Reception device, reception method, and reception program

Abstract

To provide a reception device, a reception method, and a reception program which can achieve high-precision positioning without requiring a reference satellite system.SOLUTION: A reception device includes a reception part and an estimation part. The reception part receives satellite signals from each of a plurality of satellite systems in multi-GNSS positioning using the plurality of satellite systems. The estimation part estimates a time error of the reception device, which is relative to a system time of each of the plurality of satellite systems, for each satellite system on the basis of the satellite signals received from each of the plurality of satellite systems.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a receiving device, a receiving method, and a receiving program. [Background technology]

[0002] Conventionally, for automobiles, ships, and the like, there is known a technology for performing multi-GNSS (Global Navigation Satellite System) positioning by combining multiple satellite systems such as GPS (Global Positioning System), Galileo, BDS (BeiDou System), and QZSS (Quasi-Zenith Satellite System). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-86300 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in each of the above-mentioned satellite systems, the national organizations that manage the systems use their own system time to manage the satellites, which can lead to system time errors between the satellite systems. This time error can reduce the positioning accuracy of multi-GNSS positioning.

[0005] In this regard, for example, a method can be considered in which the system time of a particular satellite system is used as a reference to estimate the time error between the system time of another satellite system.

[0006] However, with the above method, if it is not possible to receive satellite signals from a reference satellite system, it becomes difficult to estimate the time error, which may result in a decrease in positioning accuracy.

[0007] Therefore, the present disclosure proposes a receiving device, a receiving method, and a receiving program that can achieve highly accurate positioning without requiring a reference satellite system. [Means for solving the problem]

[0008] In order to solve the above problem, a receiving device according to the present disclosure includes a receiving unit and an estimating unit. The receiving unit receives satellite signals from each of a plurality of satellite systems in multi-GNSS positioning using the plurality of satellite systems. The estimating unit estimates a time error of the receiving device based on a system time of each of the plurality of satellite systems for each of the plurality of satellite systems based on the satellite signals received from the plurality of satellite systems.

[0009] This allows the receiving device to achieve highly accurate positioning without requiring a reference satellite system.

[0010] The time error according to the present disclosure includes a time error contained in the internal time of the receiving device and a time error between the multiple satellite systems.

[0011] This allows the receiving device to achieve highly accurate positioning without being affected by time errors between satellite systems.

[0012] Furthermore, when the number of the plurality of satellite systems is n (n is a natural number), the estimation unit according to the present disclosure estimates the time error of the receiving device based on n+3 satellite signals.

[0013] This allows the receiving device to estimate the time error and perform positioning calculations by receiving a number of satellite signals corresponding to the number of satellite systems.

[0014] Furthermore, when the number of the multiple satellite systems is n (n is a natural number), and the total number of satellites in the multiple satellite systems is less than a predetermined number, the estimation unit according to the present disclosure estimates the time error of the receiving device based on the n+2 satellite signals, using any two-dimensional position information of the three-dimensional position information as a variable and the remaining one-dimensional position information as a fixed value.

[0015] This allows the receiving device to estimate the time error and perform positioning calculations even when the number of received satellite signals is small.

[0016] Moreover, the estimation unit according to the present disclosure estimates the time error of the receiving device by using the position information indicating the altitude position at which the receiving device is located as the fixed value.

[0017] This enables the receiving device to estimate the time error while minimizing the deviation between the result of the positioning calculation and the actual position of the receiving device.

[0018] Furthermore, when the number of the multiple satellite systems is n (n is a natural number), and position information is known, the estimation unit according to the present disclosure estimates the time error of the receiving device based on n or more satellite signals, with three-dimensional position information set as a fixed value.

[0019] This allows the receiving device to estimate the time error and perform positioning calculations even when the number of received satellite signals is small.

[0020] Moreover, the estimation unit according to the present disclosure estimates the time error of the receiving device by using the position information indicating the three-dimensional position where the receiving device is located as the fixed value.

[0021] This allows the receiving device to estimate the time error and perform positioning calculations even when the number of received satellite signals is small.

