METHOD AND SYSTEM FOR LOCATING A SIGNAL TRANSMITTING DEVICE

Abstract: A method for positioning an instrument (1, 2, 3) transmitting a signal on an area containing communicational base stations, whereby in a position-finding situation the instrument is intercommunicating with some nearby base station and from the said station there is information related to position-finding accessible to the control central involved in position-finding or to the position-finder. In the method the instrument transmits a signal travelling through the base station network, whereby the ID data of the base station that transmitted the signal in the said network is transmitted to the position-finder and the final positioning of the instrument (1, 2, 3) is carried out on the coverage area of the base station that made the transmission by means of accessible direction-finding equipment.

Description: METHOD AND SYSTEM FOR LOCATING A SIGNAL TRANSMITTING DEVICE The invention relates to a positioning method defined in the introduction chapter of patent claim 1 and to a positioning system defined in the introduction chapter of patent claim 7. Previously known are several positioning methods for locating an instrument transmitting signals in the terrain. The most simple method used for positioning is position-finding by means of one or several direction finder antennas based on RF technology. The position of the object can then be specified on map or, alternatively, one can seek one's way to the object itself in the terrain by means of the direction. A positioning method, now rapidly generalizing, is the GPS System (Global Position System) , a global navigation and positioning system based on the evaluation of time and distance. It is formed of several satellites revolving about the earth, with a revolving time of about 11 hours. The satellites transmit a radio signal on two frequencies. Both of the carrier waves contain updated information about the satellite orbit as well as time signals. In order to carry out positioning, a position-finding instrument compatible with the system is needed for receipt of data transmitted by satellites. On basis of data received the position co-ordinates of the instrument are specified. The disadvantage of the GPS system is the high price of the equipment and great power consumption. The instrument requires a user, who finds out his position by means of the instrument. For instance, the instrument is not suited to be concealed in articles of value in order to find out their position in cases of theft. Limited capacity is a further disadvantage of the instrument, since the instrument requires direct eye contact to three satellites, at least. Therefore, an instrument indoors cannot work as a position-finding instrument. Further, from the printed Finnish application FI-964869 a positioning method is known using the mobile telephone network in a pre-set set of co-ordinates, in which method at least three base stations and the mobile telephone are used and, by means of the distances of the mobile telephone, the position of the mobile telephone is specified from different base stations, when the location of the base stations is known as co-ordinate data. In the first place, the equipment is well suited as a position indicating system for the user of a mobile telephone. The only restriction is that connection to at least three base stations is required. The method according to this invention is characterized in that a concealed or a public object transmits or is activated to transmit a signal, as a regular phone call, travelling over the signal transmitting base station network. The ID data of the base station of said network, which performed the transmission, is transmitted to the phone call receiver, control centre or the position-finder either from said base station or as information from the operator of the base station network and in the second stage the final positioning of the instrument is carried out on the coverage area of the base station that transmitted the phone call on basis of the direction-finding signal from the transmitter in the instrument by means of the direction-finding equipment accessible to the position-finder. Other embodiments of the method and system according to the invention are presented in the subclaims . The advantage of the method and system according to the invention is that it uses two known techniques combined into a unity so that the instrument detects the position by two different methods and two different signal frequencies. The user must neither build any direction finders to be installed in the towers nor any activation networks for the transmitter in the instrument, since the system works everywhere, where a mobile telephone system implemented by a cellular system, a GSM system, for instance, is in function. The invention is suitable especially as a safety transmitter, which can be activated in many ways and concealed in the object thanks to its small size and small need for antennas. The system is suitable for official use, when with the position finding method information is directed only for the use of a certain quarter. Two separate positioning methods included in the arrangement function independently also in case that either one is disturbed on the frequency it uses. The RF transmitter and GSM transmitter can be concealed as separate components in the object, whereby they communicate wirelessly with one another. In the following the invention is disclosed with reference to the enclosed figures, where Fig. 1 is a diagrammatic presentation of an example of one embodiment as per the invention. Fig. 2 is a diagrammatic presentation of