Positioning system, mobile device, and positioning method

Abstract

To achieve high-precision positioning with a simple configuration. [Solution] A positioning system comprising an antenna that receives satellite signals from satellites, and a receiver that decodes the satellite signals received by the antenna and generates satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprises a visible range calculation unit that determines the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit that outputs a positioning result based on the satellite information of satellites within the visible range.

Description

Technical Field

[0001] The present invention relates to a positioning system, a moving object, and a positioning method.

Background Art

[0002] When moving outdoors, the Global Navigation Satellite System (GNSS) is a useful means for position estimation. However, when there are obstacles in the vicinity, the positioning result becomes unstable in the GNSS. As a countermeasure, there is the technology described in WO2020 / 013284 (Patent Document 1). This publication states that "there is provided a navigation satellite system receiving device capable of effectively eliminating a multipath signal not accompanied by a direct wave of an invisible satellite and realizing high-precision time synchronization or positioning in a reception environment where the open space is severely limited. The satellite orbit information acquisition unit 42 acquires orbit information of navigation satellites, the installation position information acquisition unit 43 acquires position information of the installation position, the azimuth meter 3 acquires azimuth information of the azimuth in which the wall surface of an obstacle in the vicinity extends, and the azimuth mask generation unit 44 calculates a mask area for selecting a navigation satellite to be processed based on the azimuth information. The positioning / time synchronization processing unit 45 calculates the azimuth and elevation angle of each navigation satellite based on the orbit information and the position information, selects the navigation satellite to be processed based on the calculated azimuth and elevation angle and the mask area, and performs at least one of the positioning processing or the time synchronization processing based on the navigation satellite signal received from the selected navigation satellite."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The conventional technology described above requires detailed information about nearby obstacles, resulting in a complex configuration, and the accuracy of the positioning results heavily depends on the accuracy of the obstacle information. Furthermore, the reduction in the number of usable satellites due to masking is unavoidable, making it difficult to maintain the same level of accuracy as in an open-sky environment.

[0005] Therefore, the present invention aims to achieve high-precision positioning with a simple configuration. [Means for solving the problem]

[0006] To achieve the above objective, one representative positioning system of the present invention is a positioning system comprising: an antenna that receives satellite signals from satellites; a receiver that decodes the satellite signals received by the antenna and generates satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprises: a visible range calculation unit that determines the distribution of satellite positions in which the received signal strength is above a predetermined threshold and calculates a visible range from the distribution; and a positioning result output unit that outputs a positioning result based on the satellite information of satellites within the visible range. Furthermore, one representative mobile body of the present invention comprises an antenna that receives satellite signals from a satellite, and a receiver that decodes the satellite signals received by the antenna and generates satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and further comprises a visible range calculation unit that determines the distribution of satellite positions where the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit that outputs a positioning result based on the satellite information of satellites within the visible range. Furthermore, one representative positioning method of the present invention is a positioning method using a positioning system comprising an antenna that receives satellite signals from satellites and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, and the positioning system is characterized by including the steps of: determining the distribution of satellite positions in which the received signal strength is above a predetermined threshold; calculating a visible range from the distribution; and outputting a positioning result based on the satellite information of satellites within the visible range. [Effects of the Invention]

[0007] According to the present invention, high-precision positioning can be achieved with a simple configuration. Other problems, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] Configuration diagram of the positioning system in Example 1 [Figure 2] Flowchart showing the operation of the positioning system in Example 1 [Figure 3] Diagram explaining the visible range [Figure 4] Diagram illustrating the generation and use of the visible range (Part 1) [Figure 5] Diagram illustrating the generation and use of the visible range (Part 2) [Figure 6] Diagram illustrating the generation and use of the visible range (Part 3) [Figure 7] Diagram illustrating the generation and use of the visible range (Part 4) [Figure 8] Configuration diagram of the positioning system in Example 2 [Figure 9] Diagram explaining movement and recalculation of visible range (Part 1) [Figure 10] Diagram explaining movement and recalculation of visible range (Part 1) [Figure 11] Diagram illustrating vehicle types and obstacle heights. [Figure 12] Flowchart (Part 1) illustrating the operation of the positioning system in Example 2 [Figure 13] Flowchart (Part 2) showing the operation of the positioning system of Example 2 [Figure 14] Configuration diagram of the positioning system of Example 3 [Figure 15] Explanatory diagram of the switching of the representative visible range [Figure 16] Explanatory diagram of the integration of the visible range [Figure 17] Flowchart showing the processing procedure for determining the visible range in Example 3

Best Mode for Carrying Out the Invention

[0009] Hereinafter, examples will be described with reference to the drawings.

