Positioning device and recording media

Abstract

To provide a positioning device, etc. capable of improving a positioning rate, etc. in mixture positioning.SOLUTION: A positioning device 100 includes a receiving part 110 and a positioning part 120. The receiving part 110 receives satellite signals from a first satellite group included in a first positioning satellite system, and satellite signals from a second satellite group included in a second positioning satellite system. The positioning part 120 executes positioning by using the satellite signals received from 4 or more satellites including the satellites of the first and second satellite groups. At this time, the positioning part 120 executes the positioning by treating a first time error on the first positioning satellite system and a second time error on the second positioning satellite system as unknowns of common time error Δtc.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a positioning device, a recording medium, and the like. [Background technology]

[0002] Patent Document 1 discloses a satellite signal receiving device that performs positioning of a GPS receiver using signals from satellites belonging to a second GNSS depending on the reception state of signals from satellites belonging to a first GNSS. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-21892 Summary of the Invention [Problem to be solved by the invention]

[0004] In positioning, the time error for the first GNSS and the time error for the second GNSS are both unknowns. This poses the problem of needing to capture the number of satellites required to calculate these unknowns. If a large number of satellites are required, this can result in, for example, a decrease in the positioning rate. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a positioning device that includes a receiving unit that receives satellite signals from a first group of satellites belonging to a first positioning satellite system and satellite signals from a second group of satellites belonging to a second positioning satellite system, and a positioning unit that performs positioning using satellite signals received from four or more satellites including satellites of the first group of satellites and satellites of the second group of satellites, using a first time error related to the first positioning satellite system and a second time error related to the second positioning satellite system as common time error unknowns.

[0006] Another aspect of the present disclosure relates to a recording medium having recorded thereon a program that causes a computer to function as a positioning unit that performs positioning using satellite signals received from four or more satellites including satellites of the first satellite group and satellites of the second satellite group, based on satellite signals received by a receiving unit that receives satellite signals from a first satellite group belonging to a first positioning satellite system and satellite signals from a second satellite group belonging to a second positioning satellite system, with a first time error related to the first positioning satellite system and a second time error related to the second positioning satellite system as common time error unknowns. [Brief description of the drawings]

[0007] [Figure 1] 1 shows a first configuration example of a positioning satellite system receiver. [Diagram 2] 4 is a diagram for explaining positioning when a first time error related to a first positioning satellite system and a second time error related to a second positioning satellite system are each unknown. [Diagram 3] 11 is a diagram for explaining positioning when a first time error related to a first positioning satellite system and a second time error related to a second positioning satellite system are treated as a common unknown quantity. [Figure 4] FIG. 4 is an explanatory diagram of positioning mode switching. [Diagram 5] FIG. 4 is a diagram for explaining a method for selecting a satellite to be used for positioning. [Figure 6] 13 shows an example of the configuration of a positioning device when a third example of reliability is used. [Figure 7] The relationship between predicted pseudoranges and observed pseudoranges. [Figure 8] FIG. 1 is a diagram for explaining standardization of time errors when three positioning satellite systems are used. [Figure 9] 2 shows a second configuration example of a positioning satellite system receiver. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A preferred embodiment of the present disclosure will be described in detail below. Note that the embodiment described below does not unduly limit the contents described in the claims, and all of the configurations described in the embodiment are not necessarily essential configurations.

[0009] 1.GNSS receiver, positioning device 1 shows a first configuration example of a positioning satellite system receiver. The positioning satellite system receiver 200 includes a positioning device 100 and an antenna 190.

[0010] The antenna 190 receives satellite signals transmitted by satellites of a positioning satellite system. The positioning satellite system is, for example, GPS, QZSS, BeiDou, GLONASS, or Galileo. GPS is an abbreviation for Global Positioning System. QZSS is an abbreviation for Quasi-Zenith Satellite System. The antenna 190 receives radio waves of satellite signals from two or more positioning satellite systems. In this case, an antenna may be provided separately for each positioning satellite system, or a common antenna may be provided for two or more positioning satellite systems.

