Fixed station, terminal device, and positioning method for terminal device

Abstract

A fixed station according to the present disclosure comprises: a signal reception unit that receives a plurality of satellite signals; a fixed station location calculation unit that calculates the positioning location of the fixed station on the basis of the plurality of satellite signals received by the signal reception unit; a determination unit that detects an unauthorized signal or a normal signal by comparing the positioning location calculated by the fixed station location calculation unit with a reference location of the fixed station; and an output unit that outputs, to the outside, at least one of information on the unauthorized signal or information on the normal signal determined by the determination unit.

Description

Fixed station, terminal device, and terminal device positioning method

[0001] The present disclosure relates to a fixed station, a terminal device, and a method for positioning a terminal device.

[0002] Global Navigation Satellite System (GNSS) generally refers to a satellite positioning system.

[0003] It has been pointed out that satellite positioning systems are vulnerable to deception and tampering attacks. One solution to this problem is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-232999.

[0004] Special Publication No. 2023-534053

[0005] The technology described in Patent Document 1 involves a receiver in a base station that is aware of its own location detecting whether or not there is a suspicious interfering signal. However, in a terminal device whose own location moves, it is difficult for the receiver to filter out the suspicious interfering signal.

[0006] Therefore, the present disclosure proposes a fixed station, a terminal device, and a positioning method for a terminal device that enable discrimination between an unauthorized signal and a normal signal even if the position of the own station moves.

[0007] In order to solve the above problems, one embodiment of a fixed station according to the present disclosure includes a signal receiving unit that receives a plurality of satellite signals, a local station position calculation unit that calculates the positioning position of the local station based on the plurality of satellite signals received by the signal receiving unit, a determination unit that compares the positioning position calculated by the local station position calculation unit with a reference position of the local station to detect an illegal signal or a normal signal, and an output unit that outputs at least one of information on the illegal signal or information on the normal signal determined by the determination unit to the outside.

[0008] FIG. 1 is a diagram showing the current state of a positioning system. FIG. 2 is a diagram showing problems with the positioning system. FIG. 3 is a diagram showing an overview of a positioning system according to an embodiment. FIG. 4 is a diagram showing an example of the configuration of a positioning system according to an embodiment. FIG. 5 is a sequence diagram showing an example of processing in a base station. FIG. 6 is a sequence diagram showing an example of processing in a terminal device. FIG. 7 is a diagram showing an example of a specific method for transmitting and receiving incorrect / normal satellite signal information. FIG. 8 is a hardware configuration diagram showing an example of a computer that realizes the functions of the positioning system.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted.

[0010] The present disclosure will be described in the following order: 1. Overview 1-1. Current state of positioning systems 1-2. Issues with positioning systems 1-3. Positioning systems of embodiments 2. Embodiments 2-1. Configuration example of a positioning system 2-2. Processing example of a base station 2-3. Processing example of a terminal device 2-4. Specific example of a method for transmitting and receiving invalid / normal satellite signal information 3. Other embodiments 4. Effects of a base station, a terminal device, and a positioning method for a terminal device according to the present disclosure 5. Hardware configuration

[0011] (1. Overview) (1-1. Current Status of Positioning Systems) The current status of positioning systems will be described using Fig. 1. Fig. 1 is a diagram showing the current status of positioning systems.

[0012] In Fig. 1, a satellite positioning system is provided with multiple (five in Fig. 1) artificial satellites. A user has a terminal device. The terminal device receives satellite signals from the multiple artificial satellites and determines the user's current location.

[0013] (1-2. Issues with Positioning Systems) Issues with positioning systems will be described with reference to Fig. 2. Fig. 2 is a diagram showing issues with positioning systems.

[0014] It has been pointed out that satellite positioning systems using artificial satellites are vulnerable to deception and tampering attacks. Currently, methods for disguising the radio waves themselves to intentionally mislead positioning locations include meaconing and spoofing. Meaconing is a technique for retransmitting satellite signals either directly or with some modification. Spoofing is a technique for independently generating and transmitting satellite signals.

[0015] In Figure 2, it is assumed that four of the five satellites transmit normal satellite signals, one transmits an incorrect satellite signal, and a transmitting device located on the ground transmits an incorrect signal.

[0016] Under such circumstances, if a terminal device receives normal satellite signals from multiple satellites and determines its current location, the user can obtain highly accurate location information. On the other hand, if a terminal device receives satellite signals containing invalid signals from multiple satellites or a transmitting device and determines its current location, a discrepancy occurs between the obtained location information and the actual location information, and the user cannot obtain highly accurate location information.

[0017] (1-3. Positioning System of the Embodiment) The positioning system of the embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing the positioning system of the embodiment.

[0018] In Figure 3, a satellite positioning system is provided with multiple (five in Figure 3) artificial satellites 100A, 100B, 100C, 100D, and 100E. However, the number of artificial satellites is not limited. In the following description, it is assumed that the artificial satellites 100A, 100B, 100C, and 100D transmit normal satellite signals, and that the artificial satellite 100E transmits an incorrect satellite signal. It is also assumed that a transmitting device (an incorrect signal generating device) 200 located on the ground transmits an incorrect signal.

[0019] The base station 10 is a fixed station located on the ground and can receive satellite signals from multiple (five in FIG. 3 ) artificial satellites 100A, 100B, 100C, 100D, and 100E within a predetermined reception range. The terminal device 30 is a mobile station that can be carried by a user and can be moved and can receive satellite signals from multiple (five in FIG. 3 ) artificial satellites 100A, 100B, 100C, 100D, and 100E within a predetermined reception range. Furthermore, when the terminal device 30 is within the communication range (wireless network) of the base station 10, it can transmit and receive data to and from the base station 10. When the user moves from the communication range of a given base station 10 to the communication range of another adjacent base station, the terminal device 30 can transmit and receive data to and from the base station that covers the communication range of the new base station.

[0020] Here, the base station 10 is, for example, a base station for constructing a cellular network. The terminal device 30 is, for example, a mobile terminal such as a smartphone or a mobile phone. However, the terminal device 30 may be mounted on a mobile object other than a mobile terminal. The mobile object may be, for example, an automobile, bicycle, bus, truck, motorcycle, train, linear motor car, subway, or the like; it may also be a ship such as a passenger ship, cargo ship, or hovercraft; or it may be a submersible vessel that moves underwater, such as a submarine, a submarine, or an unmanned underwater vehicle. Furthermore, the mobile object may be, for example, an aircraft that moves within the atmosphere, such as an airplane, an airship, or a drone.

[0021] In the positioning system of this embodiment, a base station 10 receives satellite signals transmitted from multiple artificial satellites 100A, 100B, 100C, 100D, and 100E and calculates its own position based on the received satellite signals. Because the base station 10 is a fixed station, its position on the Earth is determined by its latitude, longitude, and altitude, and a reference position is defined as a coordinate system. The base station 10 detects whether a signal is invalid or normal by comparing the calculated position based on the received satellite signals with this reference position.