Examples

[0010] [[ID=二十七]] FIG. 1 is a configuration diagram of the positioning system of Example 1. The positioning system 20 shown in FIG. 1 is mounted on a vehicle and connected to an in-vehicle GNSS antenna 10. The GNSS antenna 10 receives satellite signals from artificial satellites. The positioning system 20 includes a GNSS receiver 21, a visible range calculation unit 22, an evaluation unit 23, a positioning result output unit 24, and a storage device 25.

[0011] The GNSS receiver 21 decodes the satellite signals received by the GNSS antenna 10 to generate satellite information. The satellite information includes at least the satellite positions and the received signal strengths as seen from the GNSS antenna 10. The GNSS receiver 21 calculates the position of the GNSS antenna 10 from the satellite information of a plurality of satellites. The position of the GNSS antenna 10 calculated by the GNSS receiver 21 is referred to as the receiver positioning result. The receiver positioning result corresponds to the "first positioning result" in the claims.

[0012] The visible range calculation unit 22 obtains the distribution of satellite positions where the received signal strength is equal to or greater than a predetermined threshold value, and calculates the visible range from the distribution. Although details will be described later, the visible range calculation unit 22 elliptically approximates the distribution of satellite positions where the received signal strength is equal to or greater than a predetermined threshold value, and sets the obtained ellipse as the visible range. The visible range virtually indicates the range of satellite positions that are not affected by obstacles.

[0013] The evaluation unit 23 determines the position of the GNSS receiver 21 from the satellite information of a plurality of satellites within the visible range. The position of the GNSS antenna 10 calculated by the evaluation unit 23 is referred to as the evaluation unit positioning result. The receiver positioning result corresponds to the "second positioning result" in the claims. Further, the evaluation unit 23 determines whether the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to a threshold value.

[0014] The positioning result output unit 24 outputs a positioning result based on the satellite information of the satellites within the visible range. Specifically, the positioning result output unit 24 outputs the receiver positioning result and also outputs a warning flag as information indicating the difference between the receiver positioning result and the evaluation unit positioning result. If the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to the threshold value, the value of the warning flag is "1". If the difference between the receiver positioning result and the evaluation unit positioning result is less than the threshold value, the value of the warning flag is "0".

[0015] The storage device 25 stores data such as satellite information and the receiver positioning result. The physical configurations of the GNSS receiver 21, the visible range calculation unit 22, the evaluation unit 23, the positioning result output unit 24, and the storage device 25 can be arbitrarily designed. As an example, the visible range calculation unit 22, the evaluation unit 23, and the positioning result output unit 24 may be such that a CPU (Central Processing Unit) realizes the corresponding functions by executing a predetermined program. In this case, the GNSS receiver 21 is taken as one unit and connected to a CPU and an arbitrary storage device as the storage device 25, thereby realizing the positioning system 20.

[0016] FIG. 2 is a flowchart showing the operation of the positioning system 20 of the first embodiment. The positioning system 20 sequentially executes steps S101 to S113. Step S101: The GNSS antenna 10 receives satellite radio waves, that is, satellite signals. Then, it proceeds to step S102. Step S102: The GNSS receiver 21 decodes the satellite signal and performs carrier wave analysis to obtain satellite information and the receiver positioning result. Then, it proceeds to step S103. In step S103, the GNSS receiver 21 transmits satellite information (position of each observed satellite, received signal strength, distance between satellite antennas) and the receiver positioning result, along with the calculated time, to the visible range calculation unit 22, the storage device 25, and the positioning result output unit 24, respectively. The process then proceeds to step S104.

[0017] In step S104, the visible range calculation unit 22 lists the satellites with high received signal strength (satellites with a signal strength above a predetermined threshold) from among the satellites obtained from the GNSS receiver 21. Then, the process proceeds to step S105. Step S105: Calculate the line of sight center from the satellite positions of all listed satellites. The line of sight center may be, for example, the average of the satellite positions, or it may be statistically determined from density, etc. Then proceed to step S106.

