Method and device for detecting direction bias of received signal, and receiver

Abstract

To detect arrival direction bias of a received signal with good accuracy and at least one receiving antenna.SOLUTION: Arrival direction bias of a received signal is detected by verifying at least, the degree of variability in Doppler shift time variation ΔDi for each effective transmitter Si calculated based on the received signal including a plurality of signals respectively corresponding to signals transmitted from a plurality of effective transmitters Si, and the magnitude of the Doppler shift time variation ΔDi.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for detecting bias in the direction of arrival of received signals. [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 (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, an object of the present invention is to provide a method and device for detecting bias in the direction of arrival of a received signal, which are capable of detecting bias in the direction of arrival of a received signal with high accuracy and using at least one receiving antenna, and a receiver equipped with such a device for detecting bias in the direction of arrival of a received signal.

[0006] Here, in this invention, a state in which the arrival directions of multiple received signals (in other words, radio waves transmitted after superimposing a signal on a carrier wave) are dispersed in various directions is called "no bias in the arrival direction of the received signals," and a state in which the arrival directions of multiple received signals (in other words, radio waves transmitted after superimposing a signal on a carrier wave) are concentrated in a specific direction is called "bias in the arrival direction of the received signals is occurring." [Means for solving the problem]

[0007] In order to solve the above problem, a method for detecting a bias in the direction of arrival of a received signal according to the present invention includes: If the state in which the arrival directions of multiple received signals are concentrated in a specific direction is called the arrival direction bias of received signals, then when a receiver moves with acceleration, Multiple Positioning satellite Sent from send signal receiving the transmitted signal Contains multiple signals corresponding to each of the The aforementioned Based on the degree of variation in the amount of change in Doppler shift over time for each of the transmitted signals calculated based on the received signals and the magnitude of the amount of change in Doppler shift over time, The aforementioned It is characterized by detecting the bias in the direction of arrival of the received signal.

[0008] The method for detecting bias in the direction of arrival of received signals according to the present invention comprises: Positioning satellite Further consideration of the DOP value for death , The DOP value is an abbreviation for Dilution Of Precision, and is a value that indexes the positioning state of the positioning satellites. This may be done.

[0009] The method for detecting the direction of arrival bias of a received signal according to the present invention is Positioning satellite The number of the elements may be further taken into consideration.

[0010] A method for detecting a bias in the direction of arrival of a received signal according to the present invention includes the steps of: The aforementioned The duration of a state in which the bias in the direction of arrival of the received signal is suspected may also be taken into consideration.

[0011] The method for detecting bias in the direction of arrival of received signals according to the present invention includes: The aforementionedA transmission signal having the best reception condition is selected from the transmission signals, and a transmission signal in which the absolute value of the difference between the amount of change in Doppler shift of the selected transmission signal and the amount of change in Doppler shift of each transmission signal is equal to or less than a predetermined threshold is extracted. Then, the selected transmission signal and the extracted transmission signal are used to perform a calculation. The aforementioned It is also possible to detect bias in the direction of arrival of the received signals.

[0012] The apparatus for detecting direction bias of received signals according to the present invention comprises: If the state in which the directions of arrival of a plurality of received signals are concentrated in a specific direction is called "biased direction of arrival of received signals," then a detection device provided on a receiver that moves with acceleration, Multiple Positioning satellite Sent from send Contains multiple signals corresponding to each signal The aforementioned Based on the degree of variation in the amount of change in Doppler shift over time for each of the transmitted signals calculated based on the received signals and the magnitude of the amount of change in Doppler shift over time, The aforementioned It is characterized by detecting the bias in the direction of arrival of the received signal.

[0013] The apparatus for detecting direction bias of received signals according to the present invention comprises: Positioning satellite Further consideration of the DOP value for death , The DOP value is an abbreviation for Dilution Of Precision, and is a value that indexes the positioning state of the positioning satellites. This may be done.

[0014] The apparatus for detecting direction bias of received signals according to the present invention is capable of demodulating the transmitted signal. Positioning satellite The number of the elements may be further taken into consideration.

[0015] The apparatus for detecting direction bias of received signals according to the present invention comprises: The aforementioned The duration of a state in which the bias in the direction of arrival of the received signal is suspected may also be taken into consideration.

