JP2023177275A - Method for detection and detector for detecting abnormality of reception signal - Google Patents

Abstract

To detect an abnormality of a reception signal in GNSS.SOLUTION: A GNSS signal sent from each of a plurality of GNSS satellites S-i is received through three GNSS antennas 3A, 3B, and 3C. The presence of an abnormality in the GNSS signal is determined when the standard deviation of the positioning distance between the three GNSS antennas 3A, 3B, and 3C calculated by using the positioning distance of each of the three GNSS antennas 3A, 3B, and 3C is larger than a predetermined deviation threshold value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for detecting abnormalities in received signals in GNSS (Global Navigation Satellite System).

BACKGROUND ART Devices that measure the position of a moving object using an inertial navigation device and a GNSS positioning system are conventionally known (see Patent Document 1). In addition, as a technology for detecting anomalies in received signals in GNSS, it is possible to detect whether or not received signals from GPS (Global Positioning System, Global Positioning Satellite) satellites are affected by multipath. There is a known device for determining (see Patent Document 2). Further, a device is known that detects spoofing after satellite positioning by GNSS is interrupted (see Patent Document 3).

Patent No. 4803862 Japanese Patent Application Publication No. 2010-256301 Japanese Patent Application Publication No. 2020-134350

By the way, if an abnormality occurs in the received signal in GNSS, positioning using the received signal may indicate an incorrect position, so it is necessary to accurately detect the abnormality in the received signal in GNSS. is desired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method and apparatus for detecting an abnormality in a received signal, which can accurately detect an abnormality in a received signal in GNSS.

In order to solve the above problems, a method for detecting an abnormality in a received signal according to the present invention receives GNSS signals transmitted from each of a plurality of satellites via at least three antennas, and When the standard deviation of the positioning distance between the three or more antennas calculated using the positioning positions of each of the three or more antennas is larger than a predetermined threshold, or the at least three antennas The average value of the positioning distances between the three or more antennas calculated using the positioning positions of each of the three or more antennas is the average value of the true distances between the three or more antennas. It is characterized in that it is determined that an abnormality has occurred in the GNSS signal when the value is smaller than .

The method for detecting an abnormality in a received signal according to the present invention is such that the transmission time of the GNSS signal is abnormal based on a comparison between the transmission time of the GNSS signal included in the GNSS signal and a predetermined reference transmission time. If it is determined that there is, the antenna receiving the GNSS signal may be classified as abnormal.

The method for detecting an abnormality in a received signal according to the present invention includes detecting a problem with the satellite when it is determined that the pseudorange of the satellite is abnormal based on a comparison between the pseudorange of the satellite and the pseudorange of a predetermined reference satellite. The antenna receiving the GNSS signal transmitted from the antenna may be classified as abnormal.

In the method for detecting an abnormality in a received signal according to the present invention, when a path difference index representing a difference in paths from the satellite to each of the at least three antennas is equal to or less than a predetermined path difference threshold, The antenna receiving the GNSS signal transmitted from the satellite may be classified as abnormal by determining that the difference is abnormal.

The method for detecting an abnormality in a received signal according to the present invention includes determining whether or not an abnormality has occurred in the GNSS signal at a predetermined cycle, and determining whether or not there is a difference in the route in the determination performed in the previous cycle. The satellite determined to be abnormal may perform the determination in the next cycle using a second path difference threshold having a value larger than the predetermined path difference threshold.

The method for detecting an abnormality in a received signal according to the present invention uses the predetermined path difference threshold when it is determined that the path difference of the satellite is normal, and the path difference is determined to be abnormal. The determination may be performed in the next cycle.

In the method for detecting an abnormality in a received signal according to the present invention, when there is an antenna that is not classified as abnormal, the average value of the positioning positions of each of the antennas that are not classified as abnormal is calculated, and the average value is calculated at the processing point in time. The current position may be set to .

Further, the reception signal abnormality detecting device according to the present invention includes at least three antennas that receive GNSS signals transmitted from each of a plurality of satellites, and each of three or more antennas among the at least three antennas. When the standard deviation of the positioning distance between the three or more antennas calculated using the positioning position is larger than a predetermined threshold, or when each of the three or more antennas among the at least three antennas When the average value of the positioning distance between the three or more antennas calculated using the positioning position is smaller than the average value of the true distance between the three or more antennas, the GNSS signal and means for determining that an abnormality has occurred.

The abnormality detection device for a received signal according to the present invention determines whether the transmission time of the GNSS signal is abnormal based on a comparison between the transmission time of the GNSS signal included in the GNSS signal and a predetermined reference transmission time. If it is determined that there is, the antenna receiving the GNSS signal may be classified as abnormal.

The reception signal abnormality detection device according to the present invention detects the satellite when it is determined that the pseudorange of the satellite is abnormal based on a comparison between the pseudorange of the satellite and the pseudorange of a predetermined reference satellite. The antenna receiving the GNSS signal transmitted from the antenna may be classified as abnormal.

The receiving signal abnormality detection device according to the present invention is configured to detect the path difference between the satellite and the at least three antennas when a path difference index representing a path difference from the satellite to each of the at least three antennas is equal to or less than a predetermined path difference threshold. The antenna receiving the GNSS signal transmitted from the satellite may be classified as abnormal by determining that the difference is abnormal.

The abnormality detection device of the received signal according to the present invention determines whether or not an abnormality has occurred in the GNSS signal at a predetermined cycle, and the difference in the route is determined in the determination performed in the immediately preceding cycle. The satellite determined to be abnormal may perform the determination in the next cycle using a second path difference threshold having a value larger than the predetermined path difference threshold.

The reception signal abnormality detecting device according to the present invention uses the predetermined path difference threshold when it is determined that the path difference of the satellite whose path difference is abnormal is determined to be normal. The determination may be performed in the next cycle.

The reception signal abnormality detection device according to the present invention calculates the average value of the positioning positions of each of the antennas that are not classified as abnormal when there is an antenna that is not classified as abnormal, and calculates the average value at the processing point in time. The current position may be set to .

According to the method for detecting an abnormality in a received signal and the apparatus for detecting an abnormality in a received signal according to the present invention, an abnormality is detected in a GNSS signal based on whether the standard deviation of the positioning distance between antennas is larger than a predetermined threshold. Since it is determined whether or not an abnormality has occurred, it is possible to accurately detect an abnormality in a received signal in GNSS.

FIG. 1 is a functional block diagram showing a schematic configuration of a GNSS compass according to an embodiment. 2 is a diagram showing the arrangement of multiple GNSS antennas in the GNSS compass of FIG. 1. FIG. 2 is a flowchart illustrating a processing procedure in the GNSS compass of FIG. 1 and a method for detecting an abnormality in a received signal according to an embodiment of the present invention. 3 is a diagram illustrating a path difference between the GNSS antennas in FIG. 2. FIG. 2 is a flowchart showing a path difference determination process in which a first path difference threshold value and a second path difference threshold value are switched as appropriate in the path difference determination section of FIG. 1;

The present invention will be described below based on the illustrated embodiments. In this embodiment, an example will be described in which a received signal abnormality detection device according to the present invention is incorporated into a GNSS compass, and a received signal abnormality detection method according to the present invention is implemented in the GNSS compass. do.

(Overall configuration of GNSS compass)
FIG. 1 is a functional block diagram showing a schematic configuration of a GNSS compass 1 according to an embodiment, including a receiving signal abnormality detection device according to the present invention. The GNSS compass 1 is used, for example, by being mounted on a moving body such as a ship, a vehicle, or an aircraft.

The GNSS compass 1 according to the embodiment uses satellite signals/positioning signals (" The control unit 2, the GNSS antenna 3 and the , a GNSS receiving section 4, and a positioning section 5. The respective parts constituting the GNSS compass 1 are connected to each other so that they can send and receive signals and transmit information to each other via a bus.