[0018] In step S106, the visible range calculation unit 22 sets a certain range from the center of the line of sight as the visible range and selects a satellite within the visible range from a list. Then, the process proceeds to step S107. In step S107, the visibility range calculation unit 22 sends the selected satellite to the evaluation unit 23. Then, the process proceeds to step S108.

[0019] Step S108 The evaluation unit 23 performs positioning using satellites within the visible range. Then proceed to step S109. In step S109, the evaluation unit 23 compares its own calculated positioning result with the receiver positioning result. After that, it proceeds to step S110.

[0020] In step S110, the evaluation unit 23 proceeds to step S111 if the difference between the receiver positioning result and the evaluation unit positioning result is less than the threshold. If the difference between the receiver positioning result and the evaluation unit positioning result is greater than or equal to the threshold, the evaluation unit 23 proceeds to step S112. In step S111, the evaluation unit 23 sets the warning flag to "0" and proceeds to step S113. In step S112, the evaluation unit 23 sets the warning flag to "1" and proceeds to step S113. Step S113 The positioning result output unit 24 outputs the receiver positioning result and a warning flag, and terminates the process.

[0021] Figure 3 is an explanatory diagram of the visible range. The visible range 12 is set relative to the GNSS antenna 10 mounted on the vehicle. The center of the visible range 12 is determined by the line-of-sight vector from the GNSS antenna 10 to the center of the line of sight. The visible range 12 is elliptical. The positioning system 20 uses satellites 11 located inside the visible range 12 to perform positioning, thereby suppressing the effects of obstacles and achieving highly accurate positioning.

[0022] The generation and use of the visible range will be explained with reference to Figures 4 to 7. First, as shown in Figure 4, the positioning system 20 excludes satellites 11 whose signal-to-noise ratio (SNR) is below a certain value. Next, as shown in Figure 5, the positioning system 20 approximates the distribution range of satellites 11 whose SNR is above a certain value as an ellipse and calculates the center, major axis, minor axis, and major axis direction. The positioning system 20 defines the area within the ellipse as the visible range 12.

[0023] Next, as shown in Figure 6, the positioning system 20 excludes satellites 11 that are outside the visible range. This is equivalent to setting a mask by referring to a map that shows the locations of obstacles, etc. In other words, the influence of obstacles is reduced by the visible range 12 without using map data.

[0024] Next, as shown in Figure 7, the positioning system 20 performs relative positioning using the remaining satellites and the receiver positioning results. The most reliable receiver positioning result from a certain period in the past may be used as the receiver positioning result.

[0025] As described above, the positioning system 20 shown in Example 1 can achieve high-precision positioning with a simple configuration without using external map data or the like. In Example 1, a configuration was described in which positioning results based on the visible range are used to evaluate the receiver positioning results, but a configuration that outputs positioning results based on the visible range may also be used. When outputting positioning results based on the visible range, a position calculation unit is provided instead of the evaluation unit 23, and position information calculated from satellite information of multiple satellites within the visible range is output as the positioning result. In this case, the GNSS receiver 21 does not need to calculate the receiver positioning result. Alternatively, the GNSS receiver 21 may calculate the receiver positioning result and output both the positioning result from the position calculation unit and the receiver positioning result. Furthermore, the receiver positioning result may be used to evaluate the positioning result from the position calculation unit. [Examples]

[0026] Figure 8 is a diagram showing the configuration of the positioning system of Embodiment 2. The positioning system 20a shown in Figure 8 differs from Embodiment 1 in that it further includes a relative positioning unit 26. Also, the operation of the visible range calculation unit 22 differs in part from that of Embodiment 1. The other configurations and operations are the same as in Embodiment 1, so the same reference numerals are used for the same components and their descriptions are omitted.

[0027] The relative positioning unit 26 is a movement information calculation unit that calculates movement information including the direction and distance of movement of the GNSS antenna 10. The relative positioning unit 26 acquires and stores receiver positioning results from the GNSS receiver 21. When a new receiver positioning result is acquired, it calculates the movement information of the GNSS antenna 10 by comparing it with past receiver positioning results.

[0028] In Embodiment 2, when the GNSS antenna 10 moves by more than a threshold, the visible range calculation unit 22 acquires obstacle information indicating the height of obstacles located around the visible range, and recalculates the visible range using the movement information and obstacle information.

