JP2009063539A - Position calculating system, mobile station, position calculation method, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position calculating system, synchronizing accurate time at the base station side, at low cost, and calculating the position with high accuracy using a simple device, without carrying out time synchronization with the base state on the mobile station side. <P>SOLUTION: This position calculating system includes the mobile station, the base station and a time base station. The time reference station supplies time synchronization information to the base station, and the base station performs synchronization with the time of the time base station, based on the time synchronizing means. The base station supplies the positional information and transmit the time information of the base station as position calculating information to the mobile station, at different timings by using a single frequency which is common to the respective base stations; and the mobile station obtains relational expressions representing the distance relationship between the base station and own station and the distance relation between the base stations from the position calculating information, and calculates the absolute position of own station from these relational expressions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a position calculation system, a mobile station, a position calculation method, a program, and a recording medium, and in particular, highly accurate position information (three-dimensional coordinates) of a mobile station without requiring accurate clock adjustment on the mobile station side. This technique relates to a technique that can be suitably applied in place of GPS for high-accuracy position information acquisition.

  Conventionally, as a technique for obtaining position information, GPS (Global Positioning System) that calculates a current position coordinate of a positioning target from satellite radio waves received from a plurality of artificial satellites is known. In recent years, a car navigation system for a vehicle, GPS is used for a guidance service using a portable information terminal.

  In this way, GPS is actively used for location guidance services and the like, but on the other hand, acquisition of position information by GPS requires a large-scale facility such as launching a satellite, which incurs the cost of facility investment. In addition, due to the high cost of capital investment, it is difficult to implement a measure such as installing a large number of satellites in order to reduce the area where radio wave reception is bad. Furthermore, since satellites are arranged in outer space, it is necessary to prepare a clock that takes into account the difference in time progression due to relativistic effects in order to maintain accurate time.

  In general, in a positioning system, if a method is used in which both the reference station and the mobile station maintain a highly accurate time in synchronization and calculate the position of the mobile station from the transmission and reception times of radio waves, a highly accurate position measurement is performed. However, in this case, since it is assumed that the mobile station is synchronized with the clock of the reference station, it is necessary to keep the mobile station that is not a fixed facility in a maintained state, which is difficult. Accompanied by.

  By the way, for example, Patent Document 1 discloses an observation position detection method for performing position detection by simple algorithm processing using a plurality of artificial satellites. In this observation position detection method, information on the relative positions of the three artificial satellites is given to the observer, the time reference signal is given from the time base station on the ground, and the motivation of the three artificial satellites is taken to give the observer time information. By using this information and demographic orbit information, the observer can determine his / her position without a special time device.

Further, for example, Patent Document 2 discloses a radio wave positioning system capable of measuring a distance between a reference station whose terminal position is known in advance and a terminal station using radio waves and obtaining the position of the terminal station from the distance. Has been. In the radio positioning system, the terminal station has a position calculator, and the position calculator calculates the distance to the reference station by multiplying the difference between the transmission time and reception time recorded in the radio wave by the speed of light. The position of the terminal station is calculated from the distance to the reference station obtained in the above step and the position information of the reference station.
JP-A-63-122976 Japanese Patent No. 3704867

  The invention disclosed in Patent Document 1 is a position detection method using an artificial satellite. In addition, the above-described equipment cost for eliminating the defective area of the radio wave reception state as described above and the accurate time of the mobile station are maintained. The difficulty in is not solved. The invention disclosed in Patent Document 2 uses an airship as a reference station instead of an artificial satellite. Certainly, the equipment cost is not as high as that of an artificial satellite, and the terminal station (mobile station), the reference station, The above problem has been solved in that time synchronization between the two is unnecessary. However, for example, in order to measure the position of a terminal station without performing time synchronization using four airships as reference stations, it is necessary to simultaneously transmit and receive four radio waves, and there is a risk of interference when using one frequency. When radio waves having three different frequencies are used, reception control on the terminal station side becomes complicated.

  Therefore, in view of the above-described circumstances, the present invention can synchronize the accurate time on the reference station side at a low cost, and does not synchronize the time with the reference station on the mobile station side. An object of the present invention is to provide a position calculation system that enables position calculation.