[0016] The apparatus for detecting direction bias of received signals according to the present invention comprises a plurality of The aforementionedA transmission signal having the best reception condition is selected from the transmission signals, and a transmission signal in which the absolute value of the difference between the amount of change in Doppler shift of the selected transmission signal and the amount of change in Doppler shift of each transmission signal is equal to or less than a predetermined threshold is extracted. Then, the selected transmission signal and the extracted transmission signal are used to perform a calculation. The aforementioned It is also possible to detect bias in the direction of arrival of the received signals. [Effects of the Invention]

[0018] The method, device, and receiver for detecting direction bias of received signals according to the present invention detect direction bias of received signals based on the degree and magnitude of variation in the amount of change in Doppler shift over time for each transmitted signal, making it possible to detect direction bias of received signals with high accuracy using at least one receiving antenna.

[0019] According to the method for detecting bias in the direction of arrival of received signals, the device for detecting bias in the direction of arrival of received signals, and the receiver of the present invention, if the DOP values ​​for multiple transmitters are further taken into consideration, it becomes possible to detect bias in the direction of arrival of received signals more accurately.

[0020] According to the method, device, and receiver of the present invention for detecting bias in the direction of arrival of received signals, it is possible to more accurately detect bias in the direction of arrival of received signals by further taking into consideration the number of transmitters that can demodulate the transmitted signals.

[0021] According to the method, device, and receiver of the present invention for detecting bias in the direction of arrival of received signals, it is possible to more accurately detect bias in the direction of arrival of received signals by further taking into consideration the duration of a state in which bias in the direction of arrival of received signals is suspected.

[0022] According to the method for detecting bias in arrival direction of received signals, the device for detecting bias in arrival direction of received signals, and the receiver of the present invention, when bias in arrival direction of received signals is detected for transmit signals that are selected or extracted in accordance with predetermined conditions, it becomes possible to accurately detect a state in which bias in arrival direction of received signals is occurring using some of the transmit signals. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a functional block diagram showing a schematic configuration of a receiver including a detection device for detecting bias in the direction of arrival of a received signal according to an embodiment of the present invention; [Figure 2] 2 is a flowchart showing a processing procedure in the device for detecting bias in the direction of arrival of received signals in FIG. 1 and also showing a processing procedure of a method for detecting bias in the direction of arrival of received signals according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described below based on the illustrated embodiments.

[0025] Fig. 1 is a functional block diagram showing a schematic configuration of a receiver 1 equipped with a detection device 4 for detecting direction bias of received signals according to an embodiment of the present invention. Fig. 2 is a flowchart showing the processing steps in the detection device 4 for detecting direction bias of received signals, as well as the processing steps of a method for detecting direction bias of received signals according to an embodiment of the present invention.

[0026] The receiver 1 according to the embodiment has a function for receiving transmission signals sent from each transmitter and obtaining desired information according to the purpose of the receiver 1, for example, a function for obtaining its own position information (i.e., a satellite positioning function) when it forms a GNSS (Global Navigation Satellite System) together with the transmitters, and a function for detecting the bias in the direction of arrival of the received signal, and mainly has a receiving unit 2, a desired information calculation unit 3, and a detection device 4 for detecting the bias in the direction of arrival of the received signal.

[0027] The receiver 1 is configured as a mechanism including a central processing unit (CPU) that performs arithmetic processing related to the calculation of desired information according to the purpose of the receiver 1 and the detection of bias in the direction of arrival of received signals, a readable storage device ROM (Read Only Memory), and a readable and writable storage device RAM (Random Access Memory), etc. Specifically, the receiver 1 may be configured, for example, by using a computer to execute a program, or may be configured as hardware using one or more integrated circuits (ICs).

[0028] In this embodiment, a program for controlling the operation of a computer to function as a receiver 1 equipped with a detection device 4 for detecting direction bias of received signals is stored in ROM, and a central processing unit (CPU) executes the program to realize the receiving unit 2, desired information calculation unit 3, and detection device 4 for direction bias of received signals, which constitute the receiver 1, as functional blocks. In addition, RAM is used as a working area as needed.

[0029] The receiver 2 receives radio waves transmitted from each of the multiple transmitters Si (where i is a transmitter number for distinguishing and identifying the multiple transmitters from one another) via a receiving antenna and converts them into electrical signals (particularly, digital signals).

[0030] The signal transmitted from the transmitter Si is superimposed on a carrier wave and transmitted sequentially as a radio wave from the transmitter Si. The receiver 2 receives the radio wave and demodulates the radio wave to extract the transmission signal.

[0031] The receiver 2 generates observation data such as the amount of change in Doppler shift over time ΔDi, the transmitter position, and the state of the transmitter for each transmitter Si from the extracted transmission signal.

[0032] The amount of change in Doppler shift over time is a parameter that represents the rate of change over time of the difference between the carrier frequency of the radio wave and the reception frequency at the receiver 2, which is caused by the Doppler effect.