[0022] The estimation unit estimates the time error of the receiving device by using a three-dimensional position input from the outside (user input) as the fixed value.

[0023] This allows the receiving device to estimate the time error and perform positioning calculations even when the number of received satellite signals is small.

[0024] Moreover, the estimation unit according to the present disclosure estimates the time error and performs positioning calculations using an observation model that includes the time error of the receiving device as a variable.

[0025] This allows the receiving device 1 to achieve highly accurate positioning without requiring a reference satellite system.

[0026] In addition, a receiving method according to the present disclosure is a receiving method executed by a receiving device, and in multi-GNSS positioning using a plurality of satellite systems, includes a receiving step of receiving satellite signals from each of the plurality of satellite systems, and an estimation step of estimating, for each of the plurality of satellite systems, a time error of the receiving device based on the system time of each of the plurality of satellite systems based on the satellite signals received from each of the plurality of satellite systems.

[0027] This allows the reception method to achieve highly accurate positioning without requiring a reference satellite system.

[0028] In addition, a reception program according to the present disclosure causes a computer to execute a reception procedure for receiving satellite signals from each of a plurality of satellite systems in multi-GNSS positioning using a plurality of satellite systems, and an estimation procedure for estimating, for each of the plurality of satellite systems, a time error of the receiving device based on the system time of each of the plurality of satellite systems based on the satellite signals received from each of the plurality of satellite systems.

[0029] This allows the receiving program to achieve highly accurate positioning without requiring a reference satellite system. [Brief description of the drawings]

[0030] [Figure 1] FIG. 2 is a diagram illustrating a receiving method according to an embodiment. [Diagram 2] 1 is a block diagram showing a configuration of a receiving device according to an embodiment. [Diagram 3] 10 is a flowchart showing a processing procedure executed by a receiving device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] 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 duplicated descriptions will be omitted.

[0032] The present disclosure relates to a technology for performing multi-GNSS positioning using multiple satellite systems, including satellite systems in which each country operates its own satellites, such as the Global Positioning System (GPS), Galileo, the BeiDou System (BDS), Glonass, and the Quasi-Zenith Satellite System (QZSS).

[0033] In the present disclosure, the receiving method according to the embodiment is executed to estimate the time error of the receiving device relative to the system time based on which each satellite system is based, which is included in the observation model of the pseudo distance between the receiving device and the satellite. Here, the receiving method according to the embodiment will be described in detail with reference to FIG.

[0034] Fig. 1 is a diagram for explaining a receiving method according to an embodiment. In Fig. 1, a receiving device 1 receives satellite signals from three satellites 100a, 100b, and 100c in different satellite systems to perform positioning. Fig. 1 shows three-dimensional coordinates consisting of X-axis, Y-axis, and Z-axis, which are the position information of each of the three satellites 100a, 100b, and 100c and the receiving device 1.

[0035] 1 shows an example of receiving satellite signals from one satellite in one satellite system, but in reality, satellite signals are received from multiple satellites in one satellite system. Furthermore, when there is no need to distinguish between the three satellites 100a, 100b, and 100c, they may be collectively referred to as satellite 100.

[0036] The receiving device 1 performs positioning based on the satellite signal received from the satellite 100. Specifically, the receiving device 1 calculates the pseudorange between the satellite 100 and the receiving device 1 for each satellite signal by multiplying the difference between the time the satellite signal is transmitted by the satellite 100 and the time the satellite signal is received by the receiving device 1 by the speed of light.

[0037] Furthermore, the receiving device 1 estimates its own three-dimensional coordinates using an observation model of pseudoranges that includes its own three-dimensional coordinates as variables. Specifically, the receiving device 1 determines an equation of the observation model for each calculated pseudorange of the satellite signal, and estimates the three-dimensional coordinates, which are variables, by solving simultaneous equations using each equation.

[0038] Here, in multi-GNSS positioning, the above-mentioned pseudorange observation model includes as variables the time error (internal time error) contained in the internal time of the receiving device 1 and the time error of the system time between multiple satellite systems (inter-system time error, ISB: Inter System Bias).