  In order to achieve this object, the first position calculation system of the present invention synchronizes the first holding means for holding the high-accuracy position information of the own station, the clock means for measuring the time with high accuracy, and the time of the reference station. Time reference station having a first supply means for supplying time synchronization information for performing, a second holding means for holding high-accuracy position information of the own station, and a first acquisition for acquiring time synchronization information from the first supply means Means, time synchronization means for synchronizing the time of the own station with the time of the time reference station, a reference station having second supply means for supplying position calculation information for calculating the position of the mobile station, and position calculation from the second supply means A second acquisition means for acquiring information, and a mobile station having a position calculation means for calculating the absolute position of the own station. Then, the time reference station supplies the position information of its own station and transmission time information indicating the time of supply time to the reference station as time synchronization information by the first supply means, and the position of the time reference station acquired by the first acquisition means by the reference station From the information and the transmission time information, the time taken by the time synchronization means to obtain the information is obtained and added to the transmission time information to synchronize with the time of the time reference station. The information and the transmission time information representing the time of supply are supplied to the mobile station as position calculation information. The mobile station uses the position calculation means to obtain the reference station from the position information and the transmission time information of the reference station acquired by the second acquisition means. An equation representing the distance relationship with the own station and an equation representing the distance relationship between the reference stations are obtained, and the absolute position of the own station is calculated from these equations, and the reference station uses the second supply means. Upon positional supplies information and transmission time information to the mobile station, it carried out at different timings of reference station using a common single frequency.

  Further, the first mobile station of the present invention holds the high-accuracy position information of the own station, holds a time reference station having a function of measuring the time with high accuracy, and holds the high-accuracy position information of the own station, An acquisition means for configuring the position calculation system together with a reference station having a function of synchronizing the time of the own station with the time of the time reference station based on time synchronization information from the time reference station, and acquiring position calculation information supplied from the reference station; Position calculation means for calculating the absolute position of the own station based on the position calculation information acquired by the means. Then, the acquisition means acquires the position information of the reference station and the transmission time information indicating the time of supply supplied from the respective reference stations at different timings using a common single frequency, and the position calculation means From the acquired position information and transmission time information, an expression representing the distance relationship between the reference station and the own station and an expression representing the distance relationship between the reference stations are obtained, and the absolute position of the own station is calculated from the obtained expression.

  In addition, the first position calculation method of the present invention holds a highly accurate position information of the own station and a time reference station having a function of measuring the time with high accuracy, and holds the highly accurate position information of the own station. A reference station having a function of synchronizing the time of the own station with the time of the time reference station based on time synchronization information from the time reference station, and a movement having a function of calculating the absolute position of the own station based on position calculation information from the reference station A position calculation method in a position calculation system comprising a station, wherein the time reference station supplies position information of the own station and transmission time information indicating the time of supply to the reference station as time synchronization information. In the reference station, the time taken to acquire the information is obtained from the position information and the transmission time information supplied from the time reference station, added to the transmission time information, and synchronized with the time of the time reference station. In the time synchronization step and the reference station, the position information of the own station and the transmission time information representing the time of supply are supplied to the mobile station as position calculation information at different timings using a common single frequency. In the second supply step, in the mobile station, from the position information and transmission time information supplied from the reference station, an expression representing the distance relationship between the reference station and the own station and an expression representing the distance relationship between the reference stations are obtained, and these And a position calculating step for calculating the absolute position of the own station from the equation.

  In addition, the first program of the present invention holds the high-accuracy position information of the own station, holds the time reference station that measures the time with high accuracy, and holds the high-accuracy position information of the own station. In a position calculation system comprising a reference station that synchronizes the time of its own station with the time of the time reference station based on time synchronization information, and a mobile station that calculates the absolute position of the own station based on position calculation information from the reference station A time reference station that realizes a first supply function that is a program for supplying position information of the own station and transmission time information indicating the time of supply to the reference station as time synchronization information, and the position information and transmission supplied from the time reference station From the time information, the time taken to obtain the information is obtained and added to the transmission time information, and the time synchronization function that synchronizes with the time of the time base station is realized in the base station, and the position information and supply time of the local station Position information supplied from the reference station is realized by causing the reference station to realize a second supply function for supplying the transmission time information representing the time as position calculation information to the mobile station at different timings using a common single frequency. From the transmission time information, a formula that expresses the distance relationship between the reference station and the own station and an equation that expresses the distance relationship between the reference stations are obtained, and the position calculation function that calculates the absolute position of the own station from these equations is provided to the mobile station. make it happen.

  The first recording medium of the present invention is a computer-readable recording medium on which the program is recorded.