the instrument and a base station. Figure 1 shows a set of components as per the invention that can be concealed in a car. The set includes a transmitter 1 most suitably working within a frequency range from 150 to 1800 MHz. When transmitter 1 has been activated by a burglar alarm in the car it starts to transmit a message including its own ID code and the direction-finding signal. From the transmitter ID code the identification data of transmitter can be found out and, in addition, data of the car or its owner, the instrument working as his/hers protection against burglary in this case. By means of the direction-finding signal from transmitter 1 the position of the car can be manually located for good from the terrain, a search car, a helicopter or by means of automatic mast direction-finders. Depending on the location of the transmitter, it can be activated by means of a burglary system, a motion detector, or by remote control, for instance over the telephone network or manually. There is, in association with transmitter 1, an adapter 2 receiving a code formed by different alarms from transmitter 1 and this adapter is also activating unit 3 (Cellular Card Telephone) that works in joint operation with the GSM network. Unit 3 transmits, even if necessary, also an image in the GSM network. The signalling function (CCP) contained in unit 3 is activated for position finding, whereby it transmits alarm information over the GSM network to an agreed address over base station 6. Most suitably a telephone number can be used as an agreed address to which it transmits a data signal or an alarm message. The signal contains the code, location data, the serial number or similar data of the base station of the cellular network, on whose area unit 3 is at that moment. On the basis of the message, the owner of the missing car, a security service or an authority 4 receive the signal and also information of the GSM base station area where the object is at the moment. Information is transmitted over the GSM network from the object generally in a few minutes to someone of the said superviser. Authority 4 or the control centre that has received the signal over the telephone can follow the mobile object by means of the cellular network (GSM) on the basis of collected information all over the land, while the object is moving from one base station to another within the cellular network. If, for some reason, the object disappears from the GSM base station network area, information from the last GSM base station used by the object still remains by the supervising authority. Accurate positioning of transmitter 1 and object is, for instance, carried out by patrol 5 which, at the right moment, is sent by the authorities to locate by means of direction finders the position of the object. The direction finding range is about 3 - 20 km and accuracy of positioning even 20 cm. When, for instance, reckoned from the alarm, the transmitter stays in working order for 1 - 3 days there will be enough time for the problem. It is to be noted that the object, transmitter 1 and unit 3 can be indoors, even in cellarages, with hardly any disturbance on position finding. The instrument comprised of parts 1,2 and 3 can be concealed in an article of value, a person, an animal, money deliveries, the position of which should be located for some reason. The telephone network to be used must be a public data network and the information of its base station network must be accessible to the system. Presently the GSM network is the most suitable mobile telephone network for a system according to the invention. Figure 2 shows communication between transmitter 1, adapter 2 and GSM unit 3. The GSM unit communicates over base station 6. Transmitter 1 can contain a camera, whereby the activated system can transmit an image to the control centre. Instruments 1, 2 and 3 can form a compact unity or transmitter 1 can be separated from parts 2 and 3. Communication between transmitter and parts 2 and 3 is then wireless. In another embodiment activation of the instrument takes place over the telephone network, whereby the GSM unit 3 is activated to call itself the selected address and also over adapter 2 to activate transmitter 1 to give the direction finding signal. In one embodiment the base station 6 or the cellular net operator can add to the alarm signal addressed to the control centre information of the signal intencity or of a similar selective factor observed by the cellular network on base station 6 area. Further, base station 6 can add to the signal information of the second strongest base station observed by the GSM unit, by means of which fact the location of the instrument on the area can be specified. Further, the base station or the operator can add to the signal information of the distance of the GSM unit from base station 6. The distance can be specified in a way known per se from the added time of the signal from the base station and its return, for instance. Yet, the final positioning of the object is done by means of the direction-finding signal. The instrument is very small, it can be easily produced, for instance, within size range 10 x 50 x 120 (mm) , whereby it can be concealed in objects as a safety device. In one embodiment the instrument can be activated and deactivated to transmit a signal only at times by remote control, whereby the position-finders alone are aware of the switched-on moment and able to carry out direction measurings within that time. This arrangement is battery-saving and the instrument remains better concealed. Activation can be done over the telephone network or over the direction-finding equipment.

