Detection method, detection device, and GNSS receiver when a satellite whose direction of arrival of the received signal does not match the satellite orientation occurs

Abstract

To detect a satellite for which an arrival direction of a received signal in GNSS and satellite azimuth do not match, with good accuracy and at least one receiving antenna.SOLUTION: A satellite for which the arrival direction of a received signal for a visible satellite Si and satellite azimuth do not match is detected, on the basis whether an observation code which is a code of a Doppler shift time variation ΔDi with the visible satellite Si calculated based on a satellite positioning signal transmitted from the visible satellite Si matches an inference code which is a code of a Doppler shift time variation with the visible satellite Si inferred from the travelling direction of a GNSS receiver 1 and an orientation in which the visible satellite Si is located, viewed from the GNSS receiver 1 based on satellite orbit information included in the satellite positioning signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a satellite in which the direction of arrival of the received signal in the GNSS (Global Navigation Satellite System) does not match the satellite direction. If this occurs This invention relates to a technique for detecting [Background technology]

[0002] As one method for estimating the direction of arrival of a received signal, there is known a device that determines whether a received signal from a GPS (Global Positioning System, abbreviation for Global Positioning Satellite) satellite is a signal affected by multipath (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-256301 Summary of the Invention [Problem to be solved by the invention]

[0004] The device in Patent Document 1 determines whether the received signal from each GPS satellite is affected by multipath based on the phase difference between the received signals from each GPS satellite. However, the device in Patent Document 1 needs to have multiple receiving antennas in order to estimate the direction of arrival based on information from each GPS satellite.

[0005] Therefore, the present invention provides a method for detecting with good accuracy, at least at one receiving antenna, a satellite in which the direction of arrival of a received signal does not coincide with the satellite position in the satellite orbit information (specifically, the direction in which the satellite is located as seen from the receiving antenna). If this occurs It is possible to detect Test detection method and detection device, and Test The present invention aims to provide a GNSS receiver equipped with a detection device. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention Test The method of extracting the Doppler shift signal is an observation code, which is a code of a time change amount of the Doppler shift with respect to the positioning satellite, calculated based on a satellite positioning signal transmitted from the positioning satellite. the observation code that is the same over a predetermined period of time and, Moving with acceleration A satellite in which the arrival direction of the received signal for the positioning satellite and the satellite orientation do not match based on whether an inference code, which is the code of the time change amount of Doppler shift with the positioning satellite inferred from the traveling direction of a receiver receiving the satellite positioning signal and the orientation in which the positioning satellite is located as seen from the receiver based on satellite orbit information included in the satellite positioning signal, matches. occurs, that is, when the satellite positioning signal is present on the rear side of the receiver in the traveling direction and the positioning satellite is located in front of the receiver in the traveling direction, or when the satellite positioning signal is present on the front side of the receiver in the traveling direction and the positioning satellite is located behind the receiver in the traveling direction. The present invention is characterized by detecting

[0008] The present invention Test The detection method may take into consideration the magnitude of the Doppler residual calculated as the difference between the actual measured Doppler shift amount with the positioning satellite observed based on the satellite positioning signal and the sum of the Doppler shift amount associated with the movement of the positioning satellite, the Doppler shift amount associated with the movement of the receiver, and the clock drift of the receiver.

[0009] In addition, the present invention Test The output device calculates an observation code, which is a code of a time change amount of Doppler shift with respect to the positioning satellite, based on a satellite positioning signal transmitted from the positioning satellite. the observation code that is the same over a predetermined period of time and, Moving with acceleration A satellite in which the arrival direction of the received signal for the positioning satellite and the satellite orientation do not match based on whether an inference code, which is the code of the time change amount of Doppler shift with the positioning satellite inferred from the traveling direction of a receiver receiving the satellite positioning signal and the orientation in which the positioning satellite is located as seen from the receiver based on satellite orbit information included in the satellite positioning signal, matches. occurs, that is, when the satellite positioning signal is present on the rear side of the receiver in the traveling direction and the positioning satellite is located in front of the receiver in the traveling direction, or when the satellite positioning signal is present on the front side of the receiver in the traveling direction and the positioning satellite is located behind the receiver in the traveling direction. The present invention is characterized by detecting

[0011] The present invention Test The receiver may take into consideration the magnitude of the Doppler residual calculated as the difference between the actual measured Doppler shift amount with the positioning satellite observed based on the satellite positioning signal and the sum of the Doppler shift amount associated with the movement of the positioning satellite, the Doppler shift amount associated with the movement of the receiver, and the clock drift of the receiver.