Examples of GNSS include GPS (abbreviation for Global Positioning System, Global Positioning Satellite; Global Positioning System), GLONASS (abbreviation for GLObal Navigation Satellite System), and BDS (abbreviation for BeiDou Navigation Satellite System). .

Each of the plurality of GNSS satellites transmits a GNSS signal including ephemeris, which is data indicating the current position of the GNSS satellite, as a radio wave. The GNSS signal transmitted from each of the plurality of GNSS satellites also includes information indicating the time at which the GNSS satellite transmitted the GNSS signal as a radio wave.

The control unit 2 has a function of controlling the operation of each part constituting the GNSS compass 1, and includes, for example, a central processing unit (CPU: Central Processing Unit (abbreviation for Central Processing Unit).

The control unit 2 also stores programs, various information, data, etc. that the central processing unit (CPU) uses when performing arithmetic processing related to detecting abnormalities in GNSS signals and calculating the position of the GNSS compass 1. It functions as a storage area for storing data, etc., and a work area for temporarily storing data and information generated when the central processing unit (CPU) performs the arithmetic processing. For example, a mechanism having at least one of ROM (abbreviation of Read Only Memory) which is a read-only storage device, RAM (abbreviation of Random Access Memory) which is a readable and writable storage device, and a hard disk. Constructed as.

The control unit 2 controls the processing of each part of the GNSS compass 1 according to the control program by having a central processing unit (CPU) execute a program (referred to as a "control program") for controlling the operation of the GNSS compass 1. Discipline and control the beginning, content, and ending.

The GNSS receiving unit 4 receives GNSS signals transmitted from each of a plurality of GNSS satellites S-i (where, i: a number unique to each satellite for distinguishing and identifying each of the plurality of GNSS satellites). is a mechanism for, consisting of at least three GNSS receivers each comprising a GNSS antenna (i.e. there are also at least three GNSS antennas). In this embodiment, the GNSS receiver 4 includes three GNSS receivers 4A, 4B, and 4C, the GNSS receiver 4A is equipped with a GNSS antenna 3A, the GNSS receiver 4B is equipped with a GNSS antenna 3B, and the GNSS receiver 4A is equipped with a GNSS antenna 3B. The device 4C is equipped with a GNSS antenna 3C.

The three GNSS antennas 3A, 3B, and 3C are spaced apart from each other at predetermined intervals and fixed on the moving body on which the GNSS compass 1 is mounted. In this embodiment, three GNSS antennas 3A, 3B, and 3C are arranged at the vertices of an equilateral triangle (see FIG. 2).

The line segment connecting the GNSS antennas 3A, 3B, and 3C is called a "baseline." The baseline dimension, which is the distance between the GNSS antennas 3A, 3B, and 3C, is known as a design value for the arrangement of each of the GNSS antennas 3A, 3B, and 3C. In this embodiment, the dimensions of the base line AB between GNSS antenna 3A and GNSS antenna 3B, the dimension of base line BC between GNSS antenna 3B and GNSS antenna 3C, and the dimension between GNSS antenna 3A and GNSS antenna 3C are explained. The dimensions of the baseline AC are all known. The baseline dimension, which is the distance between the GNSS antennas 3A, 3B, and 3C, is set to one wavelength or more (specifically, about several wavelengths) to avoid interference between the GNSS antennas 3A, 3B, and 3C. .

Each GNSS receiver 4A, 4B, 4C receives the GNSS signal transmitted from each GNSS satellite S-i via the GNSS antenna 3A, 3B, 3C, converts it into an electrical signal (in particular, a digital signal), and outputs it. do.

The GNSS signal is superimposed on a carrier wave and is sequentially transmitted as radio waves (referred to as "GNSS radio waves") from the GNSS satellite Si. Each GNSS receiver 4A, 4B, 4C receives a GNSS radio wave, demodulates the GNSS radio wave, extracts and outputs a GNSS signal.

Each GNSS receiver 4A, 4B, 4C also uses the GNSS signal extracted from the GNSS radio waves to determine the position of the GNSS antenna (3A, 3B, 3C) provided therein (i.e., the receiving position of the GNSS signal; Specifically, the GNSS antenna (latitude, longitude, and altitude) is calculated, and if the positioning position calculation is successful, the positioning position of the GNSS antenna (3A, 3B, 3C) is output. A well-known technique can be applied to the calculation process of the measured position by each GNSS receiver 4A, 4B, 4C, and the present invention is not limited to a specific method, so a detailed explanation will be omitted. Note that, when each GNSS receiver 4A, 4B, 4C receives GNSS signals from a plurality of GNSS satellites S-i, each GNSS receiver 4A, 4B, 4C receives a specific GNSS satellite S-i from among the plurality of GNSS satellites S-i (for example, Using the GNSS signal of the GNSS satellite S-i) whose elevation angle is the largest, the positioning position of the GNSS antenna (3A, 3B, 3C) provided on the satellite itself is calculated.

That is, the GNSS receiving unit 4 outputs a GNSS signal for each GNSS satellite S-i for each of the GNSS receivers 4A, 4B, and 4C (in other words, for each of the GNSS antennas 3A, 3B, and 3C) at a predetermined period, Moreover, the positioning position of each GNSS antenna (3A, 3B, 3C) of the GNSS antenna (3A, 3B, 3C) whose positioning position has been successfully calculated among the GNSS antennas 3A, 3B, and 3C is output.

A central processing unit (CPU) of the control unit 2 executes the control program, thereby configuring the positioning section 5 within the control unit 2.

The positioning unit 5 verifies the presence or absence of an abnormality in the GNSS signal output from the GNSS receiving unit 4, and determines the position of the own device based on the positioning positions of each of the GNSS antennas 3A, 3B, and 3C (that is, the GNSS signal including the positioning unit 5). This is a mechanism for calculating and outputting the position of the compass 1, and by extension the position of the moving object on which the GNSS compass 1 is mounted, and is a mechanism for calculating and outputting the position of the compass 1, and the GNSS reception unit 4 outputs the GNSS receiver at a predetermined period. GNSS signals for each GNSS satellite S-i for different satellites 4A, 4B, and 4C (in other words, different for GNSS antennas 3A, 3B, and 3C), and GNSS antennas (3A, 3B, and 3C) for which the positioning position has been successfully calculated. Upon receiving the input of the positioning position of each of the GNSS antennas (3A, 3B, 3C), it detects an abnormality in the GNSS signal and calculates the position of the own aircraft.

(Processing content of the positioning unit)
FIG. 3 is a flowchart showing a processing procedure in the GNSS compass 1 according to the embodiment, as well as a processing procedure of a method for detecting an abnormality in a received signal according to the embodiment of the present invention.

The method for detecting an abnormality in a received signal according to the embodiment includes receiving GNSS signals transmitted from each of a plurality of GNSS satellites S-i via three GNSS antennas 3A, 3B, and 3C, and When the standard deviation of the positioning distance between these three GNSS antennas 3A, 3B, and 3C calculated using the positioning positions of each of the antennas 3A, 3B, and 3C is larger than a predetermined deviation threshold, the GNSS signal It is determined that an abnormality has occurred.

Further, the GNSS compass 1 according to the embodiment, which includes a receiving signal abnormality detecting device as a device that implements the above-described method for detecting a received signal abnormality, is configured to detect GNSS signals transmitted from each of the plurality of GNSS satellites S-i. The three GNSS antennas 3A, 3B, 3C that receive signals and the distance between these three GNSS antennas 3A, 3B, 3C calculated using the measured positions of each of the three GNSS antennas 3A, 3B, 3C. When the standard deviation of each positioning distance is larger than a predetermined deviation threshold, an abnormality detection unit 54 is provided as means for determining that an abnormality has occurred in the GNSS signal.