[0022] Specifically, the base station 10 identifies an unauthorized signal or a normal signal based on the amount of deviation between a position (positioned position) determined using multiple satellite signals and a reference position determined using the latitude, longitude, and altitude of the base station 10. The base station 10 then identifies the satellite or transmitting device transmitting the unauthorized signal or the normal signal. Here, the base station 10 identifies the satellite signal transmitted by the satellite 100E and the signal transmitted by the transmitting device 200 as unauthorized signals. The base station 10 outputs the detected unauthorized signal, i.e., information about the identified satellite 100E or transmitting device 200, to the outside. Alternatively, the base station 10 may output information about the detected normal signal to the outside, or may output information including both normal and unauthorized signals in a format that allows them to be distinguished from each other.

[0023] Like the base station 10, the terminal device 30 can receive satellite signals transmitted from multiple satellites 100A, 100B, 100C, 100D, and 100E and calculate its own position based on the received satellite signals. However, there is a possibility that the satellite signals transmitted by the satellites 100A, 100B, 100C, 100D, and 100E may contain unauthorized signals. Therefore, the terminal device 30 acquires information on unauthorized signals or normal signals detected by the base station 10 and output to the outside. The terminal device 30 calculates its own position based on the received satellite signals excluding the unauthorized signals. Here, the terminal device 30 calculates its positioning position based on the satellite signals of the multiple satellites 100A, 100B, 100C, 100D, and 100E received and the signals of the transmitting device 200, excluding the unauthorized satellite signal of the satellite 100E and the unauthorized signal of the transmitting device 200.

[0024] Therefore, in the positioning system of the embodiment, the base station 10 distinguishes between an unauthorized signal and a normal signal and outputs the signal to the outside, so that even when the terminal device 30 moves, it can obtain information about the unauthorized signal or the normal signal from the base station 10 and determine its position using only normal satellite signals without using an unauthorized signal.

[0025] (2. Embodiment) (2-1. Configuration Example of Positioning System) A configuration example of a positioning system according to an embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing a configuration example of a positioning system according to an embodiment.

[0026] 4, the positioning system 1 of the embodiment includes a base station 10 and a terminal device 30. As described above, the base station 10 is a fixed station located on the ground and is capable of receiving satellite signals from multiple satellites 100 within a predetermined reception range. The terminal device 30 is a mobile station that can be carried by a user and is capable of receiving satellite signals from multiple satellites 100 within a predetermined reception range. Furthermore, if an unauthorized signal generator 200 (corresponding to the transmitting device 200 shown in FIG. 3) is present within the predetermined reception range in addition to the satellite 100, the base station 10 and the terminal device 30 can receive the unauthorized signal from the unauthorized signal generator 200.

[0027] When the terminal device 30 is within the communication range (wireless network) of the base station 10, it can transmit and receive data to and from the base station 10. Here, the base station 10 is, for example, a base station for constructing a cellular network. The terminal device 30 is, for example, a mobile terminal such as a smartphone or a mobile phone.

[0028] The base station 10 includes a signal receiving unit 11 , a local station position calculation unit 12 , a local station position holding unit 13 , a determining unit 14 , a data storage unit 15 , and a communication unit (output unit) 16 .

[0029] The signal receiving unit 11 can receive satellite signals transmitted from a plurality of artificial satellites 100. The signal receiving unit 11 can receive not only satellite signals transmitted from the artificial satellites 100 but also signals transmitted from an unauthorized signal generating device 200 as a separate transmitting device.

[0030] The local station position calculation unit 12 calculates the local station's position by triangulation based on the multiple satellite signals received by the signal receiving unit 11. In this case, the local station position calculation unit 12 calculates the local station's position multiple times based on different combinations of multiple satellite signals from the multiple satellite signals received by the signal receiving unit 11.

[0031] For example, first, the local station position calculation unit 12 calculates the positioning position based on four satellite signals from artificial satellites 100A, 100B, 100C, and 100D (see FIG. 3) received by the signal receiving unit 11. Next, the local station position calculation unit 12 calculates the positioning position based on four satellite signals from artificial satellites 100A, 100B, 100C, and 100E (see FIG. 3) received by the signal receiving unit 11. Furthermore, the local station position calculation unit 12 calculates the positioning position based on three satellite signals from artificial satellites 100A, 100B, and 100C (see FIG. 3) received by the signal receiving unit 11 and a signal from the unauthorized signal generator 200 received by the signal receiving unit 11.

[0032] The local station position calculation unit 12 calculates the positioning position at predetermined intervals based on different combinations of multiple satellite signals.

[0033] The base station position holding unit 13 holds the reference position of the base station 10. The reference position of the base station 10 is the position (latitude, longitude, altitude) on the Earth of the base station 10, which is a fixed station, and is a coordinate system.

[0034] The determination unit 14 detects an illegal signal and a normal signal by comparing the positioning position calculated by the local station position calculation unit 12 with the reference position held by the local station position holding unit 13. If the deviation between the positioning position and the reference position exceeds a preset threshold, the determination unit 14 determines that an illegal signal is included in the multiple signals used in the calculation by the local station position calculation unit 12.

[0035] The local station position calculation unit 12 calculates a positioning position based on multiple satellite signals in different combinations. The determination unit 14 compares multiple positioning positions calculated based on multiple satellite signals in different combinations with a reference position to detect invalid signals and normal signals. For example, the local station position calculation unit 12 calculates a positioning position P1 based on satellite signals from artificial satellites 100A, 100B, 100C, and 100D (see FIG. 3). The local station position calculation unit 12 also calculates a positioning position P2 based on satellite signals from artificial satellites 100A, 100B, 100C, and 100E (see FIG. 3).

[0036] Here, it is assumed that the satellite signals from the satellites 100A, 100B, 100C, and 100D (see FIG. 3) are normal signals, and the satellite signal from the satellite 100E (see FIG. 3) is an incorrect signal. When the determination unit 14 compares the positioning position P1 calculated using only the normal signals with the reference position P0, the deviation (amount of deviation) between the two is less than the threshold value, and it is determined that all of the satellite signals from the satellites 100A, 100B, 100C, and 100D are normal signals. On the other hand, when the determination unit 14 compares the positioning position P2 calculated using the incorrect signals with the reference position P0, the deviation (amount of deviation) between the two exceeds the threshold value, and it is determined that the satellite signals from the satellites 100A, 100B, 100C, and 100E include an incorrect signal. However, since the combination of satellites 100A, 100B, 100C, and 100D is normal and satellites 100A, 100B, 100C, and 100E are fraudulent, the judgment unit 14 can identify that satellite 100E is transmitting a fraudulent signal.

[0037] Note that the method by which the determination unit 14 detects an unauthorized signal is not limited to the above method. For example, when the determination unit 14 detects an unauthorized signal by comparing the positioning position with the reference position, if the number of positioning positions is insufficient and there are insufficient combinations, or if multiple unauthorized signals are included and a unique unauthorized signal cannot be detected, the determination unit 14 determines that an unauthorized signal is included. Furthermore, if accurate positioning cannot be performed using a specific GNSS system (GPS / GLONASS / Galileo / Baidu / QZSS / NaVIC), the system may be determined to contain unauthorized satellite information. Furthermore, if accurate positioning cannot be performed using a specific frequency (L1 / L2 / L5 / E6), the frequency may be determined to contain an unauthorized satellite signal.

