JP2023168271A - Detection method and detection device of abnormality in reception signal - Google Patents

Abstract

An object of the present invention is to detect an abnormality in a received signal including an abnormality in a path difference of a received signal in GNSS without using a satellite direction estimated from a satellite position based on ephemeris. [Solution] For each combination of two GNSS antennas that are not classified as either time synchronization abnormality or satellite number abnormality, among the GNSS satellites S#i that are simultaneously tracked by the two GNSS antennas, For each combination of two GNSS satellites S_i, when the path difference index representing the difference in path from each of the two GNSS satellites S_i to each of the two GNSS antennas is equal to or less than a predetermined path difference threshold, The two GNSS satellites S_i are always classified as having a path difference, and when the number of GNSS satellites S_i that are always classified as having a path difference is equal to or greater than a predetermined abnormality determination threshold, it is determined that an abnormality has occurred in the GNSS signal. [Selection diagram] 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

The devices of Patent Documents 1 and 2 calculate the direction of the satellite estimated from the satellite position based on ephemeris, which is data indicating the current position of the GPS satellite itself, and the direction of the satellite estimated from the direction of arrival of satellite signals received by multiple antennas. This method compares the and, and if they do not match, it is determined to be an abnormal signal.

Therefore, the present invention aims to detect abnormalities in received signals, including abnormalities in the direction of arrival of received signals in GNSS, without using the direction of the satellite estimated from the satellite position based on ephemeris. It is an object of the present invention to provide a method and a detection device.

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 For each combination of two receivers out of at least three receivers provided respectively, when the internal times of the two receivers are not synchronized with each other, A combination of two antennas corresponding to each of the receivers is classified as a time synchronization abnormality, and for each combination of two antennas among the at least three antennas, the two antennas are simultaneously tracking. If the number of satellites in question is less than a predetermined threshold, the combination of the two antennas is classified as an abnormal number of satellites, and two antennas that are not classified as either the time synchronization abnormality or the abnormal number of satellites are classified as For each combination of antennas, for each combination of two of the satellites that are simultaneously tracked by the two antennas, the path from each of the two satellites to each of the two antennas. When the track difference index representing the difference in track difference is less than or equal to a predetermined track difference threshold, the two satellites are always classified as having a track difference, and when the number of satellites that are always classified as having a track difference is greater than or equal to the predetermined threshold, The method is characterized in that it is determined that an abnormality has occurred in the GNSS signal.

The method for detecting an abnormality in a received signal according to the present invention may maintain the determination that an abnormality has occurred in the GNSS signal for a predetermined period of time.

In the method for detecting an abnormality in a received signal according to the present invention, when the determination that an abnormality has occurred in the GNSS signal is maintained, the path difference between all the GNSS signals transmitted from each of the plurality of satellites is determined. If it is determined that the GNSS signal is normal, the determination that an abnormality has occurred in the GNSS signal may be canceled.

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 always classifying the route difference in the determination performed in the previous cycle. The satellite may perform the determination in the next period using a second path difference threshold having a value larger than the predetermined path difference threshold.

In the method for detecting an abnormality in a received signal according to the present invention, when the trajectory difference of the satellite whose trajectory difference is always classified is determined to be normal, the predetermined trajectory difference threshold is used to detect the next period. The above determination may be executed.

Further, the receiving signal abnormality detecting device according to the present invention is configured to receive GNSS signals transmitted from each of a plurality of satellites via at least three antennas, and is provided corresponding to each of the at least three antennas. For each combination of at least three receivers and two of the at least three receivers, when the internal times of the two receivers are not synchronized, a time synchronization determination unit that classifies a combination of two antennas corresponding to each of the two receivers as a time synchronization abnormality; a satellite number determination unit that classifies the combination of the two antennas as a satellite number abnormality when the number of satellites simultaneously tracked by the two antennas is less than a predetermined threshold; For each combination of two antennas that are not classified as abnormal, for each combination of two of the satellites that are simultaneously tracked by the two antennas, a path difference determination unit that always classifies the two satellites according to the path difference when a path difference index representing the difference in path from each satellite to each of the two antennas is less than or equal to a predetermined path difference threshold; The present invention is characterized by comprising: an abnormality determination unit that determines that an abnormality has occurred in the GNSS signal when the number of satellites that are always classified as different is equal to or greater than a predetermined threshold value.