The positioning unit 5 receives GNSS signals for each GNSS satellite S-i for each of the GNSS receivers 4A, 4B, and 4C (in other words, for each of the GNSS antennas 3A, 3B, and 3C), which is output from the GNSS receiving unit 4 at a predetermined period. Receiving input of the signal and the positioning position of each of the GNSS antennas (3A, 3B, 3C) for which the calculation of the positioning position was successful, and based on the GNSS signal and the positioning position; Then, arithmetic processing for detecting an abnormality in the GNSS signal, which is a received signal in GNSS, and arithmetic processing for calculating the position of the own aircraft are executed. Each point in time at which a periodic process by the positioning unit 5 (referred to as a "positioning process") is executed is referred to as a "processing point." Among the GNSS antennas 3A, 3B, and 3C, the GNSS antenna (3A, 3B, 3C) whose positioning position has been successfully calculated is referred to as a "position calculation antenna."

The positioning unit 5 includes a positioning number determination unit 51, a positioning position calculation unit 52, a standard deviation determination unit 53, and an abnormality detection unit 54.

The positioning number determining unit 51 receives the input of the positioning position of each GNSS antenna (3A, 3B, 3C) regarding the position calculation antenna, and determines whether the positioning position of each of the three GNSS antennas 3A, 3B, 3C has been calculated. (Step S1).

Here, if the GNSS receiving unit 4 is composed of four or more GNSS receivers and the number of GNSS antennas is four or more (regardless of the number of 4 or more), the number of positioning determination units 51, In the process of step S1, it is determined whether the positioning positions of each of three or more GNSS antennas have been calculated.

If the positioning positions of each of the three GNSS antennas 3A, 3B, and 3C have not been calculated, in other words, if the number of position calculation antennas is 2 or less (step S1: No), the positioning number determination unit 51: Subsequently, it is determined whether the measured positions of each of the one or more GNSS antennas (3A, 3B, 3C) have been calculated (step S2).

If the positioning position of each of the one or more GNSS antennas (3A, 3B, 3C) has been calculated (step S2: Yes), the positioning number determination unit 51 calculates the positioning position of each of the one or more GNSS antennas (3A, 3B, 3C). 3C) Output each positioning position to the positioning position calculation unit 52.

When the positioning position calculation unit 52 receives the positioning position of each of the one or more GNSS antennas (3A, 3B, 3C) output from the positioning number determination unit 51, the positioning position calculation unit 52 calculates the positioning position of each of the one or more GNSS antennas (3A, 3B). , 3C) Calculate the average value of each positioning position, and output the average value as the current position of the GNSS compass 1 at the relevant processing time (step S3). In addition, when the positioning position calculation unit 52 receives the input of the positioning position of one GNSS antenna (3A, 3B, 3C), the positioning position calculation unit 52 directly inputs the positioning position of the one GNSS antenna (3A, 3B, 3C). It is output as the current position of the GNSS compass 1 at the relevant processing time.

Then, the positioning process at the relevant processing point ends (RETURN), and the process returns to step S1 to perform the positioning process at the next processing point.

In the process of step S2, if the positioning position of each of one or more GNSS antennas (3A, 3B, 3C) is not calculated, in other words, if the number of position calculation antennas is 0 (step S2: No), , the positioning number determination unit 51 determines that the positioning is not performed because the positioning position has not been calculated. In this case, the positioning unit 5 ends the positioning process at the relevant processing time without updating the position of the own device (RETURN), returns to the process in step S1, and performs the positioning process at the next processing time.

In the process of step S1, if the positioning positions of each of the three GNSS antennas 3A, 3B, 3C are calculated (step S1: Yes), the positioning number determination unit 51 calculates the positioning position of each of the three GNSS antennas 3A, 3B. , 3C are output to the standard deviation determination unit 53.

Here, if the GNSS receiving unit 4 is composed of four or more GNSS receivers and the number of GNSS antennas is four or more (regardless of the number of 4 or more), the number of positioning determination units 51, In the process of step S1, if the positioning positions of each of three or more GNSS antennas have been calculated (step S1: Yes), the positioning positions of each of the three or more GNSS antennas are output to the standard deviation determination unit 53. do.

Upon receiving the input of the positioning positions of the three GNSS antennas 3A, 3B, and 3C output from the positioning number determining unit 51, the standard deviation determining unit 53 uses the positioning positions to determine the position of the three GNSS antennas 3A, 3B, and 3C using the positioning positions. The positioning distance is calculated for each interval between 3B and 3C, that is, for each combination of two GNSS antennas (any two of 3A, 3B, and 3C) (step S4).

Specifically, there are three positioning distances: a positioning distance between GNSS antenna 3A and GNSS antenna 3B, a positioning distance between GNSS antenna 3B and GNSS antenna 3C, and a positioning distance between GNSS antenna 3A and GNSS antenna 3C. Positioning distance is calculated. Specifically, the positioning position is latitude, longitude, and altitude, and the positioning distance is the length of a line segment connecting three-dimensional coordinates.

The standard deviation determining unit 53 then determines the positioning distance between the three GNSS antennas 3A, 3B, and 3C calculated in the process of step S4, that is, the positioning distance between the two GNSS antennas (3A, 3B, and 3C). The standard deviation (referred to as the "standard deviation of inter-antenna positioning distance") of the positioning distance for each combination of (any two of them) is calculated (step S5), and the standard deviation of the inter-antenna positioning distance is determined to be a predetermined deviation. It is determined whether or not it is larger than a threshold value (step S6).

The standard deviation determination unit 53 determines whether or not an abnormality has occurred in the GNSS signal (in other words, an abnormality has occurred in the GNSS signal) based on whether the standard deviation of the inter-antenna positioning distance is larger than a predetermined deviation threshold. whether or not there is a possibility that

Here, if the GNSS receiving unit 4 is composed of four or more GNSS receivers and the number of GNSS antennas is four or more, the standard deviation determining unit 53 determines the output from the positioning number determining unit 51 in the process of step S4. Using the positioning positions of each of the three or more GNSS antennas, the positioning distance (in addition, the positioning distance between each of the three or more GNSS antennas, that is, for each combination of two GNSS antennas) ), and in the process of step S5, the standard deviation of the positioning distance between the three or more GNSS antennas, that is, the positioning distance for each combination of two GNSS antennas is calculated.

The deviation threshold is not limited to a specific value; for example, the baseline dimension, which is the distance between the GNSS antennas 3A, 3B, and 3C (as a design value for the arrangement of each GNSS antenna 3A, 3B, and 3C), the deviation threshold is not limited to a specific value. It is set to an appropriate value after taking into consideration positioning errors that are assumed to occur due to mechanical errors, etc., even if the position is known (known) or in a normal state. It is conceivable that the deviation threshold value is set to any value within a range of about 100 to 600 m, for example.

If the standard deviation of the inter-antenna positioning distance is less than or equal to the deviation threshold (step S6: No), the standard deviation determination unit 53 selects the three GNSS antennas 3A and 3B that have received the output and input from the positioning number determination unit 51. , 3C are output to the measured position calculation section 52. Note that if the standard deviation of the inter-antenna positioning distance is less than or equal to the deviation threshold, it is considered that no abnormality has occurred in the GNSS signal.

Upon receiving the input of the positioning position of each of the three GNSS antennas 3A, 3B, and 3C output from the standard deviation determination unit 53, the positioning position calculation unit 52 calculates the positioning of each of the three GNSS antennas 3A, 3B, and 3C. An average value of the positions is calculated, and the average value is output as the current position of the GNSS compass 1 at the relevant processing time (step S7). Then, the positioning process at the relevant processing point ends (RETURN), and the process returns to step S1 to perform the positioning process at the next processing point.

In the process of step S6, if the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold (step S6: Yes), the standard deviation determination unit 53 advances the procedure of the positioning process to the process of step S8. Note that if the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold, it is considered that an abnormality may have occurred in the GNSS signal.