[0038] Furthermore, the local station position calculation unit 12 calculates the positioning position at predetermined intervals. Each time the local station position calculation unit 12 calculates the positioning position, the determination unit 14 compares the positioning position with a reference position to detect whether the signal is invalid or normal.

[0039] The data storage unit 15 stores information on unauthorized signals or normal signals, or information on both unauthorized and normal signals detected by the determination unit 14. The information on unauthorized signals or normal signals may include the identification number of the satellite transmitting the unauthorized or normal signal, information on the satellite positioning system transmitting the unauthorized or normal signal, or information on the frequency of the unauthorized or normal signal. It is preferable that the data storage unit 15 updates (adds / deletes) the satellite data it stores each time, taking into account the possibility that unauthorized activity may be carried out using a different satellite signal or that the unauthorized signal attack may cease over time.

[0040] The communication unit 16 outputs to the outside at least one of the information on the abnormal signal and the information on the normal signal determined by the determination unit 14. The communication unit 16 functions as an output unit. The communication unit 16 is capable of transmitting and receiving information to and from the terminal device 30 via a network (such as the Internet) 300.

[0041] When the communication unit 16 outputs unauthorized signal information or normal signal information to the outside, for example, when an external device (e.g., a terminal device 30) requests the communication unit 16 to output unauthorized signal information or normal signal information, the communication unit 16 outputs the unauthorized signal information or normal signal information to the outside. The communication unit 16 may also output the unauthorized signal information or normal signal information to the outside in the form of a report to multiple terminal devices 30 within its range. The communication unit 16 also outputs the unauthorized signal information or normal signal information to a specific website via the network 300. In this case, it is preferable that the communication unit 16 periodically updates the unauthorized signal information or normal signal information stored on the website.

[0042] The communication unit 16 lists information about invalid signals and information about normal signals and outputs the list to the outside. Specifically, the following example shows a case where the communication unit 16 outputs a list listing the identification numbers (IDs) of satellites that transmit invalid signals. Invalid SV list: SVN=51 (PRN=20), SVN=62 (PRN=25)

[0043] The following example shows a case where the communication unit 16 outputs information on the satellite positioning system that transmits the invalid signal, such as a list listing two GPS satellites and the GLONASS system (all GLONASS satellites), in addition to the identification number (ID) of the artificial satellite. Invalid SV list: SVN=51 (PRN=20), SVN=62 (PRN=25) Invalid System list: GLONASS

[0044] In addition, the communication unit 16 outputs a list of satellite identification numbers (IDs) when the frequency band of a specific satellite is designated as invalid, for example, a list listing the GPS L5 frequency bands of GPS satellite 51 (no frequency designation) and GPS satellite 62. In this case, the L1 frequency band of GPS satellite 62 is determined to be normal. Invalid SV list: SVN=51 (PRN=20), SVN=62 (PRN=25) / L5

[0045] The following example shows a case where the communication unit 16 outputs a list listing the frequency bands of specific satellite positioning systems, such as the GPS L5 and Galileo E5 frequency bands, in addition to the identification numbers (IDs) of the satellites: Invalid SV list: SVN=51 (PRN=20), SVN=41 (PRN=22) Invalid Frequency list: L5, E5

[0046] The terminal device 30 includes a signal receiving unit 31, a local station position calculation unit 32, a data storage unit 33, and a communication unit (acquisition unit) .

[0047] The signal receiving unit 31 can receive satellite signals transmitted from a plurality of artificial satellites 100. The signal receiving unit 31 can receive not only satellite signals transmitted from the artificial satellites 100 but also signals transmitted from the unauthorized signal generating device 200 as a separate transmitting device.

[0048] The communication unit 34 acquires information about an unauthorized signal or information about a normal signal. The communication unit 34 functions as an acquisition unit. The communication unit 34 is capable of transmitting and receiving information to and from the base station 10 via a network (such as the Internet) 300.

[0049] When the communication unit 34 acquires unauthorized signal information or normal signal information from an external source, for example, the communication unit 34 outputs a request for unauthorized signal information or normal signal information to an external device (e.g., the base station 10) and acquires the unauthorized signal information or normal signal information transmitted from the external device (e.g., the base station 10) in response to the request. The communication unit 34 may also acquire unauthorized signal information or normal signal information reported from an external device (e.g., the base station 10). Furthermore, if the communication unit 16 of the base station 10 outputs unauthorized signal information or normal signal information to a specific website via the network 300 and stores the information, the communication unit 34 acquires the unauthorized signal information or normal signal information from the website. At this time, the communication unit 34 acquires the identification number of the base station 10 located within a predetermined communication range and acquires the unauthorized signal information or normal signal information from the base station 10 with the acquired identification number.

[0050] When a user carrying a terminal device 30 moves and the terminal device 30 moves out of the communication range of a predetermined base station 10, the communication unit 34 is no longer able to acquire unauthorized signal information or normal signal information from the base station 10 located within the predetermined communication range. At this time, the communication unit 34 acquires the identification number of a new base station 10 located within the current communication range, and acquires unauthorized signal information and normal signal information from the base station 10 with the acquired identification number.

[0051] The local station position calculation unit 32 calculates the local station's position by triangulation based on the multiple satellite signals received by the signal receiving unit 31. At this time, the local station position calculation unit 32 calculates the local station's position based on the multiple satellite signals received by the signal receiving unit 31, excluding any unauthorized signals based on information on unauthorized signals and normal signals acquired by the communication unit 34. In other words, the local station position calculation unit 32 calculates the local station's position based on the satellite signals excluding any unauthorized signals from the multiple satellite signals, or normal signals.

[0052] The communication unit 34 acquires information on illegal signals and information on normal signals at any timing or at predetermined intervals, and the local station position calculation unit 32 calculates the positioning position based on the satellite signals excluding the illegal signals from among the multiple satellite signals, i.e., the normal signals, each time it acquires information on illegal signals and normal signals. In other words, the local station position calculation unit 32 periodically calculates the positioning position based on the multiple satellite signals.

[0053] The data accumulation unit 33 accumulates unauthorized signal information and normal signal information acquired by the communication unit 34. When a base station 10 from which the communication unit 34 acquires unauthorized signal information or normal signal information is changed, the data accumulation unit 33 overwrites the unauthorized signal information and normal signal information acquired from the changed base station 10. Furthermore, when a base station 10 from which the communication unit 34 acquires unauthorized signal information or normal signal information is changed, the data accumulation unit 33 may accumulate the unauthorized signal information and normal signal information acquired from the changed base station 10 by linking it to the identification number of the base station 10. Furthermore, in consideration of the possibility that the unauthorized signal information and normal signal information may be updated over time, the unauthorized signal information and normal signal information may be acquired, accumulated, and updated even when the base station 10 is not changed.

[0054] (2-2. Example of Base Station Processing) Figure 5 is a sequence diagram showing an example of processing when the fixed station is a cellular base station. This sequence describes an example of detecting an unauthorized signal, storing it as data, and outputting it, but it is also possible to eliminate unauthorized signals and perform positioning using normal signals even when detecting, storing, and transmitting normal signals, or when detecting, storing, and transmitting both unauthorized and normal signals.