[0012] The GNSS receiver according to the present invention further comprises: Inspection The device is characterized by being equipped with an ejection device. [Effects of the Invention]

[0013] The present invention Test How to get out ,Check According to the GNSS receiver, a satellite whose satellite orientation does not match the direction of arrival of the received signal from the positioning satellite is detected based on whether or not the observed code of the amount of time change in Doppler shift with the positioning satellite matches the inferred code, so it is possible to detect with good accuracy, and with at least one receiving antenna, a satellite whose satellite orientation does not match the direction of arrival of the received signal in the GNSS. By detecting a satellite whose satellite orientation does not match the direction of arrival of the received signal, the receiver can, for example, , measurement This makes it possible to improve position accuracy.

[0014] The present invention Test How to get out ,Check According to the GNSS receiver, if it is considered whether the observation code is the same over a predetermined period of time, it becomes possible to more accurately detect satellites whose direction of arrival of the received GNSS signal does not match the satellite orientation.

[0015] The present invention Test How to get out ,Check According to the GNSS receiver, when the magnitude of the Doppler residual is taken into consideration, it becomes possible to more accurately detect satellites whose arrival direction of the received GNSS signal does not match the satellite orientation. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a functional block diagram showing a schematic configuration of a GNSS receiver including a detection device according to an embodiment of the present invention. [Figure 2] 3 is a flowchart showing the processing procedure in the detection device of FIG. 1 and the processing procedure of the detection method according to the embodiment of the present invention. [Figure 3] FIG. 10 is a functional block diagram showing a schematic configuration of a GNSS receiver including a detection device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below based on the illustrated embodiments.

[0018] FIG. 1 is a diagram illustrating an embodiment of the present invention. Test FIG. 2 is a functional block diagram showing a schematic configuration of a GNSS receiver 1 equipped with a transmitter 4. , Examination This is a processing procedure in the output device 4 and is also related to the embodiment of the present invention. Test 10 is a flowchart showing the processing procedure of the extraction method.

[0019] The GNSS receiver 1 according to the embodiment has a function of receiving satellite positioning signals transmitted from each of a plurality of positioning satellites constituting the GNSS (Global Navigation Satellite System) to perform satellite positioning of its own position, and a function of detecting a satellite in which the direction of arrival of the received signal in the GNSS does not match the satellite orientation (i.e., the orientation in which the positioning satellite is located as viewed from the GNSS receiver 1). The GNSS receiver 1 mainly comprises a GNSS receiving unit 2, a GNSS positioning unit 3, and , Examination and a discharge device 4.

[0020] The GNSS receiver 1 is configured as a mechanism including a central processing unit (CPU) that performs arithmetic processing related to, for example, satellite positioning of its own position and detection of satellites whose arrival direction of a received GNSS signal does not match the satellite orientation, a ROM (Read Only Memory) that is a readable storage device, and a RAM (Random Access Memory) that is a readable and writable storage device. Specifically, the GNSS receiver 1 may be configured by, for example, using a computer to execute a program, or may be configured as hardware using one or more ICs (Integrated Circuits).

[0021] In this embodiment , Examination A program for controlling the operation of a computer to function as a GNSS receiver 1 including an output device 4 is stored in the ROM, and a central processing unit (CPU) executes the program, thereby controlling the GNSS receiving unit 2, the GNSS positioning unit 3, and Biken The output device 4 is realized as a functional block. The RAM is used as a work area as needed.

[0022] The GNSS receiver 2 receives satellite positioning signals transmitted from multiple positioning satellites Si (where i is a satellite number for distinguishing and identifying each of the multiple positioning satellites) constituting the GNSS via an antenna and converts the signals into electrical signals (particularly digital signals). An example of the GNSS is the Global Positioning System (GPS, an abbreviation for Global Positioning Satellite).

[0023] The satellite positioning signal is superimposed on a carrier wave and transmitted successively from the positioning satellite Si as a radio wave (called a "GNSS radio wave"). The GNSS receiver 2 receives the GNSS radio wave and demodulates the GNSS radio wave to extract the satellite positioning signal.

[0024] The GNSS receiver 2 generates observation data such as the pseudorange ρi, the Doppler shift amount Di, the Doppler shift time change amount ΔDi, the satellite position, the satellite state, and navigation data for each positioning satellite Si from the extracted satellite positioning signal.

