WO2003089953A1

WO2003089953A1 - Emergency beacon and method of adjusting beacon transmit period

Info

Publication number: WO2003089953A1
Application number: PCT/GB2003/001693
Authority: WO
Inventors: John Ronald Hough; Andrew Clement Fuller; Anselm Fabig
Original assignee: Inmarsat Ltd
Priority date: 2002-04-22
Filing date: 2003-04-22
Publication date: 2003-10-30
Also published as: GB0209153D0; AU2003222979A1; WO2003089953B1

Abstract

An emergency beacon, such as an emergency position indicating radio beacon (EPIRB) 1, has a transmitter (8) for transmitting a distress signal over a wireless communications network, such as a satellite communications network. It also has a receiver (10) for receiving a control signal over the wireless communications network and responds to receipt of the control signal to vary its operation. In particular, the EPIRB 1 can be controlled remotely to vary the times at which the distress signal is subsequently retransmitted by the EPIRB 1.

Description

EMERGENCY BEACON AND METHOD OF ADJUSTING BEACON TRANMIT PERIOD

Field of the Invention

The present invention relates to an emergency beacon and a method of controlling an emergency beacon, It is particularly relevant to Emergency

Position Indicating Radio Beacons (EPIRBs).

Background to the Invention

A typical EPIRB comprises a waterproof housing containing an antenna, transmitter and battery, and may be mounted on a boat. If the boat sinks or has some other emergency, then the EPIRB can float free of or be released from its mounting and transmit a distress signal. The distress signal includes the position of the EPIRB and this can be relayed to search and rescue services. Modern EPIRBs are capable not only of sending a distress signal but also of receiving signals from a remote location. This allows the distress signal to be acknowledged, which can be of importance in boosting the will to live of the stranded party by letting them know that their distress signal has been received. Usually, the EPIRB is set up to repeatedly transmit distress signals at fixed regular intervals and, as they are mostly battery powered, there is therefore a risk that EPIRB' s battery may expire before a rescue craft reaches the latest position reported in the distress signals. This may be a particular problem in remote sea areas far from land and off major shipping routes, such as the Southern Ocean.

In order to conserve battery power, it is therefore desirable to fix the interval between distress signal transmissions at a reasonably long period, such as an hour or longer. However, this means that when search and rescue services arrive in the vicinity of the latest reported position, the position may be fairly old and they may need to wait for a significant period to receive an up to date position. Furthermore, as weather and ocean currents can cause an EPIRB to drift rapidly, the long intervals between transmissions can significantly hamper search and rescue operations.

The present invention seeks to improve existing EPIRB systems and, in particular, extend the lifetime of the battery without hampering search and rescue operations.

Summary of the Invention

According to the present invention, there is therefore provided an emergency beacon comprising a transmitter for transmitting distress signals over a wireless communications network; a receiver for receiving a control signal over the wireless communications network; and a processor for varying transmission of the distress signals in response to the received control signal. Also according to the present invention, there is provided a search and rescue control centre for receiving distress signals from an emergency beacon over a wireless communications network and a transmitter for transmitting a control signal over the wireless communications network to cause the beacon to vary transmission of the distress signals.

According to the present invention, there is also provided a method of operating an emergency beacon, the method comprising transmitting distress signals over a wireless communications network, receiving a control signal over the wireless communications network and varying transmission of the distress signals in response to the received control signal.

Also according to the present invention, there is provided a method of controlling an emergency beacon comprising receiving a distress signal from the beacon over a wireless communication network and transmitting a control signal to the beacon over wireless communications network to cause the beacon to vary transmissions of the distress signals.

The emergency beacon is therefore controllable remotely. This allows search and rescue authorities to optimise operation of the beacon from a remote location, which can improve the efficiency of a search and rescue operation. In particular, as the transmission of distress signals is generally the most power intensive operation of the emergency beacon, controlling the transmission of the distress signals remotely can optimise the use of the emergency beacon's battery. Usually, the emergency beacon's transmitter automatically transmits a first distress signal when the beacon is activated. Activation may be automatic or manual. Automatic activation is usually in response to a sensor or switch that responds to an emergency. Thereafter, distress signals may be sent periodically, e.g. at intervals. Preferably, the control signal causes the beacon to vary the interval between transmission of the distress signals. Thus, the interval can be increased or decreased to conserve battery power or provide more frequent distress signals as desired. As the distress signal may include an indication of the beacon's position, more frequent distress signals can improve the speed with which the beacon can be located once a rescue craft is nearby.