[0055] 4 and 5, the base station positioning method involves base station 10 receiving multiple satellite signals, calculating the position of base station 10 based on the received multiple satellite signals, comparing the calculated position with a reference position of base station 10 to detect whether an unauthorized signal or a normal signal is detected, and outputting information about the detected unauthorized signal to the outside. That is, the computer implementing base station 10 has a program that causes base station 10 to receive multiple satellite signals, calculates the position of base station 10 based on the received multiple satellite signals, compares the calculated position with a reference position of base station 10 to detect whether an unauthorized signal or a normal signal is detected, and outputting information about the detected unauthorized signal to the outside.

[0056] In step S11, the signal receiving unit 11 of the base station 10 receives satellite signals transmitted from multiple artificial satellites 100. In step S12, the local station position calculating unit 12 sets multiple signals that form a predetermined combination from the multiple received signals. In step S13, the local station position calculating unit 12 locates the position of the base station 10 based on the multiple set signals and calculates the located position.

[0057] In step S14, the determination unit 14 compares the position calculated by the local station position calculation unit 12 with the reference position stored in the local station position storage unit 13. In step S15, the determination unit 14 determines whether the positional deviation (deviation) between the position calculated by the local station position calculation unit 12 is within a threshold value. If the determination unit 14 determines that the positional deviation (deviation) between the position calculated by the local station position calculation unit 12 is within the threshold value (Yes), then in step S16, the determination unit 14 determines that no illegal signals are included in the multiple signals used in the calculation by the local station position calculation unit 12.

[0058] On the other hand, if the determination unit 14 determines that the positional deviation (deviation) between the positioning position and the reference position exceeds the threshold (No), then in step S17, it determines that one or more signals used in the calculation by the local station position calculation unit 12 contain an invalid signal. In this case, the positioning position and the reference position are position information in a coordinate system, and the latitude, longitude, and altitude are compared between the positioning position and the reference position. Then, if at least one of the positional deviations (deviations) in the latitude, longitude, and altitude exceeds the threshold, it is determined that an invalid signal is contained.

[0059] In step S18, the determination unit 14 stores the determination result or the source of the unauthorized signal (artificial satellite or unauthorized signal generator) in the data storage unit 15. The information stored in the data storage unit 15 includes the combination of satellite signals (artificial satellites) that detected the unauthorized signal, the identification number of the satellite transmitting the unauthorized signal, the satellite positioning system that transmitted the unauthorized signal, the frequency of the unauthorized signal, etc.

[0060] In step S19, the determination unit 14 determines whether the normal / false determination has been completed for all satellite signals from the satellites 100 and signals from the transmitting devices received by the signal receiving unit 11. If the determination unit 14 determines that the normal / false determination has not been completed for all satellite signals from the satellites 100 and signals from the transmitting devices (No), the process returns to step S11, and the local station position calculation unit 12 changes the settings of multiple signals with different combinations from the multiple received signals. Then, the process from step S13 onwards is executed again.

[0061] On the other hand, when the determination unit 14 determines that the normal / false determination has been completed for the satellite signals of all the artificial satellites 100 and the signals of the transmitting devices (Yes), the communication unit 16 outputs information about the fraudulent signals determined by the determination unit 14 to the outside. In this case, for example, in step S20, the communication unit 16 determines whether or not there is a request from the terminal device 30 to output the fraudulent signal information. Here, when the communication unit 16 determines that there is a request from the terminal device 30 to output the fraudulent signal information (Yes), the communication unit 16 outputs the fraudulent signal information to the terminal device 30 in step S21. However, when the communication unit 16 determines that there is no request from the terminal device 30 to output the fraudulent signal information (No), the communication unit 16 does not output the fraudulent signal information to the terminal device 30.

[0062] However, the communication unit 16 may output the unauthorized signal information to the outside regardless of whether or not there is a request to output the unauthorized signal information from the terminal device 30. In this case, the communication unit 16 outputs the unauthorized signal information to a specific website via the network 300, for example. The communication unit 16 may also output the unauthorized signal information and normal signal information to the outside in a format that notifies multiple terminal devices 30 within the range.

[0063] (2-3. Example of Processing in Terminal Device) FIG. 6 is a sequence diagram showing an example of processing in a terminal device. In this sequence diagram, a cellular base station is shown as an example of the communication partner device of the terminal device, but the communication target may be any fixed building, and the communication method may be a communication method other than cellular wireless communication. This sequence shows an example of acquiring information about an unauthorized signal, but even when acquiring information about a normal signal, or when acquiring information about both an unauthorized signal and a normal signal, the terminal device can eliminate the unauthorized signal and perform positioning using only the normal signal.

[0064] 4 and 6, the terminal device positioning method involves the terminal device 30 receiving multiple satellite signals, comparing the positioning position of the base station 10 with the reference position of the base station 10 to obtain information on any detected fraudulent signals, and calculating the terminal device's own position based on the satellite signals excluding the fraudulent signals from the multiple received satellite signals. A computer implementing the terminal device 30 has a program that receives multiple satellite signals from the terminal device 30, compares the positioning position of the base station 10 with the reference position of the base station 10 to obtain information on any detected fraudulent signals, and calculates the terminal device's own position based on the satellite signals excluding the fraudulent signals from the multiple received satellite signals.

[0065] In step S31, the terminal device 30 establishes communication (a wireless communication path and an Internet connection) with the base station 10. That is, communication is established between the communication unit 34 of the terminal device 30 and the communication unit 16 of the base station 10 via the network 300. In step S32, the communication unit 34 of the terminal device 30 acquires information (such as an identification number and location information) about the base station 10 that is currently within its communication range.

[0066] In step S33, the communication unit 34 acquires unauthorized signal information from the base station 10. In this case, the communication unit 34 requests the base station 10 to output unauthorized signal information, and acquires the unauthorized signal information transmitted from the base station 10 in response to the request to output unauthorized signal information. The communication unit 34 may also acquire unauthorized signal information and normal signal information reported by the base station 10. Furthermore, if the communication unit 16 of the base station 10 outputs unauthorized signal information and normal signal information to a specific website via the network 300 and stores the output, the communication unit 34 acquires the unauthorized signal information and normal signal information via the network 300. In step S34, the communication unit 34 stores the acquired unauthorized signal information and normal signal information in the data storage unit 33.

[0067] In step S35, the signal receiving unit 31 receives satellite signals transmitted from the multiple artificial satellites 100. In step S36, the local station position calculating unit 32, based on the acquired information about the incorrect signal, excludes any incorrect signals from the multiple satellite signals received by the signal receiving unit 31. Then, in step S37, the local station position calculating unit 32 locates the position of the terminal device 30 based on the multiple normal satellite signals from which the incorrect signals have been excluded, and calculates the located position.