[0025] The pseudorange is a distance determined from the difference between the time when a satellite positioning signal (in other words, a GNSS radio wave) is transmitted from a positioning satellite Si and the time when it is received by the GNSS receiver 2 via an antenna. The difference between the transmission time and the reception time can be calculated based on the phase shift of the C / A code. The C / A code is a code unique to each positioning satellite and functions as information indicating the source of the transmission.

[0026] The pseudorange ρi of each positioning satellite Si is calculated by multiplying the difference between the time when the positioning satellite Si transmits a satellite positioning signal (GNSS radio wave) and the time when the GNSS receiver 2 receives the satellite positioning signal (GNSS radio wave) (i.e., the radio wave propagation time) by the speed of light.

[0027] The amount of Doppler shift is a parameter that indicates the difference between the carrier frequency of the GNSS radio wave and the reception frequency at the GNSS receiver 2, which is caused by the Doppler effect.

[0028] The Doppler shift amount Di of each positioning satellite Si is calculated as the frequency difference between the carrier frequency of the GNSS radio waves transmitted by the positioning satellite Si and the carrier frequency of the GNSS radio waves received by the GNSS receiver 2. The carrier frequency of the GNSS radio waves transmitted by the positioning satellite Si is predetermined and stored in advance in a predetermined storage device provided in the GNSS receiver 1 (i.e., known). In other words, the Doppler shift amount Di of each positioning satellite Si is an observed and measured value.

[0029] The time change amount ΔDi of the Doppler shift of each positioning satellite Si is a parameter that represents the time change amount of the Doppler shift amount Di of each positioning satellite Si (that is, the magnitude of change per unit time).

[0030] The satellite position is information indicating the current position of the positioning satellite Si on the satellite orbit, and specifically, is a coordinate in an orthogonal three-dimensional coordinate system.

[0031] The satellite position (Xsi, Ysi, Zsi) of each positioning satellite Si is calculated based on the satellite orbit information of the positioning satellite Si (specifically, the almanac and ephemeris) and the time when the positioning satellite Si transmitted the satellite positioning signal (GNSS radio wave).

[0032] The navigation data includes, for example, the satellite number, satellite orbit information (specifically, almanac and ephemeris), and the time when the satellite positioning signal (GNSS radio wave) was transmitted for the positioning satellite Si.

[0033] The GNSS receiver 2 outputs the above observation data at regular intervals (for example, every time a satellite positioning signal is received) as satellite information for each positioning satellite Si, together with the signal strength of the satellite positioning signal, which is the received signal, and the time at which the satellite positioning signal (GNSS radio wave) was received. The GNSS receiver 2 may output an S / N (Signal-to-Noise ratio) or a C / N (Carrier-to-Noise ratio) instead of signal strength.

[0034] The cycle at which the GNSS receiver 2 outputs satellite information is not limited to a specific time length, but may be set to any time length within a range of, for example, about 50 to 200 milliseconds.

[0035] Furthermore, there are multiple positioning satellites, and the GNSS receiver 2 generates satellite information along with observation data from all satellite positioning signals that can be demodulated from the GNSS radio waves, and outputs all of the generated satellite information. Positioning satellites that can be used for GNSS satellite positioning (in other words, positioning satellites that can capture GNSS radio waves and demodulate satellite positioning signals from the GNSS radio waves) are called "visible satellites," and the number of visible satellites is called the "number of visible satellites."

[0036] That is, the GNSS receiver 2 outputs satellite information for each visible satellite Si at a fixed cycle, the number of which is equal to the number of visible satellites.

[0037] The GNSS positioning unit 3 receives satellite information for each visible satellite Si output at regular intervals from the GNSS receiving unit 2, and uses the satellite information to perform calculations for satellite positioning of its own position.

[0038] The method of satellite positioning in the GNSS positioning unit 3 is a well-known technology and there are various methods (for example, Patent No. 6546730), and since this invention is not limited to a specific method, detailed explanation will be omitted here.

[0039] The GNSS positioning unit 3 outputs at least information indicating the current position of the GNSS receiver 1 (specifically, coordinates in an orthogonal three-dimensional coordinate system) as a result of satellite positioning.