[0011] The positioning device 100 includes a receiving unit 110 and a positioning unit 120. The positioning device 100 is, for example, an integrated circuit device in which a plurality of circuit elements are integrated on a semiconductor substrate. However, the hardware configuration of the positioning device 100 is not limited thereto. For example, as will be described later with reference to FIG. 9, the positioning device 100 may include an integrated circuit device constituting the receiving unit 110 and a processor functioning as the positioning unit 120.

[0012] The receiving unit 110 receives satellite signals from each satellite via the antenna 190. Specifically, the satellite signals are carrier signals modulated based on navigation data. The receiving unit 110 extracts the navigation data contained in the satellite signals by demodulating the carrier signals. The navigation data includes parameters used for positioning. The navigation data includes, for example, satellite clock correction data, ephemeris data, ionospheric correction parameters, UTC correction parameters, and the like. UTC stands for Coordinated Universal Time. The receiving unit 110 is configured to receive satellite signals from two or more positioning satellite systems. For example, an RF receiving circuit is provided separately for each positioning satellite system. RF stands for Radio Frequency.

[0013] The positioning unit 120 locates the position of the positioning satellite system receiver 200 based on the satellite signal received by the receiving unit 110 and the internal time information of the positioning device 100. Specifically, the positioning unit 120 calculates the pseudo distance of each satellite based on the satellite signal from each satellite and the internal time information of the positioning device 100. The pseudo distance is obtained by multiplying the difference between the transmission time and the reception time of the satellite signal by the speed of light. The positioning device 100 acquires the position and clock error of each satellite from the navigation data of each satellite, and performs positioning processing using the information and the pseudo distance of each satellite. Various known methods may be used for the positioning processing, and for example, a method of solving simultaneous equations by gradient descent, estimation by a Kalman filter, or estimation using the least squares method is used.

[0014] 2. Positioning Method When performing positioning using one positioning satellite system, the unknowns to be obtained are three parameters indicating a three-dimensional position and the time error of the internal clock of the positioning device 100. Therefore, in order to determine the unknowns, at least four or more satellites must be captured. For example, in an environment where satellite signals are blocked or reflected by terrain or buildings, it may be difficult to capture four or more satellites of one positioning satellite system, and there is a problem that it takes time to perform the first positioning. In addition, a satellite search is performed until the required number of satellites can be captured, which hinders low power consumption or causes a problem that the positioning rate or TTFF requirements cannot be met. For this reason, the positioning device 100 of this embodiment performs positioning using two or more positioning satellite systems. Such positioning is also called mixed positioning. Below, an example using two positioning satellite systems will be described, but three or more positioning satellite systems may be used.

[0015] FIG. 2 is a diagram for explaining positioning when a first time error related to a first positioning satellite system and a second time error related to a second positioning satellite system are unknown quantities. The time error related to the positioning satellite system means the time error of the internal clock of the positioning device 100 with respect to the time of the positioning satellite system. The atomic clocks that are the references for each positioning satellite system are held by the country that operates the positioning satellite system, and are not completely synchronized with each other. For this reason, the time errors related to each positioning satellite system are different. In the following, it is assumed that the first positioning satellite system is the GPS satellite system and the second positioning satellite system is the QZSS satellite system, but the positioning satellite systems used are not limited to these.

[0016] In Fig. 2, the first to third satellites are captured as the first satellite group belonging to the GPS satellite system, and the fourth and fifth satellites are captured as the second satellite group belonging to the QZSS satellite system. When i is an integer between 1 and 5, (xi, yi, zi) represents the position of the i-th satellite, bi represents the clock error of the i-th satellite, and Ri represents the pseudorange of the i-th satellite. These parameters are parameters obtained from the satellite signals of each satellite, and are known parameters in the positioning process. The unknown parameters in the positioning process are the position (xp, yp, zp) of the positioning satellite system receiver 200, the first time error Δtgps, and the second time error Δtqzss.