Whilst the emergency beacon can be activated and deactivated remotely, it is intended that the term "varying transmission of the distress signals" refers to changing the ongoing transmission of the distress signals.

For example, the content, power, frequency or modulation of the distress signals might be changed. However, most preferably, the time of transmission of the distress signals is varied.

Both the distress signal and the control signal are generally sent over the same wireless communications network. Typically, the beacon is an

EPIRB or such like and the signals are sent via satellite. In other words, the wireless communications network may be a satellite communications network. However, the wireless communications network may additionally or alternatively include "line of sight" or "terrestrial" communications, such as radio transceivers on board aircraft or boats. This arrangement allows the interval between distress signals to be controlled initially via a satellite, and, once a rescue craft gets close to the beacon, from the rescue craft. The beacon may include any or all of a radar transponder, a light source, an acoustic alarm and a homing beacon. It is preferred that any or all of these are also remotely controllable. The acoustic alarm may be of assistance in finding the stranded party in foggy conditions, whilst the light may be of assistance in a night search operation,

Preferably the beacon comprises a floating buoy. However, it should also be appreciated that the present invention can be adapted for inclusion on an aircraft, or fitted directly to a life boat. In these embodiments suitable activation means are required. For example, the beacon may automatically activate once the lifeboat is jettisoned.

Expressed in another way, the invention also provides an emergency radio beacon including transmitting and receiving means capable of sending and receiving a signal over a wireless communications network, characterised in that the signal transmitting means is capable of being controlled from a remote position.

According to the invention, there is also provided an emergency radio beacon comprising an automatic distress detector, a transmitter, responsive to the distress detector, to transmit a distress signal over a wireless network, a receiver for receiving a control signal over the wireless network and, in response to reception of the control signal, modifying the transmission of the distress signal.

According to the invention, there is also provided an emergency radio beacon including means to automatically activate on detection of a distress condition and transmitting and receiving devices arranged to allow a two way wireless communication between the emergency radio beacon and a remote location.

According to the invention, there is also provided a method of controlling an emergency radio beacon with means of emitting a distress signal, comprising in response to reception of the distress signal, establishing a two-way communications channel to the emergency beacon over a wireless communications network and controlling the distress signal transmitting means. The above and further features of the present invention are set forth with particularity on the appended claims and together with advantages thereof will become clearer from consideration of the following detailed description of exemplary embodiments of the present invention made with reference to the accompanying drawings.

Brief description of the Drawings In the drawings:

Figure 1 is an illustration of a emergency communications system in accordance with an embodiment of the present invention; and Figure 2 is a diagrammatical representation of an emergency beacon in accordance with an embodiment of the present invention. Detailed Description of the Preferred Embodiments

The examples below are described with reference to the Inmarsat E+ Emergency Position Indicating Radio Beacon (EPIRB) system. However, it should be understood that the invention is applicable to many types of distress signal transmission systems, such as the Cosmitscheskaja Sistema Poiska

Awarinitsch Sudow (Russian for space system for search of vessels in distress) / Search And Rescue Satellite Aided Tracking COSPAS/SARSAT system.

Referring to Figure 1, an emergency communication system comprises an emergency beacon, which in this example is an EPIRB 1, a satellite 2 and a satellite land earth station (LES) 3. There may be several satellites 2 and

LESs 3 in the communications system, but just one of each is shown in this example for clarity. A control centre, which in this example is referred to as a

Maritime Rescue Coordinating Centre (MRCC) (not shown), is also arranged to communicate with the EPIRB 1 and LES 3 via satellite 2, although communication between the MRCC and the LES 2 can be via conventional terrestrial telecommunications if desired. A representative two-way communications link is shown between the LES 3 and the EPIRB 1. Also shown is rescue craft, which in this example is an aircraft 4, but could be any other suitable vehicle including a boat.