[0040] Examination The detection device 4 is a mechanism for detecting satellites whose arrival direction of a received signal in GNSS does not match the satellite orientation, and includes an acceleration vector calculation unit 41, a satellite selection unit 42, a Doppler residual calculation unit 43, a Doppler residual verification unit 44, a sign inference unit 45 of the amount of change in DS over time, and a sign verification unit 46 of the amount of change in DS over time (DS: abbreviation for Doppler Shift).

[0041] Examination The output device 4 receives satellite information for each visible satellite Si output at regular intervals from the GNSS receiver 2, in other words, acquires satellite information for each visible satellite Si (step S1), and performs calculations based on the satellite information to detect satellites whose arrival direction of the received signal in the GNSS does not match the satellite orientation.

[0042] According to the embodiment Test Output device 4 and BikenThe detection method detects satellites whose satellite orientation does not match the direction of arrival of the received signal for the visible satellite Si based on whether an observation code, which is the sign of the time change amount ΔDi of the Doppler shift with respect to the visible satellite Si calculated based on the satellite positioning signal transmitted from the visible satellite Si, matches an inference code, which is the sign of the time change amount of the Doppler shift with respect to the visible satellite Si inferred from the direction of travel of the GNSS receiver 1 and the orientation in which the visible satellite Si is located as seen from the GNSS receiver 1 based on the satellite orbit information included in the satellite positioning signal.

[0043] Examination The output device 4 executes the processing from step S2 onwards every time it receives satellite information for each visible satellite Si output at a fixed period from the GNSS receiving unit 2 (step S1), executes the processing from step S3 onwards for each visible satellite Si, and executes the processing from step S4 onwards for each visible satellite Si selected in the processing of step S3. , Examination The detection device 4 determines, for each visible satellite Si, whether or not there is a satellite whose arrival direction of the received signal does not match the satellite orientation for that visible satellite Si.

[0044] Examination The detection device 4 uses the Doppler residual to detect, from among multiple satellite positioning signals, satellites whose arrival direction of the received signal does not match the satellite orientation. By using the Doppler residual, if a satellite positioning signal arrives at the GNSS receiver 1 from a direction different from the actual position of a visible satellite due to the effects of multipath, for example, an error will be introduced into the satellite line-of-sight vector of the actual visible satellite Si, improving the detection accuracy of satellite positioning signals affected by multipath and reducing false detections.

[0045] Examination The detection device 4 also detects, from among the multiple satellite positioning signals, satellite positioning signals of satellites whose arrival direction of the received signal does not match the satellite orientation, based on the direction of change in the time change amount ΔDi of the Doppler shift for each visible satellite Si, which is inferred from the direction of travel of the GNSS receiver 1 and the relative positional relationship between the GNSS receiver 1 and each visible satellite Si.

[0046] Furthermore, if there is no satellite whose direction of arrival of the received signal in the GNSS does not match the satellite orientation, and if the positioning satellite is located directly in front of the GNSS receiver 1 in the direction of travel, the GNSS receiver 1 and the positioning satellite will move relatively closer due to the acceleration of the GNSS receiver 1, and the sign of the time change in Doppler shift will be positive.

[0047] On the other hand, if there is no satellite whose direction of arrival of the received signal in the GNSS does not match the satellite orientation, and the positioning satellite is located behind the GNSS receiver 1 in the direction of travel, the GNSS receiver 1 and the positioning satellite will move relatively farther apart due to the acceleration of the GNSS receiver 1, and the sign of the time change in Doppler shift will be negative.

[0048] On the other hand, if there is a satellite whose direction of arrival of the GNSS received signal does not match the satellite orientation, and the positioning satellite is located in front of the GNSS receiver 1 in the direction of travel, and the signal of the satellite whose direction of arrival of the received signal does not match the satellite orientation is located behind the GNSS receiver 1 in the direction of travel, the GNSS receiver 1 will move with acceleration, and the sign of the time change in Doppler shift will be negative, contrary to the expectation that the sign would be positive if the signal were from the original positioning satellite. Also, in this case, the Doppler residual will be large.

[0049] Furthermore, if there is a satellite whose direction of arrival of the GNSS received signal does not match the satellite orientation, and a positioning satellite is located behind the GNSS receiver 1 in the direction of travel, and the signal of the satellite whose direction of arrival of the received signal does not match the satellite orientation is located in front of the GNSS receiver 1 in the direction of travel, the GNSS receiver 1 will move with acceleration, causing the sign of the time change in Doppler shift to be positive, contrary to the expectation that the sign would be negative if the signal were from the original positioning satellite. In this case, the Doppler residual will also be large.