[0017] The following formula (1) shows the relationship between the known parameters and the unknown parameters. Since the following formula (1) is a set of five simultaneous equations, the positioning unit 120 can determine the five unknowns (xp, yp, zp), Δtgps, and Δtqzss by performing positioning processing based on the following formula (1).

[0018]

number

[0019] In the method of FIG. 2, five satellites need to be captured because there are five unknowns. However, positioning is not possible if, for example, only three GPS satellites and one QZSS satellite can be captured. Or, even if five satellites are captured, if the satellite signal of any one of the five satellites is of low quality due to multipath or the like, the positioning accuracy decreases. Therefore, in this embodiment, the positioning unit 120 performs positioning processing by treating the first time error related to the first positioning satellite system and the second time error related to the second positioning satellite system as a common unknown.

[0020] FIG. 3 is a diagram for explaining positioning when a first time error related to a first positioning satellite system and a second time error related to a second positioning satellite system are treated as a common unknown quantity.

[0021] In Fig. 3, the first to third satellites are captured as the first satellite group belonging to the GPS satellite system, and the fourth satellite is captured as the second satellite group belonging to the QZSS satellite system. Alternatively, the fifth satellite is also captured as the second satellite group, but is not used for positioning because the satellite signal is of low quality. The unknown parameters in the positioning process are the position (xp, yp, zp) of the positioning satellite system receiver 200, and Δtc, which is a common time error including the first time error and the second time error.

[0022] The following equation (2) shows the relationship between the known parameters and the unknown parameters. Since the following equation (2) is a system of four simultaneous equations, the positioning unit 120 can determine the four unknowns (xp, yp, zp) and Δtc by performing positioning processing based on the following equation (2). Note that even when positioning is performed using a common time error Δtc, five or more satellites may be used.

[0023]

number

[0024] According to this embodiment, positioning can be performed using four satellites in the mixed positioning, thereby improving the positioning rate and TTFF. The positioning rate is the ratio of the number of successful positionings to the total number of times positioning is performed when multiple positionings are performed. TTFF is an abbreviation for Time To First Fix, and is the time from when the power of the positioning satellite system receiver 200 is turned on to when the position information is output for the first time. For example, even if only three or less satellites of the GPS satellite system can be captured, positioning is possible if four satellites can be captured in addition to satellites of other positioning satellite systems, so the possibility of successful positioning is increased. In addition, the number of required satellites is reduced from five to four, which increases the possibility of successful positioning. In addition, the time required for satellite search is shortened, which contributes to low power consumption.

[0025] Moreover, according to this embodiment, the positioning accuracy may be better than when the positioning accuracy is reduced by multipath or the like. The positioning error due to the common use of time error is smaller than the difference between the internal time of the GPS satellite system and the internal time of the QZSS satellite system converted into distance. The time of each positioning satellite system is managed by an atomic clock, and the error of the atomic clock of each positioning satellite system is, for example, several nanoseconds to 100 nanoseconds with respect to Universal Time. Since 100 nanoseconds is converted into a distance of 30 m, the positioning error due to the common use of time error is expected to be smaller than 30 m. Therefore, even if the positioning accuracy is reduced by the common use of time error, the positioning accuracy is expected to be better than when the positioning accuracy is reduced by multipath or the like. For example, when one satellite out of five captured satellites is affected by multipath, the positioning accuracy may be improved by performing positioning using four satellites excluding that satellite.

[0026] In this embodiment, the positioning device 100 includes a receiving unit 110 and a positioning unit 120. The receiving unit 110 receives satellite signals from a first group of satellites belonging to a first positioning satellite system and satellite signals from a second group of satellites belonging to a second positioning satellite system. The positioning unit 120 performs positioning using satellite signals received from four or more satellites including the satellites of the first group of satellites and the satellites of the second group of satellites. At this time, the positioning unit 120 performs positioning using a first time error related to the first positioning satellite system and a second time error related to the second satellite system as unknowns of a common time error Δtc.

