Transmission reference station, positioning system, method for transmission, and program

Abstract

To provide a transmission reference station, a positioning system, a method for transmission, and a program which allow precise positioning of a mobile body in an environment in which satellite radio waves are difficult to receive.SOLUTION: A transmission base station includes: a synchronization unit for synthesizing a time with other transmission reference stations; and a transmission unit for transmitting a positioning signal including a transmission time to a mobile body which performs an autonomous movement after the time is synchronized.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a transmission reference station, a positioning system, a transmission method, and a program.

Background Art

[0002] Patent Document 1 discloses a positioning system that transmits a positioning signal from a transmitter disposed on a structure to a positioning terminal such as a car navigation device or a smartphone.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in an environment where it is difficult to receive satellite radio waves, such as indoors, there is a problem that the accuracy of positioning when a moving body moves autonomously decreases.

[0005] The present disclosure has been made to solve such problems, and an object thereof is to provide a transmission reference station, a positioning system, a transmission method, and a program that enable high-precision positioning of a moving body in an environment where it is difficult to receive satellite radio waves.

Means for Solving the Problems

[0006] A transmission reference station according to an aspect of the present disclosure includes: a synchronization unit that synchronizes time with other transmission reference stations; a transmission unit that transmits a positioning signal including a transmission time to a moving body that performs autonomous movement after synchronizing the time. and is provided with.

[0007] A positioning system according to an aspect of the present disclosure includes: A positioning system including a plurality of transmission reference stations and a mobile body that performs autonomous movement, Each transmission reference station, synchronizes time with other transmission reference stations, after synchronizing the time, transmits a positioning signal including the transmission time to the mobile body, The mobile body, calculates the position information of the mobile body based on the positioning signal.

[0008] A transmission method according to an aspect of the present disclosure, synchronizes time with other transmission reference stations, after synchronizing the time, transmits a positioning signal including the transmission time to a mobile body that performs autonomous movement.

[0009] A program according to an aspect of the present disclosure, a process of synchronizing time with other transmission reference stations, and a process of transmitting a positioning signal including the transmission time to a mobile body that performs autonomous movement after synchronizing the time are executed by a computer.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a transmission reference station, a positioning system, a transmission method, and a program that enable high-precision positioning of a mobile body in an environment where it is difficult to receive satellite radio waves.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] Embodiment 1 Hereinafter, with reference to FIG. 1, a configuration example of the positioning system 1 will be described. The positioning system 1 accurately positions the position of a moving object and controls the movement of the moving object in a place where it is difficult to receive satellite radio waves from a satellite positioning system. The positioning system 1 includes a plurality of transmission reference stations 10 fixed on the ground and a moving object 20.

[0013] The transmission reference station 10 is fixed on the ground, but transmits (transmits) a positioning signal in the same manner as a positioning satellite of GNSS (Global Navigation Satellite System).

[0014] The moving object 20 can be an unmanned aircraft such as a drone, but is not limited thereto, and various moving objects that can be understood by those skilled in the art can be used.

[0015] FIG. 2 is a block diagram showing a configuration example of the transmission reference station 10 according to the present disclosure. The transmission reference station 10 includes a synchronization unit 11 and a transmission unit 12.

[0016] The synchronization unit 11 synchronizes the time with other transmission reference stations. The synchronization unit 11 may correct the time error in the transmission reference station 10, or may perform processing for correcting the time error in other transmission reference stations. Note that the synchronization unit 11 may transmit information regarding the time in the transmission reference station 10 to a server (not shown), and correct the time in the transmission reference station 10 based on the information received from the server.

[0017] After the synchronization unit 11 synchronizes the time, the transmission unit 12 transmits a positioning signal including the transmission time (transmission start time) to the mobile body 20. The transmission time is the time when the positioning signal is transmitted. The positioning signal may include the position information of the transmission reference station 10. When the position information of the transmission reference station 10 is stored in the storage unit of the mobile body 20, the positioning signal may include the identification information of the transmission reference station 10.

[0018] Returning to FIG. 1, the mobile body 20 calculates the position information of the mobile body 20 based on the positioning signal. The mobile body 20 may calculate the position information of the mobile body 20 based on, for example, the distance corresponding to the difference between the reception time and the transmission time of the positioning signal. Further, the mobile body 20 may calculate the position information based on the phase of the carrier wave that carries information such as the transmission time.

