DEVICE AND METHOD FOR POSITION FINDING AND DEBITING OF RECEIVERS

Abstract: The present invention relates to a system and a device for position finding and debiting of a receiver (m). For the position finding a DGPS-system is utilized, where transmission of the correction signal is transmitted by PTM-G. The identity of the users are found by means of PTM-G because this is allowed via this system. In DGPS signals from satellites which are received are utilized in mobile units (m) and correction stations (t). The latter calculate a correction factor which is utilized at the calculation of the position of the receiver (m). Calculation of the position is allowed to be made either in the correction station (t) of the receiver (m).

Description: TITLE OF THE INVENTION Device and method for position finding and debiting of receivers . TECHNICAL FIELD The present invention relates to position finding systems utilizing radio transmitters, the positions of which are known, for finding the current positions of receivers. For the purpose, primarily satellites are utilized, located in orbit round the globe, and the positions of which are known. TECHNICAL PROBLEM At differential GPS, a correction signal/correction factor must be calculated and transmitted to the receiver from a correction station. The characteristics of the correction signal are defined in international standard RTCM SC-104. In existing systems, special receivers are required, the positions of which are known, for calculation of correction factors, which are utilized by the receivers for calculation of one for the receiver corrected position. Because the correction factor is determined in a specific receiver, the information shall be transmitted from the receiver which calculates the correction factor to the receiver the position of which shall be found. For mobile telephones are, from authorities, expressed demands that the position shall be possible to indicate with a sufficiently high degree of accuracy. This demand originates from an ever increasing use of mobile telephones in emergencies where turnout of ambulance, fire brigade etc is required. A person alarming has in these situations in many cases no idea of his/her position, or is capable of giving such information. In existing position finding systems which utilize GPS, an accuracy of 100 m can be expected. In emergency cases this accuracy is not sufficient, because it can result in unnecessary delays at turnout to find the place in question. Accuracy as exact as about one meter is desirable. At the utilization of services at mobile telephony, there will be a need at the telecommunication operators to be able to debit users of mobile telephones for services where the position is important. This can for instance relate to navigation systems while traveling in vehicles of different kinds. It is in this connection of importance that the capacity in existing communication systems is not limited by the position finding system. PRIOR ART In order to find the position of a receiver, radio transmitters, the positions of which are known, are used. Different methods are at that used, on the one hand ground- based transmitters, on the other satellite stations. Examples of ground-based systems are triangulation, where bearings of at least three different stations are taken from a receiver. Satellite based systems are GPS (Global Positioning System), Figure 1, which is based on exact time and position information. Each satellite in the system transmits continuously information about time information and its position, which is received by the receivers. At finding/determining its position, the receiver listens to time and position information from a number of transmitters. The position is found by identification of the time intervals between the satellites and the receivers. By utilizing the information from at least three satellites it is possible to find the position of a receiver on the surface of the ground or in the air space. The found position is at that indicated as longitude, latitude and altitude. The from the transmitters transmitted signal follows a standard according to Standard Positioning Service, SPS, which is interfered by a signal SA, Selective Availability, at which the accuracy of the calculated position will be about 100 m. One development of the GPS-system is DGPS (Differential GPS), the aim of which is to overcome the SA-interference . This system utilizes one at the ground level located fixed receiver the exact position of which determined. The at the soil surface located receiver receives the signals from the transmitters and from them calculates correction factors which are forwarded to mobile receivers within a geographically defined area. This technology has made possible that the accuracy of the position finding has improved to about 10 m. The accuracy of the position finding is depending on the distance from the correction station. It accordingly is known that the accuracy is highest in the neighborhood of the correction station, and lower on the fringes of the coverage area of the correction station. To achieve sufficient accuracy, the coverage areas therefore are not allowed to exceed certain sizes. The receivers which shall find their positions shall in these cases have receivers for the signals of the satellites, and other receivers for reception of from the earth station transmitted correction information. Calculation of the position is made in a calculation module, which is arranged in, or is connected to, the receivers. The technology can without difficulties be applied in systems where the need for space and the weight are of secondary importance. In mobile telephones, respective position finding systems utilized by ordinary people, weight and size of the systems utilized are, however, of definite importance. It is here important that systems are created which are easy to use and ergonomically attractive to the users. The existing systems cannot identify or debit the users at utilization of the position finding system. Further, possibilities are lacking to arrange services adapted to the individual user's needs and possibilities. The transmission of correction signals is, as such, known, at which GSM-data, GSM SMS-CB, the RDS-channel of the FM- band are utilized. The technologies of the existing systems are, however, not considered to fulfill the demands and wishes the users are making. Another argument for improved accuracy is that authorities in different parts of the world make greater demands on that positions of calls from mobile telephones shall be possible to find exactly, which above all is of immediate interest at accidents or other emergency cases. Mentioned conditions have emanated from the fact that positions of emergency calls from mobile telephones are difficult to find exactly, on