Referring to figure 2, the EPIRB 1 has a first antenna 5 associated with a Global Positioning System (GPS) receiver 6. The first antenna 5 and GPS receiver 6 are adapted to receive signals from GPS satellites (not shown) and input position data to a first processor 7. The first processor 7 can use the position data to calculate the EPIRB's position, as known in the prior art. A transmitter 8 is connected to receive the calculated position from the first processor 7 and to transmit a distress signal, including the calculated position, to the LES 3 via the first antenna 5 and satellite 2.

The EPIRB 1 also has a second antenna 9 associated with a communications receiver 10 and a second processor 11. The second antenna 8 is adapted to receive signals sent by the LES 3 via the satellite 2. In this example, radio receiver 10 is a conventional super heterodyne receiver. It should be appreciated that first and second processors 7, 11 can be combined in a single processor and, likewise, first and second antennas 5, 9 can be combined in a single antenna to save space.

The EPIRB 1 usually has a waterproof case (not shown). Typically, it is mountable on a boat or aircraft, although in other examples the EPIRB 1 may be designed to be carried by an individual person as a personal distress beacon. As well as the components described above, the EPIRB 1 can have an acoustic alarm 12, a light 13 and/or a radar transponder 14. These components are connected such that they can be controlled by, and in particular activated and deactivated by, second processor 11. The radar transponder 14 is, in this example, operable as a Search and Rescue

Transponder (SART), as known in the prior art. The EPIRB 1 is powered by a battery (not shown) and, optionally, by an additional photovoltaic cell, i.e. by solar power. In an emergency, the boat, aircraft or person carrying the EPIRB 1 may need to alert search and rescue authorities using the EPIRB 1. Activation of the EPIRB 1 can be initiated manually. For example, it may be mounted such when it is released, for example by either being physically removed from its mounting and thrown overboard from a boat or by being released from its mounting remotely from a ship's bridge, it automatically activates. In addition, the EPERB 1 can be mounted such that if a boat on which it is carried becomes waterlogged or sinks, then the EPIRB 1 can float free of its mounting and automatically activate. Automatic activation can be provided by an immersion switch (not shown) which is switched on by immersion in salt water (i.e. the sea).

Upon activation, the first processor 7 initiates sending of a distress signal. More specifically, the first processor 7 calculates the position of the EPIRB 1 using the position data received by the first antenna 5 and the GPS receiver 6. The first processor 7 outputs the calculated position to the transmitter 8, which sends the distress signal via the antenna 5. The distress signal is then sent periodically, i.e. sent at intervals, such as every hour (60 minutes). The interval is regulated by a timer (not shown), typically integrated with the processor 7. Each time a distress signal is sent, it includes an up to date indication of the EPRIB's position, calculated by the first processor 7.

The Inmarsat E and Inmarsat E+ EPIRB systems reserve 667 channels in the L-band (approximately 1.6 GHz) for transmission of signals from EPIRBs 1 to satellites 2. In this example, the EPIRB 1 is therefore capable of transmitting the distress signal in any one of these channels, which are numbered from channel 000 to channel 666 where channel 000 is at 1645.6000 MHz, channel 666 is at 1645.7998 MHz and the channels in between are spaced by 300 Hz. However, each EPIRB 1 is actually programmed to transmit the distress signal in one of channels 349 to 479 first. Different EPIRBs 1 are programmed to use different channels first. The EPIRB 1 then changes the channel of transmission of each subsequent transmission of the distress signal according to a known algorithm. Dispersing the transmission of distress signals amongst the different channels improves the reliability with which distress signals are received by the satellite 2 in the presence of interference.

When a distress signal is received by the satellite 2, the satellite 2 relays the distress signal to the LES 3 in a downlink channel. The LES 3 transmits the distress signal back to the satellite 2 in an uplink channel and the satellite then broadcasts the distress signal in a specified return channel, usually at 1544.2300 MHz, although 1544.2100 MHz can also be used. Consequently, the distress signal is re-transmitted over the whole of the satellite's coverage area.