[0050] For this reason, if the Doppler residual is large and the sign of the observed value of the time change ΔDi of the Doppler shift with respect to the visible satellite Si does not match the sign of the time change of the Doppler shift with respect to the visible satellite Si inferred from the direction in which the visible satellite Si is located as seen from the GNSS receiver 1 and the direction in which the GNSS receiver 1 is traveling, it is considered that there is (a high possibility that) a satellite exists for which the direction of arrival of the received signal does not match the satellite direction for that visible satellite Si.

[0051] Examination Based on the above concept, the detection device 4 performs the following processes in each unit to detect, for each visible satellite Si, a satellite whose arrival direction of a received GNSS signal does not match the satellite orientation.

[0052] The acceleration vector calculation unit 41 calculates the acceleration vector of the GNSS receiver 1 (step S2).

[0053] The method of calculating the acceleration vector of the GNSS receiver 1 is a well-known technique and there are various methods available, and the present invention is not limited to a specific method, so a detailed description will be omitted here.

[0054] The acceleration vector calculation unit 41 calculates the relative acceleration of the GNSS receiver 1 with respect to each visible satellite Si based on, for example, the amount of change in Doppler shift over time ΔDi included in the satellite information for each visible satellite Si, and calculates the acceleration vector of each visible satellite Si based on the satellite orbit information (specifically, almanac and ephemeris) included in the satellite information for each visible satellite Si and the time at which the positioning satellite Si transmitted a satellite positioning signal (GNSS radio wave).

[0055] The acceleration vector calculation unit 41 also calculates the direction of each visible satellite Si as seen from the GNSS receiver 1 (specifically, the orientation in which each visible satellite Si is located as seen from the GNSS receiver 1) based on information indicating the current position of the GNSS receiver 1 (specifically, coordinates in a Cartesian three-dimensional coordinate system) output from the GNSS positioning unit 3 and the satellite position (Xsi, Ysi, Zsi) included in the satellite information for each visible satellite Si.

[0056] The acceleration vector calculation unit 41 further calculates the acceleration of the GNSS receiver 1 for each direction of each visible satellite Si based on the relative acceleration of the GNSS receiver 1 with respect to each visible satellite Si calculated above, the acceleration vector of each visible satellite Si, and the direction of each visible satellite Si as seen from the GNSS receiver 1, and calculates the acceleration vector of the GNSS receiver 1 based on the acceleration of the GNSS receiver 1 for each direction of each visible satellite Si.

[0057] Alternatively, the acceleration vector calculation unit 41 may calculate the acceleration vector of the GNSS receiver 1 based on the information output from the acceleration sensor 5 and the information output from the gyro sensor 6 (or the yaw rate sensor) (see FIG. 3).

[0058] The acceleration sensor 5 detects and outputs the acceleration of the GNSS receiver 1, in other words, the acceleration of the moving body (for example, a vehicle, a ship, an aircraft, etc.) on which the GNSS receiver 1 is mounted.

[0059] The gyro sensor 6 (or yaw rate sensor) detects and outputs the yaw rate of the GNSS receiver 1, in other words, the yaw rate of the moving body (for example, a vehicle, a ship, an aircraft, etc.) on which the GNSS receiver 1 is mounted.

[0060] In this case, the acceleration vector calculation unit 41 receives an input of the detected acceleration value output from the acceleration sensor 5, receives an input of the detected yaw rate value output from the gyro sensor 6, and calculates the traveling direction of the GNSS receiver 1 by integrating the yaw rate based on the detected yaw rate value to obtain the amount of change in the yaw angle (in other words, azimuth angle), and also calculates the acceleration vector of the GNSS receiver 1 based on the traveling direction and the detected acceleration value. Note that the actual traveling direction (in other words, azimuth) is determined at least once and given as a reference / initial value.

[0061] The satellite selection unit 42 selects visible satellites Si to be subjected to a process of detecting satellites whose arrival direction of the received signal does not match the satellite orientation (step S3).

[0062] The satellite selection unit 42 first generates a set of the Doppler shift time change amount ΔDi for each visible satellite Si using the Doppler shift time change amount ΔDi included in the satellite information acquired in the most recent N (where N is a natural number) chronologically successive processing of step S1 (including the most recent processing of step S1).