The reception signal abnormality detecting device according to the present invention may maintain the determination that an abnormality has occurred in the GNSS signal for a predetermined period of time.

The receiving signal abnormality detection device according to the present invention detects the path difference between all the GNSS signals transmitted from each of the plurality of satellites when the determination that an abnormality has occurred in the GNSS signal is maintained. If it is determined that the GNSS signal is normal, the determination that an abnormality has occurred in the GNSS signal may be canceled.

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 always classifies the route difference in the determination performed in the immediately preceding cycle. The satellite may perform the determination in the next period using a second path difference threshold having a value larger than the predetermined path difference threshold.

The receiving signal abnormality detecting device according to the present invention uses the predetermined path difference threshold to detect the next period when the path difference of the satellite whose path difference is always classified is determined to be normal. The above determination may be executed.

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, for each combination of two antennas that are not classified as either time synchronization abnormality or satellite number abnormality, the relevant Based on ephemeris, path difference abnormalities (in other words, abnormalities in the direction of arrival of GNSS signals) are detected for each combination of two satellites that are simultaneously tracked by two antennas. Without using the satellite direction estimated from the satellite position, it is possible to improve the reliability of the process for detecting abnormalities in received signals 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. 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, an anomaly detecting section 5, and a positioning section 6. 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 when 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) that performs arithmetic processing related to detecting abnormalities in GNSS signals and calculating the position of the GNSS compass 1. : Abbreviation for Central Processing Unit).

The control unit 2 also stores programs, various information, and data used by the central processing unit (CPU) to perform calculations related to detecting abnormalities in GNSS signals and calculating the position of the GNSS compass 1. A function that serves as a storage area for storing data or as a work area for temporarily storing data and information generated when the central processing unit (CPU) performs the arithmetic processing. For example, a device having at least one of ROM (abbreviation for Read Only Memory), which is a read-only storage device, RAM (abbreviation), which is a readable and writable storage device, and a hard disk. It is structured as an introduction.

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 is configured to receive 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 a plurality of GNSS satellites). A mechanism consisting of at least three GNSS receivers, each with 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 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 the signal.

Each GNSS receiver 4A, 4B, 4C is equipped with an internal clock that starts operating when the GNSS compass 1 is powered on, and has a 1-second cycle pulse obtained by receiving the GNSS signal transmitted from each GNSS satellite S_i. An internal time obtained by synchronizing the internal clock with a 1PPS (One Pulse Per Second) signal is also output.

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 S_i. Each GNSS receiver 4A, 4B, 4C receives a GNSS radio wave, demodulates the GNSS radio wave, and extracts a GNSS signal. Then, the GNSS signal is output from the GNSS receiving section 4.

That is, the GNSS receiving unit 4 outputs combination data of the GNSS signal and the internal time at the time of reception of the GNSS signal for each GNSS satellite S_i for each of the GNSS receivers 4A, 4B, and 4C.

By executing the control program by the central processing unit (CPU) of the control unit 2, an abnormality detection section 5 and a positioning section 6 are configured within the control unit 2.

The abnormality detection unit 5 is a mechanism for detecting an abnormality in the GNSS signal output from the GNSS receiving unit 4 and outputting a detection result.

The positioning unit 6 is a mechanism for calculating and outputting positioning information using the GNSS signal output from the GNSS receiving unit 4.

Although the positioning information calculated by the positioning unit 6 is not limited to specific items, for example, at least one of the position, direction, and attitude (e.g., rolling, pitching, rate of turn (ROT)) of the own aircraft, etc. These include: The calculation process of the positioning information by the positioning unit 6 can be performed using well-known techniques, and the present invention is not limited to specific items or methods, so a detailed explanation will be omitted.

The positioning unit 6 determines the GNSS satellite S_i to be excluded from the satellite group used in the positioning information calculation process based on the detection result of the abnormality in the GNSS signal output from the anomaly detection unit 5 (in other words, the positioning information (Determine the GNSS satellite S_i to be used in calculation processing).