  According to the present invention, accurate time can be synchronized at a low cost on the reference station side, and highly accurate position calculation can be performed with a simple device without time synchronization with the reference station on the mobile station side. A position calculation system is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a system configuration of a position calculation system according to an embodiment of the present invention. The position calculation system includes a mobile station 10, a reference station 20, and a time reference station 30. The mobile station 10 is a position calculation target in this system, and includes a position calculation unit 11 and a second acquisition unit 12. The reference station 20 transmits radio waves including information for position calculation to the mobile station 10 and includes a second supply unit 21, a time synchronization unit 22, a second holding unit 23, and a first acquisition unit 24. . The time reference station 30 transmits radio waves including information for time synchronization to the reference station 20 and includes a clock unit 31, a first supply unit 32, and a first holding unit 33.

  In the clock reference station 30, the clock means 31 holds the accurate time, the first holding means 33 holds the high-accuracy position information of the own station, and the first supply means 32 stores the position information of the own station and the time information (the radio wave). (Information on transmission time) is transmitted to the reference station 20 over radio waves.

  In the reference station 20, the first acquisition unit 24 receives the radio wave from the time reference station 30 and acquires the position information of the time reference station 30 and the radio wave transmission time. In the reference station 20, the second holding means 23 holds the highly accurate position information of the own station, and the time synchronizing means 22 uses the position information of the time reference station 30, the radio wave transmission time, and the position information of the own station. Synchronize with 30 times. Further, in the reference station 20, the second supply means 21 transmits the position information and time information (radio wave transmission time information) of the local station to the mobile station 10 on the radio wave.

  The time synchronization by the time synchronization means 22 is specifically as follows. The position information acquired by the first acquisition unit 24 is three-dimensional coordinates (latitude, longitude, altitude), and the time synchronization unit 22 determines the acquired three-dimensional coordinates of the time reference station 30 and the own holding station held by the second holding unit 23. The distance between both stations is calculated from the three-dimensional coordinates, and the time taken from radio wave transmission to radio wave reception is obtained from the distance and radio wave speed. Then, the obtained time is added to the radio wave transmission time acquired from the time reference station 30, and the time at the own station (reference station 20) is calculated. Thereby, the time of the reference station 20 can be synchronized with the highly accurate time of the time reference station 30.

  In the mobile station 10, the second acquisition unit 12 receives the radio wave from the reference station 20 and acquires the position information and radio wave transmission time of the reference station 20, and the position calculation unit 11 acquires the position information, radio wave transmission time, and movement of the reference station 20. The absolute position of the own station is calculated from the information of the radio wave reception time of the station 10.

  The position calculation by the position calculation means 11 is specifically as follows. The reference station 20 is a set of four or more stations, each of which transmits a radio wave including its own three-dimensional coordinates and radio wave transmission time at regular time intervals, and the position calculation means 11 includes the acquired three-dimensional coordinates of the reference station 20, From the radio wave transmission time and the radio wave reception time of the own station (mobile station 10), an equation representing the distance relationship between the reference station 20 and the own station and an equation representing the distance relationship between the reference stations 20 are obtained. Then, the simultaneous equations consisting of the obtained relational expressions are solved to calculate the three-dimensional coordinates of the own station. Thereby, the three-dimensional coordinates can be calculated with high accuracy as the absolute position of the mobile station 10.

  Subsequently, a car navigation system will be described as a specific application example of the position calculation system of the present embodiment.

  FIG. 2 is a diagram showing a system configuration of the car navigation system in the present embodiment. The car navigation system includes a car navigation device 100, a reference station 200, and a time reference station 300. The car navigation device 100 is mounted on a vehicle and is a position calculation target of the host vehicle necessary for navigation in the present system. The control unit 110, the position information acquisition unit 120, the clock 130, and the user interface unit 140 Have The reference station 200 transmits radio waves including information for position calculation to the car navigation device 100, and includes a position information supply device 210, a control unit 220, a position information storage device 230, a time synchronization information acquisition unit 240, and A clock 250 is included. The time reference station 300 transmits radio waves including information for time synchronization to the reference station 200, and includes a clock 310, a time synchronization information supply unit 320, a position information storage device 330, and a control unit 340.

  The car navigation device 100 corresponds to the mobile station 10 of FIG. 1, the control unit 110 corresponds to the position calculation means 11, and the position information acquisition means 120 corresponds to the second acquisition means. The control unit 110 controls the operation of the entire car navigation device 100 and calculates the position of the own device based on information acquired by receiving radio waves from the reference station 200. The position information acquisition unit 120 receives a radio wave transmitted from the reference station 200, and acquires three-dimensional coordinate information and radio wave transmission time information of the reference station 200 included in the radio wave as information for position calculation. The clock 130 measures the radio wave reception timing from the reference station 200 as a relative radio wave reception time. The user interface unit 140 displays map information on a display device and receives user input from an input device. Actually, the user interface unit 140 is realized as a map display screen, an input device, and the like, and the position information acquisition unit 120 is realized as a radio wave receiver.

