthen the period between transmissions from selected user units thereby managing the user units transmissions preventing radio channel congestion.

14. A rescue transceiver device according to claim 13 characterized in that the MCU (2) comprises means to command at least one user unit to transmit signals (4a) for direction finding purposes via transmitting means (3) on a suitable frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue systems.

15. A rescue transceiver device according to claim 14, characterized in that the MCU (2) comprises means (23) to command at least one user unit to transmit an International distress signal via means (12) for transmitting on the International Distress and SAR systems of 121.5/243/406 MHz.

16. A rescue transceiver device according to claim 15, characterized in that the MCU (2) comprises means to command a separate dedicated transmitter to transmit an International distress signal on the International Distress and SAR systems of 121.5/243/406 MHz.

17. A rescue transceiver device according to claim 16, characterized in that the MCU (2) comprises means to indicate course for SAR personnel in order to direct themselves to a certain point.

18. A rescue transceiver device according to claim 17, characterized in that the MCU (2) comprises control relay means enabling external actions, such as indicating visually and audibly alarm, control an engine or helm steer.

19. A rescue transceiver device according to claim 18, characterized in that the MCU (2) comprises means to command a high energy light emitting object on the user unit (1) to be activated for close range detection.

20. A rescue transceiver device according to claim 19, characterized in that the MCU (2) comprises means (17) for receiving GPS signals (18).

21. A rescue transceiver device according to claim 20, characterized in that the MCU (2) comprises a MCU display (20) for displaying the information in and derived from the distress signal (4a) from each user unit (1).

22. A rescue transceiver device according to claim 21, characterized in that the rescue information in the rescue signal (6) comprises information about distance and bearing.

23. A rescue transceiver device according to claim 22, characterized in that the MCU (2) comprises means for communication with another MCU.

24. A rescue transceiver device according to claim 11 and claim 23, characterized in that the regularly updated position is in the form of global coordinates, e.g. GPS coordinates.

25. An aerial device for use with a rescue transceiver device, characterized in that an aerial (25), connected to the rescue transceiver device, is fitted into an inflatable bag (26, 34), which aerial (25) being raised in a vertical orientation when the inflatable bag is inflated.

26. An aerial device for use with a rescue transceiver device according to claim 25, characterized in that the aerial (25) is made of a flexible material.

27. An aerial device for use with a rescue transceiver device according to claim 26, characterized in that the rescue transceiver device is a user unit (1), and fitted inside the inflatable bag (26, 34).

28. An aerial device for use with a rescue transceiver device according to claim 27, characterized in that the inflatable bag (26, 34) is in the form of a lifejacket (32).

29. An aerial device for use with a rescue transceiver device according to claim 27, characterized in that the inflatable bag (26,

34) is mounted on a lifejacket (32).

30. An aerial device for use with a rescue transceiver device according to any of claims 25-29, characterized in that the inflatable bag (26) is made from a transparent or partially transparent/"high visibility" colour material (35), in which bag (26, 34) a location light (28) is fitted, such that the light from the location light (28) illuminates the full surface of the inflated bag from the inside, making it readily visible.

31. A method for use of a rescue transceiver device for a person or an object, user unit (1), in distress, or hazardous situation or potentially causing a danger or hazard, where the rescue transceiver device transmits a digital, coded alarm and information signal, distress signal (4a), characterized in that the user unit (1) transmits the distress signal (4a) on a frequency outside one or several predetermined frequencies for the International Distress and Search and Rescue systems, the digital distress signal being based on an identity code unique for the user unit 1 and a continuously updated position, the user unit also receives a digital signal, rescue signal (6), from at least one master control unit, MCU (2), which rescue signal (6) comprises information, for example command, progress, warning, alerting and advisory information, the user unit (1) also communicates the information in the rescue signal (6) to a user of the user unit (1), the user unit (1) also transmits an International distress signal (4b) on one or several predetermined frequencies for the International Distress and Search and Rescue systems or commanding a separate transmitter to transmit on such frequencies, when at least one predetermined condition is fulfilled.

32. A method for use of a rescue transceiver device according to claim 31, characterized in that the distress signal (4a) is transmitted in a local search area.

33. A method for use of a rescue transceiver device according to claim 32, characterized in that the transmittal of an International distress signal (4b) on one or several predetermined frequencies for the International Distress and Search and Rescue systems is being transmitted on any or all of the predetermined frequencies for the International Distress and Search and Rescue systems of 121.5/243/406 MHz.

34. A method for use of a rescue transceiver device according to claim 33, characterized in that the user unit (1) receives GPS signals (9).

35. A method for use of a rescue transceiver device according to claim 34, characterized in that the user unit (1) communicates the information in the rescue signal (6) to the user via audible means (10).

36. A method for use of a rescue transceiver device according to claim 35, characterized in that the user unit (1) communicates the information in the rescue signal (6) to the user via a light emitting object (11).

37. A method for use of a rescue transceiver device according to claim 36, characterized in that the user unit (1) may communicate with a second user unit.

38. A method for use of a rescue transceiver device according to claim 37, characterized in that the user unit (1) transmits the International distress signal (4b) on the International Distress and SAR systems of 121.5/243/406 MHz after a predetermined time limit.