[0027] According to this embodiment, it is possible to reduce the number of satellites required for positioning by reducing the number of unknowns in the hybrid positioning using the first positioning satellite system and the second positioning satellite system. This increases the possibility of capturing the satellites required for positioning, and as described above, improves the positioning rate, TTFF, or positioning accuracy, or contributes to low power consumption.

[0028] As described in FIG. 3, the four or more satellites include a first satellite to a fourth satellite. The receiving unit 110 receives a first satellite signal from a first satellite, a second satellite signal from a second satellite, a third satellite signal from a third satellite, and a fourth satellite signal from a fourth satellite. The positioning unit 120 uses a first pseudo-range R1 based on the first satellite signal, a second pseudo-range R2 based on the second satellite signal, a third pseudo-range R3 based on the third satellite signal, and a fourth pseudo-range R4 based on the fourth satellite signal to obtain three position variables (xp, yp, zp) indicating the position of the positioning device 100 and an unknown value of a common time error Δtc.

[0029] Conventionally, five or more satellites are required for hybrid positioning using two positioning satellite systems. According to this embodiment, the time error is standardized, so the number of unknowns required for positioning is four. As a result, if four or more satellites can be used for positioning in hybrid positioning, positioning becomes possible.

[0030] The method of the present embodiment may be implemented as a program or a recording medium. The program and the recording medium will be described later with reference to FIG. 9. The recording medium records a program that causes a computer to function as the positioning unit 120. The positioning unit 120 performs positioning based on satellite signals received by the receiving unit 110, which receives satellite signals from a first satellite group belonging to a first positioning satellite system and satellite signals from a second satellite group belonging to a second positioning satellite system. The positioning unit 120 performs positioning using satellite signals received from four or more satellites including the satellites of the first satellite group and the satellites of the second satellite group, with a first time error related to the first positioning satellite system and a second time error related to the second positioning satellite system as unknowns of a common time error Δtc.

[0031] 3. Switching positioning modes 4 is an explanatory diagram of switching of positioning modes. As shown in FIG 4, the positioning unit 120 may switch whether or not to standardize the time error.

[0032] In the first positioning mode, the positioning unit 120 performs positioning using a first time error Δtgps related to the GPS satellite system and a second time error Δtqzss related to the QZSS satellite system as unknowns. In the first positioning mode, the positioning unit 120 performs positioning using five or more satellites. In the second positioning mode, the positioning unit 120 performs positioning using a first time error related to the GPS satellite system and a second time error related to the QZSS satellite system as a common unknown. In the second positioning mode, the positioning unit 120 performs positioning using four or more satellites.

[0033] The positioning mode may be switched, for example, from outside by a register setting, or may be automatically switched by the positioning unit 120 depending on the number of captured satellites, or may be fixed depending on the system in which the positioning satellite system receiver 200 is incorporated.

[0034] In this embodiment, the positioning unit 120 has a first positioning mode in which positioning is performed using each of the first time error and the second time error as unknowns, and a second positioning mode in which positioning is performed using the first time error and the second time error as a common unknown time error Δtc.

[0035] According to this embodiment, it is possible to switch between a first positioning mode that prioritizes positioning accuracy over positioning rate or TTFF, and a second positioning mode that prioritizes positioning rate or TTFF over positioning accuracy, thereby making it possible to select an appropriate positioning mode depending on the application, situation, etc.

[0036] 4. Satellite selection Fig. 5 is a diagram for explaining a method of selecting satellites to be used for positioning. As shown in Fig. 5, the positioning unit 120 may exclude satellites that satisfy a given condition from among the captured satellites, and perform positioning using the remaining satellites. Fig. 5 shows an example in which four satellites are selected from five satellites, but it is sufficient that four or more satellites are selected from five or more satellites.

[0037] The positioning unit 120 determines whether each satellite satisfies a given condition based on the satellite signal from each satellite. The positioning unit 120 excludes the satellites determined to satisfy the given condition, and performs positioning using the satellites determined not to satisfy the given condition. In the example of FIG. 5, the first to third satellites of the GPS satellite system and the fourth and fifth satellites of the QZSS satellite system are captured. Assume that the positioning unit 120 determines that the third satellite satisfies the given condition, and that the first, second, fourth, and fifth satellites satisfy the given condition. At this time, the positioning unit 120 selects the first, second, fourth, and fifth satellites as satellites to be used for positioning, and excludes the third satellite. The positioning unit 120 performs positioning using the selected four satellites by the method of making the time error common, as described in FIG. 3.