  The reference station 200 corresponds to the reference station 20 of FIG. 1, the position information supply unit 210 is the second supply unit 21, the control unit 220 is the time synchronization unit 22, and the position information storage device 230 is the second holding unit 23. The information acquisition means 240 corresponds to the first acquisition means 24, respectively. The position information supply unit 210 transmits a radio wave including the three-dimensional coordinates (latitude, longitude, altitude) of the own station and a radio wave transmission time to the car navigation apparatus 100. The control unit 220 controls the operation of the entire reference station 200 (here, each reference station), and performs time synchronization with the time reference station 100 based on information acquired by radio wave reception from the time reference station 100. In addition, the control unit 220 sends control information for transmitting a radio wave to the position information supply unit 210 at a timing according to a scheduling performed in advance. The position information storage device 230 holds the highly accurate three-dimensional coordinates of the local station. The time synchronization information acquisition unit 240 receives a radio wave transmitted from the time reference station 300, and acquires the three-dimensional coordinate information and the radio wave transmission time information of the time reference station 300 included in the radio wave as information for time synchronization. The clock 250 measures the time at which radio waves are transmitted based on time synchronization with the time base station 300 by the control unit 220. Actually, the position information supply unit 210 and the time synchronization information acquisition unit 240 are realized as a radio broadcast device and a radio wave reception device, respectively.

  The time reference station 300 corresponds to the time reference station 30 of FIG. 1, the clock 310 corresponds to the clock means 31, the time synchronization information supply means 320 corresponds to the first supply means 32, and the position information storage device 330 corresponds to the first holding means 33. To do. The clock 310 keeps the accurate time of its own station, and measures the time when the radio wave is transmitted. The time synchronization information supply unit 320 transmits a radio wave including the three-dimensional coordinates (latitude, longitude, altitude) of the own station and a radio wave transmission time to the reference station 200. The position information storage device 330 holds highly accurate three-dimensional coordinates of the local station. The controller 340 controls the operation of the time base station 300 as a whole. Actually, the time synchronization information supply means 320 is realized as a radio wave transmitter.

  By the way, the reference station 200 may arrange a dedicated device in the road or near the road, or may be arranged on a road such as a traffic light or incorporated in equipment outside the road, and in any case, arranged on the ground. It is desirable. In addition, since the time reference station 300 also has a function as the reference station 200, the time reference station 300 may serve as the reference station 200 and may be configured as one of the reference stations 200.

  The time synchronization and position calculation performed in the car navigation system in the present embodiment will be described in more detail.

  FIG. 3 is a diagram for explaining time synchronization and position calculation in the car navigation system. In this system, as described above, after the time synchronization with the time reference station is performed at the reference station, the position is calculated by receiving the radio broadcast from each reference station in the car navigation system. For example, it is assumed that the radio wave transmission timing to the car navigation apparatus 100 is in the order of the reference station a201, the reference station b202, the reference station c203, and the reference station d204 due to scheduling performed between the reference stations. At this time, first, in order to perform time synchronization, the time reference station 300 transmits the position information (three-dimensional coordinates) of the own station and the radio transmission time information from the reference station a201 to the reference station d204 on the radio wave (arrow (1)). (4)). At this time, radio wave transmission may be performed simultaneously or sequentially. However, transmission at a predetermined frequency can be performed at a single frequency, and simple transmission control can be performed at the time base station 300 on the transmission side.

  Then, after the reference station performs time synchronization with the time reference station and holds the same time that is synchronized between the reference stations, radio waves are transmitted from the reference station to the car navigation device. At this time, since each reference station transmits radio waves using a single frequency, each reference station transmits radio waves at different timings. That is, radio wave transmission is performed in the order determined by scheduling. Here, an example in which radio waves are transmitted at regular intervals will be described. However, radio waves may be transmitted at arbitrary intervals instead of regular intervals, and in any case, the radio wave transmission timing may be different at the same time.