the one hand due to that the caller does not know his/her position, and on the other due to that the caller is confused or chocked. In these emergency cases it is often of decisive importance that aid is correctly directed from the beginning, without unnecessary time being spent on searching for the person/persons in distress. Other situations in which persons can land up are to have to take their bearings, or find the route to services which are needed in a situation where immediate danger to person does not exist. It can for instance be a need to find a car repair shop, a restaurant, navigation means, or other functionalities. Long wave are mainly used at sea and covers primarily coastal regions. In addition to that existing systems are bulky, the introduction of an extra receiver in mobile units constitutes big disadvantages since the known systems are susceptible to disturbances/interference. THE SOLUTION The present invention relates to a device for position finding and debiting of a first receiver (t) . For the purpose a second receiver (m) , the position of which is known, is utilized. The second receiver (m) receives signals from transmitter (g) and calculates by means of received information correction factors related to the different transmitters (g) . The first receivers (t) are further arranged to receive signals from the transmitters (g) for finding the position of the receiver. Correction of this position is after that made by means of produced correction factors. A separate communication is further established between first and second receivers, at which a correction factor can be connected. The communication between the first and second receivers are further established via Point to Point Multigroup ( PTM- G) , and that the first receivers are arranged to be identified, at which one to the receiver defined identity can be supplied with a debiting function. Finding of the positions of the first receivers can further be calculated in one in the second receiver integrated calculation function, alternatively that the calculation function can be connected to the second receiver. The calculated position is further transmitted to the first receivers which, via presentation devices are presented via the first receivers. The presentation is made visually and/or verbally. By utilizing PTM-G is made possible to obtain identities, as individuals or as groups, for the first receivers. The • invention further relates to a method for correction of position, calculated for receiver (m) , and debiting of said receiver. A correction station (t) communicates with the receiver (m) and produces information utilized to correct the for the receiver (m) calculated position. Further, information is produced utilized for debiting of the receiver. Both the correction station (t) and the receiver (m) receive signals transmitted via a general position finding system (g) . Calculation of the receiver's (m) position is made on basis of received signals, and correction of the calculated position is made on basis of correction signals produced in the correction station (t). The receivers (m) are further allocated identities, which are identified by the correction system (t) for storing of the debiting information, which are made up and debited/billed users. The debiting function is introduced in a database which is included into, or can communicate with, the correction station (t). In the position finding system, a number of satellites (g) are included, the positions of which are known, at which the receivers respective the correction stations via transmitted signals are made possible to identify the different, in the system included, satellites. Calculation of the positions of the receivers is made by means of calculation functions included in, or connectable to, the receivers (m) , alternatively that these calculation functions are included in, or are connectable to, the correction station (t) . The correction station calculates, on basis of from the satellites received signals, correction factors for respective satellites. In one variant, said correction factors are transmitted to the receivers (m) , which include or are connectable to, a calculation function which calculates the for the receivers (m) corrected position. In this case, the correction functions are transmitted from the correction station (t) to the receiver (m) . Transmission between receiver and correction station is made by utilization of Point To Multigroup (PTM-G), which makes possible that individual contact is established between the receivers and the correction station, at which the receivers are identified individually or in groups. The characteristics of the correction signals are further defined by international standard RTCM SC-104. ADVANTAGES The suggested invention makes possible that mobile units can be carried like mobile telephones. This in contrast to in certain cases bulky and heavy equipment which is firmly arranged in vehicles and boats. Further, no separate receivers are needed because the in the invention suggested receivers can be included as a part of, for instance, a mobile telephone or a mobile unit intended for position finding. The invention further makes possible that the users are allocated subscriptions which are adapted to the need of the individual. These adaptations can be accuracy in the position finding, identification of certain in advance specified services, or services which are defined by the user in the present moment. Possibility is further given to identify the user, via subscription, and charge the user's account for utilized services. In combination there consequently are the possibility to define specific services and the debiting possibility; functionalities which have not previously been possible to offer. For telecommunication operators, these possibilities of extended supplying of services, possibly in combination with information pertaining to local areas, are a possibility to improve and extend existing service, or to create new services which previously have not been of immediate interest or possible. Another advantage is that the calculation function can be separated from the receiver and be transmitted to, or arranged in connection to, the correction station. This results in that the receivers can be made cheaper and more user-friendly. Changes in the calculation model at this can be introduced centrally for each area and be adapted to the area of current interest. DESCRIPTION OF FIGURES Figure 1 shows the known technology. Figure 2 shows a system according to the invention. Figure 3 shows a flow chart over the invention. A = Start B = Transmitted signals C = The correction station receives signals D = The receiver receives signals E = Calculation of correction factor F = Selfcalculation of preliminary position ? G = Calculate preliminary position H = Calculate preliminary position I = Calculate corrected position J = Present the position K = Identify receiver L = Register user; debit him/her M = Transmit to database N = End PREFERRED EMBODIMENT In the following, the invention is described on basis of the figures and the designations in them. The present invention relates to a system and a device for position finding and debiting of a receiver. For the position finding a DGPS-system is utilized, where transmission of the correction signal is made by PTM-G. The identities of the users are found by means of PTM-G, because this is possible via this system. In DGPS, signals from satellites which are received in mobile units and correction stations are utilized. The latter calculate a correction factor which is utilized at the calculation of the position of the receiver. Calculation of the position is allowed to be made either in the correction station or in the receiver. The present invention includes transmitter, which consists of satellites (g) in orbit, on the ground located correction stations (t), and receivers (m) , the position of which shall be found. The transmitters (g) are part of a satellite based position finding system, for instance GPS. This type of system is since before well known, but has the disadvantage that it primarily is intended for military purposes and that transmitted signals are deliberately interfered with in order to reduce the accuracy in civilian applications. In one development of the GPS-system, ground based fixed stations have been introduced. These stations have a position which is exactly known. The ground-based stations receive the signals from the transmitters and calculate, with knowledge about their positions, correction factors which are utilized to improve one for the receivers calculated finding of position. This technology is since before known as DGPS. The accuracy of GPS is about 100 m, and for DGPS about 10 m. The accuracy for DGPS goes down proportionally in relation to the distance between the correction station and the receiver, which results in that closely located correction stations will increase the accuracy, and more sparsely located correction stations will reduce the accuracy of the system. To reach the accuracy of 10 m, the coverage area of the correction stations is estimated to have a radius of about 200 km. Point To Multipoint-Group (PTM-G) is a known technology for transmission of information between transmitters and receivers which allows individual information transmission to/from the receivers and transmitters, and that the receivers can be identified individually, alternatively that groups of receivers can be identified collectively. Identification is made by the receivers being allocated identifications which on one hand are transmitted into a database, and on the other that each receiver includes said identification which is transmitted at contact between the receivers (m) and the correction station (t). The identity of the users are allowed to be permanent or possible to be introduced by program to the receivers. Different technologies for this purpose are known since before; for instance is in connection with mobile telephones a so called SIM-card used, which is applied in the mobile telephone to give this a specific identity. The database further includes storing functions for assembling of the utilization of services in connection with the position finding, which are made up for debiting of the user. In Figure 3 is shown a flow chart for the position finding. Initially, signals are transmitted from the satellite located transmitters (g) which on one hand are received by the correction stations, t, and on the other are received by the receivers. After that a calculation is made of the correction factors in the correction stations, t. Parallelly, the receivers, m, receive signals from the transmitters, g. After that is checked whether calculation of the position of the receiver shall be made in the receiver or in the correction station. The calculation procedure is the same irrespective of where the calculation is made. The difference is that the receiver, in the case the calculation shall be made in the correction station, transmits signal information to the correction station, which also receives information for identification of the receiver in question. The position of the receiver is after that calculated on basis of the from the signal obtained information, at which a preliminary position finding is acquired. This position finding has normally an accuracy amounting to about 100 m. The correction station utilizes after that the produced correction factors to calculate one for the receivers corrected position indication, the accuracy of which is improved to at least 1/10 of the in the first step indicated accuracy. The calculated position is after that, by utilization of PTM-G, transmitted to the receiver where the position is presented visually or verbally to the user. In this connection an international protocol RTCM SC-104 is utilized. Alternatively can the position finding information, at for instance mobile telephone communication, be transmitted directly to a receiver, for instance an emergency service center, and be utilized for direction of emergency vehicles. The position finding information further can be utilized for activation of services which the mobile telephone user wants to utilize, which are connected to the area in which the user is. These services can be address information, descriptions of traveling routes etc. Alternatively can the corrected position be calculated in the receiver, m, provided that the receiver is equipped with a calculation module, alternatively that the calculation module can be connected to the receiver. It seems to be most advantageous to calculate the position and corrected position centrally, because this reduces the receiver's need for different components, which raise the price and also influences the weight and size of the receiver. Further it is with a centrally located calculation unit possible take into consideration specific characteristics in the area the calculations relate to. Irrespective of which alternative that is selected is, in the correction station, a registration made of the receiver when this is utilized for calculation of its position. The information is stored in a database which on one hand registers the identity of the receiver, and on the other registers which service/services that are utilized. The information after that are stored, in order to later in usual way be debited the user by sending an invoice. The invention is not limited to the in the above described example of embodiment, or to the following patent claims, but can be subject to modifications within the limit of the idea of invention.