[0033] The amount of change over time ΔDi in the Doppler shift of each transmitter Si is found as the rate of change over time of the frequency difference between the carrier frequency of the radio wave transmitted by the transmitter Si and the carrier frequency of the radio wave received by the receiver 2. The carrier frequency of the radio wave transmitted by the transmitter Si is predetermined and stored in advance in a predetermined storage device provided in the receiver 1 (i.e., it is known).

[0034] The transmitter position is information indicating the current position of the transmitter Si, and specifically, is a coordinate in a Cartesian three-dimensional coordinate system.

[0035] The transmitter position (Xsi, Ysi, Zsi) of each transmitter Si is calculated based on information about the transmitter Si. For example, if the purpose of the receiver 1 is satellite positioning using GNSS, the transmitter position (Xsi, Ysi, Zsi) is calculated based on the ephemeris, which is orbital information, and the time when the transmitter Si (positioning satellite) transmitted the radio wave (satellite positioning signal).

[0036] The receiver 2 periodically (for example, every time it receives radio waves) outputs the observation data as reception information for each transmitter Si, along with the signal strength of the radio waves and the time at which the radio waves were received. The receiver 2 may output S / N (Signal-to-Noise ratio) or C / N (Carrier-to-Noise ratio) instead of signal strength.

[0037] The cycle at which the receiving unit 2 outputs the received information is not limited to a specific time length, but may be set to any time length within the range of, for example, about 50 to 200 milliseconds.

[0038] The receiver 2 also generates received information along with observation data from all transmission signals that can be demodulated from the received radio waves, and outputs all generated received information. Here, transmitters that can be used to calculate desired information according to the purpose of the receiver 1 are called "effective transmitters," and the number of effective transmitters is called the "number of effective transmitters."

[0039] That is, the receiving unit 2 outputs reception information for each valid transmitter Si at a fixed period, the number of which is equal to the number of valid transmitters.

[0040] The desired information calculation unit 3 receives the received information for each effective transmitter Si output from the receiving unit 2 at regular intervals, and uses the received information to perform calculations to calculate the desired information according to the purpose of the receiver 1.

[0041] As a result of calculating the desired information, the desired information calculation unit 3 outputs desired information according to the purpose of the receiver 1. For example, if the purpose of the receiver 1 is satellite positioning using GNSS, the desired information calculation unit 3 outputs at least information indicating the current position of the receiver 1 (specifically, coordinates in an orthogonal three-dimensional coordinate system).

[0042] The device 4 for detecting bias in the direction of arrival of a received signal is a mechanism for detecting whether the direction of arrival of a received signal is biased or not, and comprises a correlation verification unit 41, a DS time change verification unit 42, a DOP value verification unit 43, a transmitter number verification unit 44, and a duration verification unit 45 (note that DS is an abbreviation for Doppler Shift).

[0043] The detection device 4 for detecting the bias in the direction of arrival of the received signal receives the reception information for each effective transmitter Si output from the receiving unit 2 at regular intervals, in other words, acquires the reception information for each effective transmitter Si (step S1), and performs a calculation process to detect the bias in the direction of arrival of the received signal based on the reception information.

[0044] The detection device 4 for detecting direction bias of a received signal according to the embodiment includes a correlation verification unit 41 that verifies the degree of variation in the time change ΔDi of the Doppler shift for each effective transmitter Si, calculated based on a received signal including a plurality of signals corresponding to each of the signals transmitted from the plurality of effective transmitters Si; a DS time change verification unit 42 that verifies the magnitude of the time change ΔDi of the Doppler shift; a DOP value verification unit 43 that verifies the DOP value for the plurality of effective transmitters Si; a transmitter number verification unit 44 that verifies the number of effective transmitters Si; and a duration verification unit 45 that verifies the duration of a state in which direction bias of the received signal is suspected to have occurred, and detects direction bias of the received signal based on the verification results of the units 41 to 45.

[0045] Furthermore, the method for detecting bias in the direction of arrival of a received signal according to the embodiment detects bias in the direction of arrival of a received signal by the following steps: verifying the degree of variation in the amount of change in Doppler shift over time ΔDi for each effective transmitter Si, which is calculated based on a received signal including a plurality of signals corresponding to each of the signals transmitted from the plurality of effective transmitters Si (steps S2 and S3); verifying the magnitude of the amount of change in Doppler shift over time ΔDi (step S4); verifying the DOP values ​​for the plurality of effective transmitters Si (steps S5 and S6); verifying the number of effective transmitters Si (step S7); and verifying the duration of a state in which bias in the direction of arrival of a received signal is suspected (step S8).