(Processing content of the abnormality detection unit)
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 , 3B, and 3C. For each combination of two GNSS receivers among the three GNSS receivers 4A, 4B, and 4C provided corresponding to each of the three GNSS receivers, the internal time of each of the two GNSS receivers is When the time is not synchronized, the combination of two GNSS antennas corresponding to each of the two GNSS receivers is classified as a time synchronization abnormality, and two of the three GNSS antennas 3A, 3B, and 3C are For each combination of GNSS antennas in For each combination of two GNSS antennas that are classified as either time synchronization abnormality or satellite number abnormality, two of the GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas are For each combination of GNSS satellites S_i, when the path difference index representing the difference in path from each of the two GNSS satellites S_i to each of the two GNSS antennas is equal to or less than a predetermined path difference threshold, Two GNSS satellites S_i are always classified as having different routes, and when the number of GNSS satellites S_i that are always classified as having different routes is equal to or greater than a predetermined abnormality determination threshold, it is determined that an abnormality has occurred in the GNSS signal. ing.

Further, the GNSS compass 1 according to the embodiment, which includes a receiving signal abnormality detection device as a device that implements the above-described method for detecting a received signal abnormality, detects GNSS signals transmitted from each of the plurality of GNSS satellites S_i. Three GNSS receivers 4A, 4B, 4C provided corresponding to the three GNSS antennas 3A, 3B, 3C and three GNSS For each combination of two GNSS receivers among the receivers 4A, 4B, and 4C, when the internal times of the two GNSS receivers are not synchronized, the two GNSS receivers The time synchronization determination unit 52 classifies the combination of two GNSS antennas corresponding to each device as a time synchronization abnormality, and the When the number of GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas is less than a predetermined satellite number threshold, a satellite number determination unit 53 that classifies the combination of the two GNSS antennas as a satellite number abnormality; , for each combination of two GNSS antennas that are not classified as either time synchronization abnormality or satellite number abnormality, the GNSS of two GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas. For each combination of satellites S_i, when the path difference index representing the difference in path from each of the two GNSS satellites S_i to each of the two GNSS antennas is less than or equal to a predetermined path difference threshold, A path difference determination unit 54 that always classifies GNSS satellites S_i with path differences, and determines that an abnormality has occurred in the GNSS signal when the number of GNSS satellites S_i whose path differences are always classified is equal to or greater than a predetermined abnormality determination threshold. An abnormality determination section 55 is provided.

The abnormality detection unit 5 is a mechanism for detecting an abnormality in the GNSS signal, and the abnormality detection unit 5 is a mechanism for detecting an abnormality in the GNSS signal. Receiving input of combined data of a GNSS signal and an internal time at the time of reception of the GNSS signal, calculation processing for detecting an abnormality in a GNSS signal that is a received signal in GNSS based on the GNSS signal and the internal time ( (referred to as "abnormality detection calculation processing"). The abnormality detection calculation process may be executed at the predetermined cycle in accordance with a predetermined cycle in which the GNSS receiving unit 4 outputs the combination data of the GNSS signal and the internal time at the time of reception of the GNSS signal. Alternatively, the process may be executed at a cycle different from the predetermined cycle. Each point in time at which the abnormality detection calculation process in the abnormality detection unit 5 is executed is referred to as a "processing point in time."

The abnormality detection section 5 includes a path difference calculation section 51, a time synchronization determination section 52, a satellite number determination section 53, a path difference determination section 54, and an abnormality determination section 55.

The route difference calculation unit 51 calculates the GNSS signal for each GNSS satellite S_i, which is output from the GNSS reception unit 4 at the relevant processing time, and the internal information at the time of receiving the relevant GNSS signal. Upon receiving the input of the data combined with the time, the difference between the routes from the GNSS satellite S_i to each of 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 51 is referred to as "path difference calculation process."

The path difference calculation unit 51 calculates the distance from the GNSS satellite S_i to each of the GNSS antennas 3A, 3B, and 3C, which is caused by the fact that the plurality of GNSS antennas 3A, 3B, and 3C are spaced apart from each other at predetermined intervals. The difference (absolute value) in the path of , 3C).

FIG. 3 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. 3. In the example shown in FIG. 3, 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 between GNSS antenna 3A and GNSS antenna 3B) The difference) will be taken up and explained.

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 in the following formula 1, and is the difference between the path from GNSS satellite S_2 to GNSS antenna 3A and the path to GNSS antenna 3B. The difference C_2AB is expressed as in Equation 2 below (see FIG. 3(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 of GNSS radio wave of GNSS satellite S_1 (cycle or more)
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; This is the difference in carrier phase integrated value of one GNSS satellite S_i with respect to the antennas (in the example shown in FIG. 3, GNSS antenna 3A and GNSS antenna 3B).