[0019] FIG. 3 is a flowchart showing the transmission method according to the present disclosure. First, the synchronization unit 11 of the transmission reference station 10 synchronizes the time with other transmission reference stations (step S11). Next, the transmission unit 12 transmits a positioning signal including the transmission time to the mobile body 20 (step S12).

[0020] By synchronizing the time with each other and transmitting the positioning signal to the mobile body 20 by a plurality of transmission reference stations 10, highly accurate positioning of the mobile body 20 becomes possible.

[0021] Embodiment 2 Embodiment 2 is a specific example of Embodiment 1. FIG. 4 is an explanatory diagram schematically showing a configuration example of the positioning system according to the present disclosure. The positioning system includes transmission reference stations 10a, 10b, 10c, and a mobile body 20 that are present indoors where it is difficult to receive satellite radio waves from a satellite positioning system. The mobile body 20 can be a drone, but is not limited thereto and is applicable to various mobile bodies. When the transmission reference stations 10a, 10b, and 10c are not distinguished from each other, they may simply be referred to as the transmission reference station 10. The number of transmission reference stations 10 is not limited to three, and may be two or four or more.

[0022] The transmitting reference stations 10a, 10b, and 10c may be arranged in a predetermined area (e.g., indoors, in a tunnel, underground) located below a shielding object that blocks radio waves transmitted (emitted) by the navigation satellite. The shielding object includes, for example, artificial objects such as the roof or walls of a building, or natural objects such as soil or water.

[0023] The upper diagram of FIG. 4 shows the arrangement of the transmitting reference stations 10a, 10b, and 10c and the mobile body 20 at the stage of synchronizing time (also referred to as the initial stage). At the initial stage, the transmitting reference stations 10a, 10b, and 10c are arranged in the vicinity of the mobile body 20. The lower diagram of FIG. 4 shows the arrangement of the transmitting reference stations 10a, 10b, 10c, and the mobile body 20 at the stage of transmitting the positioning signal (also referred to as the positioning stage).

[0024] FIG. 5 is a block diagram showing a configuration example of the mobile body 20 according to the present disclosure. The mobile body 20 includes a positioning signal receiver 21, a drive mechanism 22, and a control unit 23. The positioning signal receiver 21 receives a positioning signal from the transmitting reference stations 10a, 10b, and 10c. The drive mechanism 22 includes a drive source that uses electric power supplied from a battery, and a rotary wing that operates by the power obtained from the drive source. The control unit 23 may be a computer including a processor, a memory, and the like.

[0025] The control unit 23 synchronizes the time of the mobile body 20 with the times of the transmitting reference stations 10a, 10b, and 10c. The control unit 23 may synchronize the time by exchanging signals with the transmitting reference stations 10a, 10b, and 10c via a cable such as an optical fiber cable.

[0026] Further, the control unit 23 controls the movement of the mobile body 20 by driving the drive mechanism 22 so as to head toward the destination based on the received positioning signal. First, the control unit 23 receives a positioning signal from the transmitting reference stations 10a, 10b, and 10c, and acquires the transmission time and information (e.g., position information, identification information) of the transmitting reference stations 10a, 10b, and 10c. The control unit 23 may acquire the carrier phase in the received positioning signal.

[0027] Then, the control unit 23 calculates the position information of the moving body 20 using the acquired information. For example, the control unit 23 may calculate the distance between the transmission reference station 10 and the moving body 20 by multiplying the propagation time corresponding to the difference between the transmission time and the reception time of the positioning signal by the propagation speed of the positioning signal (e.g., the speed of light, approximately 300,000 km / s). The control unit 23 can calculate the position information of the moving body 20 based on the position information of the transmission reference station 10 and the distance from the transmission reference station 10. Further, the control unit 23 may calculate the position of the moving body 20 with high precision using carrier phase positioning. In this case, the control unit 23 calculates the position information of the moving body 20 using the carrier phase of the positioning signal.