[0029] Figures 9 and 10 are explanatory diagrams regarding movement and recalculation of the visible range. First, as shown in Figure 9, if an obstacle exists near the GNSS antenna 10, the visible center (center of the visible range) shifts to the opposite side of the obstacle, centered on the antenna position. When the GNSS antenna 10 moves in the presence of such an obstacle, the visible satellites shift. Considering that the main cause of the shift in visible satellites is shielding by obstacles, it is preferable to change the range that masks the satellites, i.e., the visible range, depending on the direction of movement of the antenna position. When the antenna position moves in the direction of the visible center, the vehicle is moving away from the obstacle. When the antenna position moves in the opposite direction to the visible center, the vehicle is moving towards the obstacle. The ellipse becomes smaller as it approaches the obstacle and larger as it moves away. From these points, the ellipse is enlarged by virtually moving the visible center, with θ being the angle between the azimuth from the antenna position to the visible center and the direction of travel.

[0030] As shown in Figure 10, if the amount of antenna movement is ν, the amount of movement in the direction of the visible center is ν × cosθ. Let η be the angle between the nearest point to the antenna on the outer edge of the visible range and the antenna position, and let h be the height of the obstacle. If η changes from η0 to η1 due to antenna movement, η1=h×tan(η0) / (h+ν×cosθtan(η0)) The visible range calculation unit 22 moves the visible center toward the antenna position by η0-η1 and recalculates the visible range after the movement by recalculating the major and minor axes.

[0031] The obstacle height h is determined not by the height of the actual obstacles in the surrounding area, but by the area in which the vehicle is traveling. If the vehicle's type specifies its intended use, it is also possible to determine the obstacle height by identifying the area in which the vehicle will be used based on its type.

[0032] Figure 11 is an explanatory diagram of vehicle types and obstacle heights. If the positioning system 20a is installed on construction machinery used in urban areas, the estimated obstacle height is 50m. If the positioning system 20a is installed on construction machinery used in rural areas, the estimated obstacle height is 20m. If the positioning system 20a is installed on agricultural machinery used in mountainous areas, the estimated obstacle height is 20m. If the positioning system 20a is installed in agriculture used in plains, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used within a company premises, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used on public roads, the estimated obstacle height is 10m. If the positioning system 20a is installed on work machinery used on expressways, the estimated obstacle height is 5m. If the positioning system 20a is installed on work machinery used on the Metropolitan Expressway, the estimated obstacle height is 20m. The positioning system 20a maintains a table showing these correspondences and reads out and uses the estimated obstacle altitude corresponding to the vehicle on which it is installed.

[0033] Figures 12 and 13 are flowcharts showing the operation of the positioning system 20a in Example 2. The operation of the positioning system 20a differs from that of Example 1 in that steps S201 to S203 are inserted between steps S107 and S108. The other steps are the same as in Example 1, so their explanation is omitted.

[0034] Step S201: After step S107, the relative positioning unit 26 calculates the relative position from the past position. Then, the process proceeds to step S202. Step S202 The relative positioning unit 26 determines whether the amount of antenna movement is greater than or equal to a threshold. If it is less than the threshold, proceed to step S108. If it is greater than or equal to the threshold, proceed to step S203. In step S203, the visible range calculation unit 22 acquires obstacle information and recalculates the visible range using the movement information and obstacle information. Then, the process proceeds to step S108.

[0035] Thus, the positioning system 20a shown in Example 2 can respond to antenna movement with a simple configuration and achieve high-precision positioning without using detailed map data, etc. In Example 2, antenna movement was evaluated by changes in the receiver positioning result, but antenna movement may also be determined by acquiring information about movement from the vehicle. [Examples]

[0036] Figure 14 is a diagram of the positioning system of Embodiment 3. The positioning system 20b shown in Figure 13 differs from Embodiment 2 in that it further includes a visible range storage unit 27. Also, the operation of the visible range calculation unit 22 differs in part from that of Embodiment 2. The other configurations and operations are the same as in Embodiment 2, so the same reference numerals are used for the same components and their descriptions are omitted.

[0037] The visible range calculation unit 22 of Embodiment 3 can generate multiple visible ranges for a single time interval. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 uses one of them as a representative visible range for positioning. To simplify the explanation, we will describe the case where up to two visible ranges are generated as an example. The two visible ranges are distinguished as the first visible range and the second visible range, and the first visible range is designated as the representative visible range.