[0046] Here, if there is no bias in the direction of arrival of the received signals (i.e., the directions of arrival of the multiple received signals are dispersed in various directions), as the receiver 1 moves with acceleration (or deceleration), the amount of Doppler shift in the line of sight increases for transmitters approaching the receiver 1, while the amount of Doppler shift in the line of sight decreases for transmitters moving away from the receiver 1. For this reason, the amount of change in Doppler shift over time takes on various values ​​depending on the azimuth and elevation angle of the transmitter as seen from the receiver 1, resulting in large variations in the amount of change in Doppler shift over time for each of the multiple transmitters.

[0047] On the other hand, if bias in the direction of arrival of the received signals occurs (i.e., the directions of arrival of the multiple received signals are concentrated in a specific direction), the amount of Doppler shift in the same line of sight will change for multiple transmitters as the receiver 1 moves with acceleration. The amount of change in Doppler shift over time is detected as the rate of change in the acceleration of the receiver 1 relative to each of the multiple transmitters. For this reason, if the variation in the amount of change in Doppler shift over time for each of the multiple transmitters is small and the amount of change in each Doppler shift over time is relatively large, it is highly likely that bias in the direction of arrival of the received signals has occurred.

[0048] Based on the above concept, the device 4 for detecting bias in the direction of arrival of received signals verifies the following items in order to detect bias in the direction of arrival of received signals.

[0049] Furthermore, the start time Ts used in the process of step S8 below is set to NULL as an initial state (in other words, set to an unset state).

[0050] The correlation verification unit 41 verifies the degree of variation in the amount of change ΔDi in the Doppler shift over time for each of all effective transmitters Si.

[0051] The method for verifying the degree of variation in the amount of change in Doppler shift over time ΔDi is not limited to a specific index or method, and any appropriate index or method can be used, for example, in consideration of whether the characteristics of the bias in the direction of arrival of the received signal, which is the reduction in variation in the amount of change in Doppler shift over time ΔDi for each of the multiple effective transmitters Si, can be appropriately evaluated.

[0052] Specifically, in this embodiment, the correlation verification unit 41 uses the amount of change in Doppler shift over time ΔDi for each of all effective transmitters Si to calculate the standard deviation ΔDs of the amount of change in Doppler shift over time ΔDi, and also calculates the coefficient of variation ΔDcv of the amount of change in Doppler shift over time ΔDi according to the following Equation 1 (step S2). (Equation 1) ΔDcv = ΔDs / ΔDavg however, ΔDcv: Coefficient of variation of the time change in Doppler shift ΔDi for all effective transmitters Si ΔDs: Standard deviation of the time change in Doppler shift ΔDi for all effective transmitters Si ΔDavg: Average value of the time change in Doppler shift ΔDi for all effective transmitters Si

[0053] The correlation verification unit 41 further determines whether or not the value of the standard deviation ΔDs of the time change amount ΔDi of the Doppler shift calculated in the processing of step S2 is equal to or less than the standard deviation threshold value Sthr, and whether or not the absolute value of the coefficient of variation ΔDcv of the time change amount ΔDi of the Doppler shift calculated in the processing of step S2 is equal to or less than the coefficient of variation threshold value CVthr (step S3).

[0054] The standard deviation threshold value Sthr is not limited to a specific value, and is appropriately set to an appropriate value, taking into consideration the ability to appropriately evaluate the characteristics of the bias in the direction of arrival of the received signal, for example, reducing the variation in the amount of time change ΔDi of the Doppler shift with each of the multiple effective transmitters Si. The standard deviation threshold value Sthr may be set to any value within the range of, for example, 0.2 / λ to 0.3 / λ [Hz / s], where λ is the wavelength [m] of the carrier wave and α is the relative acceleration [m / s 2 ], time is t [s], and the differential symbol is δ, then the differential value δd / δt [Hz / s] of the Doppler shift amount d is expressed as δd / δt = α / λ.

[0055] The variation coefficient threshold value CVthr is not limited to a specific value, and is appropriately set to an appropriate value, taking into consideration the ability to appropriately evaluate the characteristics of the bias in the direction of arrival of the received signal, which reduces the variation in the amount of change in Doppler shift over time ΔDi between each of the multiple effective transmitters Si. The variation coefficient threshold value CVthr may be set to any value within the range of approximately 0.05 to 0.15, for example.