Claims: CLAIMS 1. A method for positioning an instrument (1, 2, 3) transmitting a signal on an area containing communicational base stations (6), whereby in a position finding situation the instrument is intercommunicating with some nearby base station (6) and from the said station there is information related to position finding accessible to the control central (4) involved in positioning or to the position-finder (5), c h a r a c t e r i z e d in that in the method - with phone (3) unit, that belongs to the instrument, a phone message is sent over the communicative base station network, - the ID code data of the said network base station (6) that transmitted the signal is included in the phone message or transmitted to the control centre or position-finder either from the said base station or as information by the operator of the base station, - final positioning of instrument (1,2,3) is carried out on the coverage area of the base station that made the transmission and on basis of the direction-finding signal from transmitter (1) by means of direction-finding equipment accessible to the position-finder (5) . 2. A method according to claim 1 c h a r a c t e r i z e d in that the mobile phone cellular net, most suitably the GSM net, works as communication network. 3. A method according to claim 1 and 2 c h a r a c t e r i z e d in that the instrument is placed in an object, the travel of which one wants to control geographically or objects liable to thefts or illicit use and the position of the object should be found. 4. A method according to any of the above claims 1 - 3 c ar a c t e r i z e d in that transmitter (1) is activated manually or by means of a burglary system, motion detector, remote control or phone unit (3) . 5. A method according to any of the above claims 1 - 4 c h ar a c t e r i z e d in that phone unit (3) Cellular Card Phone (CCP) , connected to the instrument, transmits after activation a signal to a pre-set address, such as a phone number, and that information of the instrument location, i.e. ID data of the base station used by phone unit (3), is included in the signal. 6. A method according to any of the above claims 1 - 5 c h ar a c t e r i z e d in that transmitter (1) and phone unit (3) (CCP) are in different places in the object, thus working independently and intercommunicating wirelessly. 7. A system for positioning an instrument (1, 2, 3) transmitting a signal on an area containing communicational base stations c h a r a c t e r i z e d in that the system is comprised of a transmitter (1) and a phone unit (3) and, capable of intercommunication with them, an adapter (2) transmitting different alarm signals between transmitter (1) and phone (3) at least in one direction, whereby phone unit (3) (Cellular Card Phone) becomes activated for intercommunication with base station (6) in the telephone system, and that phone unit (3) is arranged to send to the control centre (4) involved in position-finding a signal of the alarm that includes the base station ID data and that the system comprises a direction-finding equipment, such as directional antennas and a receiver for more accurate positioning on the said specified coverage area of base station (6) on basis of the direction-finding signal given by transmitter (1) . 8. A system according to claim 7 c h a r a c t e r i z e d in that the communication base stations are base stations of the mobile telephone network, most suitably base stations of the GSM net. 9. A system according to claim 7 and 8 c h a r a c t e r i ze d in that the instrument (1,2,3) includes a function for receiving an activation impulse from a burglary system, motion detector, by remote control or from the alarm switch, in order to start transmission of signal by transmitter (1) and/or to transmit the alarm signal by phone unit (3) . 10. A system according to any of the above claims 7 - 8 c ar a c t e r i z e d in that activation in the system takes place over the telephone network to phone unit (3) , further activating transmitter (1) into transmission state.

Inventors: KARINTAUS HEIKKI, KARINTAUS, HEIKKI
Applicants: TRACKSEC LTD OY, OY TRACKSEC LTD.
Application year: 1998
Main classification: H04Q7
IPC codes: G01S3, G01S5