[0039] This inter-system time error occurs because each country's system management organization manages its satellites using its own unique system time, resulting in discrepancies in the system time of each system. If this inter-system time error cannot be accurately estimated, there is a risk that the positioning accuracy of multi-GNSS positioning will decrease.

[0040] In this regard, for example, a method can be considered in which the system time of a specific satellite system is used as a reference to estimate the time error with the system time of another satellite system. Specifically, when the GPS system time is used as a reference, the time error of the system time is set to zero in the observation model of the GPS satellite signal (i.e., only the internal time error is included as a variable), and the time error of the Galileo system time with respect to the GPS system time is included as a variable in the observation model of the Galileo satellite signal (i.e., the internal time error and the system time error are included as variables). With this method, if the reference GPS satellite signal can be received, the internal time error and the system time error can be estimated using the simultaneous equations described above.

[0041] However, with the above method, if it is not possible to receive satellite signals from a reference satellite system, such as GPS, it is not possible to obtain an observation model for that GPS, making it difficult to estimate the inter-system time error and resulting in a decrease in positioning accuracy.

[0042] Therefore, the reception method according to the embodiment performs positioning without needing a reference satellite system. Specifically, the reception method according to the embodiment estimates the time error of the reception device 1 based on the system time of each of a plurality of satellite systems.

[0043] More specifically, the receiving device 1 sets the time error of the receiving device 1 based on each system time as a variable, as shown in the observation models of the following equations (1) and (2). Specifically, equation (1) is an observation model when the satellite system is GPS, and equation (2) is an observation model when the satellite system is Galileo. In equations (1) and (2), ρ n is the pseudorange, and x n , y n , z n are the three-dimensional coordinates of the satellite 100, and x, y, and z are the three-dimensional coordinates of the receiving device 1. GPS is the time error of the receiver 1 relative to the GPS system time, and b Galileois the time error of the receiver 1 relative to the Galileo system time. n is the observation error, and n is the number that identifies the satellite.

[0044]

number

[0045]

number

[0046] In the above observation model, equations (1) and (2), ρ n , x n , y n , z n are known values, and x, y, z, b GPS , b Galileo are unknown values. That is, the receiving device 1 calculates the unknown values ​​x, y, z, and b by simultaneous equations. GPS , b Galileo Estimate.

[0047] Also, b GPS and b Galileo is a time error including the time error included in the internal time (clock frequency) of the receiving device 1 and the time error between multiple satellite systems (time error with other satellite systems, ISB). GPS and b Galileo is a variable that combines a variable of the time error included in the internal time of the receiving device 1 and a variable of the time error between multiple satellite systems.

[0048] That is, in this disclosure, the receiving device 1 does not estimate the time error included in the internal time of the receiving device 1 and the time error between multiple satellite systems separately, but estimates a time error that is a combination of the respective time errors.

[0049] For example, when the number of satellite systems is two (GPS and Galileo), the receiving device 1 receives x, y, z, b GPS , bGalileo Since there are five unknown values, the five unknown values ​​are estimated by a simultaneous equation using five satellite signals. Note that, since the time error b increases by one every time the number of satellite systems increases by one, the number of required satellite signals also increases by one. Note that the receiving device 1 may use five or more satellite signals when estimating the five unknown values.

[0050] That is, when the number of multiple satellite systems is n (n is a natural number), the receiver 1 calculates the time error (b GPS , b Galileo ) is estimated.

[0051] The five satellite signals only need to include at least one satellite signal from each satellite system, and can be configured in various patterns, such as including four GPS satellite signals and one Galileo satellite signal, or including three GPS satellite signals and two Galileo satellite signals.

[0052] Furthermore, when the number of satellites 100 from which the receiving device 1 receives satellite signals from a plurality of satellite systems is less than a predetermined number, the receiving device 1 may perform position estimation by using any one of the three-dimensional coordinates of the receiving device 1 as a fixed value.