[0038] In Embodiment 3, the visible range calculation unit 22 registers and stores one or more generated visible ranges in the visible range storage unit 27. Furthermore, when calculating the visible range, the visible range calculation unit 22 refers to past visible ranges stored in the visible range storage unit 27 to switch representative visible ranges, merge visible ranges, and delete visible ranges.

[0039] Figure 15 is an explanatory diagram for switching representative visible ranges. The visible range calculation unit 22 evaluates the change in area of ​​multiple visible ranges using the newly calculated visible range and the visible ranges stored in the visible range storage unit 27. If the area of ​​a representative visible range becomes smaller than that of other visible ranges, the unit sets the other visible range as the new representative visible range.

[0040] In Figure 15, the visible range calculation unit 22 monitors the expansion rate of the first visible range and the second visible range, which are representative visible ranges. When the first visible range is shrinking and the second visible range is expanding, and the area of ​​the second visible range exceeds that of the first visible range, the visible range calculation unit 22 switches between the first and second visible ranges.

[0041] Figure 16 is an explanatory diagram of the integration of the visible range. The visible range calculation unit 22 uses the newly calculated visible range and the visible range stored in the visible range storage unit 27 to evaluate the changes in the representative visible range and the overlapping range of other visible ranges. If the overlapping range exceeds half the area of ​​the representative visible range, the unit integrates the representative visible range and the other visible ranges and recalculates the visible range.

[0042] Here, we will explain how to erase the visible range. The visible range calculation unit 22 erases the visible range if there are no satellites within the visible range, or if either the major axis or minor axis falls below a certain threshold.

[0043] Figure 17 is a flowchart showing the processing procedure for determining the visible range in Example 3. The series of processes in Figure 17 are included in step S106 shown in Example 1. The visible range calculation unit 22 calculates the new visible range and then sequentially executes steps S301 to S317.

[0044] In step S301, the visible range calculation unit 22 determines whether a second visible range exists in the visible range storage unit 27. If a second visible range exists, the process proceeds to step S302. If a second visible range does not exist, the process proceeds to step S309.

[0045] In step S302, the visible range calculation unit 22 obtains the line of sight center of the second visible range. Then, the process proceeds to step S303. In step S303, the visible range calculation unit 22 calculates the second visible range. Then, the process proceeds to step S304. In step S304, the visible range calculation unit 22 calculates the magnification ratio from the previous visible range for the first and second visible ranges. Then, the process proceeds to step S305.

[0046] Step S305 The visible range calculation unit 22 determines whether the magnification ratio of the first visible range is less than 1. If the magnification ratio of the first visible range is 1 or greater, the process proceeds to step S306. If the magnification ratio of the first visible range is less than 1, the process proceeds to step S313. Step S306: The visible range calculation unit 22 calculates the overlapping range of the first visible range and the second visible range. Then, the process proceeds to step S307. Step S307 The visible range calculation unit 22 determines whether the overlapping range is half or more of the first visible range. If the overlapping range is half or more of the first visible range, the process proceeds to step S308. If the overlapping range is less than half of the first visible range, the process proceeds to step S316. In step S308, the visible range calculation unit 22 recalculates the visible range and integrates the visible ranges. Then, the process proceeds to step S316.

[0047] In step S309, the visible range calculation unit 22 determines whether or not there are visible satellites outside the visible range. If there are no visible satellites, the process proceeds to step S316. If there are visible satellites outside the visible range, the process proceeds to step S310. In step S310, the visible range calculation unit 22 lists the visible satellites that are outside the visible range. Then, the process proceeds to step S311. Step S311: The visible range calculation unit 22 calculates the visible range from the listed satellite positions. Then, the process proceeds to step S312. In step S312, the visible range calculation unit 22 sets the calculated visible range as the second visible range. Then, the process proceeds to step S316.

[0048] Step S313 The visible range calculation unit 22 determines whether the magnification ratio of the second visible range is less than 1. If the magnification ratio of the second visible range is 1 or greater, the process proceeds to step S314. If the magnification ratio of the second visible range is less than 1, the process proceeds to step S306. Step S314 The visible range calculation unit 22 determines whether the area of ​​the first visible range is smaller than the area of ​​the second visible range. If the area of ​​the first visible range is smaller than the area of ​​the second visible range, the process proceeds to step S315. If the area of ​​the first visible range is greater than or equal to the area of ​​the second visible range, the process proceeds to step S316. In step S315, the visible range calculation unit 22 switches the visible range by setting the second visible range to the first visible range. Then, the process proceeds to step S316.