[0068] (2-4. An example of a specific method for transmitting and receiving unauthorized / normal satellite signal information) Figure 7 is a diagram showing an example of a specific method for transmitting and receiving unauthorized / normal satellite signal information. The format of the data to be transmitted and received may be a case where unauthorized signal information is transmitted and received, a case where normal signal information is transmitted and received, or a case where both unauthorized signal information and normal signal information are transmitted and received. In any method, it is possible to eliminate unauthorized signals and perform positioning using only normal signals.

[0069] 7, in the positioning system 1, a standard specification such as LPP (or RRLP) is defined as a protocol for exchanging GNSS information between a terminal device 30 and a server in a cellular network. LPP is used to identify the location of the terminal device 30 using measurements of positional relationships obtained by one or more reference sources. LPP is used point-to-point between a location server (e.g., E-SMLC / LMF / SLP) 400 and the terminal device 30.

[0070] The LPP session is used between the location server 400 and the terminal device 30 to obtain positional measurements or position estimates or to transfer assistance data.

[0071] For example, the satellite assist information broadcast from the location server 400 is defined as Positioning System Information Blocks in 3GPP (registered trademark), and a format called positioning SIB type is specified. For example, by amending the positioning SIB type specification and expanding it so that information on incorrect / normal satellite signals can be transmitted and received, information on incorrect / normal satellite signals observed at a fixed station such as a cellular base station can be notified to the location server 400, and the location server 400 can include the information on incorrect / normal satellite signals in the posSibType that it transmits to the terminal device 30, allowing the terminal device 30 to acquire the information on incorrect / normal satellite signals.

[0072] On the other hand, there are cases where a location server 400 is not provided and a communication protocol such as LPP is not used, or where unauthorized signals are detected locally using communication functions such as Wi-Fi (registered trademark) or Bluetooth (registered trademark). In such cases, in a system that does not use LPP, or in a case where the terminal device 30 wants to acquire the list at any timing, the terminal device 30 can acquire information on unauthorized / normal satellite signals detected by the base station 10 from the network 300 at any timing. As another means for the base station 10 to notify the terminal device 30 when it is within range without using a location protocol such as LPP, the information on unauthorized / normal satellite signals may be notified by extending a 3GPP signaling message for cellular use broadcast from a cellular base station.

[0073] The positioning system 1 can detect unauthorized signals over a wide area, such as a country or region, even if the satellite signal itself is unauthorized or if the satellite is out of order. Furthermore, since the system can widely store and share information on unauthorized / normal signals, the information can be shared between fixed base stations (different servers) to provide users with information on unauthorized / normal signals. Furthermore, if a specific base station is not operating correctly, the system can be used for auxiliary operation or countermeasures.

[0074] On the other hand, when an unauthorized signal is being used in a small or medium-sized area, the positioning system 1 can detect the unauthorized signal at a nearby fixed station such as a mobile phone base station, store the information as unauthorized / normal signal, and provide the information on unauthorized / normal signal to the user.

[0075] In the case where information on unauthorized signals is used in a very localized area, the positioning system 1 can also enable the terminal device 30 to acquire information on unauthorized / normal signals that has been measured and accumulated on buildings, etc., using proximity wireless technology (wireless LAN, etc.) deployed in the building.

[0076] When local spoofing is performed, the receiver of the spoofed party will detect the signal as an unknown signal that cannot be measured in locations where spoofing is not performed. Therefore, signals that are not measured by nearby fixed stations can be determined to be spoof signals. In this case, the fixed station will not detect the fraudulent signal, and the spoof signal will not be included in the fraudulent signal information that the terminal device can acquire. However, by using a method of sending and receiving information on normal signals or both fraudulent and normal signals, the terminal device can eliminate the spoof signal and use only normal satellite signals to enable normal positioning. If a nearby fixed station also receives a spoof signal, the positioning position at the fixed station will be shifted, so the signal can be detected as a fraudulent signal and provided to the terminal device, allowing normal positioning to be achieved using only normal satellite signals.

[0077] In the case of meaconing, there are cases where both radio waves from normal satellites and unauthorized radio waves are detected at the same time, but if positioning is performed using normal signals, the positioning will be correct, but if positioning is performed using unauthorized signals, a position error will be detected.The relevant signal band is determined to have been processed or retransmitted, and whether it is a normal signal or an unauthorized signal, it is identified and stored at the fixed station as an inappropriate satellite signal, and by providing this information to the terminal device, it can be determined not to use it for positioning the terminal device.

[0078] In other words, a fixed station having information on fraudulent / normal satellite signals and a mobile terminal device can share a list of fraudulent / normal signals via communication, thereby making it possible to exclude in advance satellites that transmit fraudulent signals from the satellites used by the terminal device when determining its position based on satellite position.This makes it possible to determine the position of the terminal device by using correct signals without being affected by fraudulent signals.

[0079] (3. Other Embodiments) The processing according to the above-described embodiment may be implemented in various different forms other than the above-described embodiment.

[0080] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using known methods. In addition, the information including the processing procedures, specific names, various data, and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified. For example, the various information shown in each drawing is not limited to the information shown in the drawings.

[0081] Furthermore, the components of each device shown in the figure are conceptual functional components and do not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0082] Furthermore, the above-described embodiments can be combined as appropriate within the scope of not causing any contradiction in the processing content.

[0083] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0084] (4. Effects of the base station, terminal device, and terminal device positioning method according to the present disclosure) As described above, the base station 10 according to the present disclosure includes a signal receiving unit 11 that receives a plurality of satellite signals, a local station position calculation unit 12 that calculates the local station's position based on the plurality of satellite signals received by the signal receiving unit 11, a determination unit 14 that compares the position calculated by the local station position calculation unit 12 with the local station's reference position to detect an illegal signal or a normal signal, and a communication unit 16 as an output unit that outputs at least one of information about the illegal signal or information about the normal signal determined by the determination unit 14 to the outside.

[0085] Therefore, the base station 10 compares its positioning position with its reference position to detect an unauthorized signal or a normal signal, and outputs at least one of the detected information on the unauthorized signal or the normal signal to the outside. Therefore, even when the terminal device 30 is carried by a user and moving, it can identify an unauthorized signal using the output information on the unauthorized signal or the normal signal, and can locate its own position using information on normal satellite signals excluding unauthorized signals.

[0086] The base station 10 according to the present disclosure has a data storage unit 15 that stores information on an unauthorized signal or information on a normal signal detected by the determination unit 14. Therefore, the data storage unit 15 can store information on an unauthorized signal or information on a normal signal each time the determination unit 14 determines a satellite signal.

[0087] In the base station 10 according to the present disclosure, the communication unit 16 outputs unauthorized signal information or normal signal information to the outside when an external request for output of unauthorized signal information or normal signal information is received. Therefore, the base station 10 outputs unauthorized signal information or normal signal information to the outside only when an external request for output of unauthorized signal information or normal signal information is received, thereby reducing the number of times unauthorized signal information or normal signal information is output and simplifying processing. Furthermore, the communication unit 16 may output unauthorized signal information or normal signal information to the outside in a format that notifies a terminal device 30 within its range, regardless of whether an external request for output of unauthorized signal information or normal signal information is received. Therefore, the base station 10 can simultaneously transmit unauthorized signal information or normal signal information to multiple terminal devices 30 within its range, thereby improving notification efficiency.