[0056] If ΔDs>Sthr or |ΔDcv|>CVthr holds (step S3: No), the correlation verification unit 41 determines that there is no bias in the direction of arrival for the received transmission signal, and ends the process of detecting bias in the direction of arrival for the reception information acquired in the process of step S1 (step S9). Then, the start time Ts is set to NULL, and the process procedure for detecting bias in the direction of arrival for the reception signal returns to the process of step S1.

[0057] On the other hand, if ΔDs≦Sthr and |ΔDcv|≦CVthr are satisfied (step S3: Yes), the correlation verification unit 41 advances the processing procedure for detecting bias in the directions of arrival of received signals to the processing of step S4.

[0058] The DS time variation verification unit 42 verifies the magnitude of the time variation ΔDi of the Doppler shift for each of all effective transmitters Si.

[0059] Specifically, in this embodiment, the DS time change verification unit 42 determines whether the absolute values ​​of the time change ΔDi of the Doppler shift for each of all effective transmitters Si are equal to or greater than the Doppler shift time change threshold Dthr (step S4).

[0060] The Doppler shift time change threshold Dthr is not limited to a specific value and is set to an appropriate value, for example, taking into consideration whether it is possible to determine whether the receiver 1 is moving with appropriate acceleration to the extent that the degree of variation in the Doppler shift time change ΔDi between each of the multiple effective transmitters Si can be verified. The Doppler shift time change threshold Dthr may be set to any value within the range of approximately 1 / λ to 2 / λ [Hz / s], for example.

[0061] And, for at least one of the plurality of active transmitters Si, when |ΔDi| < Dthr (step S4: No), the DS time change amount verification unit 42 cannot say that the degree of movement accompanied by the acceleration of the receiver 1 is sufficient. Therefore, there is a possibility that the process of detecting the arrival direction bias of the received signal cannot be appropriately performed. Thus, the process of detecting the arrival direction bias of the received signal for the received information obtained in the process of step S1 is terminated (step S9). Then, after the start time Ts is set to NULL, the process procedure for detecting the arrival direction bias of the received signal returns to the process of step S1.

[0062] On the other hand, when |ΔDi| ≥ Dthr for all the active transmitters Si (step S4: Yes), the DS time change amount verification unit 42 advances the process procedure for detecting the arrival direction bias of the received signal to the process of step S5.

[0063] The DOP value verification unit 43 (DOP: abbreviation of Dilution Of Precision; accuracy degradation rate) verifies the DOP values for all the active transmitters Si. The DOP value is an index of the arrangement state of the transmitters and is used in satellite positioning calculations by GNSS, etc. It is a parameter that indicates that the smaller the value, the more the positions of the transmitters vary, and the higher the positioning accuracy tends to be.

[0064] The DOP value verification unit 43 first calculates the DOP values for all the active transmitters Si (step S5).

[0065] The DOP value calculated by the DOP value verification unit 43 may be any of the geometrical accuracy degradation rate (GDOP), horizontal accuracy degradation rate (HDOP), position accuracy degradation rate (PDOP), relative accuracy degradation rate (RDOP), and vertical accuracy degradation rate (VDOP).

[0066] The DOP value verification unit 43 further determines whether the DOP value calculated in the processing of step S5 is equal to or less than the DOP threshold value (step S6).

[0067] The DOP threshold value is not limited to a specific value, and is set to an appropriate value, for example, taking into consideration whether the arrangement of the effective transmitters Si is good or not. The DOP threshold value may be set to any value within the range of about 1.5 to 2.5.

[0068] If the DOP value is greater than the DOP threshold value (step S6: No), the DOP value verification unit 43 determines that the arrangement of the effective transmitters Si is not good, and therefore the process of detecting bias in the direction of arrival of the received signal may not be performed appropriately, so it terminates the process of detecting bias in the direction of arrival of the received signal for the reception information acquired in the process of step S1 (step S9).Then, the start time Ts is set to NULL, and the process procedure of detecting bias in the direction of arrival of the received signal returns to the process of step S1.

[0069] On the other hand, if the DOP value is equal to or less than the DOP threshold value (step S6: Yes), the DOP value verification unit 43 advances the processing procedure for detecting bias in the directions of arrival of received signals to the processing of step S7.

[0070] The transmitter number verification unit 44 verifies the number of valid transmitters.

[0071] Specifically, the transmitter number verification unit 44 determines whether the number of valid transmitters is equal to or greater than the transmitter number threshold value (step S7).

[0072] The threshold value for the number of transmitters is not limited to a specific value, and may be set to an appropriate value, for example, taking into consideration whether or not the number of effective transmitters is sufficient. The threshold value for the number of transmitters may be set to any value within a range of approximately 6 to 10.