In this example, the MRCC receives the re-transmitted distress signal from the satellite 2, although in other examples the LES 3 relays the distress signal to the MRCC via conventional terrestrial communications. The distress signal includes a code, unique to the particular EPIRB 1, which is used by the MRCC to identify the EPIRB 1 transmitting the distress signal. The MRCC holds records, typically in a look-up table or database, identifying the EPIRB 1 that is programmed to use each unique code. Provided the EPIRB 1 transmitting the distress signal has been registered to the boat that carries it, the MRCC can identify the boat in distress and which particular EPIRB 1, should the boat be carrying more than one, is transmitting the signal. Personnel at the MRCC can then coordinate a search and rescue operation using the position data included in the distress signal and the boat's identification. The signal re-transmitted by the LES 3 is also received at the antenna 9 of the EPIRB 1. The receiver 10 filters and amplifies the retransmitted signal to a level suitable for demodulation and decoding, using digital and/or analogue techniques where appropriate, and outputs the demodulated signal to second processor 11. The second processor 11 has a record of the EPIRB 's unique code and is programmed to compare the code in the received signal with the EPIRB 's stored unique code. When the processor 11 detects that the EPIRB 's unique code matches that of the received signal, it activates the light 13 or acoustic alarm 12 to acknowledge that the distress signal has been received. In the event that a survivor is near the EPTRB 1, the survivor is therefore re-assured that the distress signal has been received. Re-transmitted signals concerning other EPIRBs are ignored.

The MRCC can send control signals to the EPIRB 1 to vary its operation. Generally, personnel at the MRCC monitor the search and rescue operation and initiate the sending of control signals when appropriate. However, control signals can also be sent automatically.

Each control signal includes the EPIRB 's unique code and a command. In this example, the control signals are sent by the MRCC to the satellite 2 in an uplink channel. In another example, the control signals are sent by the MRCC to the LES 3 and then to the satellite 2 by the LES 3 in an uplink channel. The satellite 2 then broadcasts the control signals in the return channel, i.e. at 1544.2300 MHz or 1544.2100 MHz.

The control signals are received at second antenna 9 of the EPIRB 1, amplified and demodulated by communications receiver 10 and output to second processor 11. Second processor 11 compares the code in the received control signal with the EPIRB 's unique code. When the second processor 11 detects that the EPIRB's unique code matches that of the received control signal, it processes the command in the signal as appropriate. Control signals that do not include the EPIRB's unique code are ignored.

Particular responses to the commands are stored or pre-programmed in the second processor 11. Particular commands include varying the interval between transmissions of the distress signal by the EPIRB 1 to any length of time between one minute and three hours; and requesting the EPIRB 1 to send a distress signal immediately, for example to double-check the EPIRB's position.

The command is basically a code that can be recognised by the second processor 11. The second processor 11 stores actions to be taken along with corresponding command codes. For example, when a command code corresponding to immediate transmission of a distress signal is received, the second processor 11 looks up the appropriate action, i.e. causing the first processor 7 to send a distress signal via transmitter 8 and antenna 5 straightaway, and carries it out. Similarly, if the command code corresponds to changing the periodicity of the transmission of the distress signal, the second processor 11 alters the timer setting to the appropriate period.

An internal battery (not shown) powers the EPIRB 1. By controlling the periodicity of the distress signals the life of the internal battery can be conserved. For example, after receiving the first distress signal, the MRCC can send a control signal that increases the period between transmissions of subsequent distress signals to say three hours or longer to conserve battery power. When the first rescue craft is say an hour away from the position included in the latest distress signal, the MRCC can send another control signal requesting the EPRIB to send a distress signal straightaway and the rescue craft can then be directed to the position in the newly received distress signal. Subsequently, the MRCC can send a control signal that decreases the period between transmissions of subsequent distress signals to say ten minutes so that the MRCC can provide the rescue craft with frequent position updates. Thus, battery power is conserved when the transmission of distress signals is less useful and frequent distress signals are sent when the rescue craft is close to the EPIRB 1 to improve the efficiency with which the close quarters search can be carried out. This optimises use of the EPIRB's power supply and reduces risk if the battery expiring before the EPIRB 1 has been reached by a rescue craft.^'