  The reference station a201 determined as the first reference station that broadcasts radio waves transmits radio waves including the three-dimensional coordinates of the own station and radio wave transmission time to the car navigation device 100 at time (t1) (arrow (5)). Note that t1 is a time measured by the reference station a201 and is a radio wave transmission time. Next, the reference station b202 determined as the second radio broadcast station transmits the radio wave including the three-dimensional coordinates of the local station and the radio wave transmission time at the time (t1 + i) after the elapse of the predetermined time i from the time t1. (Arrow (6)). Similarly, the reference station c203, which is the third radio broadcast station, sets its own three-dimensional coordinates and radio transmission time at the time (t1 + i × 2), and the reference station d204 of the fourth radio broadcast station has the time (t1 + i × 3). The radio wave including is transmitted (arrow (7), arrow (8)). Note that radio transmission by the above four reference stations is repeated (reference station a201 to reference station d204 → reference station a201 to reference station d204 →...).

  4A and 4B are diagrams for explaining the relationship between the radio wave transmission time point of the reference station and the radio wave reception time point of the navigation device. FIG. 4A shows the time axis based on the radio wave transmission time point of the reference station, and FIG. The time axis is expressed based on the reception time of radio waves. Referring to FIG. 4A, radio broadcasting by the reference station is performed at regular intervals i. When the transmission time of the reference station a201 is set to time 0, the reference station b202 is time (i) and the reference station c203 is time (i). × 2), the reference station d204 has a time (i × 3), the reference station a201 (second time) has a time (i × 4), and so on. Note that time (i), time (i × 2), and the like are relative times (time when the transmission time of the reference station a201 is set to time 0). The car navigation device 100 receives radio waves from each reference station, but the time from radio wave transmission to radio wave reception differs depending on the distance from each reference station.

  On the other hand, referring to FIG. 4B, in addition to the time axis based on the radio wave transmission time of the reference station, the time axis based on the radio wave reception time of the car navigation device is represented. On the time axis based on this radio wave reception time, the reception time of the first radio wave (radio wave from the reference station a201) of the car navigation device 100 is the time (t2), and then the reception time of the radio wave from the reference station b202 is the time (t3). ), Radio wave reception time from the reference station c203 is time (t4), radio wave reception time from the reference station d204 is time (t5), radio wave reception time from the reference station a201 (second time) is time (t6), and so on. In addition, the reception times of radio waves are represented in time series. Note that time (t2), time (t3), and the like are times measured by the timepiece 130 (FIG. 1) of the car navigation device 100.

  As shown in FIG. 4B, the radio wave transmission time (time (i) to time (i × 7)) is constant, whereas the radio wave reception time (time (t2) to The interval of time (t9)) is not constant. Taking time (t3) as an example, time (t3) is slightly larger than time (t2) plus interval i (t3> t2 + i), which is the distance between car navigation device 100 and reference station a201. This is because the distance between the car navigation device 100 and the reference station b202 is not the same, and the difference between the two appears as a fluctuation from the regular reception interval i.

  FIG. 5 is a diagram for explaining a relational expression used for position calculation in the car navigation system. The three-dimensional coordinates of the car navigation device 100, the three-dimensional coordinates of each reference station, the radio wave reception time of the car navigation device 100, the radio wave speed, the radio wave transmission interval of each reference station, and the distance between the car navigation device 100 and each reference station are used as variables. To obtain the relational expression. Among these variables, the three-dimensional coordinates of the car navigation device 100 and the distance between the car navigation device 100 and each reference station are unknown variables. As a relational expression, an expression that expresses the distance between the car navigation apparatus 100 and each reference station by the coordinates of the car navigation apparatus and the coordinates of each reference station (an expression that expresses the distance relation between the car navigation apparatus 100 and the reference station), and car navigation. Two types of formulas are used which represent the difference in distance between the apparatus 100 and each reference station as a radio wave reception time, radio wave transmission interval, and radio wave speed (a formula representing the distance relationship between the reference stations). As shown in FIG. 5, relational expressions 1 to 4 are the preceding expressions, and relational expressions 5 to 7 are the succeeding expressions. Relational expressions 5 to 7 are derived from the time axis based on the radio wave reception time in FIG. 4B.

  In this way, the car navigation device 100 does not perform time synchronization by solving simultaneous equations composed of an equation representing the distance relationship between the car navigation device 100 and the reference station and an equation representing the distance relationship between the reference stations. Position information (three-dimensional coordinates) can be obtained.

  Next, a time synchronization operation and a position calculation operation performed in the car navigation system according to this embodiment will be described.

  FIG. 6 is a flowchart showing a flow of time synchronization operation performed in the car navigation system in the present embodiment. As described above, the time synchronization operation is performed between the time reference station 300 and the reference station 200.