The anomaly detection unit 54 is configured to detect an anomaly in the GNSS signal, and detects the GNSS signal for each GNSS satellite S-i, which is different from the GNSS receiver (4A, 4B, 4C) connected to the position calculation antenna. In response to the input, arithmetic processing (referred to as "abnormality detection calculation processing") for detecting an abnormality in a GNSS signal, which is a received signal in GNSS, is executed based on the GNSS signal.

The abnormality detection section 54 includes a transmission time determination section 541, a pseudo distance determination section 542, a path difference calculation section 543, and a path difference determination section 544.

(Verification of sending time)
The transmission time determination unit 541 determines, for each GNSS satellite S-i, the GNSS receiver (4A, 4B, 4C) connected to the position calculation antenna, which is output from the GNSS reception unit 4 at the relevant processing time. Upon receiving the input of the GNSS signal, it is determined whether the transmission time of the GNSS signal is normal. The processing performed by the transmission time determination unit 541 is referred to as "transmission time determination processing."

The transmission time determination unit 541 determines the transmission time and predetermined time of the GNSS signal included in the GNSS signal for each GNSS satellite S-i for each GNSS receiver (4A, 4B, 4C) connected to the position calculation antenna. It is determined whether the absolute value of the difference from the reference transmission time is greater than or equal to a predetermined time difference threshold.

The reference transmission time may be set for each GNSS satellite S-i, or may be set as a common time for all GNSS satellites S-i.

When the reference transmission time is set for each GNSS satellite S-i, the reference transmission time for the GNSS satellite S-i is the time that was included in the GNSS signal transmitted from the GNSS satellite S-i in the past and was acquired. A time obtained by adding the elapsed time from the time when the GNSS signal was received to the stored transmission time may be used.

The elapsed time is measured using, for example, a temperature-compensated crystal oscillator (TCXO) mounted on the GNSS receiver 4 as a measuring device for elapsed time. In this case, the elapsed time may be corrected by taking into account the error of the elapsed time measuring device (for example, a temperature-compensated crystal oscillator) or the Doppler shift deviation of the GNSS satellite S-i, which changes over time. . Note that the Doppler shift is caused by the Doppler effect, which is caused by the difference between the carrier frequency of the GNSS radio waves transmitted from the GNSS satellite S-i and the reception frequency at the GNSS receiver 4 (specifically, the GNSS receivers 4A, 4B, and 4C). It is determined as a frequency difference.

When determining whether the transmission time of the GNSS signal is normal (that is, in the transmission time determination process), only the decimal part of the transmission time of the GNSS signal may be used.

The time difference threshold is not limited to a specific value, but is appropriately set to an appropriate value, taking into account errors that are assumed to occur due to, for example, mechanical errors. The time difference threshold is, for example, 1 to 3 milliseconds when the time obtained by adding the elapsed time to the transmission time acquired in the past for the GNSS satellite S-i is used as the reference transmission time for the GNSS satellite S-i. It is conceivable that the value may be set to any value within a range of degrees.

When the absolute value of the difference between the transmission time of the GNSS signal and the reference transmission time included in the GNSS signal is equal to or greater than the time difference threshold, the transmission time determination unit 541 determines that the transmission time of the GNSS signal is abnormal. , the GNSS antenna (3A, 3B, 3C) that is receiving the GNSS signal (in other words, the GNSS receiver (4A, 4B, 4C) that is outputting the GNSS signal) is classified as having a received signal abnormality.

On the other hand, when the reference transmission time is set as common to all GNSS satellites S-i, the reference transmission time for GNSS satellite S-i is set as the reference transmission time for other GNSS satellites S-j (where j: multiple GNSS satellites). It is a unique number for each satellite to distinguish and identify each satellite, and the transmission time of the GNSS signal included in the GNSS signal transmitted from i≠j; the same applies hereinafter) is used. You can. The other GNSS satellites S-j may be selected from among the plurality of GNSS satellites S-i whose GNSS signals are being received by the GNSS receiver 4 at the time of execution of the relevant (or most recent) abnormality detection calculation process, for example. , the GNSS satellite S-i with the largest satellite elevation angle is selected.

In this case, the transmission time determination unit 541 determines, for each GNSS satellite S-i, the transmission time of the GNSS signal included in the GNSS signal transmitted from the GNSS satellite S-i, and the reception time of the GNSS signal. The absolute value of the difference between the transmission time of the GNSS signal included in the GNSS signal transmitted from another GNSS satellite S-j and the reception time of the GNSS signal is the predetermined time. It is determined whether the difference is greater than or equal to the difference threshold. The reception time of the GNSS signal is specified by the clock function/time information held by the GNSS receiving unit 4. The clock function/time information held by the GNSS receiver 4 is supplied from, for example, a temperature compensated crystal oscillator (TCXO) installed in the GNSS receiver 4 as a device common to the plurality of GNSS receivers 4A, 4B, and 4C.

When the transmission time of the GNSS signal included in the GNSS signal transmitted from another GNSS satellite S-j is used as the reference transmission time for the GNSS satellite S-i, the time difference threshold It may be set to different values depending on the combination of the GNSS type of -i (for example, GPS, GLONASS, BDS) and the GNSS type of the other GNSS satellite S-j. For example, in the case of a combination of GPS, the time difference threshold is set to a value in the range of about 20 to 30 milliseconds, and in the case of a combination of GPS and BDS, the time difference threshold is set to a value of 90 to 110 milliseconds. It is conceivable that the value may be set to any value within a range of degrees.

The transmission time determination unit 541 calculates the difference between the transmission time of the GNSS signal included in the GNSS signal transmitted from the GNSS satellite S-i and the reception time of the GNSS signal, and the difference between the transmission time and the reception time of the GNSS signal transmitted from the other GNSS satellite S-j. When the absolute value of the difference between the transmission time of the GNSS signal contained in the GNSS signal and the reception time of the GNSS signal is greater than or equal to the time difference threshold, the GNSS signal is transmitted from the GNSS satellite S-i. Assuming that the transmission time of the GNSS signal is abnormal, the GNSS antenna (3A, 3B, 3C) that is receiving the GNSS signal (in other words, the GNSS receiver (4A, 4B, 4C) that is outputting the GNSS signal) ) is classified as a received signal abnormality.

(Verification of pseudorange)
The pseudorange determination unit 542 determines the following information for each GNSS satellite S-i for each GNSS receiver (4A, 4B, 4C) connected to the position calculation antenna, which is output from the GNSS reception unit 4 at the relevant processing time. Upon receiving the input of the GNSS signal, it is determined whether the pseudorange of the GNSS satellite S-i that transmitted the GNSS signal is normal. The process performed by the pseudorange determination unit 542 is referred to as "pseudorange determination process."

The pseudorange is the propagation distance of the GNSS signal transmitted from the GNSS satellite S-i and received via the GNSS antennas 3A, 3B, and 3C, and the received GNSS signal (in other words, GNSS radio waves) -i and the time received via the GNSS antennas 3A, 3B, and 3C (so-called propagation time of the GNSS signal).

The pseudorange ρ-i of the GNSS satellite S-i is based on the time when the GNSS signal (GNSS radio wave) is transmitted from the GNSS satellite S-i and the time when the GNSS signal (GNSS radio wave) is transmitted via the GNSS antennas 3A, 3B, and 3C. It is calculated by multiplying the difference from the received time by the propagation speed of radio waves (specifically, the speed of light).

The time at which the GNSS signal was transmitted from the GNSS satellite S-i is included in the GNSS signal. Further, the time when the GNSS signal is received via the GNSS antennas 3A, 3B, and 3C is specified by the clock function/time information held by the GNSS receiving unit 4. The clock function/time information held by the GNSS receiver 4 is supplied from, for example, a temperature compensated crystal oscillator (TCXO) installed in the GNSS receiver 4 as a device common to the plurality of GNSS receivers 4A, 4B, and 4C. Note that the propagation time of the GNSS signal, which corresponds to the difference between the time when the GNSS signal was transmitted and the time when the GNSS signal was received, may be specified based on the amount of phase shift of the C/A code. Note that the C/A code is a code unique to each GNSS satellite S-i, and functions as information indicating the transmission source.