Claims: PATENT CLAIMS 1. Device for position finding and debiting of first receiver (m) , at which second receiver (t), the position of which is known, is arranged to receive signals from transmitters (g) and calculate correction factors for the received signals, c h a r a c t e r i z e d in that the signals from the transmitters (g) are arranged to be received in the first receivers (m) , at which the position of the first receivers are calculated on basis of the received signals and that the position is corrected by means of the in the second receivers (t) calculated correction factors, and that a separate communication is established between the first and second receivers, at which a debiting function can be connected. 2. Device as claimed in patent claim 1, c h a r a c t e r i z e d in that the communication between first and second receivers is established via Point To Point-Group (PTM-G) . 3. Device as claimed in patent claim 2, c h a r a c t e r i z e d in that at the communication between first and second receivers, the first receivers are arranged to be identified, at which the debiting function is arranged to receive said identification and to supply said identity with information regarding the debiting. 4. Device as claimed in patent claim 2, c h a r a c t e r i z e d in that the calculation of the position of the first receiver (m) , is arranged to be made in the second receiver, or in connection to, to the second receiver arranged, calculation module. Device as claimed in patent claim 4, c h a r a c t e r i z e d in that the second receivers (t) are arranged to transmit the position information to the first receivers (m) , that the position can be possible to present via the first receivers (m) . Device as claimed in patent claim 5, c h a r a c t e r i z e d in that the presentation is arranged to be made visually or by sound. 7. Device as claimed in any of the patent claims 2-6, c h a r a c t e r i z e d in that PTM-G is arranged to allocate identities to individual first users or groups of first users, which identities are utilized for the debiting. 8. Method for correction of position, calculated for a receiver (m) , and debiting of said receiver, c h a r a c t e r i z e d in that a correction station (t) communicates with the receiver (m) and produces information utilized to correct the for the receiver (m) calculated position, and produces information utilized for debiting of the receiver (m) . 9. Method as claimed in patent claim 8, c h a r a c t e r i z e d in that the correction station (t) and the receiver (m) receives signals via a general position finding system (g) , at which the signals are utilized for calculation of the position of the receiver (m) , and for calculation of correction signals produced in the correction station (t) . 10. Method as claimed in patent claim 9 or 10, c h a r a c t e r i z e d in that the receiver (m) includes a first receiver (GP) for reception of the signals from the position finding system (g) and a second receiver for communication with the correction station (t ) . 11. Method as claimed in patent claim 10, c h a r a c t e r i z e d in that the receiver (m) is allocated an identity, which the correction system identifies, at which the identity is utilized by the correction system for storing of the debiting information, which is compiled and debited/billed a user. 12. Method as claimed in patent claim 11, c h a r a c t e r i z e d in that the debiting information is transmitted to a database which is included in, or can communicate with, the correction station (t) . 13. Method as claimed in any of the patent claims 8-12, c h a r a c t e r i z e d in that the position finding system (g) includes a number of satellites, the positions of which are known, at which the satellites can be identified by both the receiver (m) and the correction station (t). 14. Method as claimed in patent claim 13, c h a r a c t e r i z e d in that the receiver (m) on basis of the received signals calculates its position. 15. Method as claimed in patent claim 14, c h a r a c t e r i z e d in that the correction station (t), the position of which is known, on basis of received information calculates correction factors which are transmitted to the receivers (m) , that the receivers (m) utilize the correction factors to adjust the calculated position. 16. Method as claimed in patent claim 13, c h a r a c t e r i z e d in that the receiver (m) transmit the from the satellites received signals to the correction station (t), which on basis of the information and own, from the satellites received, information calculates the for the receiver (m) corrected position, which position is transmitted to the receiver (m) , in which the position is presented. 17. Method as claimed in any of the patent claims 8-16, c h a r a c t e r i z e d in that Point To Multi-Point Group (PTM-G) is utilized for the communication between the receiver (m) and the correction station (t), at which individual contact is allowed to be established between the receiver (m) and the correction station (t) , and that the receiver (m) is identified by the correction station (t). 18. Method as claimed in patent claim 17, c h a r a c t e r i z e d in that the characteristics of the correction signal are defined by international standard RTCM SC-104.

Inventors: FRANK ROBERT, FRANK, ROBERT
Applicants: TELIA AB, TELIA AB (PUBL)
Application year: 2001
Main classification: H04Q7
IPC codes: G01S5