[0053] For example, when the z-axis coordinate (height) is a fixed value, if there are two satellite systems, the receiving device 1 can calculate the x, y, and b coordinates. GPS , b Galileo In order to estimate the four unknown values, the above four unknown values ​​are estimated by a simultaneous equation using four satellite signals.

[0054] That is, the receiving device 1 estimates the time error of the receiving device 1 based on n+2 satellite signals, using any two-dimensional coordinates of the three-dimensional coordinates as variables and the remaining one-dimensional coordinate as a fixed value. This makes it possible to estimate the time error even if the number of received satellite signals is less than a certain number (for example, less than n+3).

[0055] Moreover, it is preferable that the coordinate to be set as a fixed value is a height position (z-axis coordinate). This is because the height position does not change significantly in automobiles and ships in which the receiving device 1 is mounted. Note that the receiving device 1 may prohibit setting the height position as a fixed value if the height position from the current time to a predetermined period ago has changed by more than a threshold value.

[0056] The receiving device 1 may also estimate the time error using three-dimensional position information of x, y, and z as fixed values. For example, when the number of satellite systems is n (n is a natural number) and the position information is known, the receiving device 1 estimates the time error of the receiving device 1 based on n or more satellite signals, using three-dimensional position information as fixed values. For example, when the number of satellite systems is two (for example, GPS and Galileo), the receiving device 1 estimates the time error of b GPS , b Galileo In order to estimate the two unknown values, the two unknown values ​​are estimated by simultaneous equations using two satellite signals. In this case, the position information used is the position information from the previous positioning or the position information input from outside. The position information input from outside is the position information measured by another system or the position information manually input by the user.

[0057] In the above observation model, the receiving device 1 uses an observation error ε n Therefore, it is necessary to use mathematical techniques such as the least squares method and the Kalman filter to estimate the three-dimensional coordinates and time error (b GPS , b Galileo ) is estimated so as to be most likely.

[0058] In this way, the receiving device 1 according to the embodiment estimates the time error of the receiving device 1 based on the system time of each satellite system, and therefore does not need to use a specific satellite system as a reference.

[0059] As a result, even if a satellite signal cannot be received from a satellite of one of multiple satellite systems, the receiver 1 can estimate the time error between the receiver 1 and another satellite system that received the satellite signal. In other words, the receiver 1 can achieve highly accurate positioning without requiring a reference satellite system.

[0060] Next, a configuration example of the receiving device 1 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of the receiving device 1 according to the embodiment. As shown in Fig. 2, the receiving device 1 includes a receiving unit 2, a control unit 3, and a storage unit 4.

[0061] The receiver 2 is a receiving antenna that receives satellite signals. The receiver 2 receives satellite signals transmitted from satellites of a plurality of satellite systems.

[0062] The control unit 3 is a controller, and is realized by, for example, a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs (corresponding to an example of an information processing program) stored in a storage device inside the receiving device 1 using a RAM or the like as a working area. The control unit 3 is also a controller, and may be realized by, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a GPGPU (General Purpose Graphic Processing Unit).

[0063] The control unit 3 performs processing such as positioning calculation and time error estimation using the observation model for each satellite system such as the above formula (1) and formula (2). The control unit 3 outputs the positioning result estimated by the positioning calculation to an external device (not shown). The control unit 3 corresponds to the estimation unit in this disclosure.

[0064] The storage unit 4 is realized by, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, or a storage device such as a hard disk or an optical disk.

[0065] Next, a processing procedure of the processing executed by the receiving device 1 according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the processing procedure of the processing executed by the receiving device 1 according to the embodiment.

[0066] As shown in FIG. 3, the receiving device 1 receives satellite signals from satellites in a plurality of satellite systems (step S101).

[0067] Next, the receiving device 1 performs positioning calculation using the received satellite signals (step S102). Specifically, the receiving device 1 calculates the pseudoranges described above, and estimates the three-dimensional coordinates of the receiving device 1 by simultaneous equations using the pseudoranges and an observation model. The receiving device 1 also performs estimation using a mathematical method such as the least squares method or a Kalman filter so as to minimize errors in the three-dimensional coordinates estimated from each satellite signal.