The pseudorange determination unit 542 determines, for each GNSS satellite S-i, that the absolute value of the difference between the pseudorange ρ-i of the GNSS satellite S-i and the pseudorange ρr of a predetermined reference satellite Sr is a predetermined pseudorange difference threshold. Determine whether it is greater than or not. As the reference satellite Sr, for example, the elevation angle of a satellite is selected from among the plurality of GNSS satellites S-i whose GNSS signals are being received by the GNSS receiver 4 at the time of execution of the relevant (or most recent) abnormality detection calculation process. The GNSS satellite S-i with the largest is selected.

The pseudorange difference threshold is not limited to a specific value; for example, the maximum value assumed as the difference in pseudoranges between GNSS satellites is taken into account when assuming the orbits of GNSS satellites. , is appropriately set to an appropriate value. It is conceivable that the pseudo distance difference threshold is set to any value within a range of, for example, about 1 to 2 km.

The pseudorange determination unit 542 determines that the GNSS satellite S-i is a pseudorange when the absolute value of the difference between the pseudorange ρ-i of the GNSS satellite S-i and the pseudorange ρr of the reference satellite Sr is larger than a pseudorange difference threshold. Since the distance is abnormal, the GNSS satellite S-i is classified as a pseudorange abnormality.

The pseudorange determination unit 542 determines that the absolute value of the difference between the pseudorange ρ-i of the GNSS satellite S-i and the pseudorange ρr of the reference satellite Sr is larger than the pseudorange difference threshold, and that the GNSS satellite S-i is larger than the pseudorange difference threshold. When the signal strength/reception strength of the GNSS signal transmitted from i is higher than a predetermined threshold, the GNSS satellite S-i classifies the GNSS satellite S-i as having an abnormal pseudorange. You may also do so.

Then, the pseudorange determining unit 542 determines whether the GNSS antennas (3A, 3B, 3C) that are receiving the GNSS signal transmitted from the GNSS satellite S-i that has been classified as having a pseudorange anomaly (in other words, the GNSS antenna that has been classified as a pseudorange anomaly) The GNSS receivers (4A, 4B, 4C) that are outputting GNSS signals transmitted from GNSS satellite S-i are classified as having received signal abnormalities.

(Verification of route difference)
The route difference calculation unit 543 calculates the information for each GNSS satellite S-i for each GNSS receiver (4A, 4B, 4C) connected to the position calculation antenna, which is output from the GNSS reception unit 4 at the relevant processing time. Upon receiving the input of the GNSS signal, the difference in path from the GNSS satellite S-i to each position calculation antenna (specifically, the GNSS antennas 3A, 3B, and 3C) is calculated using the information of the GNSS signal. The process performed by the path difference calculation unit 543 is referred to as "path difference calculation process."

The path difference calculation unit 543 calculates the distance between each GNSS antenna 3A, 3B, and 3C from the GNSS satellite S-i, which is caused by the fact that the plurality of GNSS antennas 3A, 3B, and 3C are spaced apart from each other at a predetermined interval. The difference (absolute value) in the path to 3C is calculated for each GNSS satellite S-i and between GNSS antennas 3A, 3B, and 3C (in other words, for each baseline AB, BC, and AC), that is, for each GNSS antenna. Calculate for each combination of (any two of 3A, 3B, and 3C).

FIG. 4 is a diagram illustrating the difference in routes. Although the path difference is actually determined in three dimensions, the principle of the path difference will be explained in two dimensions in FIG. 4. In the example shown in FIG. 4, for each of GNSS satellite S-1 and GNSS satellite S-2, the difference between the route to GNSS antenna 3A and the route to GNSS antenna 3B (i.e., the difference between the route to GNSS antenna 3A and GNSS antenna 3B) The difference in path between

The difference C-1AB between the path from GNSS satellite S-1 to GNSS antenna 3A and the path to GNSS antenna 3B is expressed as the following formula 1, and the difference between the path from GNSS satellite S-2 to GNSS antenna 3A and the path to GNSS antenna 3B is The difference C-2AB from the path to the antenna 3B is expressed as in the following equation 2 (see FIG. 4(A)).
(Math. 1) C-1AB = L-AB×cos(θ-1)
(Math. 2) C-2AB = L-AB×cos(θ-2)
Here,
L-AB: Dimension of base line AB between GNSS antenna 3A and GNSS antenna 3B θ-1: Elevation angle of GNSS satellite S-1 θ-2: Elevation angle of GNSS satellite S-2

The difference C-1AB between the path from the GNSS satellite S-1 to the GNSS antenna 3A and the path to the GNSS antenna 3B, expressed as in Equation 1 above, is calculated according to Equation 3 below. Further, the difference C-2AB between the path from the GNSS satellite S-2 to the GNSS antenna 3A and the path to the GNSS antenna 3B, expressed as in Equation 2 above, is calculated according to Equation 4 below.
(Math 3) C-1AB = λ-1×(N-1+P-1AB)
(Math. 4) C-2AB = λ-2×(N-2+P-2AB)
Here,
λ-1: Wavelength of carrier wave of GNSS radio wave of GNSS satellite S-1 λ-2: Wavelength of carrier wave of GNSS radio wave of GNSS satellite S-2 N-1: Integer bias (cycle) of GNSS radio wave of GNSS satellite S-1 that's all)
N-2: Integer bias of GNSS radio waves of GNSS satellite S-2 (more than one cycle)
P-1AB: Single difference between antennas of GNSS radio waves of GNSS satellite S-1 (less than a cycle)
P-2AB: Single difference between antennas of GNSS radio waves of GNSS satellite S-2 (less than a cycle)

The inter-antenna single difference P-iXY for the GNSS satellite S-i (where, X, Y: antenna symbols for mutually distinguishing multiple GNSS antennas and identifying each one; This is the difference in carrier phase integrated value of one GNSS satellite Si with respect to two GNSS antennas (in the example shown in FIG. 4, GNSS antenna 3A and GNSS antenna 3B).

The path difference calculation unit 543 calculates the difference for each GNSS satellite S-i for each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, for each baseline AB, BC, and AC). The difference (absolute value) C-iXY between the path from the GNSS satellite S-i to the GNSS antenna X and the path to the GNSS antenna Y is calculated.

The path from the GNSS satellite S-i to the GNSS antenna X and the path to the GNSS antenna Y for the GNSS satellite S-i in the combination of the GNSS antenna X and the GNSS antenna Y calculated by the path difference calculation unit 543. The difference (absolute value) C-iXY from the path is called "path difference C-iXY between the GNSS antennas X and Y of the GNSS satellite S-i."

The path difference calculation unit 543 calculates the difference for each GNSS satellite S-i for each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, for each baseline AB, BC, and AC). Calculate the path difference C-iXY between the GNSS antennas X and Y of the GNSS satellite S-i.

Next, the path difference determination unit 544 determines whether the path difference C-iXY between the GNSS antennas X and Y of the GNSS satellite S-i, which is calculated by the path difference calculation unit 543, is normal. The process performed by the path difference determination unit 544 is referred to as "path difference determination process."

Here, in the example shown in FIG. 4, since GNSS satellite S-1 and GNSS satellite S-2 are usually located at different spatial positions, the satellites viewed from GNSS compass 1 (specifically, GNSS antenna 3) Each elevation angle θ-1 and elevation angle θ-2 are different from each other. Since the elevation angle θ-1 of GNSS satellite S-1 and the elevation angle θ-2 of GNSS satellite S-2 are different from each other, the difference in path C-1AB for GNSS satellite S-1 and GNSS satellite S-2 is The path difference C-2AB is mutually different (see FIG. 4(A) and Equations 1 and 2 above).