  First, the time base station 300 starts radio wave broadcasting for sending time synchronization information to the base station 200 at an arbitrary timing (step S11). Here, the start of radio wave broadcasting means preparation for acquiring information to be put on radio waves rather than actual radio wave transmission. Next, the time base station 300 acquires its own location information (latitude, longitude, altitude) from the location information storage device 330 (step S12). Subsequently, the time base station 300 acquires time using the clock 310 (step S12). Then, the time base station 300 uses the time synchronization information supply means 320 to identify the position information acquired from the position information storage device 330, the time acquired from the clock 310, and the radio wave from the time base station 300. Is transmitted by radio waves (step S14).

  Next, the reference station 200 receives the radio wave from the time reference station 300 using the time synchronization information acquisition unit 240, and the position information (latitude, longitude, altitude) of the time reference station 300 included in the radio wave, the radio wave transmission time, and Identification information is acquired (step S15). Subsequently, the reference station 200 determines the time reference station 300 from the acquired information (position information of the time reference station 300, radio wave transmission time) and the position information (latitude, longitude, altitude) of the own station stored in the position information storage device 230. The time required for the radio wave to travel the distance is calculated and added to the radio wave transmission time to obtain the radio wave reception time (step S16). Then, the reference station 200 synchronizes the time with the time reference station 300 by adopting the calculated reception time as the current time of the own station at the time of receiving the radio wave (step S17).

  FIG. 7 is a flowchart showing the flow of the position calculation operation performed in the car navigation system in the present embodiment. The position calculation operation is performed between each reference station and the car navigation apparatus 100 as described above. Note that the reference station 200 to be described below refers to each reference station (reference station a201 to reference station d204 in FIG. 3), and the operation according to the same flow is performed in each reference station.

  First, the reference station 200 starts a radio broadcast for sending position information after a predetermined interval has elapsed since the previous radio broadcast (a radio broadcast for sending position calculation information to the car navigation device 100) (step S21). . Here, the start of radio wave broadcasting means preparation for acquiring information to be put on radio waves rather than actual radio wave transmission. Next, the reference station 200 acquires the position information (latitude, longitude, altitude) of the own station from the position information storage device 230 (step S22). Subsequently, the reference station 200 acquires time using the clock 250 (step S23). The reference station 200 uses the position information supply unit 210 to transmit the position information acquired from the position information storage device 230, the time acquired from the clock 250, and identification information that uniquely identifies the reference station 200 by radio waves ( Step S24).

  Next, the car navigation apparatus 100 receives the radio wave from the reference station 200 using the position information acquisition unit 120, the position information (latitude, longitude, altitude) of the reference station 200 included in the radio wave, the radio broadcast time, and the identification. Information is acquired (step S25). And the car navigation apparatus 100 repeats the step (step S25) which acquires a positional information and radio wave broadcast time until it receives a radio wave from the reference | standard station 200 from which four or more different identification information differs (step S26). Next, the car navigation apparatus 100 uses the relational expression (simultaneous simultaneous) shown in FIG. 5 based on the acquired information (position information of the reference station 200, radio wave transmission time) and the time (relative time) when the mobile device receives the radio wave. By solving the equation, position information (latitude, longitude, altitude) of the own device is calculated (step S27). Then, the car navigation apparatus 100 displays the position information (longitude, longitude, altitude) of the own device obtained by the calculation on the user interface unit in the form of numerical values, map display, or the like (step S28).

  Note that the information transmitted and received between the position information supply unit 210 and the position information acquisition unit 120 via radio waves is not limited to the position information, radio wave transmission time, and identification information of the reference station 200. For example, the broadcast interval can be made variable by including the broadcast interval as information. Moreover, you may comprise so that it may display on the user interface part 140 including the additional information according to a use use, for example, traffic information, shop guidance information, etc.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  That is, the car navigation device, the reference station, and the like in the above-described embodiment operate by processing, means, and functions that are executed by a computer according to program instructions. The program sends a command to each component of the computer, and predetermined processing and functions as described above, for example, the position information of the own station held in the position information storage device 230 by the control unit 220 of the reference station 200 And processing for causing the position information supply unit 210 to transmit the radio wave transmission time acquired by the clock 250 to the position information supply unit 210 and causing the position information supply unit 210 to perform radio wave transmission in accordance with the order and timing scheduled in advance. I do. Further, for example, based on the position information of the reference station 200 acquired by the position information acquisition unit 120, the radio wave transmission time, and the radio wave reception time acquired by the clock 130 by the control unit 110 of the car navigation apparatus 100, a relational expression (simultaneous equations). To calculate the position information of the own aircraft by solving these equations. As described above, the processes and means in the above-described embodiment are realized by specific means in which the program and the computer cooperate.