In order to reduce battery consumption, in this example the communications receiver 10 operates only for regular pre-defined periods. These periods are, in this example, synchronised to the time at which the

EPIRB 1 sends distress signals. The MRCC and LES 3 can therefore synchronise the time at which they send control signals to the EPIRB 1 to the expected times at which the receiver 10 is activated if desired.

The acoustic alarm 12, light 13 and radar transponder 14 are also controllable by the second processor 11 in response to the receipt of control signals. These devices can therefore be controlled by the MRCC and LES 3 in a similar way to the transmission of the distress signal. In other words, second processor 11 is pre-programmed to recognise the command codes sent to it from the MRCC and LES 3, and to control the appropriate device on receipt of such a command. The acoustic alarm 12, light 13 or radar transponder 14 can be turned on or off by appropriate control signals. For example, in bad visibility, when a rescue craft is close to the EPIRB 1, the light 13 and acoustic alarm 12 can be turned on to aid location of the EPIRB 1. Similarly, when a search and rescue operation comes to an end without the EPIRB being located, the radar transponder can be turned off to avoid other vessels detecting unnecessary radar transponder signals from the EPIRB 1 on their radars. During search and rescue operations, it can be also desirable for the EPIRB 1 to be controlled from a rescue craft, such as the aircraft 4. Consequently, the aircraft 4 is also equipped with a transmitter for sending control signals to the EPIRB 1. In this example, the aircraft's transmitter is able to send control signals in the same return channels as the satellite 2, i.e. at 1544.2300 MHz or 1544.2100 MHz. The second antenna 9 and communications receiver 10 are therefore able to receive control signals from the aircraft 4. In other examples, the aircraft's transmitter sends control signals in another communications link and the second antenna 9 and communications receiver 10 are adapted to receive control signals from the satellite 2 and the aircraft 4 in different communications links. In yet another example, the EPRTB 1 has an additional VHF antenna and an additional NHF receiver for receiving control signals from aircraft 4. A switch (not shown) for switching between receiving signals from the satellite 2 or the aircraft 4 can be incorporated in the EPIRB 1 and controlled by the transmission of appropriate control signals if desired.

It is to be understood that the above embodiments are described by way of example only and that many modification and variations are possible within the scope of the present invention.

Claims

1. An emergency beacon comprising a transmitter for transmitting distress signals over a wireless communications network; a receiver for receiving a control signal over the wireless communications network; and a processor for varying transmission of the distress signals in response to the received control signal.

2. An emergency beacon comprising a transmitter for sending distress signals over a wireless communications network; a receiver for receiving a control signal; and a processor for varying operation of the beacon in response to the received control signal.

3. The emergency beacon of claim 1 or claim 2, wherein the transmitter is adapted to transmit a first distress signal upon activation of the beacon and the processor is adapted to vary transmission of subsequent distress signals in response to the received control signal.

4. The emergency beacon of any one of the preceding claims, wherein the transmitter is adapted to transmit the distress signals periodically and the processor is adapted to vary an interval between transmissions of the distress signals in response to the received control signal.

5. The emergency beacon of any one of the preceding claims, further comprising a position determining device for determining the position of the beacon and wherein the transmitter is adapted to include an indication of the determined position in the distress signals.

6. The emergency beacon of any one of the preceding claims, further comprising a position indicating device and wherein the processor is adapted to vary operation of the position indicating device in response to the received control signal.

7. The emergency beacon of claim 6, wherein the position indicating device is a light, an acoustic alarm or a radar transponder.

8. The emergency beacon of any one of the preceding claims, wherein the transmitter is adapted to transmit the distress signals and receiver is adapted to receive the control signal via a satellite.

9. The emergency beacon of any one of the preceding claims, wherein the receiver is adapted to receive the control signal via line of sight communication.