[0063] The above N (referred to as "continuation count N") is not limited to a specific value (in other words, a time length) and is set to an appropriate value, taking into consideration, for example, whether or not the positioning signals are transmitted / emitted from the same direction, taking into account that the GNSS receiver 1 is moving with acceleration. The continuation count N may be set to any value in the range of about 3 to 5 (i.e., about 300 to 500 milliseconds), for example, when satellite information is output from the GNSS receiver 2 every 100 milliseconds and the GNSS positioning unit 3 performs calculation processing for satellite positioning of its own position.

[0064] The satellite selection unit 42 then determines whether or not the signs of the amounts of change in Doppler shift over time ΔDi included in the set of amounts of change in Doppler shift over time ΔDi (that is, for N consecutive times) are all the same.

[0065] Then, if the signs of the time change amount ΔDi of the Doppler shift for the N consecutive times are different (step S3: No), the satellite selection unit 42 determines that there is no satellite for the visible satellite Si whose arrival direction of the received signal does not match the satellite orientation (step S8).

[0066] On the other hand, if the signs of the time change amounts ΔDi of the Doppler shift for the N consecutive times are all the same (step S3: Yes), the satellite selection unit 42 proceeds to step S4 in the processing procedure for detecting a satellite whose arrival direction of the received signal for the visible satellite Si does not match the satellite orientation.

[0067] When the signs of the time change amounts ΔDi of the Doppler shift for N consecutive times are all the same, it means that the GNSS receiver 1 and the signal source (including the source of a satellite signal whose arrival direction of the received signal does not match the satellite orientation) are continuously moving closer to or farther away from each other with acceleration over a predetermined period of time.

[0068] The Doppler residual calculation unit 43 calculates the Doppler residual (step S4).

[0069] Specifically, the Doppler residual calculation unit 43 calculates the Doppler residual Ri of a visible satellite Si according to the following equation 1. The Doppler residual Ri of a visible satellite Si is the difference between the amount of Doppler shift Di from the visible satellite Si and the sum of the amount of Doppler shift Dsi associated with the movement of the visible satellite Si, the amount of Doppler shift Dr associated with the movement of the GNSS receiver 1, and the clock drift Δfrc of the GNSS receiver 1. (Equation 1) Ri = Di-(Dsi+Dr+Δfrc) where Ri is the Doppler residual of the visible satellite Si Di: Doppler shift amount with visible satellite Si Dsi: Doppler shift due to movement of visible satellite Si Dr: Doppler shift amount due to movement of GNSS receiver 1 Δfrc: Clock drift of GNSS receiver 1

[0070] Specifically, Dsi is the amount of Doppler shift in the satellite line of sight direction relative to the visible satellite Si that accompanies a change in relative distance due to the movement of the visible satellite Si, and is calculated as a quantity in the satellite line of sight direction relative to the visible satellite Si based on the velocity vector of the visible satellite Si and the current position of the GNSS receiver 1 (specifically, coordinates in an orthogonal three-dimensional coordinate system).

[0071] Specifically, Dr is the amount of Doppler shift in the satellite line of sight to the visible satellite Si due to a change in the relative distance caused by movement of the GNSS receiver 1, and is calculated as a quantity in the satellite line of sight to the visible satellite Si based on the velocity vector of the GNSS receiver 1 and the satellite position (Xsi, Ysi, Zsi) of the visible satellite Si.

[0072] Δfrc is the clock drift of the GNSS receiver 1, and is successively estimated by the GNSS receiver 1 itself by calculating the velocity of the receiver using the least squares method, a Kalman filter, or the like.

[0073] The Doppler residual verification unit 44 determines whether the absolute value of the Doppler residual Ri of the visible satellite Si is equal to or greater than the Doppler residual threshold value Rthr (step S5).

[0074] The Doppler residual threshold value Rthr is not limited to a specific value, but is set to an appropriate value, taking into consideration, for example, whether the Doppler residual Ri deviates from the level normally expected when receiving satellite positioning signals from the original positioning satellites that make up the GNSS. The Doppler residual threshold value Rthr may be set to any value within the range of approximately 0.6 / λ to 2.0 / λ [Hz], where λ is the wavelength [m] of the carrier wave and v is the relative movement speed [m / s], and the Doppler shift amount d [Hz] is expressed as d = v / λ.

[0075] When |Ri| < Rthr (step S5: No), since the Doppler residual Ri of the visible satellite Si is small, the Doppler residual verification unit 44 determines that there is no satellite for which the arrival direction of the received signal and the satellite azimuth do not match for the visible satellite Si (step S8).