[0073] If the number of valid transmitters is smaller than the transmitter number threshold (step S7: No), the transmitter number verification unit 44 determines that the number of valid transmitters is insufficient and therefore the process of detecting bias in the direction of arrival of the received signal may not be performed properly, so it terminates the process of detecting bias in the direction of arrival of the received signal for the transmitter information acquired in the process of step S1 (step S9).Then, the start time Ts is set to NULL, and the process procedure of detecting bias in the direction of arrival of the received signal returns to the process of step S1.

[0074] On the other hand, if the number of valid transmitters is equal to or greater than the transmitter number threshold (step S7: Yes), the transmitter number verification unit 44 advances the processing procedure for detecting bias in the direction of arrival of received signals to the processing of step S8.

[0075] The duration verification unit 45 verifies the duration of a state in which the occurrence of bias in the direction of arrival of the received signals is suspected.

[0076] Specifically, the duration verification unit 45 determines whether or not a state in which bias in the direction of arrival of received signals is suspected has continued for a duration equal to or longer than a duration threshold (step S8).

[0077] A state in which bias in the direction of arrival of the received signal is suspected means a state in which the results are Yes in all of the processes in steps S3, S4, S6, and S7. A state in which bias in the direction of arrival of the received signal is suspected is called a "state in which bias in the direction of arrival of the received signal is suspected."

[0078] In the processing of step S8, the start time Ts and the time at which the transmission signal in question was received, which is included in the reception information, are used to determine whether the state in which the arrival direction bias of the received signal is suspected has continued for more than the duration threshold time.

[0079] The duration threshold time is not limited to a specific time length, and is set to an appropriate time length, taking into consideration, for example, whether or not multiple transmission signals are signals transmitted / emitted from the same direction, taking into account that the receiver 1 is moving with acceleration. The duration threshold time may be set to any time length in the range of about 1 to 2 seconds, for example, when reception information is output from the receiving unit 2 every 100 milliseconds and the desired information calculation unit 3 performs calculation processing to calculate the desired information.

[0080] If the start time Ts is NULL (including an unset state) (i.e., no specific time was assigned to the start time Ts in the previous processing of step S8), the duration verification unit 45 sets the start time Ts to the time when the transmission signal was received, and then ends the processing of detecting bias in the direction of arrival of the received signal for the reception information acquired in the processing of step S1 (step S9). This procedure corresponds to the case of "step S8: No" in the flowchart shown in FIG. 2, and the processing procedure of detecting bias in the direction of arrival of the received signal then returns to the processing of step S1.

[0081] Furthermore, when the start time Ts is not NULL (including an unset state) (i.e., a specific time has been assigned to the start time Ts in the previous processing of step S8), and the length of time from the start time Ts to the time the transmission signal is received is shorter than the duration threshold time (step S8: No), the duration of the suspected state of arrival direction bias of the received signal is insufficient, so the duration verification unit 45 suspends the determination of whether or not arrival direction bias of the received signal has occurred, and terminates the processing of detecting arrival direction bias of the received signal for the reception information acquired in the processing of step S1 (step S9).Then, the processing procedure for detecting arrival direction bias of the received signal returns to the processing of step S1.

[0082] On the other hand, when the start time Ts is not NULL (including an unset state) and the length of time from the start time Ts to the time the transmission signal is received is equal to or longer than the duration threshold time (step S8: Yes), the duration verification unit 45 determines that bias in the direction of arrival of the received signal has occurred (step S10).

[0083] When the detection device 4 for detecting bias in the direction of arrival of the received signal detects bias in the direction of arrival of the received signal, it may notify the user that bias in the direction of arrival of the received signal has occurred (or is highly likely to occur), 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 of the method for detecting bias in direction of arrival of received signals, the device 4 for detecting bias in direction of arrival of received signals, and the receiver 1, the bias in direction of arrival of received signals is detected based on the degree and magnitude of variation in the amount of time change ΔDi of Doppler shift for each effective transmitter Si, so that it is possible to detect the bias in direction of arrival of received signals with high accuracy and with at least one receiving antenna. Furthermore, if the bias in direction of arrival of received signals is detected simultaneously using multiple receiving antennas and receivers, the duration threshold time may be shortened.

[0085] According to the method for detecting bias in the direction of arrival of a received signal, the device 4 for detecting bias in the direction of arrival of a received signal, and the receiver 1 of the embodiment, the DOP values ​​for a plurality of effective transmitters Si are taken into consideration, so that it is possible to detect bias in the direction of arrival of a received signal more accurately.