[0028] Referring to the upper diagram of FIG. 4, the synchronization unit (not shown) of the transmission reference station 10a, the synchronization unit (not shown) of the transmission reference station 10b, the synchronization unit (not shown) of the transmission reference station 10c, and the control unit (not shown) of the moving body 20 synchronize the times in the transmission reference station 10a, the transmission reference station 10b, the transmission reference station 10c, and the moving body 20. The transmission reference station 10a, the transmission reference station 10b, the transmission reference station 10c, and the moving body 20 are interconnected via a cable 31 (e.g., an optical fiber cable). The synchronization unit and the control unit may synchronize the times by exchanging signals (e.g., optical signals) via the cable 31. A cable 31 with a known signal (e.g., optical signal) transmission time may be used.

[0029] The synchronization unit and the control unit may set any one of the transmission reference station 10a, the transmission reference station 10b, the transmission reference station 10c, and the moving body 20 as the master and synchronize the times of the devices not set as the master with the time of the device set as the master. For example, the control unit of the moving body 20 may transmit information indicating the time serving as a reference for the transmission reference stations 10a, 10b, and 10c. The technique for performing time synchronization is not particularly limited. The synchronization unit and the control unit may synchronize the times of the transmission reference station 10a, the transmission reference station 10b, the transmission reference station 10c, and the moving body 20 using methods such as PTP (Precision Time Protocol) or NTP (Network Time Protocol).

[0030] Referring to the lower diagram of FIG. 4, the transmission units (not shown) of the transmission reference stations 10a, 10b, and 10c transmit positioning signals to the mobile body 20. The transmission unit (not shown) of the transmission reference station 10a transmits a positioning signal including the transmission time and information of the transmission reference station 10a (e.g., position information, identification information). The transmission unit (not shown) of the transmission reference station 10b transmits a positioning signal including the transmission time and information of the transmission reference station 10b. The transmission unit (not shown) of the transmission reference station 10c transmits a positioning signal including the transmission time and information of the transmission reference station 10c.

[0031] Each transmission reference station 10 is arranged at a specific one position. One position information may be preset for each transmission reference station 10. In this case, each transmission reference station 10 may transmit a positioning signal including the position information. Alternatively, the position information of the transmission reference stations 10a, 10b, and 10c may be preset in the mobile body 20. The position information may be absolute coordinates such as latitude and longitude, or may be relative coordinates with respect to an arbitrary reference position.

[0032] The positioning signal is generated, for example, by modulating a carrier wave using the transmission time and information of the transmission reference station 10 and the like. The mobile body 20 can extract the transmission time and information of the transmission reference station 10 from the received positioning signal. Also, when the mobile body 20 performs carrier wave phase positioning, it may perform positioning using the phase of the carrier wave.

[0033] The control unit (not shown) of the mobile body 20 calculates the position information of the mobile body 20 assuming that there is no time difference between the time at the transmission reference station 10 and the time at the mobile body 20. Specifically, the control unit assumes that the phase at the transmission reference station 10 and the phase at the mobile body 20 are synchronized and there is no phase difference. In this case, the time required for calculating the position information is reduced.

[0034] Specifically, when performing high-precision positioning, carrier phase positioning is used. When performing carrier phase positioning, the moving body 20 calculates the distance between the transmitting reference station 10 and the moving body 20 based on the phase of the carrier wave of the positioning signal. When using related technologies, since there is a time difference between the time at the transmitting reference station 10 and the time at the moving body 20, it is impossible to calculate the correct distance due to the influence of the time difference. Therefore, the related positioning system removed the influence of the time difference by performing sequential calculations so that the phase error corresponding to the time difference was minimized, but there were problems such as a large amount of calculation in the sequential calculation and a long convergence time. Embodiment 2 removes the above time difference by synchronizing the time of the transmitting reference station 10 and the time of the moving body 20 in advance. As a result, the above sequential calculation becomes unnecessary, and the time required to calculate the position information of the moving body 20 can be shortened.

[0035] Next, the effects achieved by Embodiment 2 will be described. Methods for calculating position information by motion capture and methods for calculating position information by transmitting a reference signal from a moving body have been proposed. However, the method using motion capture has a problem that it is affected by indoor illuminance. In addition, when transmitting a reference signal from a moving body, since it is necessary to feedback the position information to the moving body, there is a problem that it is difficult to use it for autonomous movement of the moving body.

