Position locating device and position determining system

Field of the invention

The present invention relates to a position locating device for determining and transmitting its own position, and a position determining system comprising the position locating device and a base station for receiving transmissions from the position locating device

Background to the invention There are a number of situations in which a device which can transmit its position to a base station may be useful Particularly, such a device would be invaluable in a case of an emergency where it may be necessary to deploy search and rescue units to assist a person in distress or in need of assistance

Such situations may involve remote locations where a standard mobile telephone network has no coverage, and other forms of radio communication lack sufficient range to any nearby assistance Examples include skiers or mountain climbers on a mountain, drivers in remote regions such as deserts or yachtsmen at sea, or a crashed aeroplane Furthermore, in such situations, even if a person was able to obtain voice communication with a rescue unit via radio or telephone, they may be incapable of describing their location as they may be incapacitated or separated from instruments which can determine their location This may be the case if skiers or mountain climbers have been caught in an avalanche or a boat has been capsized in a storm Furthermore, drivers in remote regions, such as aid workers or oil workers may be in a kidnap situation

A device which can be activated to automatically determine and transmit its position would be useful in such situations, but would also be useful to any drivers, in the case of, for instance, a breakdown in a remote location late at night

Summary of the invention

The present invention provides a position locating device comprising

position determining means for periodically determining a position of the device and storing position data in a memory, position transmitting means for, on activation, periodically transmitting a terminal identifier and position data to a satellite, and power management means comprising means for setting the periodicity of the transmission by the position transmitting means

The transmission of the terminal identifier and position data allows a receiving party to identify the particular device which is transmitting the signal and to locate its position The periodic transmission allows a receiving party to follow the device if it is moving However, each transmission of data will deplete a power source of the device Therefore, the device allows the periodicity of the transmission to be set to a level which is appropriate for the circumstances of the use of the device In some circumstances of use, it is likely that a first responder such as a rescue unit may take a long time to reach the position locating device, such as if the device is used in a very remote location In such circumstances, it is important that the battery power be conserved and therefore a longer period between transmissions may be set In other circumstances, there is a high likelihood that the device will be moving, such as on a yacht, and therefore shorter periods between transmission may be more appropriate to enable accurate tracking of the device

Preferably, on activation, the position transmitting means immediately retrieves the most recently stored position data from the memory and transmits the most recently stored position data and the terminal identifier as an initial transmission Therefore, even if, for instance, the position determining means determines a position of the device every thirty minutes, and the device is activated twenty-eight minutes from the last position determination, the device immediately transmits the last position to the satellite Thus, a receiving party can be notified immediately that a user of the device is in distress and initiate a response, even if the initial position data may not be the most accurate up-to-date position The first responder, when notified, will shortly obtain a more accurate position when the next transmission of position data takes place

The position determining means may change the frequency of the position determination after the device is activated In particular, the position determining means may increase the frequency of position determination after activation of the device

Preferably, the position determining means comprises a GPS receiver The GPS receiver receives position and timing information from GPS satellites and stores the GPS data in a memory Other forms of position determining means may be used In particular, other satellite navigation systems such as Galileo may be used

Preferably, the position transmitting means transmits the terminal identifier and position data to an IRIDIUM satellite The IRIDIUM satellites are low earth orbiting satellites which relay the data to its destination, such as a base station

Preferably, the position locating device comprises a rechargeable power source Preferably, the device further comprises a solar cell configured to recharge the power source

Preferably, the device further comprises encrypting means for encrypting the terminal identifier and position data before transmission Preferably the encryption means encrypts the data according to the Advanced Encryption Standard

Preferably, the device further comprising means for receiving a position request from a satellite and, in response to receipt of the position request, transmitting the terminal identifier and position data Thus, the base station can send a request for position information to the device at any time after activation of the device to obtain its current position

Preferably, the position locating device includes means for receiving a setting command from a base station via a satellite, wherein the power management means sets the periodicity of the transmission based on the setting command Thus, the periodicity of the transmission can be set remotely by a receiving party For instance, if a receiving party determines that the position locating device is in an

area which is very remote and a rescue unit or response unit may take a long time to reach the position locating device, then the receiving party can adjust the periodicity of the transmission to provide a longer period between transmission and thus conserve battery power Alternatively, if a receiving party realises that a rescue unit can reach the position locating device quickly and particularly if it notes that the position locating device is moving, then the frequency of transmissions can be increased to provide more detailed monitoring of the position