[0049] In step S316, the visible range calculation unit 22 stores the first visible range and the second visible range in the visible range storage unit 27. Then, the process proceeds to step S317. In step S317, the visibility range calculation unit 22 selects satellites within the first visibility range as targets to output to the evaluation unit. After that, the process shown in Figure 17 is completed, and the process proceeds to step S107.

[0050] Thus, the positioning system 20b shown in Example 3 can achieve highly accurate positioning by setting multiple visible ranges.

[0051] As described above, the positioning system 20 disclosed in the embodiment comprises a GNSS antenna 10 which is an antenna that receives satellite signals from satellites, and a GNSS receiver 21 which is a receiver that decodes the satellite signals received by the antenna and generates satellite information, and the positioning system includes at least the satellite position as seen from the antenna and the received signal strength in the satellite information, and further comprises a visible range calculation unit 22 which determines the distribution of satellite positions in which the received signal strength is above a predetermined threshold and calculates a visible range from the distribution, and a positioning result output unit 24 which outputs a positioning result based on the satellite information of satellites in the visible range. With this configuration, the positioning system 20 can achieve highly accurate positioning with a simple configuration.

[0052] Furthermore, the positioning system 20 further includes a relative positioning unit 26 as a movement information calculation unit that calculates movement information including the direction and distance of movement of the antenna, and the visible range calculation unit 22 acquires obstacle information indicating the height of obstacles located around the visible range when the antenna moves, and recalculates the visible range using the movement information and the obstacle information. This configuration allows for highly accurate positioning that reflects the movement status.

[0053] Furthermore, the obstacle information includes the height of the nearest obstacle to the antenna on the outer edge of the visible range. This configuration allows for highly accurate positioning by referencing information indicating the height of surrounding obstacles and reflecting the movement status.

[0054] In one configuration example, the receiver further includes an evaluation unit 23 that calculates the position of the antenna as a first positioning result from satellite information of multiple satellites and calculates the position of the antenna as a second positioning result from satellite information of multiple satellites within the visible range, and the positioning result output unit 24 outputs the first positioning result and also outputs information indicating the difference between the first positioning result and the second positioning result. With this configuration, by adding information to the positioning results obtained by the receiver, it is possible to notify the results of highly accurate positioning.

[0055] In one configuration example, the system further includes a position calculation unit that calculates the position of the antenna from satellite information of multiple satellites within the visible range, and the positioning result output unit outputs the position of the antenna calculated by the position calculation unit as the positioning result. This configuration allows for the output of highly accurate positioning results obtained from satellites within the visible range.

[0056] In one configuration example, the system further includes a visible range storage unit 27 that stores the visible range calculated by the visible range calculation unit 22. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 selects one of the multiple visible ranges as a representative visible range. The positioning result output unit 24 outputs a positioning result based on the satellite information of the satellite in the representative visible range. The visible range calculation unit 22 evaluates the change in the area of ​​the multiple visible ranges using the newly calculated visible range and the visible range stored in the visible range storage unit. If the area of ​​the representative visible range becomes smaller than that of the other visible ranges, the other visible range becomes the new representative visible range. This configuration allows you to set multiple visibility ranges and switch between representative visibility ranges.

[0057] In one configuration example, the system further includes a visible range storage unit 27 that stores the visible range calculated by the visible range calculation unit 22. When multiple visible ranges exist simultaneously, the visible range calculation unit 22 selects one of the multiple visible ranges as a representative visible range. The positioning result output unit 24 outputs a positioning result based on the satellite information of the satellite in the representative visible range. The visible range calculation unit 22 uses the newly calculated visible range and the visible range stored in the visible range storage unit 27 to evaluate the change in the overlapping range between the representative visible range and other visible ranges. If the overlapping range exceeds half the area of ​​the representative visible range, the system integrates the representative visible range and other visible ranges and recalculates the visible range. This configuration allows for the setting and integration of multiple visibility ranges.

[0058] Furthermore, the visible range calculation unit 22 approximates the distribution of satellite positions where the received signal strength is above a predetermined threshold as an ellipse, and defines the resulting ellipse as the visible range. With this configuration, the visible range can be determined with a simple process.