[0068] Next, the receiving device 1 substitutes the estimated three-dimensional coordinates into the observation model to estimate a time error based on the system time for each satellite system (step S103), and ends the process.

[0069] As described above, according to an embodiment of the present disclosure, the receiving device 1 includes a receiving unit 2 and an estimating unit (control unit 3). The receiving unit 2 receives satellite signals from each of the multiple satellite systems in multi-GNSS positioning using the multiple satellite systems. The estimating unit estimates the time error of the receiving device 1 based on the system time of each of the multiple satellite systems for each of the multiple satellite systems, based on the satellite signals received from each of the multiple satellite systems. As a result, even if the receiving device 1 cannot receive a satellite signal from a satellite of one of the multiple satellite systems, it can estimate the time error between the receiving device 1 and the other satellite systems from which it has received the satellite signal. In other words, the receiving device 1 can achieve high-precision positioning without requiring a reference satellite system.

[0070] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. For example, the technical scope of the present invention includes forms obtained by appropriately combining the above-described embodiments within the scope of the claims. [Explanation of symbols]

[0071] 1. Receiving device 2. Receiving section 3. Control Unit 4 Storage section 100 satellites

Claims

1. A receiver that receives satellite signals from each of a plurality of satellite systems in multi-GNSS positioning using a plurality of satellite systems; an estimation unit that estimates a time error of the receiving device based on a system time of each of the plurality of satellite systems, for each of the plurality of satellite systems, based on the satellite signals received from the respective plurality of satellite systems; A receiving device comprising:

2. The time error is A time error included in the internal time of the receiving device and a time error among the plurality of satellite systems 2. The receiving device according to claim 1.

3. The estimation unit is When the number of the plurality of satellite systems is n (n is a natural number), the time error of the receiving device is estimated based on n+3 or more of the satellite signals.

2. The receiving device according to claim 1.

4. The estimation unit is When the number of the plurality of satellite systems is n (n is a natural number), and when the total number of satellites in the plurality of satellite systems is less than a predetermined number, any two-dimensional position information among the three-dimensional position information is set as a variable, and the remaining one-dimensional position information is set as a fixed value, and the time error of the receiving device is estimated based on the n+2 satellite signals.

2. The receiving device according to claim 1.

5. The estimation unit is The position information indicating the altitude position where the receiving device is located is set as the fixed value, and the time error of the receiving device is estimated.

5. The receiving device according to claim 4.

6. The estimation unit is When the number of the plurality of satellite systems is n (n is a natural number) and the position information is known, the time error of the receiving device is estimated based on n or more of the satellite signals, with three-dimensional position information being a fixed value.

2. The receiving device according to claim 1.

7. The estimation unit is The time error of the receiving device is estimated using the position information indicating the three-dimensional position where the receiving device is located as the fixed value.

7. The receiving device according to claim 6.

8. The estimation unit is The time error of the receiving device is estimated using an externally input three-dimensional position as the fixed value.

7. The receiving device according to claim 6.

9. The estimation unit is The time error is estimated and a positioning calculation is performed using an observation model including the time error of the receiving device as a variable.

2. The receiving device according to claim 1.

10. A receiving method performed by a receiving device, comprising: A receiving step of receiving a satellite signal from each of a plurality of satellite systems in a multi-GNSS positioning using a plurality of satellite systems; an estimation step of estimating, for each of the plurality of satellite systems, a time error of the receiving device based on a system time of each of the plurality of satellite systems, based on the satellite signals received from the respective plurality of satellite systems; A receiving method including:

11. A receiving step of receiving a satellite signal from each of a plurality of satellite systems in a multi-GNSS positioning using a plurality of satellite systems; an estimation step of estimating, for each of the plurality of satellite systems, a time error of the receiving device based on a system time of each of the plurality of satellite systems based on the satellite signals received from the respective plurality of satellite systems; A receiving program that causes a computer to execute the above.

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