[0038] The given condition is a condition related to the reliability of the satellite signal. In other words, the given condition indicates that the satellite signal has a reliability that does not warrant its use for positioning. When the reliability of a satellite signal is lower than a threshold, the positioning unit 120 determines that the satellite will not be used for positioning. The reliability of a satellite signal is information indicating the reliability of a satellite signal received from a satellite, or the reliability of a pseudorange obtained from a satellite signal. Various indexes or parameters can be used as the reliability, and the following examples are possible:

[0039] A first example of the reliability is the elevation angle of a satellite. The elevation angle is the angle between the direction from the positioning position to the satellite and the horizontal plane. The positioning unit 120 calculates the elevation angle of the satellite based on the position of the satellite obtained from the navigation data, for example. If the elevation angle of the satellite is lower than a threshold value, the positioning unit 120 determines not to use the satellite for positioning.

[0040] A second example of reliability is the signal strength of a satellite signal. Receiving unit 110 receives a satellite signal, detects the signal strength of the satellite signal, and outputs information on the detected signal strength to positioning unit 120. If the signal strength of a satellite signal is lower than a threshold, positioning unit 120 determines not to use that satellite for positioning.

[0041] The third example of the reliability is the difference between the predicted pseudorange predicted based on the initial value of the observed pseudorange and the observed pseudorange. Figure 6 shows an example of the configuration of a positioning device when the third example of the reliability is used. Note that the same reference numerals are used to designate the components described in Figure 1, and the description of the components is omitted as appropriate.

[0042] The positioning device 100 further includes a reliability calculation unit 130. The reliability calculation unit 130 calculates the difference between a predicted pseudorange predicted based on an initial value of the observed pseudorange and the observed pseudorange, and calculates a reliability based on the difference. Fig. 7 shows the relationship between the predicted pseudorange and the observed pseudorange. In Fig. 7, the predicted pseudorange is shown by a dashed line, and the observed pseudorange is plotted with X marks. Times t0, t1, t2, ..., tn on the horizontal axis indicate the times at which the pseudoranges are observed.

[0043] The observed pseudorange is the pseudorange actually observed based on the satellite signal at each time when the pseudoranges are observed in the time series t0, t1, t2, ..., tn. The predicted pseudorange is the pseudorange predicted to be observed at each time when the pseudoranges are observed in the time series t0, t1, t2, ..., tn. The reliability calculation unit 130 calculates the predicted pseudorange by adding Doppler information and drift information to the initial pseudorange, for example, as shown in the following formula (3). The initial pseudorange is the observed pseudorange at the initial time when calculation of the predicted pseudorange starts.

[0044]

number

[0045] The reliability calculation unit 130 calculates the variance of the difference between the predicted pseudorange and the observed pseudorange as the reliability. Specifically, the reliability calculation unit 130 calculates the absolute difference value at each time of the time series t0, t1, t2, ..., tn, and calculates the standard deviation of the n+1 absolute difference values ​​as the reliability. Alternatively, the reliability calculation unit 130 may calculate the maximum value of the n+1 absolute difference values ​​as the reliability.

[0046] The positioning unit 120 determines not to use the satellite for positioning when the standard deviation or maximum value as the reliability is greater than a threshold value. Alternatively, the reliability calculation unit 130 may use the reciprocal of the standard deviation or the maximum value as the reliability. In this case, the positioning unit 120 determines not to use the satellite for positioning when the reciprocal of the standard deviation or the reciprocal of the maximum value is smaller than the threshold value.