[0059] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace or add configurations, not just delete them. For example, although the above embodiment was described using a vehicle as an example, it can also be applied to ships and the like. [Explanation of symbols]

[0060] 10: GNSS antenna, 11: satellite, 12: visible range, 20: positioning system, 21: GNSS receiver, 22: visible range calculation unit, 23: evaluation unit, 24: positioning result output unit, 25: memory device, 26: relative positioning unit, 27: visible range memory unit

Claims

1. A positioning system comprising an antenna that receives satellite signals from a satellite, and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, A visible range calculation unit determines the distribution of satellite positions where the received signal strength is above a predetermined threshold, and calculates the visible range from the distribution. A positioning result output unit that outputs positioning results based on satellite information of the satellites within the visible range, A positioning system characterized by further comprising the following features.

2. A positioning system according to claim 1, The system further includes a movement information calculation unit that calculates movement information including the direction of movement and distance of movement of the antenna, The positioning system is characterized in that, when the antenna moves, the visible range calculation unit acquires obstacle information indicating the height of obstacles located around the visible range, and recalculates the visible range using the movement information and the obstacle information.

3. A positioning system according to claim 2, The positioning system is characterized in that the obstacle information includes the height of the nearest obstacle to the antenna on the outer edge of the visible range.

4. A positioning system according to claim 1, The receiver calculates the position of the antenna as a first positioning result from satellite information of multiple satellites. The system further includes an evaluation unit that calculates the position of the antenna as a second positioning result from satellite information of multiple satellites within the visible range. The positioning system is characterized in that the positioning result output unit outputs the first positioning result and also outputs information indicating the difference between the first positioning result and the second positioning result.

5. A positioning system according to claim 1, The system further includes a position calculation unit that calculates the position of the antenna from satellite information of multiple satellites within the visible range. The positioning system is characterized in that the positioning result output unit outputs the position of the antenna calculated by the position calculation unit as the positioning result.

6. A positioning system according to claim 1, The system further includes a visible range storage unit that stores the visible range calculated by the visible range calculation unit, The visible range calculation unit selects one of the multiple visible ranges as a representative visible range when multiple visible ranges exist simultaneously. The positioning result output unit outputs positioning results based on satellite information of the representative visible range satellites. The positioning system is characterized in that the visible range calculation unit evaluates the change in the area of ​​the plurality of visible ranges using the newly calculated visible range and the visible ranges stored in the visible range storage unit, and when the area of ​​the representative visible range becomes smaller than that of the other visible ranges, the other visible ranges are designated as the new representative visible range.

7. A positioning system according to claim 1, The system further includes a visible range storage unit that stores the visible range calculated by the visible range calculation unit, The visible range calculation unit selects one of the multiple visible ranges as a representative visible range when multiple visible ranges exist simultaneously. The positioning result output unit outputs positioning results based on satellite information of the representative visible range satellites. The positioning system is characterized in that the visible range calculation unit evaluates the change in the overlapping range between the representative visible range and other visible ranges using the newly calculated visible range and the visible range stored in the visible range storage unit, and if the overlapping range exceeds half the area of ​​the representative visible range, it integrates the representative visible range and other visible ranges to recalculate the visible range.

8. A positioning system according to claim 1, The positioning system is characterized in that the visible range calculation unit approximates the distribution of satellite positions where the received signal strength is above a predetermined threshold with an ellipse, and the resulting ellipse is defined as the visible range.

9. A mobile device comprising an antenna that receives satellite signals from a satellite, and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, A visible range calculation unit determines the distribution of satellite positions where the received signal strength is above a predetermined threshold, and calculates the visible range from the distribution. A positioning result output unit that outputs positioning results based on satellite information of the satellites within the visible range, A mobile body further characterized by having the following features.

10. A positioning method using a positioning system comprising an antenna that receives satellite signals from a satellite, and a receiver that decodes the satellite signals received by the antenna to generate satellite information, wherein the satellite information includes at least the satellite position as seen from the antenna and the received signal strength, The positioning system, The steps include determining the distribution of satellite positions where the received signal strength is above a predetermined threshold, A step of calculating the visible range from the aforementioned distribution, The steps include outputting a positioning result based on satellite information from satellites within the visible range, and A positioning method characterized by including the following.

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