Preferably, the position locating device comprises means for receiving from a satellite a message and display means for displaying the message Therefore, the position locating device can receive messages from a receiving party For instance, the receiving party may send a message indicating when a rescue can be expected Alternatively, if a receiving party determines that the position locating device is in a region inconvenient for rescue, such as an area where a helicopter cannot land, it can send a message to the position locating device directing the user to a nearby region where rescue is more convenient Similarly, a receiving party can direct the user to a nearby settlement where medical assistance may be available or a nearby water source

Preferably, the device comprises means for monitoring the output of a power source, wherein the periodicity of the transmission is set dependent on the output of the power source Preferably, if the power source output is low, a time interval between transmissions is increased Thus the device can automatically conserve battery power by reducing the number of transmissions

Preferably, the device comprises means for comparing position data determined at intervals, wherein the periodicity of the transmission is set dependent on a change in the position data Preferably, if the device is determined to be moving by comparison of the position data, a time interval between transmissions is decreased Thus, the device can automatically conserve battery power by reducing transmissions if the device is stationary and hence less position data is required to track the device The present invention further provides a position determining

system comprising a position determining device as set out above and a base station comprising position receiving means for receiving the terminal identifier and position data from a satellite, and contact means for contacting a first responder identifying the position determining device and its position

Preferably, the contact means contacts the first responder by telephone or email

Preferably, the contact means includes storage means storing contact details of a plurality of responders and, if no response is received from the first responder, the contact means contacts a second responder If the second responder does not respond, then the contact means can contact a third responder, and so on

Preferably, the base station comprises decryption means for decrypting the received terminal identifier and position data

Preferably, the base station comprises means for transmitting a setting command to the position locating device via a satellite, wherein the power management means sets the periodicity of the transmission based on the setting command

Preferably, the base station comprises means for transmitting a position request to the position locating device via a satellite wherein, in response to receipt of the position request, the position transmitting means transmits the terminal identifier and position data

Brief description of the drawings

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which Figure 1 illustrates a position determining system including a position locating device in accordance with the present invention,

Figure 2 illustrates schematically the components of a position locating device in accordance with the present invention,

Figure 3 is a flow diagram illustrating a method of operation of the position location device, and

Figure 4 is a perspective view of the device of Figure 2

Detailed description

Figure 1 illustrates a position determining system comprising a position determining device 1 which may be carried by a user or placed in a vehicle such as a car, boat or aeroplane, and a base station 2 for receiving transmissions from the position locating device 1 and for contacting a first responder 3a and/or a plurality of further responders 3b, 3c, 3d

The position locating device 1 is in communication with two satellite systems The first satellite system is the GPS satellite system 4 for providing position information, and the second satellite system comprises the IRIDIUM satellite system 5, for relaying communications between the position locating device 1 and the base station 2 The position locating device 1 periodically receives position information from a GPS satellite 4a and, on activation, periodically transmits position data together with a terminal identifier which identifies the particular device to an IRIDIUM satellite 5a

The transmitted data also includes a destination identifier which allows the satellite 5a to forward the data by relaying it, either directly or via one or more other satellite 5b in the IRIDIUM system 5, to the base station 2 The base station 2 can contact the first and subsequent responders 3a-3d by a number of means of communication The base station 2 may contact the first responder 3a by means of the IRIDIUM satellite system 5, or by telephone or email or radio communication The base station includes stored contact details for the responders 3a-3d, and sends a message first to the first responder 3a, including information identifying the position locating device 1 which has been activated and its position determined from the received position data If the base station 2 receives no response from the first responder 3a, then it contacts the second responder 3b If no response is received from the second responder 3b, then the base station 2 retrieves details of, and contacts, a third responder 3c, and so on Once one of the responders

responds, the base station 2 opens communication with that entity and forwards future received position data to that entity