[0076] On the other hand, when |Ri| ≥ Rthr (step S5: Yes), the Doppler residual verification unit 44 proceeds with the processing procedure for detecting a satellite for which the arrival direction of the received signal and the satellite azimuth do not match for the visible satellite Si to the processing of step S6.

[0077] The sign inference unit 45 for the time change amount of DS infers whether the sign of the time change amount ΔDi of the Doppler shift with the visible satellite Si is expected to be positive or negative (step S6).

[0078] Specifically, the sign inference unit 45 for the time change amount of DS infers whether the sign of the time change amount ΔDi of the Doppler shift with the visible satellite Si should be positive or negative based on the relative relationship between the traveling direction of the GNSS receiver 1 based on the acceleration vector of the GNSS receiver 1 calculated in the processing of step S2 and the azimuth of the visible satellite Si as seen from the GNSS receiver 1 based on the ephemeris included in the satellite information.

[0079] That is, based on the traveling direction of the GNSS receiver 1 and the azimuth of the visible satellite Si, when the GNSS receiver 1 with acceleration and the visible satellite Si are approaching, the time change amount ΔDi of the Doppler shift with the visible satellite Si should be positive, while when the GNSS receiver 1 with acceleration and the visible satellite Si are moving away, the time change amount ΔDi of the Doppler shift with the visible satellite Si should be negative.

[0080] The sign verification unit 46 of the time change amount of DS determines whether the sign of the time change amount of Doppler shift ΔDi included in the satellite information for each visible satellite Si (called the "observation code") matches the sign of the time change amount of Doppler shift with the visible satellite Si inferred in the processing of step S6 (called the "inference code") (step S7).

[0081] If the observed code of the time change in Doppler shift matches the inferred code (step S7: Yes), the DS time change code verification unit 46 determines that the signs of the observed values ​​of the time change in Doppler shift ΔDi are not contradictory, and therefore that there is no satellite for the visible satellite Si in question whose arrival direction of the received signal does not match the satellite orientation (step S8).

[0082] On the other hand, if the observed code of the time change amount of Doppler shift and the inferred code do not match (step S7: No), the DS time change amount sign verification unit 46 determines that the sign of the observed value of the time change amount of Doppler shift ΔDi is inconsistent, and therefore that a satellite has occurred for which the arrival direction of the received signal and the satellite orientation do not match for the visible satellite Si in question (step S9).

[0083] Examination When the output device 4 detects a visible satellite Si whose satellite orientation does not match the direction of arrival of the received signal, it may exclude the satellite information about the visible satellite Si from the information used in the calculation process of satellite positioning, and may also notify the user that a satellite whose satellite orientation does not match the direction of arrival of the received signal has occurred (or is highly likely to exist), for example, by displaying a message on a display (not shown) or emitting a sound from a speaker (not shown).

[0084] According to the embodiment Test How to get out ,CheckAccording to the detection device 4 and the GNSS receiver 1, a satellite whose direction of arrival of the received signal for a visible satellite Si does not match the satellite orientation is detected based on whether the observed code and the inferred code of the time change amount ΔDi of the Doppler shift with respect to the visible satellite Si match. Therefore, it is possible to detect with good accuracy, and with at least one receiving antenna, a satellite whose direction of arrival of the received signal in the GNSS does not match the satellite orientation.

[0085] According to the embodiment Test How to get out ,Check The detection device 4 and the GNSS receiver 1 also take into consideration whether the sign (i.e., the observation code) of the time change ΔDi of the Doppler shift with respect to a visible satellite Si is the same for N consecutive times (in other words, a predetermined time length), making it possible to more accurately detect satellites whose arrival direction of the received signal in the GNSS does not match the satellite orientation.

[0086] According to the embodiment Test How to get out ,Check The detection device 4 and GNSS receiver 1 also take into account the magnitude of the Doppler residual, making it possible to more accurately detect satellites whose arrival direction of the received GNSS signal does not match the satellite orientation.

[0087] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes or the like within the scope of the gist of the present invention, they are included in the present invention.