[0047] The observed pseudorange contains various errors, including not only the geometric distance between the positioning satellite system receiver 200 and the satellite, but also the effects of delays in radio waves from the satellite. If there is a large variance in the difference between the observed pseudorange and the predicted pseudorange, or if there is a large deviation between the observed pseudorange and the predicted pseudorange, the observed pseudorange contains many errors due to non-geometric factors, and the reliability of the observed pseudorange is considered to be low. In such cases, the reliability of the satellite signal is considered to be low and it is not used for positioning, thereby improving the accuracy of positioning.

[0048] In this embodiment, when five or more satellites are captured, the positioning unit 120 selects four or more of the five or more satellites, and performs positioning using satellite signals received from the selected four or more satellites.

[0049] By standardizing the time error in mixed positioning, the number of satellites required for positioning becomes four. In this embodiment, four or more satellites are selected from the five or more captured satellites, and positioning can be performed using the selected four or more satellites.

[0050] Furthermore, in this embodiment, the positioning unit 120 selects four or more satellites from among five or more satellites, excluding satellites that satisfy a given condition.

[0051] According to this embodiment, by excluding satellites that satisfy a given condition, it is possible to exclude satellites whose satellite signals are of low quality. This allows positioning to be performed using only satellites whose satellite signals are of relatively good quality, thereby improving the accuracy of positioning.

[0052] In this embodiment, the given condition is a condition related to the reliability of the satellite signal.

[0053] According to this embodiment, the positioning unit 120 can select four or more satellites from among five or more satellites, excluding satellites whose satellite signals are less reliable. This allows positioning to be performed using only satellites whose satellite signals are relatively more reliable, improving the accuracy of positioning.

[0054] As explained in the third example of the reliability, the given condition may be a condition regarding the difference between the predicted pseudorange predicted based on the initial value of the observed pseudorange and the observed pseudorange for each time series.

[0055] The difference between the predicted pseudoranges, which are predicted based on the initial values ​​of the observed pseudoranges, and the observed pseudoranges for each time series represents the reliability of the observed pseudoranges obtained from the satellite signals. That is, when the variance of the differences or the maximum value of the differences is large, the reliability of the observed pseudoranges is low. According to this embodiment, when the reliability of the observed pseudoranges is low, the reliability of the satellite signals is deemed to be low, and the satellite can be excluded from positioning.

[0056] As explained in the first example of the reliability, the given condition may be a condition related to the elevation angle of the satellite.

[0057] When the elevation angle is low, the satellite signal is easily affected by the atmosphere, terrain, buildings, etc., and the accuracy of the pseudorange obtained from the satellite signal decreases. Therefore, when the elevation angle is low, the reliability of the satellite signal is low. According to this embodiment, when the elevation angle is low, the reliability of the satellite signal is considered to be low, and the satellite can be excluded from positioning.

[0058] As explained in the second example of the reliability, the given condition may be a condition related to the signal strength of the satellite signal.

[0059] When the signal strength of a satellite signal is low, the quality of the received satellite signal is low, and the accuracy of the pseudorange calculated from the satellite signal is reduced. Therefore, when the signal strength of a satellite signal is low, the reliability of the satellite signal is low. According to this embodiment, when the signal strength of a satellite signal is low, the reliability of the satellite signal is considered to be low, and the satellite can be excluded from positioning.

[0060] 5. When three or more positioning satellite systems are used Fig. 8 is a diagram for explaining the sharing of time errors when three positioning satellite systems are used. Here, an example is explained in which satellites of the GPS satellite system, the QZSS satellite system, and the BeiDou satellite system are captured. Note that four or more positioning satellite systems may be used, in which case the number of sharing combinations simply increases.

[0061] In positioning mode A, the positioning unit 120 performs positioning using a first time error Δtgps for the GPS satellite system, a second time error Δtqzss for the QZSS satellite system, and a third time error Δtbd for the BeiDou satellite system as unknowns. In positioning mode A, six or more satellites must be captured.

[0062] In positioning mode B, the positioning unit 120 performs positioning by using a first time error for the GPS satellite system and a second time error for the QZSS satellite system as a common time error Δtc, and a third time error Δtbd for the BeiDou satellite system as an unknown quantity separate from Δtc. In positioning mode B, five or more satellites must be captured.