[0036] The positioning system according to Embodiment 2 can shorten the time required to calculate the position information of a moving body that performs autonomous movement indoors or the like.

[0037] Embodiment 3 Embodiment 3 is a modification of Embodiment 2. FIG. 6 is an explanatory diagram schematically showing a configuration example of the positioning system according to the present disclosure.

[0038] The upper diagram of FIG. 6 shows the arrangement of the transmission reference stations 10a, 10b, and 10c in the initial stage. The lower diagram shows the arrangement of the transmission reference stations 10a, 10b, and 10c in the positioning stage. The distances between the transmission reference stations 10a, 10b, and 10c in the positioning stage are longer than the distances between the transmission reference stations 10a, 10b, and 10c in the initial stage.

[0039] Each of the transmission reference stations 10a, 10b, and 10c is equipped with an oscillator with high frequency accuracy, such as an atomic oscillator (e.g., cesium, hydrogen maser, rubidium), and generates time using such an oscillator. Note that the transmission reference stations 10a, 10b, and 10c may be equipped with high-precision crystal oscillators. Note that the mobile body 20 may also generate time using an oscillator with high frequency accuracy.

[0040] Referring to the upper diagram, the transmission reference stations 10a, 10b, and 10c are gathered in one place, and the times of the transmission reference stations 10a, 10b, and 10c are synchronized. The transmission reference stations 10a, 10b, and 10c may be connected to each other via the cable 31.

[0041] Referring to the lower diagram, the transmission reference stations 10a, 10b, and 10c are disconnected from the cable 31 and moved to predetermined positions. The transmission reference stations 10a, 10b, and 10c need to be arranged at appropriate positions so that there is no area in the environment where the positioning signal does not arrive. Also, when the arrival directions of the positioning signals are close, the positioning accuracy will decrease, so the transmission reference stations 10a, 10b, and 10c need to be arranged at appropriate positions.

[0042] The transmission reference stations 10a, 10b, and 10c transmit the positioning signal to the mobile body 20 in the same manner as in Embodiment 2. Since the transmission reference stations 10a, 10b, and 10c are equipped with oscillators with high frequency accuracy, the times at the transmission reference stations 10a, 10b, and 10c are synchronized even after being disconnected from the cable 31.

[0043] The times of the plurality of transmission reference stations 10 are synchronized, but the time of the mobile body 20 and the time of the transmission reference stations 10 do not have to be synchronized. In this case, the mobile body 20 may calculate the position information of the mobile body 20 by performing the above sequential calculation in consideration of the time difference between the time at the transmission reference station 10 and the time at the mobile body 20.

[0044] The transmission reference stations 10a, 10b, and 10c according to Embodiment 3 do not need to be connected to a cable in the positioning stage. Therefore, the positioning system according to Embodiment 3 can calculate the position information of the mobile body 20 even in an environment where cable wiring is difficult. In addition, the complexity of the work of performing cable wiring is reduced.

[0045] Embodiment 4 Embodiment 4 is a modification of Embodiment 2. FIG. 7 is an explanatory diagram schematically showing the configuration of the positioning system according to Embodiment 4. The positioning system includes transmission reference stations 10a, 10b, 10c, and a mobile body 20 that exist indoors where it is difficult to receive satellite radio waves from a satellite positioning system.

[0046] Similar to Embodiments 2 and 3, the synchronization units (not shown) of the transmission reference stations 10a, 10b, and 10c synchronize the times at the transmission reference stations 10a, 10b, and 10c.

[0047] The transmission units (not shown) of the transmission reference stations 10a, 10b, and 10c transmit positioning signals by a TDMA (Time Division Multiple Access) method. The positioning system assigns different time slots to the transmission reference stations 10a, 10b, and 10c. Since the times of the transmission reference stations 10a, 10b, and 10c are synchronized, the transmission unit can transmit positioning signals by the TDMA method.

[0048] The transmission units (not shown) of the transmission reference stations 10a, 10b, and 10c transmit positioning signals using the assigned time slots. For example, the transmission reference station 10a transmits the positioning signal A using the first time slot, the transmission reference station transmits the positioning signal B using the second time slot, and the transmission reference station 10c transmits the positioning signal C using the third time slot.