[0088] In the base station 10 according to the present disclosure, the communication unit 16 outputs information on an unauthorized signal or information on a normal signal to a website or a terminal device 30. This allows for simplification of the processing of the base station 10.

[0089] In the base station 10 according to the present disclosure, the communication unit 16 outputs the identification number of the satellite 100 that transmits the unauthorized signal or the normal signal. Therefore, the source of the unauthorized signal or the normal signal can be identified on a satellite 100-by-satellite basis.

[0090] In the base station 10 according to the present disclosure, the communication unit 16 outputs information about the satellite positioning system that transmits the unauthorized signal or the normal signal, so that the transmission source of the unauthorized signal or the normal signal can be identified for each satellite positioning system.

[0091] In the base station 10 according to the present disclosure, the communication unit 16 outputs information about the frequency of an unauthorized signal or a normal signal, so that the transmission source of the unauthorized signal or the normal signal can be identified in frequency units.

[0092] In the base station 10 according to the present disclosure, the base station position calculation unit 12 calculates the positioning position multiple times based on different combinations of satellite signals from the multiple satellite signals received by the signal receiving unit 11, and the determination unit 14 compares the multiple positioning positions calculated based on the different combinations of satellite signals with a reference position to detect an incorrect signal or a normal signal. This makes it possible to appropriately identify the satellite transmitting the incorrect signal or a normal signal and quickly output it.

[0093] In the base station 10 according to the present disclosure, when the deviation between the positioning position and the reference position exceeds a preset threshold, the determination unit 14 determines that one or more signals used in the calculation by the base station position calculation unit 12 include an unauthorized signal. Therefore, it is possible to appropriately identify the satellite transmitting the unauthorized signal.

[0094] In the base station 10 according to the present disclosure, the local station position calculation unit 12 calculates the positioning position at predetermined intervals, and the determination unit 14 compares the positioning position with a reference position each time the local station position calculation unit 12 calculates the positioning position to detect whether the signal is fraudulent or normal. Therefore, even if the fraudulent signal being transmitted is changed, the satellite transmitting the fraudulent signal can be quickly identified.

[0095] The terminal device 30 according to the present disclosure includes a signal receiving unit 31 that receives multiple satellite signals, a communication unit (acquisition unit) 34 that acquires information on an unauthorized signal or information on a normal signal, and a local station position calculation unit 32 that calculates the positioning position of the local station based on a satellite signal that corresponds to the information on the unauthorized signal or the information on the normal signal acquired by the communication unit 34 from among the multiple satellite signals received by the signal receiving unit 31.

[0096] Therefore, since the terminal device 30 acquires information on unauthorized signals or normal signals output by the base station 10, even when the user is carrying it and moving, it can identify unauthorized signals using the information on unauthorized signals or normal signals output, and can locate its own position using information on normal satellite signals or normal signals excluding unauthorized signals.

[0097] The terminal device 30 according to the present disclosure includes a data storage unit 33 that stores information about unauthorized signals or information about normal signals acquired by the communication unit 34. Therefore, the data storage unit 33 can store information about unauthorized signals or information about normal signals every time the communication unit 34 acquires information about unauthorized signals or information about normal signals.

[0098] In the terminal device 30 according to the present disclosure, the communication unit 34 acquires unauthorized signal information or normal signal information transmitted in response to an output request for unauthorized signal information or normal signal information output to the outside. Therefore, the terminal device 30 can acquire unauthorized signal information or normal signal information directly from the base station 10 when necessary, thereby improving security performance. Furthermore, when the base station 10 outputs unauthorized signal information or normal signal information to the outside in a format that notifies the terminal device 30, multiple terminal devices 30 within its coverage area can simultaneously receive the unauthorized signal information or normal signal information, thereby improving the efficiency of information transmission.

[0099] In the terminal device 30 according to the present disclosure, the communication unit 34 acquires unauthorized signal information or normal signal information from a website or a fixed station, so that the terminal device 30 can quickly acquire unauthorized signal information or normal signal information at the required timing.

[0100] In the terminal device 30 according to the present disclosure, the communication unit 34 acquires the identification number of the base station 10 located within a predetermined communication range, and acquires unauthorized signal information or normal signal information from the base station 10 with the acquired identification number. Therefore, the terminal device 30 can acquire appropriate unauthorized signal information or normal signal information from the appropriate base station 10.

[0101] In the terminal device 30 according to the present disclosure, when the communication unit 34 is no longer able to acquire unauthorized signal information or normal signal information from a base station 10 located within a predetermined communication range, it acquires the identification number of a new base station 10 located within the current communication range and acquires unauthorized signal information or normal signal information from the base station 10 with the acquired identification number. Therefore, even if the terminal device 30 is moving, unauthorized signal information or normal signal information can be constantly acquired and appropriate positioning can be performed.

[0102] The terminal device 30 according to the present disclosure includes a data storage unit 33 that stores unauthorized signal information or normal signal information acquired by the communication unit 34. When a base station 10 from which the communication unit 34 acquires unauthorized signal information or normal signal information is changed, the data storage unit 33 may overwrite the unauthorized signal information or normal signal information acquired from the new base station. This allows only appropriate unauthorized signal information or normal signal information to be used without increasing the amount of data stored in the data storage unit 33. Furthermore, for purposes such as leaving history or evidence, the unauthorized signal information or normal signal information may continue to be stored without being overwritten so that past performance can be referenced and viewed.

[0103] The terminal device 30 according to the present disclosure has a data storage unit 33 that stores unauthorized signal information or normal signal information acquired by the communication unit 34, and when there is a change in the base station 10 from which the communication unit 34 acquires unauthorized signal information or normal signal information, the data storage unit 33 stores the unauthorized signal information or normal signal information acquired from the changed base station 10 in association with the identification number of the base station 10. Therefore, even if the base station 10 from which the terminal device 30 acquires unauthorized signal information or normal signal information is changed, the terminal device 30 can perform positioning by utilizing the unauthorized signal information or normal signal information within the current communication range from the data storage unit 33.

[0104] In the terminal device 30 according to the present disclosure, the communication unit 34 acquires information on unauthorized signals or normal signals at any timing or at predetermined intervals, and the local station position calculation unit 32 calculates the positioning position based on the satellite signals excluding the unauthorized signals or the normal signals from among the multiple satellite signals each time the communication unit 34 acquires information on unauthorized signals or normal signals. Therefore, even if the transmitted unauthorized signal is changed, the satellite transmitting the unauthorized signal or normal signal can be quickly identified, and highly accurate positioning can be performed at all times.

[0105] In the positioning method for the terminal device 30 disclosed herein, the terminal device 30 receives multiple satellite signals, acquires information on detected unauthorized signals or normal signals by comparing the positioning position of the base station 10 with the reference position of the base station 10, and calculates the positioning position of the terminal device 30 based on the satellite signal corresponding to the information on the unauthorized signal or the information on the normal signal among the multiple received satellite signals. Therefore, since the terminal device 30 acquires the information on the unauthorized signal or the normal signal output by the base station 10, even when the terminal device 30 is carried by a user and moving, it can identify the unauthorized signal using the information on the output unauthorized signal or the information on the normal signal, and can locate the position of the terminal device 30 using normal satellite signals excluding the unauthorized signals.