The path difference calculation unit 51 calculates the relevant information 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 GNSS satellite S_i to GNSS antenna X and the path to GNSS antenna Y is calculated.

Difference between 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 51 (Absolute value) C_iXY is called "path difference C_iXY between GNSS antennas X and Y of GNSS satellite S_i."

The path difference calculation unit 51 calculates the relevant information 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). Outputs the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i.

The time synchronization determination unit 52 determines the GNSS signal of each GNSS satellite S_i for each GNSS receiver 4A, 4B, and 4C, which is output from the GNSS reception unit 4 at the relevant processing time, and the internal information at the time of receiving the relevant GNSS signal. Upon receiving the input of the combination data with the time, it is determined whether the internal times are synchronized with each other. The process performed by the time synchronization determination unit 52 is referred to as "time synchronization determination process."

Here, if no abnormality has occurred in the GNSS signal, the internal times of each of the GNSS receivers 4A, 4B, and 4C should be synchronized, and the internal times of each of the GNSS receivers 4A, 4B, and 4C should be synchronized. If the time is not synchronized, it is considered that an abnormality has occurred in the GNSS signal.

The time synchronization determination unit 52 determines whether each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, the baseline AB, BC, AC ), the absolute value of the difference between the internal times that are combined with the GNSS signal used to calculate the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i for each GNSS satellite S_i It is determined whether the time difference is greater than a threshold value.

The time difference threshold is not limited to a specific value, but can be set to an appropriate value by taking into account errors that are expected to occur due to mechanical errors even under normal conditions. Set as appropriate. It is conceivable that the time difference threshold is set to a value within a range of about 1 to 5 milliseconds, for example.

The time synchronization determination unit 52 determines the corresponding 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). When the absolute value of the difference between the internal times that are combined with the GNSS signals used to calculate the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i is greater than the time difference threshold, the path difference C_iXY is calculated. Assuming that the internal time of the GNSS signal used for this is abnormal, the combination of the two GNSS antennas is classified as having a time synchronization abnormality. In other words, for each combination of two GNSS receivers among the three GNSS receivers 4A, 4B, and 4C, the time synchronization determination unit 52 determines whether the internal times of the two GNSS receivers are time synchronized with each other. If not, the combination of two GNSS antennas corresponding to the two GNSS receivers is classified as having a time synchronization abnormality.

The number of satellites determining unit 53 determines each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, base line AB, Receiving the input of the path difference C_iXY between the GNSS antennas 2), it is determined whether the number of GNSS satellites S_i that the two GNSS antennas are simultaneously tracking at the time of the processing is appropriate. The process performed by the satellite number determining unit 53 is referred to as "satellite number determining process."

Here, in order to calculate the path difference C_iXY between the GNSS antennas It is necessary that the GNSS receiver equipped with antenna Y is tracking the same GNSS satellite S_i. However, in a mobile object, even if the plurality of GNSS antennas 3A, 3B, and 3C are located in close proximity to each other, for example, when the GNSS compass 1 is mounted on a ship and the ship is shaking, each The reception environment/shielding environment of the GNSS antennas 3A, 3B, and 3C may be different. In this case, the GNSS satellite S_i tracked by each of these GNSS antennas in a combination of two certain GNSS antennas (any two of 3A, 3B, and 3C) is different, and therefore the certain two GNSS antennas With the combination of GNSS antennas (in other words, the baseline), it is not possible to calculate the path difference C_iXY (including the inter-antenna singlet difference P_iXY).

In the example shown in Fig. 3, since GNSS satellite S_1 and GNSS satellite S_2 are usually located at different spatial positions, the elevation angle θ_1 of each satellite as seen from GNSS compass 1 (specifically, GNSS antenna 3) The elevation angle θ_2 is different from each other. Since the elevation angle θ_1 of the GNSS satellite S_1 and the elevation angle θ_2 of the GNSS satellite S_2 are different from each other, the path difference C_1AB for the GNSS satellite S_1 and the path difference C_2AB for the GNSS satellite S_2 are different from each other (see Fig. 3). A) and see Equations 1 and 2 above).