[0086] According to the method for detecting bias in the direction of arrival of a received signal, the device 4 for detecting bias in the direction of arrival of a received signal, and the receiver 1 of the embodiment, the number of effective transmitters Si is taken into consideration, so that it is possible to detect bias in the direction of arrival of a received signal more accurately.

[0087] According to the method for detecting bias in the direction of arrival of a received signal, the device 4 for detecting bias in the direction of arrival of a received signal, and the receiver 1 of the embodiment, the duration of the suspected bias in the direction of arrival of the received signal is taken into consideration, thereby making it possible to more accurately detect bias in the direction of arrival of the received signal.

[0088] 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 within the scope of the present invention that do not deviate from the gist of the present invention, they are included in the present invention.

[0089] Specifically, in the above embodiment, whether or not bias in the direction of arrival of the received signal occurs is determined using the reception information from all effective transmitters Si, but whether or not bias in the direction of arrival of the received signal occurs may also be determined using the reception information from some of the multiple effective transmitters Si. In this case, for example, from the multiple effective transmitters Si, the effective transmitter Si having the best reception state for the transmitted signal may be selected as a reference effective transmitter, and from the remaining effective transmitters Si, an effective transmitter Si for which the absolute value of the difference between the time change of each Doppler shift and the time change of the Doppler shift of the reference effective transmitter is extracted, and a calculation process may be performed to detect bias in the direction of arrival of the received signal based on the reception information for the reference effective transmitter and the extracted effective transmitter Si.

[0090] Then, by selecting the effective transmitter Si having the best reception state for the transmitted signal from among the multiple effective transmitters Si and extracting the effective transmitter Si for which the absolute value of the difference between the amount of change in Doppler shift over time ΔDi of the selected effective transmitter Si and the amount of change in Doppler shift over time ΔDi of each Doppler shift is equal to or less than a predetermined threshold, and then detecting the bias in the direction of arrival of the received signal for the selected effective transmitter Si and the extracted effective transmitter Si, it becomes possible to accurately detect the state in which bias in the direction of arrival of the received signal occurs for some of the multiple effective transmitters Si.

[0091] In the above case, the effective transmitter Si with the best reception condition of the transmitted signal can be selected by comprehensively considering, for example, the received signal strength, the tracking stability state, the elevation angle of the transmitter, and the like.

[0092] Furthermore, the threshold value for the difference in the amount of change in Doppler shift over time in the above case is not limited to a specific value, but is set to an appropriate value in consideration of the ability to appropriately evaluate the characteristics of the bias in the direction of arrival of the received signal, which reduces the variation in the amount of change in Doppler shift over time ΔDi between each of the multiple effective transmitters Si. The threshold value for the difference in the amount of change in Doppler shift over time may be set to any value within the range of approximately 0.2 / λ to 0.3 / λ [Hz / s], for example.

[0093] In the above embodiment, the detection device 4 for detecting direction of arrival bias of received signals according to the present invention is incorporated into the receiver 1 whose schematic configuration is shown in Fig. 1, but the equipment / device in which the detection device 4 for detecting direction of arrival bias of received signals according to the present invention can be incorporated or linked is not limited to the receiver 1 whose schematic configuration is shown in Fig. 1. The detection device for detecting direction of arrival bias of received signals according to the present invention may be incorporated into a receiver having another configuration or linked with a receiver having another configuration. Furthermore, the detection device for detecting direction of arrival bias of received signals according to the present invention may be incorporated into or linked with another type of equipment or device that uses transmitted signals. Furthermore, the detection device for detecting direction of arrival bias of received signals according to the present invention may be used alone. Therefore, the detection device for direction of arrival bias of received signals according to the present invention does not necessarily have to link with the desired information calculation unit 3, and the receiving unit 2 may output only the observation data / reception information necessary for the detection device 4 for detecting direction of arrival bias of received signals to perform the calculation process for detecting direction of arrival bias of received signals.

[0094] As an example of application of the above embodiment, for example, in GNSS satellite positioning, by applying this invention to determine whether a receiver is receiving a transmitted signal affected by multipath in an environment with a row of high-rise buildings, if the direction of arrival of the received signal is biased, it becomes possible to determine that the receiver is being affected by multipath.

[0095] As another example of application of the above embodiment, for example, in GNSS satellite positioning, 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, applying this invention makes it possible to determine whether the received signal is a signal transmitted from a single transmitting antenna. This situation can also be said to be a situation in which signals are disguised as being transmitted from multiple transmitters. In this regard, the term "signals transmitted from multiple transmitters" in this invention includes signals transmitted from a single transmitting antenna while disguising them as being transmitted from multiple transmitters.