Figures 2 and 4 illustrate in more detail the components of the position locating device 1 , which is a hand held device which may for example be placed on the dashboard of a vehicle The position locating device 1 comprises a main processor 20 The device 1 further comprises a position determining means in the form of a GPS receiver 21 which periodically receives position data from the GPS satellite 4a The position data is stored in a memory 22

The device 1 further comprises a power management means 23 The device 1 is powered by a power source comprising a rechargeable battery 24 The rechargeable battery 24 can be recharged via the power management means 23 from either a DC input 25 or a solar panel 26 mounted on the exterior of the position locating device 1 The exterior of the device 1 includes an on/off button 27, and an emergency activation button 28 and an LCD display 29 Both the on/off button 27 and the emergency activation button 28 may be covered by flip-up covers to prevent accidental activation

The position locating device 1 further comprises encrypting means 30 and a position transmitting means 31

Figure 3 is a flow diagram illustrating the operation sequence of the device when the emergency activation button 28 is operated

On operation of the emergency activation button 28 at step S l , the main processor 20 immediately recalls the most recently stored position data from the memory 22 The position data comprises a 120 character string The main processor 20 adds a 20 character terminal identifier to form a 140 character string, and a destination identifier which identifies where the transmission is to be sent This information isforwarded to the encryption means 30 The encryption means 30 carries out encryption on the terminal identifier and the position data in accordance with the advanced encryption standard (AES) and the encrypted data and the destination

identifier is transmitted at step S2 by the position transmitting means 31 to the IRIDIUM satellite system 5

The main processor 20 recalls duty cycle data at step S3 from the power management means 23 The duty cycle data can be set in accordance with the circumstances in which the position determining device 1 is to be used The duty cycle data is used by the main controller 20 to determine the periodicity at which position data is transmitted by the position transmitting means 31 to the base station 2 via the IRIDIUM satellite system 5

The main processor 20 then controls the GPS receiver 21 to periodically update the position data stored in memory 22 (step S4) and to periodically retrieve position data from the memory 22 and to forward it to the encrypting means 30 for transmission by the position transmitting means 31 (step S5)

The base station 2 may also send messages or commands to the position determining device 1 via the IRIDIUM satellite system 5 once the position determining device 1 has been activated by pressing of the emergency button 28 The base station 2 may send a position request at any time after activation of the position determining device 1 When the position determining device 1 receives the position request, it immediately responds by transmitting the most recently stored position data and its terminal identifier to the base station 2 via the IRIDIUM satellite system 5

The base station 2 may also send a setting command which includes duty cycle data, commanding the position determining device to reset the duty cycle to a specified time interval for transmissions Thus if, for some reason, a receiving party decides that more or less frequent position data is required, they can control the duty cycle of the position determining device 1 accordingly

The base station 2 may also send messages to the position determining device 1, which may be displayed on a display such as an LCD display Therefore, the position locating device 1 can receive messages from the receiving party For

instance, the receiving party may send a message indicating when a rescue can be expected. Alternatively, if a receiving party determines that the position locating device 1 is in a region inconvenient for rescue, such as an area where a helicopter cannot land, it can send a message to the position locating device 1 directing the user to a nearby region where rescue is more convenient. Similarly, a receiving party can direct the user to a nearby settlement where medical assistance may be available or a nearby water source.

The main processor 20 may also be programmed to control the duty cycle by monitoring the position data or the power output of the battery 24. The output of the battery may be monitored and, if the battery output is low, a time interval between transmissions may be increased. Thus the device 1 can automatically conserve battery power by reducing the number of transmissions. Also, the main processor can be programmed to compare position data determined at time intervals, wherein the periodicity of the transmission is set dependent on a change in the position data. In particular, if the device 1 is determined to be moving by comparison of the position data, then in order to track the device 1 accurately, more frequent position data is required and therefore a time interval between transmissions is decreased. On the other hand, if the device is determined to be stationary, it is not necessary for a receiving party to receive such frequent position updates, and so the time interval between transmissions can be increased. Thus, the device can automatically conserve battery power by reducing transmissions if the device is stationary and hence less position data is required to track the device.

Both of the base station 2 and the position determining device 1 may be programmed with anti-spam and anti-spoof software to preclude unauthorised access