[0088] For example, in the above embodiment, the GNSS receiver 1 shown in FIG. 1 is Test The ejection device 4 is incorporated in the present invention. Test The equipment / devices in which the output device 4 can be incorporated or linked are not limited to the GNSS receiver 1 whose schematic configuration is shown in FIG. 1, and the present invention can be applied to GNSS receivers having other configurations. Test The present invention may also be implemented in conjunction with or incorporate a radiation detector. TestThe detection device may be incorporated into or cooperate with other types of equipment or devices that use GNSS. Test The GNSS receiver 2 may be used alone. , Examination Alternatively, the output device 4 may output only the observation data / satellite information required to perform a calculation process for detecting satellites whose satellite orientations do not match the arrival direction of the received GNSS signal.

[0089] In addition to the configurations in the above embodiments, for example, if a certain number or more of positioning satellites are detected as positioning satellites whose arrival direction of the received signal and satellite orientation do not match, it may be determined that there is a risk of a decrease in positioning accuracy, and satellite positioning may be interrupted. In that case, if a gyro sensor or acceleration sensor is available, it may be switched to inertial navigation.

[0090] Furthermore, as an example of application of the above embodiment, for example, when a transmission signal containing positioning information and orbit information from multiple positioning satellites is transmitted from a single transmitting antenna and received by a receiver, application of this invention makes it possible to detect satellites whose arrival direction of the received signal does not match the satellite orientation. Note that the above situation can also be said to be a situation in which signals are disguised as being transmitted from multiple positioning satellites. In this respect, the "signals transmitted from multiple positioning satellites" in this invention includes signals transmitted from a single transmitting antenna while disguising them as being transmitted from multiple positioning satellites. [Explanation of symbols]

[0091] 1 GNSS receiver 2 GNSS receiver 3 GNSS positioning unit 4 Examination output device 41 Acceleration vector calculation unit 42 Satellite Selection Department 43 Doppler residual calculation unit 44 Doppler residual verification unit 45 Sign inference part of DS time change amount 46 DS time change sign verification section 5 Accelerometer 6 Gyro sensor

Claims

1. Among observation codes which are codes of the time change amount of Doppler shift with respect to the positioning satellite calculated based on the satellite positioning signal transmitted from the positioning satellite, the observation codes which remain the same over a predetermined time length; an inference code that is a code of a time change amount of Doppler shift with respect to the positioning satellite, which is inferred from the traveling direction of a receiver that receives the satellite positioning signal while moving with acceleration and the orientation of the positioning satellite as seen from the receiver based on satellite orbit information included in the satellite positioning signal; and detects whether or not there is a satellite whose arrival direction of the received signal for the positioning satellite does not match the satellite orientation, i.e., whether or not the satellite positioning signal is present behind the receiver in the traveling direction and the positioning satellite is located in front of the receiver in the traveling direction, or whether or not the satellite positioning signal is present in front of the receiver in the traveling direction and the positioning satellite is located behind the receiver in the traveling direction. A detection method characterized by:

2. taking into consideration the magnitude of a Doppler residual calculated as the difference between the actual measured Doppler shift amount with respect to the positioning satellite observed based on the satellite positioning signal and the sum of the Doppler shift amount associated with the movement of the positioning satellite, the Doppler shift amount associated with the movement of the receiver, and the clock drift of the receiver; 2. The detection method according to claim 1 .

3. Among observation codes which are codes of the time change amount of Doppler shift with respect to the positioning satellite calculated based on the satellite positioning signal transmitted from the positioning satellite, the observation codes which remain the same over a predetermined time length; an inference code that is a code of a time change amount of Doppler shift with respect to the positioning satellite, which is inferred from the traveling direction of a receiver that receives the satellite positioning signal while moving with acceleration and the orientation of the positioning satellite as seen from the receiver based on satellite orbit information included in the satellite positioning signal; and detects whether or not there is a satellite whose arrival direction of the received signal for the positioning satellite does not match the satellite orientation, i.e., whether or not the satellite positioning signal is present behind the receiver in the traveling direction and the positioning satellite is located in front of the receiver in the traveling direction, or whether or not the satellite positioning signal is present in front of the receiver in the traveling direction and the positioning satellite is located behind the receiver in the traveling direction. A detection device characterized by:

4. taking into consideration the magnitude of a Doppler residual calculated as the difference between the actual measured Doppler shift amount with respect to the positioning satellite observed based on the satellite positioning signal and the sum of the Doppler shift amount associated with the movement of the positioning satellite, the Doppler shift amount associated with the movement of the receiver, and the clock drift of the receiver; 4. The detection device according to claim 3.

5. A detection device according to claim 3 or 4, GNSS receiver characterized by:

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