On the other hand, if both GNSS satellite S-1 and GNSS satellite S-2 exist at the same spatial position, the elevation angle θ-1 of each satellite as seen from GNSS compass 1 (specifically, GNSS antenna 3) and the elevation angle θ-2 are the same (see Fig. 4(B)). If the elevation angle θ-1 of GNSS satellite S-1 and the elevation angle θ-2 of GNSS satellite S-2 are the same, then the difference in path C-1AB for GNSS satellite S-1 and the difference in trajectory for GNSS satellite S-2 is calculated. The path difference C-2AB is the same (see Equations 1 and 2 above).

For example, when the elevation angle θ-1 of GNSS satellite S-1 and the elevation angle θ-2 of GNSS satellite S-2 are the same, for example, a signal containing positioning information and orbit information of multiple GNSS satellites is transmitted in a single transmission. In other words, GNSS signals (in other words, GNSS radio waves) may be transmitted from a single transmitting antenna (in other words, GNSS radio waves) from multiple GNSS satellites. It is possible that GNSS signals from multiple GNSS satellites are being transmitted from a point (including antenna stations installed on the ground), that is, a single transmitting antenna/multiple fake GNSS signals from the same point. An example is when a signal is being transmitted. In this respect, the "GNSS signal transmitted from each of the plurality of GNSS satellites S-i" in this invention is a single Transmitting antenna/contains signals originating from the same point.

Therefore, the path difference determination unit 544 determines whether the GNSS satellite S-i The following process is performed using the path difference C-iXY between the GNSS antennas X and Y of another GNSS satellite S-i.

For each combination of two GNSS antennas (any two of 3A, 3B, and 3C), the route difference determination unit 544 determines the GNSS that the two GNSS antennas are simultaneously tracking at the processing time. For each combination of two GNSS satellites S-i among the satellites S-i, the absolute value of the difference in path difference C-iXY between the GNSS antennas X-Y of each of the two GNSS satellites S-i. is less than a predetermined path difference threshold, the two GNSS satellites S-i are considered to have abnormal arrival directions of GNSS signals, and the two GNSS satellites S-i are always classified as having a path difference. This process is performed for each combination of two GNSS antennas (any two of 3A, 3B, and 3C), and the GNSS satellite S- This is done for all combinations of two GNSS satellites S-i of i.

The track difference threshold is not limited to a specific value; for example, even if GNSS signals from multiple GNSS satellites are actually transmitted from a single transmitting antenna/same point, it may be due to mechanical errors, etc. It is set to an appropriate value after taking into account the errors that are expected to occur.

Here, when a plurality of GNSS satellites S-i exist in mutually different spatial positions, the inter-antenna singlet difference P-iXY for each of the plurality of GNSS satellites S-i is usually different from each other. If the GNSS signals of multiple GNSS satellites are transmitted from a single transmitting antenna/same point, the inter-antenna singlet difference P-iXY for each of the multiple GNSS satellites S-i will be the same. Therefore, in the process of determining the path difference for each GNSS satellite S-i, the single antenna difference P-iXY for each of the plurality of GNSS satellites S-i may be verified (Formula 3, Formula 4 reference).

Note that GNSS satellite S-1 and GNSS satellite S-2 exist in mutually different spatial positions, and the difference in path C-1AB for GNSS satellite S-1 and the difference in path C-1AB for GNSS satellite S-2. 2AB are actually different from each other, as can be seen from Equations 3 and 4 above, although the integer biases N-1 and N-2 are different, the two GNSS satellites S-1 and S It is also conceivable that the inter-antenna singlet differences P-1AB and P-2AB for -2 may be even or the same. However, since the GNSS satellites S-1 and S-2 are moving, this state will not last for a long time (for example, more than a few seconds). Furthermore, since the direction of the baseline differs between the GNSS antennas 3A, 3B, and 3C, for example, in the combination of the GNSS antenna 3A and the GNSS antenna 3B, the direction between the antennas for the two GNSS satellites S-1 and S-2 is different. Even if the singleness differences P-1AB and P-2AB are even or the same, the singleness difference P between the antennas for the two GNSS satellites S-1 and S-2 in the combination of the GNSS antenna 3A and the GNSS antenna 3C is -1AB and P-2AC are not the same.

When verifying the inter-antenna singlet difference P-iXY for each of the plurality of GNSS satellites S-i, the path difference determination unit 544 verifies the inter-antenna singlet difference P-iXY of each of the two GNSS antennas (any two of 3A, 3B, and 3C). For each combination, two GNSS satellites S-i of the GNSS satellites S-i that the two GNSS antennas are simultaneously tracking at the time of the processing. When the absolute value of the difference between the single antenna differences P-iXY for each S-i is less than or equal to a predetermined path difference threshold, the directions of arrival of the GNSS signals of the two GNSS satellites S-i are abnormal. As such, the two GNSS satellites S-i are always classified according to their path difference.

The path difference threshold in this case is not limited to a specific value; for example, even if GNSS signals from multiple GNSS satellites are actually transmitted from a single transmitting antenna/same point, mechanical errors etc. It is set to an appropriate value after taking into consideration the error that is assumed to occur due to the above.

The path difference between antennas for GNSS satellite S-i, which represents the difference in path from GNSS satellite S-i to each GNSS antenna 3A, 3B, and 3C, is used to determine the path difference for each GNSS satellite S-i. The difference C-iXY and the single difference between antennas P-iXY are called "path difference index."

Then, the path difference determination unit 544 determines whether the GNSS antenna (3A, 3B, 3C ) (In other words, the GNSS receivers (4A, 4B, 4C) that are outputting the GNSS signal transmitted from the GNSS satellite S-i, which has always been classified as having a path difference) are classified as receiving signal abnormalities.

The abnormality detection unit 54 determines whether there is a GNSS antenna (3A, 3B, 3C) classified as receiving signal abnormality by the above-described transmission time determination processing, pseudorange determination processing, and route difference determination processing. (Step S8).

If there are no GNSS antennas (3A, 3B, 3C) classified as receiving signal abnormalities (Step S8: No), the abnormality detection unit 54 determines that the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold (Step S6: Yes) and the fact that there are no GNSS antennas (3A, 3B, 3C) classified as receiving signal abnormalities do not match (in other words, it is considered that the correct positioning position has not been obtained), so the positioning is determined to be non-positioning. In this case, the positioning unit 5 ends the positioning process at the relevant processing time without updating the position of the own device (RETURN), returns to the process in step S1, and performs the positioning process at the next processing time.

On the other hand, if there is a GNSS antenna (3A, 3B, 3C) classified as receiving signal abnormality (step S8: Yes), the abnormality detection unit 54 determines that the receiving signal is not classified as abnormal (that is, normal). ) It is determined whether or not there is a GNSS antenna (3A, 3B, 3C) (step S9).

If there is a GNSS antenna (3A, 3B, 3C) that is not classified as receiving signal abnormality (that is, normal) (step S9: Yes), the abnormality detection unit 54 detects that the received signal is not classified as receiving signal abnormality ( That is, the positioning position of each normal) GNSS antenna (3A, 3B, 3C) is output to the positioning position calculation unit 52.

Upon receiving the input of the positioning position of each of the GNSS antennas (3A, 3B, 3C) output from the abnormality detection unit 54, the positioning position calculation unit 52 calculates the average position of each of the GNSS antennas (3A, 3B, 3C). The average value is output as the current position of the GNSS compass 1 at the processing time (step S10). In addition, when the positioning position calculation unit 52 receives the input of the positioning position of one GNSS antenna (3A, 3B, 3C), the positioning position calculation unit 52 directly inputs the positioning position of the one GNSS antenna (3A, 3B, 3C). It is output as the current position of the GNSS compass 1 at the relevant processing time. This makes it possible to perform correct positioning using only the GNSS antennas (3A, 3B, 3C) that are not classified as receiving signal abnormalities (that is, normal).