[0096] Furthermore, in relation to the above, the above embodiment gives a specific example in which the purpose of the receiver 1 is satellite positioning using GNSS, but the application of the present invention is not limited to cases in which satellite positioning using GNSS is performed, and the transmitter Si in the above embodiment is not limited to a satellite, and the present invention can be applied to cases in which signals transmitted from various facilities for various purposes are received.

[0097] Furthermore, in the above embodiment, the verification items for detecting bias in the direction of arrival of the received signal include the DOP value, the number of valid transmitters, and the duration of the state in which bias in the direction of arrival of the received signal is suspected. However, the DOP value, the number of valid transmitters, and the duration of the state in which bias in the direction of arrival of the received signal is suspected are not essential verification items in this invention, and some or all of the DOP value, the number of valid transmitters, and the duration of the state in which bias in the direction of arrival of the received signal is suspected may not be included in the verification items. [Explanation of symbols]

[0098] 1 receiver 2. Receiving section 3 Desired information calculation unit 4. Device for detecting direction bias of received signals 41 Correlation Verification Unit 42 DS time change verification section 43 DOP Value Verification Unit 44 Transmitter Number Verification Section 45 Duration Verification Unit

Claims

1. If the state in which the directions of arrival of a plurality of received signals are concentrated in a specific direction is called "bias in the direction of arrival of received signals," then: A receiver moving with acceleration receives transmission signals transmitted from a plurality of positioning satellites, detecting a bias in the direction of arrival of the received signals based on the degree of variation in the amount of change in Doppler shift over time for each of the transmitted signals, the variation being calculated based on the received signals including a plurality of signals corresponding to each of the transmitted signals, and the magnitude of the amount of change in Doppler shift over time; 2. A method for detecting bias in the direction of arrival of a received signal, comprising:

2. Further considering DOP values ​​for the plurality of positioning satellites, The DOP value is an abbreviation for Dilution Of Precision (Dilution of Precision), and is a value that indexes the positioning state of the positioning satellite.

2. A method for detecting bias in the direction of arrival of received signals according to claim 1.

3. Further considering the number of positioning satellites that can demodulate the transmission signal; 3. A method for detecting bias in the direction of arrival of received signals according to claim 1 or 2.

4. Further taking into consideration the duration of a state in which the occurrence of direction-of-arrival bias of the received signal is suspected.

4. A method for detecting bias in the direction of arrival of received signals according to claim 1.

5. selecting a transmission signal with the best reception state from the plurality of transmission signals, extracting transmission signals for which the absolute value of the difference between the amount of change in Doppler shift of the selected transmission signal and the amount of change in Doppler shift of each transmission signal is equal to or less than a predetermined threshold, and then detecting a bias in the direction of arrival of the received signal using the selected transmission signal and the extracted transmission signal; 5. A method for detecting bias in the direction of arrival of received signals according to claim 1.

6. If the state in which the directions of arrival of a plurality of received signals are concentrated in a specific direction is called "bias in the direction of arrival of received signals," then: A detection device provided on a receiver that moves with acceleration, detecting a bias in the direction of arrival of the received signals based on the degree of variation in the amount of change in Doppler shift over time for each of the transmitted signals calculated based on the received signals including a plurality of signals corresponding to each of the transmitted signals transmitted from a plurality of positioning satellites and the magnitude of the amount of change in Doppler shift over time; 2. A detection device for detecting bias in the direction of arrival of a received signal.

7. Further considering DOP values ​​for the plurality of positioning satellites, The DOP value is an abbreviation for Dilution Of Precision (Dilution of Precision), and is a value that indexes the positioning state of the positioning satellite.

7. The apparatus for detecting bias in the direction of arrival of received signals according to claim 6.

8. Further considering the number of positioning satellites that can demodulate the transmission signal; 8. The apparatus for detecting bias in the direction of arrival of received signals according to claim 6 or 7.

9. Further taking into consideration the duration of a state in which the occurrence of direction-of-arrival bias of the received signal is suspected.

9. The apparatus for detecting bias in the direction of arrival of received signals according to claim 6.

10. selecting a transmission signal with the best reception state from the plurality of transmission signals, extracting transmission signals for which the absolute value of the difference between the amount of change in Doppler shift of the selected transmission signal and the amount of change in Doppler shift of each transmission signal is equal to or less than a predetermined threshold, and then detecting a bias in the direction of arrival of the received signal using the selected transmission signal and the extracted transmission signal; 10. The device for detecting bias in the direction of arrival of received signals according to claim 6.

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