10. The emergency beacon of any one of the preceding claims, wherein the receiver is adapted to operate only periodically to conserve power.

11. The emergency beacon of any one of the preceding claim, housed in a waterproof case and being powered by an integral power supply.

12. A buoy including the emergency beacon of any one of the preceding claims.

13. Use of the buoy of claim 12 on a vessel.

14. A search and rescue control station comprising a receiver for receiving distress signals from an emergency beacon over a wireless communications network and a transmitter for transmitting a control signal over the wireless communications network to cause the beacon to vary transmission of the distress signals.

15. A search and rescue control station comprising a receiver for receiving distress signals from an emergency beacon over a wireless communications network and a transmitter for transmitting a control signal to cause the beacon to vary its operation.

16. The search and rescue control station of claim 14 or claim 15, wherein the transmitter is adapted to transmit, in response to receipt of a first distress signal by the receiver, a control signal to cause the beacon to vary transmission of subsequent distress signals.

17. The search and rescue control station of any one of claims 14 to 16, wherein the transmitter is adapted to transmit a control signal to cause the beacon to vary an interval between transmissions of the distress signals.

18. The search and rescue control station of any one of claims 14 to 17, wherein the transmitter is adapted to transmit a control signal to cause the beacon to vary operation of a position indicating device.

19. The search and rescue control station of any one of claims 14 to 18, wherein the receiver is adapted to receive the distress signals and transmitter is adapted to transmit the control signal via a satellite.

20. The search and rescue control station of any one of claims 14 to 19, wherein the transmitter is adapted to transmit the control signal via line of sight communication.

21. A method of operating an emergency beacon, the method comprising: transmitting distress signals over a wireless communications network; receiving a control signal over the wireless communications network; and varying transmission of the distress signals in response to the received control signal.

22. A method of operating an emergency beacon, the method comprising transmitting distress signals over a wireless communications network; receiving a control signal; and varying operation of the beacon in response to the received control signal.

23. The method of claim 21 or claim 22, comprising transmitting a first distress signal and varying transmission of subsequent distress signals in response to the received control signal.

24. The method of any one of claims 21 to 23, comprising transmitting the distress signals periodically and varying an interval between transmissions, of the distress signals in response to the received control signal.

25. The method of any one of claims 21 to 24, comprising determining the position of the beacon and including an indication of the determined position in the distress signals.

26. The method of any one of claims 21 to 25, comprising varying operation of a position indicating device in response to the received control signal.

27. The method of claim 26, wherein the position indicating device is a light, an acoustic alarm or a radar transponder.

28. The method of any one of claims 21 to 27, comprising transmitting the distress signals and receiving the control signal via a satellite.

29. The method of any one of claims 21 to 28, comprising receiving the control signal via line of sight communication.

30. The method of any one of claims 21 to 29, comprising controlling a receiver to operate only periodically to conserve power.

31. A method of controlling an emergency beacon, the method comprising receiving distress signals from the emergency beacon over a wireless communications network and transmitting a control signal over the wireless communications network to cause the beacon to vary transmission of the distress signals.

32. A method of controlling an emergency beacon, the method comprising receiving distress signals from the emergency beacon over a wireless communications network and transmitting a control signal to cause the beacon to vary its operation.

33. The method of claim 31 or claim 32, comprising transmitting, in response to receipt of a first distress, a control signal to cause the beacon to vary transmission of subsequent distress signals.

34. The method of any one of claims 31 to 33, comprising transmitting a control signal to cause the beacon to vary an interval between transmissions of the distress signals.

35. The method of any one of claims 31 to 34, comprising transmitting a control signal to cause the beacon to vary operation of a position indicating device.

36. The method of any one of claims 31 to 35, comprising receiving the distress signals and transmitting the control signal via a satellite.

37. The method of any one of claims 31 to 36, comprising transmitting the control signal via line of sight communication.

38. An emergency beacon substantially as described with reference to any of the accompanying drawings.

39. A method substantially as described with reference to any of the accompanying drawings.