Then, the positioning process at the relevant processing point ends (RETURN), and the process returns to step S1 to perform the positioning process at the next processing point.

In the process of step S9, if there is no GNSS antenna (3A, 3B, 3C) that is not classified as receiving signal abnormality (that is, normal) (step S9: No), the abnormality detection unit 54 detects the correct positioning position. Since it is unknown, positioning is not performed. In this case, the positioning unit 5 ends the positioning process at the relevant processing time without updating the position of the own device (RETURN), returns to the process in step S1, and performs the positioning process at the next processing time.

An output device (not shown), which is attached to the GNSS compass 1 and includes, for example, a monitor and a speaker, is provided, and the GNSS compass 1 outputted from the positioning position calculation section 52 of the positioning section 5 is displayed on the monitor of the output device. The current location may also be displayed. Further, the occurrence of an abnormality in the GNSS signal may be notified to the user by displaying an alarm screen on the monitor of the output device or emitting an alarm from the speaker of the output device. Further, other devices that use GNSS signals (for example, radar, inertial navigation device) may be notified that an abnormality has occurred in the GNSS signals.

According to the method for detecting an abnormality in a received signal and the GNSS compass 1 according to the embodiment, it is possible to determine whether an abnormality has occurred in the GNSS signal based on whether the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold. (In other words, whether or not there is a possibility that an abnormality has occurred in the GNSS signal), it is possible to accurately detect an abnormality in the received signal in the GNSS.

Although the embodiments of this invention have been described above, the specific configuration is not limited to the above embodiments, and even if there are changes in the design within the scope of the gist of this invention, Included in invention.

For example, in the above embodiment, a receiving signal abnormality detecting device according to the present invention is incorporated in the GNSS compass 1 whose schematic configuration is shown in FIG. The apparatus/device in which the apparatus for detecting an abnormality in a received signal according to the present invention is incorporated or the method for detecting an abnormality in a received signal according to the present invention is applied is shown in FIG. The present invention is not limited to the GNSS compass 1 showing the above, but the received signal abnormality detection device according to the present invention may be incorporated into a GNSS compass having other configurations, or the received signal abnormality detection method according to the present invention may be applied. Furthermore, the device for detecting abnormalities in received signals according to the present invention may be incorporated into other types of equipment or devices that utilize GNSS, or the device for detecting abnormalities in received signals according to the present invention may be incorporated into The abnormality detection method may be applied to other types of equipment or devices that utilize GNSS.

Further, in the above embodiment, the standard deviation determining unit 53 determines whether an abnormality has occurred in the GNSS signal based on whether the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold (step S6). However, the average value of the positioning distance between the three GNSS antennas 3A, 3B, and 3C is 3. Based on whether it is smaller than the average value of the true distance between each of the GNSS antennas 3A, 3B, and 3C (i.e., the average value of the dimensions of base line AB, base line BC, and base line AC) It may be determined whether an abnormality has occurred in the GNSS signal. For example, all three GNSS antennas 3A, 3B, and 3C receive GNSS signals (which are fake GNSS signals) from multiple GNSS satellites transmitted from a single transmitting antenna/same point. When the positioning position is calculated using the same method, each of the GNSS antennas 3A, 3B, and 3C calculates the same point based on the same satellite information (which is false information) as the positioning position, and the three GNSS antennas 3A , 3B, and 3C are close to 0. On the other hand, the known true distance between each of the GNSS antennas 3A, 3B, and 3C (i.e., the dimensions of the base line AB, the dimensions of the base line BC, and the dimensions of the base line AC) is one wavelength or more as described above, and the positioning Since the average value of the distance and the average value of the dimensions of the known baseline will deviate, it is possible to detect that an abnormality may have occurred in the GNSS signal. When using the average value of the positioning distances, the standard deviation determining unit 53 calculates the positioning distances between the three GNSS antennas 3A, 3B, and 3C, that is, the average value of the two GNSS antennas (3A , 3B, and 3C). Further, in the case where the average value of the positioning distance is used, and the GNSS receiving unit 4 is composed of four or more GNSS receivers and the number of GNSS antennas is four or more, the standard deviation determining unit 53 performs the processing in step S4. In this step, positioning is performed between each of the three or more GNSS antennas, that is, for each combination of two GNSS antennas, using the positioning position of each of the three or more GNSS antennas output from the positioning number determination unit 51. The distances (three or more) are calculated, and in the process of step S5, the positioning distance for each of the three or more GNSS antennas, that is, the positioning distance for each combination of two GNSS antennas, is calculated. In addition to calculating the average value, the average value of the true distance between the three or more GNSS antennas (ie, the average value of the dimensions of each baseline) is calculated, and the two average values are compared.

Further, in the above embodiment, the standard deviation determining unit 53 determines whether an abnormality has occurred in the GNSS signal based on whether the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold (step S6). and whether there is a possibility that an abnormality has occurred in the GNSS signal), and if it is considered that there is a possibility that an abnormality has occurred in the GNSS signal (step S6: Yes). The abnormality detection unit 54 detects an abnormality in the GNSS signal (step S8), but if the standard deviation of the inter-antenna positioning distance is less than or equal to the deviation threshold, the current position of the GNSS compass 1 is calculated, and If the standard deviation of the inter-antenna positioning distance is larger than the deviation threshold, an abnormality has occurred in the GNSS signal, so positioning may be determined as non-positioning.

Further, in the above embodiment, the abnormality detection unit 54 performs transmission time determination processing, pseudo-range determination processing, and route difference determination processing to detect abnormality in the GNSS signal. 54 may detect an abnormality in the GNSS signal by performing at least one of a transmission time determination process, a pseudo distance determination process, and a route difference determination process.

Further, according to the GNSS compass 1 described in the above embodiment, the time synchronization between the GNSS receivers 4A, 4B, and 4C is insufficient, multipath or noise occurs in the GNSS signal, or If the Doppler frequency of the GNSS signal differs for each satellite due to differences in the orbiting direction of each satellite, this may cause slight variations or offsets in the path difference between the GNSS receivers 4A, 4B, and 4C. There is. When a slight variation or offset occurs in the path difference, the path difference determination process described above assumes that the path difference index in the previous cycle is less than or equal to the predetermined path difference threshold (that is, the path difference matches), and the path difference is always determined. When a classified satellite is judged for the next cycle, the track difference index becomes larger than the predetermined track difference threshold due to minute variations or offsets (i.e., a track difference mismatch), and it is incorrectly determined to be a normal GNSS signal. there is a possibility. In order to suppress such misjudgments, it is possible to loosen the path difference threshold by considering in advance the minute variations and offsets that occur in the path difference (in other words, set it to a large value), but In this case, an erroneous determination occurs when there are no minute variations or offsets in the path difference.

In order to solve the above problem, the predetermined path difference threshold described above (hereinafter referred to as a first path difference threshold) and a second path difference threshold having a value larger than this first path difference threshold are used. It is preferable to perform the path difference determination process by appropriately switching the path difference. The relationship between the first path difference threshold and the second path difference threshold is “first path difference threshold<second path difference threshold”. More specifically, it is determined whether or not an abnormality has occurred in the GNSS signal at a predetermined cycle, and satellites that are always classified as having a track difference in the track difference determination process performed in the previous cycle are A second path difference threshold having a value larger than the first path difference threshold is used to execute the process of determining the path difference in the next cycle. Further, when it is determined that the path difference of a satellite whose path difference is always classified is normal, the path difference determination process for the next cycle is executed using the first path difference threshold.

FIG. 5 is a flowchart showing the procedure of the above-mentioned path difference determination process. Specifically, the route difference determination unit 544 determines each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, and each base line AB, BC, AC), the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i is input, and the following processing is performed using it.