[0063] In positioning mode C, the positioning unit 120 performs positioning by using the second time error for the QZSS satellite system and the third time error for the BeiDou satellite system as a common time error Δtc, and the first time error Δtgps for the GPS satellite system as an unknown quantity separate from Δtc. In positioning mode C, five or more satellites must be captured.

[0064] In positioning mode D, the positioning unit 120 performs positioning using a first time error for the GPS satellite system, a second time error for the QZSS satellite system, and a third time error for the BeiDou satellite system as a common time error Δtc. In positioning mode D, four or more satellites must be captured.

[0065] The positioning modes A to D may be switched, for example, from outside by a register setting, or may be automatically switched by the positioning unit 120 depending on the number of captured satellites, or may be fixed depending on the system in which the positioning satellite system receiver 200 is incorporated.

[0066] In this embodiment, the receiving unit 110 receives satellite signals from a first group of satellites belonging to a first satellite system, satellite signals from a second group of satellites belonging to a second satellite system, and satellite signals from a third group of satellites belonging to a third satellite system. As in positioning modes B and C, the positioning unit 120 may perform positioning using a common time error Δtc as the first time error related to the first positioning satellite system and the second time error related to the second positioning satellite system, and a third time error related to the third satellite system as unknowns.

[0067] In the conventional hybrid positioning using three positioning satellite systems, six satellites are required for positioning. According to this embodiment, the first time error related to the first positioning satellite system and the second time error related to the second positioning satellite system are set as a common time error Δtc. This makes it possible to reduce the number of satellites required for positioning to five in the hybrid positioning using three positioning satellite systems.

[0068] In this embodiment, as in positioning mode D, the positioning unit 120 may perform positioning using a first time error related to the first positioning satellite system, a second time error related to the second positioning satellite system, and a third time error related to the third satellite system as common unknown time errors.

[0069] According to this embodiment, by setting the time errors related to the three positioning satellite systems as a common time error Δtc, the number of satellites required for positioning in mixed positioning using the three positioning satellite systems can be reduced to four.

[0070] 6. Second Configuration Example of Positioning Satellite System Receiver Fig. 9 shows a second configuration example of a positioning satellite system receiver. The positioning satellite system receiver 200 includes an antenna 190, a receiving unit 110, and a processing device 2. Components similar to those described in Fig. 1 are given the same reference numerals, and descriptions of those components will be omitted as appropriate.

[0071] The receiving unit 110 is configured as an integrated circuit device separate from the processing unit 2. The processing unit 2 is a device that functions as the positioning unit 120, and includes a communication unit 3, a memory 4, an output unit 5, a processing unit 6, and a bus BUS. The processing unit 2 is, for example, a processor such as a CPU or a microcomputer.

[0072] The communication unit 3, memory 4, output unit 5, and processing unit 6 transmit and receive information to and from each other via a bus BUS. The communication unit 3 is an interface circuit that performs communication between the receiving unit 110 and the processing device 2. The memory 4 stores a program 7 in which the processing to be performed by the positioning unit 120 is described. The processing unit 6 executes the processing of the positioning unit 120 by executing the program 7 stored in the memory 4. The output unit 5 is an interface circuit that transmits the positioning results calculated by the processing unit 6 to the outside of the processing device 2. Although the memory 4 is described as an internal memory of the processor in FIG. 9, it may be an external memory of the processor.

[0073] The program 7 may be recorded on a non-transitory recording medium readable by a computer. The processing unit 6 executes the program 7 loaded from the recording medium to the memory 4, thereby performing the processing of the positioning unit 120. The recording medium is, for example, an optical disk, a hard disk drive, or a non-volatile semiconductor memory.