  Then, the program code stored in the storage medium by the computer (CPU) of the car navigation device is recorded via a computer-readable recording medium that records the program code of the software that realizes the functions of the above-described embodiment, that is, the storage medium. The object of the present invention is also achieved by executing the reading. Further, the program can be loaded and executed directly on a computer through a communication line without going through a recording medium, and the object of the present invention can be achieved similarly.

  In this case, the program code itself read from the storage medium or loaded and executed through the communication line realizes the functions of the above-described embodiment. And the storage medium which memorize | stored the program code comprises this invention.

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a nonvolatile memory card, a ROM, and a magnetic tape. Can be used.

  The first effect of the above-described embodiment is that the time of the reference station can be synchronized with high accuracy and at a relatively low cost. The reason is that both the reference station and the time reference station that is the synchronization source of the time of the reference station are installed on the ground, and the time is synchronized based on the transmission time and reception time of radio waves performed between both stations, This is because the correction in consideration of the relativistic effect that needs to be taken into consideration with the GPS arranged in outer space is unnecessary.

  The second effect of the above-described embodiment is that the equipment on the mobile station side can be simplified. The reason is that each base station transmits radio waves at regular intervals based on the time of the synchronized clock, so there is no risk of interference even if only one frequency is used, and it is necessary to receive on the mobile station side. This is because only one frequency of a certain radio wave is required.

  The third effect of the above-described embodiment is that it is not necessary to synchronize the time with the reference station on the mobile station side in order to calculate the position information (three-dimensional coordinates) of the mobile station. The reason for this is that, as can be seen from the relational expression shown in FIG. 5, the mobile station is the interval at which the reference station transmits radio waves, the relative time when the broadcast from each reference station is received (the time at which the mobile station receives radio waves) If only the three-dimensional coordinates and the radio wave transmission time transmitted from each reference station are known, it is sufficient to calculate the three-dimensional coordinates of the mobile station, and it is not necessary to know the absolute time when the broadcast is received.

  The fourth effect of the above-described embodiment is that it is relatively easy to install a large number of reference stations in order to reduce places where the radio wave reception state is bad. The reason for this is not to use a device that is costly to launch and maintain, such as a satellite, and has a short life as a reference station, but to use a relatively low-cost device installed on the ground as a reference station. Another reason is to schedule the transmission of radio waves from each reference station so that the transmission of radio waves from a plurality of reference stations does not have the same timing.

It is the figure which showed the system configuration | structure of the position calculation system which concerns on embodiment of this invention. It is the figure which showed the system configuration | structure of the position calculation system which concerns on embodiment of this invention. It is a figure for demonstrating the time synchronization and position calculation in the position calculation system which concerns on embodiment of this invention. It is a figure for demonstrating the relationship between the radio wave transmission time of the reference | standard station in the embodiment of this invention, and the radio wave reception time of a mobile station (car navigation apparatus). It is a figure for demonstrating the relational expression used for the position calculation in embodiment of this invention. It is the flowchart which showed the flow of the time synchronous operation | movement in embodiment of this invention. It is the flowchart which showed the flow of the position calculation operation | movement in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile station 11 Position calculation means 12 2nd acquisition means 20,200 Reference station 21 2nd supply means 22 Time synchronization means 23 2nd holding means 24 1st acquisition means 30,300 Time reference station 31 Clock means 32 1st supply means 33 1st DESCRIPTION OF SYMBOLS 1 Holding means 100 Car navigation apparatus 110,220,340 Control part 120 Position information acquisition means 130,250,310 Clock 140 User interface part 210 Position information supply means 230,330 Position information storage apparatus 240 Time synchronization information acquisition means 320 Time synchronization Information supply means

Claims (9)