For each combination of two GNSS antennas (any two of 3A, 3B, and 3C), the route difference determination unit 544 determines the GNSS that the two GNSS antennas are simultaneously tracking at the processing time. For each combination of two GNSS satellites S_i among the satellites S_i, it is confirmed whether the satellites are always classified as having route differences based on the determination of the immediately preceding cycle (step S1).

If it is confirmed in step S1 that the satellite is not always classified as having a track difference (NO in step S1), the track difference determining unit 544 determines the GNSS antennas X-Y of each of the two GNSS satellites S_i. It is determined whether the absolute value of the difference between the path differences C_iXY between them is less than or equal to a first path difference threshold (step S2). When the absolute value of the difference in path difference C_i Satellite S_i determines that the direction of arrival of the GNSS signal is abnormal, and classifies the two GNSS satellites S_i as having different routes (step S3).

In step S1 of the next cycle, the track difference determination unit 544 checks whether the satellite is always classified as having a track difference in the previous cycle, and if it is confirmed that the satellite is always classified as having a track difference. (YES in step S1), the absolute value of the difference between the path differences C_iXY between the GNSS antennas It is determined whether or not the path difference is less than or equal to the path difference threshold value of 2 (step S4). When the absolute value of the difference between the track differences C_i Satellite S_i determines that the direction of arrival of the GNSS signal is abnormal, and classifies the two GNSS satellites S_i as having different routes (step S3).

Further, in the determination in step S4, if the absolute value of the difference between the path differences C_iXY between the GNSS antennas X and Y of the two GNSS satellites S_i is larger than the second path difference threshold (NO in step S4 ), the two GNSS satellites S_i are classified as having normal course differences, assuming that the directions of arrival of the GNSS signals are normal (step S5).

The two GNSS satellites S_i whose track difference is classified as normal in step S5 are determined by the absolute value of the difference between the track difference C_iXY between each GNSS antenna X-Y in the next cycle's track difference determination process. It is determined whether or not is less than or equal to a first path difference threshold (steps S1 and S2).

The first path difference threshold is not limited to a specific value; for example, even if GNSS signals from multiple GNSS satellites are actually transmitted from a single transmitting antenna/same point, mechanical errors etc. It is set to an appropriate value after taking into consideration the error that is assumed to occur due to the above. In addition, the second path difference threshold value is determined by the time synchronization accuracy of the GNSS receivers 4A, 4B, and 4C, the frequency and amount of multipath or noise occurrence, changes in the Doppler frequency of the GNSS signal, and individual differences between each GNSS compass. Based on the above, minute variations and offsets occurring in the path difference are identified, and the value is appropriately set to a value larger than the first path difference threshold so as not to be influenced by these.

In this way, by appropriately switching between the first path difference threshold value and the second path difference threshold value and performing the path difference determination process, it is possible to suppress erroneous judgments that occur due to minute variations or offsets that occur in the path difference. It is possible to do so.

1 GNSS compass 2 Control unit 3 GNSS antenna 3A, 3B, 3C GNSS antenna 4 GNSS receiver 4A, 4B, 4C GNSS receiver 5 Positioning unit 51 Positioning number determination unit 52 Positioning position calculation unit 53 Standard deviation determination unit 54 Abnormality detection unit 541 Transmission time determination unit 542 Pseudo distance determination unit 543 Route difference calculation unit 544 Route difference determination unit

Claims (14)

Receiving GNSS signals transmitted from each of a plurality of satellites via at least three antennas,
When the standard deviation of the positioning distance between the three or more antennas calculated using the positioning positions of each of three or more antennas among the at least three antennas is larger than a predetermined threshold, or The average value of the positioning distance between the three or more antennas calculated using the positioning positions of each of three or more antennas among the at least three antennas is the average value of the positioning distance between the three or more antennas. determining that an abnormality has occurred in the GNSS signal when the true distance is smaller than the average value of the true distance;
A method for detecting an abnormality in a received signal, characterized in that: When it is determined that the transmission time of the GNSS signal is abnormal based on a comparison between the transmission time of the GNSS signal included in the GNSS signal and a predetermined reference transmission time, the GNSS signal is received. classifying said antenna as abnormal;
2. The method for detecting an abnormality in a received signal according to claim 1. The antenna receiving the GNSS signal transmitted from the satellite when it is determined that the pseudorange of the satellite is abnormal based on a comparison between the pseudorange of the satellite and the pseudorange of a predetermined reference satellite. classify as abnormal,
2. The method for detecting an abnormality in a received signal according to claim 1. When a path difference index indicating a difference in paths from the satellite to each of the at least three antennas is less than or equal to a predetermined path difference threshold, it is determined that the difference in the path from the satellite is abnormal, and the path difference from the satellite is determined to be abnormal. classifying the antenna receiving transmitted GNSS signals as abnormal;
2. The method for detecting an abnormality in a received signal according to claim 1. A determination as to whether or not an abnormality has occurred in the GNSS signal is performed at a predetermined cycle, and the satellite for which the difference in path is determined to be abnormal in the determination performed in the immediately preceding cycle is performing the determination in the next cycle using a second path difference threshold having a value larger than the path difference threshold;
5. The method for detecting an abnormality in a received signal according to claim 4. performing the determination in the next cycle using the predetermined path difference threshold when it is determined that the path difference of the satellite for which the path difference is determined to be abnormal is normal;
6. The method for detecting an abnormality in a received signal according to claim 5. If there are antennas that are not classified as abnormal, calculate the average value of the measured positions of each of the antennas that are not classified as abnormal, and set the average value as the current position at the time of the processing;
2. The method for detecting an abnormality in a received signal according to claim 1. at least three antennas receiving GNSS signals transmitted from each of the plurality of satellites;
When the standard deviation of the positioning distance between the three or more antennas calculated using the positioning positions of each of three or more antennas among the at least three antennas is larger than a predetermined threshold, or The average value of the positioning distance between the three or more antennas calculated using the positioning positions of each of three or more antennas among the at least three antennas is the average value of the positioning distance between the three or more antennas. means for determining that an abnormality has occurred in the GNSS signal when the true distance is smaller than the average value of the true distance;
A device for detecting an abnormality in a received signal, characterized in that: When it is determined that the transmission time of the GNSS signal is abnormal based on a comparison between the transmission time of the GNSS signal included in the GNSS signal and a predetermined reference transmission time, the GNSS signal is received. classifying said antenna as abnormal;
The apparatus for detecting an abnormality in a received signal according to claim 8. The antenna receiving the GNSS signal transmitted from the satellite when it is determined that the pseudorange of the satellite is abnormal based on a comparison between the pseudorange of the satellite and the pseudorange of a predetermined reference satellite. classify as abnormal,
The apparatus for detecting an abnormality in a received signal according to claim 8. When a path difference index indicating a difference in paths from the satellite to each of the at least three antennas is less than or equal to a predetermined path difference threshold, it is determined that the difference in the path from the satellite is abnormal, and the path difference from the satellite is determined to be abnormal. classifying the antenna receiving transmitted GNSS signals as abnormal;
The apparatus for detecting an abnormality in a received signal according to claim 8. A determination as to whether or not an abnormality has occurred in the GNSS signal is performed at a predetermined cycle, and the satellite for which the difference in path is determined to be abnormal in the determination performed in the immediately preceding cycle is performing the determination in the next cycle using a second path difference threshold having a value larger than the path difference threshold;
The apparatus for detecting an abnormality in a received signal according to claim 11. performing the determination in the next cycle using the predetermined path difference threshold when it is determined that the path difference of the satellite for which the path difference is determined to be abnormal is normal;
The apparatus for detecting an abnormality in a received signal according to claim 12. If there are antennas that are not classified as abnormal, calculate the average value of the measured positions of each of the antennas that are not classified as abnormal, and set the average value as the current position at the time of the processing;
The apparatus for detecting an abnormality in a received signal according to claim 8.