39. A method for use of a rescue transceiver device according to claim 38, characterized in that the user unit (1) transmits the International distress signal (4b) on the International Distress and SAR systems of 121.5/243/406 MHz if the user unit (1) is out of range from the MCU (2).

40. A method for use of a rescue transceiver device according to claim 39, characterized in that the user unit (1) activates a high energy light emitting object (36) on command from the MCU (2).

41. A method for use of a rescue transceiver device according to claim 40, characterized in that the user unit (1) transmits the International distress signal (4b) on the International Distress and SAR systems of 121.5/243/406 MHz if initiated by the MCU (2).

42. A method for use of a rescue transceiver device according to claim 41, characterized in that the user unit (1 ) is fitted into an inflatable bag (26), and that when the user unit (1) is activated, the inflatable bag (26) inflates, which bag also contains an aerial (25) connected to the user unit (1), which aerial (25) raises into a vertical orientation by the inflatable bag (26) when being inflated.

43. A method for use of a rescue transceiver device for alarm, search and rescue units, being master control unit, MCU (2), for receiving digital distress signals (4a), preferably transmitted from one or more user units (1 ) according to claim 21, characterized in that the MCU (2) identifies unique identity codes and also identifies a regularly updated position, the MCU (2) also transmits a digital rescue signal (6) comprising rescue information, which may be in the form of command, progress, warning, alerting and advisory information, to the user unit (1), the MCU (2) also continuously calculates range, bearing and direction to the user unit (1), the MCU (2) further cause a temporary halt to or lengthen the period between transmissions from selected user units thereby managing the user unit transmissions preventing radio channel congestion.

44. A method for use of a rescue transceiver device according to claim 43, characterized in that the MCU (2) commands at least one user unit (1) to transmit signals for direction finding purposes on a data channel frequency or another suitable frequency.

45. A method for use of a rescue transceiver device according to claim 44, characterized in that the MCU (2) commands at least one user unit (1) to transmit an International distress signal (4b) on the International Distress and SAR systems of 121.5/243/406 MHz.

46. A method for use of a rescue transceiver device according to claim 45, characterized in that the MCU (2) commands a separate dedicated transmitter to transmit the International distress signal (4b) on the International Distress and SAR systems of 121.5/243/406 MHz.

47. A method for use of a rescue transceiver device according to claim 46, characterized in that the MCU (2) indicates course for SAR personnel in order to direct themselves to a certain point.

48. A method for use of a rescue transceiver device according to claim 47, characterized in that the MCU (2) controls relay means enabling external actions, such as indicating visually and audibly alarm, control an engine or helm steer.

49. A method for use of a rescue transceiver device according to claim 48, characterized in that the MCU (2) commands a high energy light emitting object (36) on the user unit to be activated for close range detection.

50. A method for use of a rescue transceiver device according to claim 49, characterized in that the MCU (2) receives GPS signals (18).

51. A method for use of a rescue transceiver device according to claim 50, characterized in that the MCU (2) displays the information in the distress signal (4a) from each user unit (1) on a MCU display (20).

52. A method for use of a rescue transceiver device according to claim 51, characterized in that the rescue information (6) communicates information about distance and bearing to the user of the user unit (1).

53. A method for use of a rescue transceiver device according to claim 52, characterized in that the MCU (2) may communicate with another MCU.

54. A method for use of a rescue transceiver device according to any of claims 43-53 characterized in that the regularly updated position is supplied in the form of global coordinates, e.g. GPS coordinates.

55. A method for use of an aerial device for use with a rescue transceiver device, characterized in that an inflatable bag (26, 34) is being inflated when a predetermined condition is fulfilled, which inflatable bag extends an aerial (25) fitted into the bag (26, 34).

56. A method for use of an aerial device for use with a rescue transceiver device according to claim 55, characterized in that the rescue transceiver device in the form of a user unit (1), is fitted inside the inflatable bag (26, 34), and that the bag (26, 34) activates the user unit (1) during the inflating period.

57. A method for use of an aerial device for use with a rescue transceiver device according to claim 56, characterized in that the inflatable bag (26, 34) inflates into the shape of a lifejacket.

58. A method for use of an aerial device for use with a rescue transceiver device according to claim 56, c h a r a c t e r i z e d i n that the inflatable bag (26, 34) extends the aerial when inflated and mounted on a lifejacket.

59. A method for use of an aerial device for use with a rescue transceiver device according to any of claims 55-58, characterized in that the inflatable bag (26) is made from a transparent or partially transparentfhigh visibility" colour material (35), and when the bag (26, 34) is inflated a location light (28) placed in the bag (26,

34) is lit, such that the light from the location light (28) illuminates the full surface of the inflated bag from the inside, making it readily visible.

60. The use of devices according to claims 1-42 and/or a method according to claims 43-59 at rescue operations at sea.

61. The use of devices according to claims 1-42 and/or a method according to claims 43-59 for tracing an object, and determining the position of the object.

62. A rescue transceiver device substantially as described herein with reference to the accompanying description and drawings.

63. An aerial device for use with a rescue transceiver device substantially as described herein with reference to the accompanying description and drawings.

64. A method for use of a rescue transceiver device substantially as described herein with reference to the accompanying description and drawings.

65. A method for use of an aerial device for use with a rescue transceiver device substantially as described herein with reference to the accompanying description and drawings.