[0049] The mobile unit 20 identifies the transmission reference station 10 that is the source of the received positioning signal. The mobile unit 20 knows the order in which the transmission reference stations 10a, 10b, and 10c transmit the positioning signals, and can easily identify the transmission reference station 10 that is the source of the received positioning signal. The mobile unit 20 may determine the above order, or the above order may be notified to the mobile unit 20.

[0050] Then, the mobile unit 20 calculates the position information of the mobile unit 20 based on the positioning signal and the position information of the identified transmission reference station 10. The mobile unit 20 may calculate the position information of the mobile unit 20 using the carrier phase of the positioning signal.

[0051] As in the related art, when the transmission reference stations 10a, 10b, and 10c transmit positioning signals using the CDMA (Code Division Multiple Access) method, there is a problem that the code length becomes long and the time required for synchronization processing is long. In addition, there is a problem that it is difficult to increase the number of transmission reference stations 10 due to inter-symbol interference.

[0052] In Embodiment 4, it is possible to construct a positioning system that is not affected by the influence of the synchronization time length due to the code length in the CDMA method and the constraints regarding the number of installed transmission reference stations 10. By increasing the number of installed transmission reference stations 10, it is possible to improve the calculation accuracy of the position information and expand the area in which the position information can be calculated.

[0053] FIG. 8 is a block diagram showing a configuration example of transmission reference stations 10, 10a, 10b, and 10c (hereinafter referred to as transmission reference stations 10 etc.). Referring to FIG. 8, transmission reference stations 10 etc. include a network interface 1201, a processor 1202, and a memory 1203. The network interface 1201 is used to communicate with other network node devices (for example, other transmission reference stations, mobile unit 20) constituting the communication system. The network interface 1201 may be used to perform wireless communication. For example, the network interface 1201 may be used to perform wireless LAN communication defined in the IEEE 802.11 series or mobile communication defined in 3GPP (registered trademark) (3rd Generation Partnership Project). Alternatively, the network interface 1201 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0054] The processor 1202 reads and executes software (computer program) from the memory 1203 to perform the processing of the transmission reference stations 10 etc. described using the flowchart or sequence in the above-described embodiment. The processor 1202 may be, for example, a microprocessor, an MPU (Micro Processing Unit), a CPU (Central Processing Unit), or a GPU (Graphics Processing Unit). The processor 1202 may include a plurality of processors.

[0055] The memory 1203 is composed of a combination of a volatile memory and a non-volatile memory. The memory 1203 may include storage disposed separately from the processor 1202. In this case, the processor 1202 may access the memory 1203 via an I / O interface (not shown).

[0056] In the example of FIG. 8, the memory 1203 is used to store a group of software modules. The processor 1202 can perform the processing of the transmission reference station 10 and the like described in the above embodiments by reading out and executing these groups of software modules from the memory 1203.

[0057] As described with reference to FIG. 3 and the like, each of the processors included in the transmission reference station 10 and the like executes one or more programs including a group of instructions for causing a computer to perform the algorithms described with reference to the drawings.

[0058] As described above, the present disclosure has been described with reference to the embodiments, but the present disclosure is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure. And each embodiment can be combined with other embodiments as appropriate.

[0059] Each drawing is merely an example for explaining one or more embodiments. Each drawing is not associated with only one specific embodiment, but may be associated with one or more other embodiments. As can be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with the features or steps shown in one or more other drawings to create, for example, embodiments not explicitly illustrated or described. Not all of the features or steps shown in any one drawing for explaining exemplary embodiments are necessarily essential, and some features or steps may be omitted. The order of the steps described in any drawing may be changed as appropriate.