[0106] (5. Hardware Configuration) FIG. 8 is a hardware configuration diagram showing an example of a computer that realizes the functions of the positioning system.

[0107] Information devices such as the positioning system 1 according to the embodiment described above are realized by, for example, a computer 1000 configured as shown in Fig. 8. The positioning system 1 according to the embodiment will be described below as an example. The computer 1000 includes a CPU 1100, a RAM 1200, a ROM (Read Only Memory) 1300, a HDD (Hard Disk Drive) 1400, a communication interface 1500, and an input / output interface 1600. The components of the computer 1000 are connected by a bus 1050.

[0108] The CPU 1100 operates and controls each component based on programs stored in the ROM 1300 or the HDD 1400. For example, the CPU 1100 loads the programs stored in the ROM 1300 or the HDD 1400 into the RAM 1200 and executes processing corresponding to the various programs.

[0109] The ROM 1300 stores boot programs such as a Basic Input Output System (BIOS) that is executed by the CPU 1100 when the computer 1000 is started, and programs that depend on the hardware of the computer 1000 .

[0110] HDD 1400 is a computer-readable recording medium that non-temporarily records programs executed by CPU 1100 and data used by such programs. Specifically, HDD 1400 is a recording medium that records a positioning program according to the present disclosure, which is an example of program data 1450.

[0111] The communication interface 1500 is an interface for connecting the computer 1000 to an external network 1550 (e.g., the Internet). For example, the CPU 1100 receives data from other devices and transmits data generated by the CPU 1100 to other devices via the communication interface 1500.

[0112] The input / output interface 1600 is an interface for connecting the input / output device 1650 and the computer 1000. For example, the CPU 1100 receives data from an input device such as a keyboard or a mouse via the input / output interface 1600. The CPU 1100 also transmits data to an output device such as a display, a speaker, or a printer via the input / output interface 1600. The input / output interface 1600 may also function as a media interface for reading programs and the like recorded on a predetermined recording medium. Examples of media include optical recording media such as a DVD (Digital Versatile Disc) or a PD (Phase Change Rewritable Disc), magneto-optical recording media such as an MO (Magneto-Optical Disk), tape media, magnetic recording media, and semiconductor memories.

[0113] For example, when the computer 1000 functions as the positioning system 1 according to the embodiment, the CPU 1100 of the computer 1000 executes a program loaded onto the RAM 1200 to realize functions of the base station 10, the control unit of the terminal device 30, and the like. Here, the control unit corresponds to the local station position calculation unit 12, the determination unit 14, the local station position calculation unit 32, and the like. The HDD 1400 stores data such as the program of the positioning system 1 according to the present disclosure. The CPU 1100 reads and executes the program data 1450 from the HDD 1400, but as another example, the CPU 1100 may obtain these programs from another device via an external network 1550.

[0114] The present technology may also be configured as follows: (1) A fixed station including: a signal receiving unit that receives a plurality of satellite signals; a host station position calculation unit that calculates a positioning position of the fixed station based on the plurality of satellite signals received by the signal receiving unit; a determination unit that detects an illegal signal or a normal signal by comparing the positioning position calculated by the host station position calculation unit with a reference position of the fixed station; and an output unit that outputs at least one of information about the illegal signal or information about the normal signal determined by the determination unit to an external device. (2) The fixed station according to (1), including a data storage unit that stores information about the illegal signal or information about the normal signal detected by the determination unit. (3) The fixed station according to (1) or (2), wherein the output unit outputs information about the illegal signal or information about the normal signal to an external device when an output request for information about the illegal signal or information about the normal signal is received from an external device. (4) The fixed station according to any one of (1) to (3), wherein the output unit outputs information about the illegal signal or information about the normal signal to a website or a terminal device. (5) The fixed station according to any one of (1) to (4), wherein the output unit outputs an identification number of a satellite transmitting the unauthorized signal or the normal signal. (6) The fixed station according to any one of (1) to (5), wherein the output unit outputs information about a satellite positioning system transmitting the unauthorized signal or the normal signal. (7) The fixed station according to any one of (1) to (6), wherein the output unit outputs information about the frequency of the unauthorized signal or the normal signal. (8) The fixed station according to any one of (1) to (7), wherein the host station position calculation unit calculates the positioning position multiple times based on multiple satellite signals in different combinations from multiple satellite signals received by the signal receiving unit, and the determination unit detects an unauthorized signal or a normal signal by comparing the multiple positioning positions calculated based on multiple satellite signals in different combinations with the reference position. (9) The fixed station according to any one of (1) to (8), wherein the determination unit determines that one or more signals used in the calculation of the local station position calculation unit include an incorrect signal when the deviation between the positioning position and the reference position exceeds a preset threshold value.(10) The fixed station according to any one of (1) to (9), wherein the local station position calculation unit calculates the positioning position at predetermined intervals, and the determination unit compares the positioning position with the reference position each time the local station position calculation unit calculates the positioning position to detect an illegal signal or a normal signal. (11) A terminal device comprising: a signal receiving unit that receives a plurality of satellite signals; an acquisition unit that acquires illegal signal information or normal signal information; and a local station position calculation unit that calculates the positioning position of the local station based on a satellite signal corresponding to the illegal signal information or the normal signal information acquired by the acquisition unit from the plurality of satellite signals received by the signal receiving unit. (12) The terminal device according to (11), further comprising a data storage unit that stores the illegal signal information or the normal signal information acquired by the acquisition unit. (13) The terminal device according to (11) or (12), wherein the acquisition unit acquires the illegal signal information or the normal signal information transmitted in response to an output request for the illegal signal information or the normal signal information output to the outside. (14) The terminal device according to any one of (11) to (13), wherein the acquisition unit acquires the unauthorized signal information or the normal signal information from a website or a fixed station. (15) The terminal device according to any one of (11) to (14), wherein the acquisition unit acquires an identification number of a fixed station located within a predetermined communication range, and acquires the unauthorized signal information or the normal signal information from the fixed station having the acquired identification number. (16) The terminal device according to any one of (11) to (15), wherein, when the acquisition unit is unable to acquire the unauthorized signal information or the normal signal information from a fixed station located within a predetermined communication range, it acquires an identification number of a new fixed station located within a current communication range, and acquires the unauthorized signal information or the normal signal information from the fixed station having the acquired identification number.(17) The terminal device according to any one of (11) to (16), further comprising: a data storage unit that stores the unauthorized signal information or the normal signal information acquired by the acquisition unit, wherein when a fixed station from which the acquisition unit acquires the unauthorized signal information or the normal signal information is changed, the data storage unit overwrites or stores the unauthorized signal information or normal signal information acquired from the new fixed station. (18) The terminal device according to any one of (11) to (17), further comprising: a data storage unit that stores the unauthorized signal information acquired by the acquisition unit, wherein when a fixed station from which the acquisition unit acquires the unauthorized signal information or the normal signal information is changed, the data storage unit stores the unauthorized signal information or the normal signal information acquired from the new fixed station in association with an identification number of the fixed station. (19) The terminal device according to any one of (11) to (18), wherein the acquisition unit acquires the information on the illegal signal or the information on the normal signal at any timing or at predetermined intervals, and the host station position calculation unit calculates the positioning position based on the information on the satellite signals excluding the illegal signal or the information on the normal signal from among a plurality of satellite signals each time the acquisition unit acquires the information on the illegal signal or the information on the normal signal. (20) A positioning method for a terminal device, wherein the terminal device receives a plurality of satellite signals, acquires information on the illegal signal or the information on the normal signal detected by comparing the positioning position of a fixed station with a reference position of the fixed station, and calculates the positioning position of the host station based on the satellite signal corresponding to the information on the illegal signal or the information on the normal signal from among the received plurality of satellite signals. (21) A method for positioning a fixed station, comprising: a fixed station receiving a plurality of satellite signals; calculating a positioning position of the fixed station based on the received plurality of satellite signals; comparing the calculated positioning position with a reference position of the fixed station to detect an illegal signal or a normal signal; and outputting at least one of information on the determined illegal signal or information on the determined normal signal to the outside.(22) A positioning program that causes a computer to execute the following processing: receiving a plurality of satellite signals by a terminal device, acquiring information on detected illegal signals or information on normal signals by comparing the positioning position of a fixed station with a reference position of the fixed station, and calculating the positioning position of the own station based on a satellite signal corresponding to the information on the illegal signal or the information on the normal signal among the plurality of received satellite signals. (23) A positioning program that causes a computer to execute the following processing: receiving a plurality of satellite signals, calculating the positioning position of the own station based on the plurality of received satellite signals, comparing the calculated positioning position with a reference position of the own station to detect an illegal signal or a normal signal, and outputting at least one of the determined information on the illegal signal or the information on the normal signal to the outside.