[0074] Although the present embodiment has been described in detail as above, it will be easily understood by those skilled in the art that many modifications are possible that do not substantially deviate from the novel matters and effects of the present disclosure. Therefore, all such modifications are intended to be included in the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term having a broader meaning or synonymy can be replaced with that different term anywhere in the specification or drawings. In addition, all combinations of the present embodiment and modifications are also included in the scope of the present disclosure. In addition, the configurations and operations of the positioning satellite system receiver, positioning device, receiving unit, positioning unit, reliability calculation unit, processing device, etc. are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0075] 2... processing device, 3... communication unit, 4... memory, 5... output unit, 6... processing unit, 7... program, 100... positioning device, 110... receiving unit, 120... positioning unit, 130... reliability calculation unit, 190... antenna, 200... positioning satellite system receiver, R1 to R5... pseudo range, Δtbd, Δtgps, Δtqzss... time error, Δtc... common time error

Claims

1. a receiving unit that receives satellite signals from a first group of satellites belonging to a first positioning satellite system and satellite signals from a second group of satellites belonging to a second positioning satellite system; a positioning unit that performs positioning using satellite signals received from four or more satellites including a satellite of the first satellite group and a satellite of the second satellite group, with a first time error related to the first positioning satellite system and a second time error related to the second positioning satellite system as a common unknown time error; A positioning device comprising:

2. 2. The positioning device according to claim 1, the four or more satellites include a first satellite, a second satellite, a third satellite, and a fourth satellite; The receiving unit is receiving a first satellite signal from the first satellite, a second satellite signal from the second satellite, a third satellite signal from the third satellite, and a fourth satellite signal from the fourth satellite; The positioning unit is A positioning device characterized in that it determines three position variables indicating a position of the positioning device and the unknown common time error using a first pseudorange based on the first satellite signal, a second pseudorange based on the second satellite signal, a third pseudorange based on the third satellite signal, and a fourth pseudorange based on the fourth satellite signal.

3. 3. The positioning device according to claim 2, The positioning unit is a first positioning mode in which positioning is performed using each of the first time error and the second time error as unknowns; a second positioning mode in which positioning is performed using the first time error and the second time error as the common unknown time error; A positioning device comprising:

4. 2. The positioning device according to claim 1, The positioning unit is A positioning device characterized in that, when five or more satellites are captured, four or more of the five or more satellites are selected, and positioning is performed using satellite signals received from the four or more selected satellites.

5. 5. The positioning device according to claim 4, The positioning unit is A positioning device comprising: a positioning unit that selects, from among said five or more satellites, satellites that satisfy a given condition, and selects said four or more satellites.

6. 6. The positioning device according to claim 5, The positioning device, wherein the given condition is a condition related to the reliability of a satellite signal.

7. 6. The positioning device according to claim 5, The positioning device according to claim 1, wherein the given condition is a condition regarding a difference between a predicted pseudorange, which is predicted based on an initial value of an observed pseudorange, and the observed pseudorange for each time series.

8. 6. The positioning device according to claim 5, A positioning device, wherein the given condition is a condition related to an elevation angle of a satellite.

9. 6. The positioning device according to claim 5, The positioning device, wherein the given condition is a condition related to the signal strength of a satellite signal.

10. 2. The positioning device according to claim 1, The receiving unit is receiving satellite signals from a third group of satellites belonging to a third satellite system; The positioning unit is A positioning device, which performs positioning using the common time error and the third time error related to the third satellite system as unknowns.

11. 2. The positioning device according to claim 1, The receiving unit is receiving satellite signals from a third group of satellites belonging to a third satellite system; The positioning unit is A positioning device, comprising: a positioning device that performs positioning using the first time error, the second time error, and a third time error related to the third satellite system as unknowns of the common time error.

12. a positioning unit that performs positioning using satellite signals received from four or more satellites including satellites of the first satellite group and satellites of the second satellite group, with a first time error related to the first positioning satellite system and a second time error related to the second positioning satellite system as common unknowns of time errors, based on satellite signals received by a receiving unit that receives satellite signals from a first satellite group belonging to a first positioning satellite system and satellite signals from a second satellite group belonging to a second positioning satellite system, A recording medium having a program recorded thereon for causing a computer to function.

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