[0060] In the above example, when the program is loaded into a computer, it includes a set of instructions (or software code) for causing the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray (registered trademark) disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, the transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0061] Some or all of the above embodiments may be described as follows, but are not limited thereto. (Appendix 1) A synchronization unit that synchronizes time with other transmitting reference stations, After synchronizing the time, a transmitting unit that transmits a positioning signal including the transmission time to a moving body that performs autonomous movement A transmitting reference station provided with the above. (Appendix 2) The synchronization unit further synchronizes the time with the moving body The transmitting reference station according to Appendix 1. (Appendix 3) The transmitting unit transmits the positioning signal by a TDMA (Time Division Multiple Access) method The transmitting reference station according to Appendix 1 or 2. (Appendix 4) The transmitting reference station is provided with an atomic oscillator, and the time is generated using the atomic oscillator The transmitting reference station according to Appendix 1 or 2. (Appendix 5) The distance between the transmitting reference station and the other transmitting reference stations in the step of transmitting the positioning signal is longer than the distance between the transmitting reference station and the other transmitting reference stations in the step of synchronizing the time. The transmitting reference station according to Appendix 4. (Appendix 6) A positioning system including a plurality of transmitting reference stations and a moving body that performs autonomous movement, each transmitting reference station synchronizes time with other transmitting reference stations, after synchronizing the time, transmits a positioning signal including the transmission time to the moving body, the moving body calculates the position information of the moving body based on the positioning signal Positioning system. (Appendix 7) each transmitting reference station further synchronizes the time with the moving body, the moving body calculates the position information assuming that there is no time difference between the time at each transmitting reference station and the time at the moving body The positioning system according to Appendix 6. (Appendix 8) the plurality of transmitting reference stations transmit the positioning signal to the moving body by a time-division multiple access method The positioning system according to Appendix 6 or 7. (Appendix 9) synchronizes time with other transmitting reference stations, after synchronizing the time, transmits a positioning signal including the transmission time to a moving body that performs autonomous movement Transmission method. (Appendix 10) a process of synchronizing time with other transmitting reference stations, and a process of transmitting a positioning signal including the transmission time to a moving body that performs autonomous movement after synchronizing the time A program for causing a computer to execute.

[0062] Some or all of the elements (e.g., configuration and function) described in Appendices 2 to 5 that are subordinate to Appendix 1 may be subordinate to the positioning system of Appendix 6, the transmission method of Appendix 9, and the program of Appendix 10 in the same subordinate relationship as Appendices 2 to 5. Some or all of the elements described in any appendix may be applied to various hardware, software, recording means for recording software, systems, and methods.

Explanation of Signs

[0063] 1 Positioning system 10, 10a, 10b, 10c Transmission reference station 11 Synchronization unit 12 Transmission unit 20 Mobile body 21 Positioning signal receiver 22 Driving mechanism 23 Control unit 31 Cable

Claims

1. A synchronization unit that synchronizes time with other transmitting reference stations, and a transmitting unit that transmits a positioning signal including a transmission time to a moving body that performs autonomous movement after synchronizing the time. A transmitting reference station comprising the above.

2. The synchronization unit further synchronizes the time with the moving body. The transmitting reference station according to Claim 1.

3. The transmitting unit transmits the positioning signal by a TDMA (Time Division Multiple Access) method. The transmitting reference station according to Claim 1 or 2.

4. The transmitting reference station includes an atomic oscillator, and the time is generated using the atomic oscillator. The transmitting reference station according to Claim 1 or 2.

5. The distance between the transmitting reference station and the other transmitting reference station in the stage of transmitting the positioning signal is longer than the distance between the transmitting reference station and the other transmitting reference station in the stage of synchronizing the time. The transmitting reference station according to Claim 4.

6. A positioning system comprising a plurality of transmitting reference stations and a moving body that performs autonomous movement, wherein each transmitting reference station synchronizes time with other transmitting reference stations, and after synchronizing the time, transmits a positioning signal including a transmission time to the moving body, and the moving body calculates the position information of the moving body based on the positioning signal. A positioning system.

7. Each transmitting reference station further synchronizes the time with the moving body, and the moving body calculates the position information assuming that there is no time difference between the time at each transmitting reference station and the time at the moving body. The positioning system according to Claim 6.

8. The plurality of transmitting reference stations transmit the positioning signal to the moving body by a time-division multiple access method. The positioning system according to Claim 6 or 7.

9. Synchronize time with other transmitting reference stations, and after synchronizing the time, transmit a positioning signal including a transmission time to a moving body that performs autonomous movement. A transmission method.

10. A process of synchronizing time with other transmitting reference stations, and a process of transmitting a positioning signal including a transmission time to a moving body that performs autonomous movement after synchronizing the time. A program for causing a computer to execute the above.

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