[0115] REFERENCE SIGNS LIST 1 Positioning system 10 Base station (fixed station) 11 Signal receiving unit 12 Own station position calculation unit 13 Own station position holding unit 14 Determination unit 15 Data accumulation unit 16 Communication unit (output unit) 30 Terminal device 31 Signal receiving unit 32 Own station position calculation unit 33 Data accumulation unit 34 Communication unit (acquisition unit) 100 Artificial satellite 200 Unauthorized signal generator 300 Network 400 Location server

Claims

1. A fixed station comprising: a signal receiving unit that receives a plurality of satellite signals; a local station position calculation unit that calculates the local station's position based on the plurality of satellite signals received by the signal receiving unit; a determination unit that compares the local station's position calculated by the local station position calculation unit with a reference position of the local station to detect whether the signal is invalid or normal; and an output unit that outputs at least one of information about the invalid signal or information about the normal signal determined by the determination unit to the outside.

2. The fixed station according to claim 1, further comprising a data storage unit that stores information on the incorrect signal or the normal signal detected by the determination unit.

3. The fixed station according to claim 1, wherein the output unit outputs the information on the unauthorized signal or the information on the normal signal to the outside when an output request for the information on the unauthorized signal or the information on the normal signal is received from the outside.

4. The fixed station according to claim 1, wherein the output unit outputs the information on the incorrect signal or the information on the normal signal to a website or a terminal device.

5. The fixed station according to claim 1, wherein the output unit outputs an identification number of a satellite transmitting the incorrect signal or the normal signal.

6. The fixed station according to claim 1, wherein the output unit outputs information about a satellite positioning system that transmits the incorrect signal or the normal signal.

7. The fixed station according to claim 1, wherein the output unit outputs information about the frequency of the unauthorized signal or the normal signal.

8. The fixed station according to claim 1, wherein the local station position calculation unit calculates the positioning position multiple times based on multiple different combinations of satellite signals from multiple satellite signals received by the signal receiving unit, and the determination unit compares the multiple positioning positions calculated based on multiple different combinations of satellite signals with the reference position to detect an incorrect signal or a normal signal.

9. The fixed station according to claim 1, wherein the determination unit determines that one or more signals used in the calculation by the local station position calculation unit contain an incorrect signal when the deviation between the positioning position and the reference position exceeds a preset threshold value.

10. The fixed station according to claim 1, wherein the local station position calculation unit calculates the positioning position at predetermined intervals, and the determination unit compares the positioning position with the reference position each time the local station position calculation unit calculates the positioning position to detect an incorrect signal or a normal signal.

11. A terminal device comprising: a signal receiving unit that receives a plurality of satellite signals; an acquisition unit that acquires information on an invalid signal or information on a normal signal; and a local station position calculation unit that calculates the positioning position of the local station based on a satellite signal that corresponds to the information on the invalid signal or the information on the normal signal acquired by the acquisition unit from among the plurality of satellite signals received by the signal receiving unit.

12. The terminal device according to claim 11, further comprising a data storage unit that stores the information on the incorrect signal or the information on the normal signal acquired by the acquisition unit.

13. The terminal device according to claim 11, wherein the acquisition unit acquires the unauthorized signal information or the normal signal information transmitted in response to an output request for the unauthorized signal information or the normal signal information output to the outside.

14. The terminal device according to claim 11, wherein the acquisition unit acquires the information on the unauthorized signal or the information on the normal signal from a website or a fixed station.

15. The terminal device according to claim 11, wherein the acquisition unit acquires an identification number of a fixed station located within a predetermined communication range, and acquires information on the incorrect signal or information on the normal signal from the fixed station with the acquired identification number.

16. The terminal device described in claim 15, wherein when the acquisition unit is no longer able to acquire the unauthorized signal information or the normal signal information from a fixed station located within a predetermined communication range, it acquires the identification number of a new fixed station located within the current communication range and acquires the unauthorized signal information or the normal signal information from the fixed station with the acquired identification number.

17. A terminal device according to claim 16, further comprising a data storage unit that stores the unauthorized signal information or the normal signal information acquired by the acquisition unit, wherein when there is a change in the fixed station from which the acquisition unit acquires the unauthorized signal information or the normal signal information, the data storage unit overwrites or stores the unauthorized signal information or normal signal information acquired from the new fixed station.

18. A terminal device as described in claim 16, further comprising a data storage unit that stores the unauthorized signal information acquired by the acquisition unit, wherein when there is a change in the fixed station from which the acquisition unit acquires the unauthorized signal information or the normal signal information, the data storage unit stores the unauthorized signal information or normal signal information acquired from the new fixed station in association with the identification number of the fixed station.

19. The terminal device described in claim 11, wherein the acquisition unit acquires information on the unauthorized signal or information on the normal signal at any timing or at predetermined intervals, and the local station position calculation unit calculates the positioning position based on information on the satellite signals excluding the unauthorized signal from among multiple satellite signals or information on the normal signal each time the acquisition unit acquires information on the unauthorized signal or information on the normal signal.

20. A positioning method for a terminal device, in which the terminal device receives multiple satellite signals, obtains information on detected incorrect signals or normal signals by comparing the positioning position of a fixed station with a reference position of the fixed station, and calculates the positioning position of the terminal device based on the satellite signal corresponding to the incorrect signal information or the normal signal information among the multiple received satellite signals.

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