A time reference station having first holding means for holding high-accuracy position information of the own station, clock means for measuring time with high accuracy, and first supply means for supplying time synchronization information for synchronizing the time of the reference station;
A second holding means for holding high-accuracy position information of the own station, a first acquisition means for obtaining the time synchronization information from the first supply means, and time synchronization for synchronizing the time of the own station with the time of the time reference station Means, the reference station having second supply means for supplying position calculation information for calculating the position of the mobile station;
A position calculation system comprising: second acquisition means for acquiring the position calculation information from the second supply means; and the mobile station having position calculation means for calculating the absolute position of the own station,
The time reference station supplies the reference station with transmission time information indicating the position information of the own station and the time of supply by the first supply means as the time synchronization information, and the reference station has acquired by the first acquisition means. From the position information and the transmission time information of the time base station, the time synchronization means obtains the time taken to acquire the information and adds to the transmission time information to synchronize with the time of the time base station,
The reference station supplies the mobile station with position information of the local station and transmission time information indicating the time at the time of supply as the position calculation information by the second supply means, and the mobile station acquires the information by the second acquisition means. From the position information and the transmission time information of the reference station, the position calculation means obtains an expression representing the distance relationship between the reference station and the own station and an expression representing the distance relationship between the reference stations. Calculate the absolute position of your station from
When the reference station supplies the position information and the transmission time information to the mobile station by the second supply means, each reference station performs a different timing using a common single frequency. system.   2. The reference station according to claim 1, wherein each of the reference stations supplies the mobile station with the second supply unit at a timing determined at predetermined intervals according to scheduling performed between the reference stations in advance. Position calculation system.   The reference station includes supply interval information, which is information related to a supply interval performed by each reference station, in the information to be supplied to the mobile station, and is sent to the mobile station by the second supply unit at an arbitrary timing based on the supply interval information. The position calculation system according to claim 1, wherein supply is performed.   The position calculation system according to claim 1, wherein the time base station and the reference station are installed on the ground.   The position calculation system according to any one of claims 1 to 4, wherein the time base station functions as one of the reference stations. A time base station that has a function of holding high-accuracy position information of its own station and measuring time with high accuracy, and a high-accuracy position information of its own station, and based on time synchronization information from the time reference station. A mobile station constituting a position calculation system together with a reference station having a function of synchronizing the time of the station with the time of the time reference station,
Obtaining means for obtaining position calculation information supplied from the reference station;
Position calculation means for calculating the absolute position of the own station based on the position calculation information acquired by the acquisition means;
The acquisition means acquires position information of the reference station supplied at different timings using a common single frequency from each of the reference stations and transmission time information indicating the time of supply,
The position calculation means obtains an expression representing a distance relationship between the reference station and the own station and an expression representing a distance relationship between the reference stations from the position information and the transmission time information acquired by the acquisition means, A mobile station characterized in that the absolute position of the own station is calculated from the obtained formula. A time base station that has a function of holding high-accuracy position information of its own station and measuring time with high accuracy, and a high-accuracy position information of its own station, and based on time synchronization information from the time reference station. A position calculation system comprising: a reference station having a function of synchronizing the time of the station with the time of the time reference station; and a mobile station having a function of calculating the absolute position of the own station based on position calculation information from the reference station A position calculation method in
In the time reference station, a first supply step of supplying position information of the own station and transmission time information indicating a time of supply time to the reference station as the time synchronization information;
In the reference station, time synchronization is performed in which the time taken to acquire the information is obtained from the position information and the transmission time information supplied from the time reference station, added to the transmission time information, and synchronized with the time of the time reference station. Steps,
In the reference station, a second time at which the reference station supplies position information of the own station and transmission time information indicating the time of supply to the mobile station as the position calculation information at different timings using a common single frequency. A supply step;
In the mobile station, from the position information and the transmission time information supplied from the reference station, an equation representing a distance relationship between the reference station and the own station and an equation representing a distance relationship between the reference stations are obtained, and these A position calculating step for calculating the absolute position of the own station from the equation;
A position calculation method characterized by comprising: A time base station that holds high-accuracy position information of its own station and measures time with high accuracy, and a high-accuracy position information of its own station that holds its own time based on time synchronization information from the time reference station. Is a program in a position calculation system comprising a reference station that synchronizes with the time of the time reference station, and a mobile station that calculates the absolute position of the own station based on position calculation information from the reference station,
The time base station realizes a first supply function for supplying the base station with position information of the local station and transmission time information representing the time of supply as the time synchronization information,
A time synchronization function for obtaining a time taken to obtain information from the position information and the transmission time information supplied from the time reference station, adding the time to the transmission time information, and performing synchronization with the time of the time reference station. To realize
A second supply function for supplying the position information of the own station and the transmission time information indicating the time of supply time to the mobile station as the position calculation information at different timings using different single reference frequencies Realize in the reference station,
From the position information and the transmission time information supplied from the reference station, an equation representing the distance relationship between the reference station and the own station and an equation representing the distance relationship between the reference stations are obtained, and from these equations, A program for causing the mobile station to realize a position calculation function for calculating an absolute position.   A recording medium which records the program according to claim 8 and is readable by a computer.

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