On the other hand, if GNSS satellite S_1 and GNSS satellite S_2 are both located at the same spatial position, the elevation angle θ_1 and elevation angle θ_2 of each satellite as seen from GNSS compass 1 (specifically, GNSS antenna 3) are the same. (See Figure 3(B)). If the elevation angle θ_1 of the GNSS satellite S_1 and the elevation angle θ_2 of the GNSS satellite S_2 are the same, the difference C_1AB in the path for the GNSS satellite S_1 and the difference C_2AB in the path for the GNSS satellite S_2 will be the same (formula 1 above). , see Equation 2).

An example of a case where the elevation angle θ_1 of GNSS satellite S_1 and the elevation angle θ_2 of GNSS satellite S_2 are the same is when, for example, a signal containing positioning information and orbit information of multiple GNSS satellites is transmitted from a single transmitting antenna. In other words, it is possible to pretend that GNSS signals (in other words, GNSS radio waves) are being transmitted from multiple GNSS satellites, and then use a single transmitting antenna (in other words, at the same location; however, it is installed on the ground). There may be cases in which GNSS signals from multiple GNSS satellites are being transmitted from multiple GNSS satellites (including antenna stations that are located at Can be mentioned. In this respect, the "GNSS signal transmitted from each of the plurality of GNSS satellites S_i" in this invention is made to appear as if the GNSS signal is being transmitted from each of the plurality of GNSS satellites S_i, and then It includes a signal emitted from a point.

In relation to the above, the baseline dimension, which is the distance between the GNSS antennas 3A, 3B, and 3C, should be set at one wavelength or more (specifically, several wavelengths) to avoid interference between the GNSS antennas 3A, 3B, and 3C. degree). Therefore, even though the GNSS satellite S_1 and the GNSS satellite S_2 exist in mutually different spatial positions and the difference in path C_1AB for the GNSS satellite S_1 and the difference in path C_2AB for the GNSS satellite S_2 are actually different from each other. First, as can be seen from Equations 3 and 4 above, although the integer biases N_1 and N_2 are different, it is also possible that the antenna-to-antenna singlet differences P_1AB and P_2AB for the two GNSS satellites S_1 and S_2 are even or the same. It will be done. However, since the GNSS satellites S_1 and S_2 are moving, the above state does 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 GNSS antenna 3B, the inter-antenna singlet difference P_1AB for the two GNSS satellites S_1 and S_2, Even if P_2AB becomes even or the same, the inter-antenna singlet differences P_1AB and P_2AC for the two GNSS satellites S_1 and S_2 will not become the same in the combination of the GNSS antenna 3A and the GNSS antenna 3C.

The number of satellites determining unit 53 determines each combination of two GNSS antennas among the three GNSS antennas 3A, 3B, and 3C (in other words, the baseline AB, Based on the path difference C_iXY between the GNSS antennas The number of GNSS satellites S_i for which the path difference C_iXY is calculated is counted for each combination of GNSS satellites S_i (in other words, for each base line AB, BC, AC). This number of GNSS satellites S_i is, in other words, the number of GNSS satellites S_i that the two GNSS antennas are simultaneously tracking at the time of the processing.

Then, for each combination of two GNSS antennas (any two of 3A, 3B, and 3C) (in other words, for each baseline AB, BC, and AC), the satellite number determination unit 53 determines the It is determined whether the number of GNSS satellites S_i that the GNSS antenna is simultaneously tracking at the time of the processing is less than a predetermined satellite number threshold.

The threshold for the number of satellites is not limited to a specific value; for example, the number of GNSS satellites S_i that can be simultaneously tracked by two GNSS antennas in a normal (in other words, normal) reception environment is the number of satellites S_i. It is set to an appropriate value after consideration. It is conceivable that the satellite number threshold is set to a value in a range of about 2 to 4, for example.

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 satellite number determination unit 53 determines whether the two GNSS antennas are When the number of GNSS satellites S_i that are simultaneously tracked at the time of the relevant processing is less than the satellite number threshold, the number of GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas is considered to be abnormal, and the two GNSS antennas are tracked simultaneously. The combination of GNSS antennas is classified as an abnormal number of satellites.

The path difference determination unit 54 determines whether the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i, which is output from the path difference calculation unit 51, is normal. The process performed by the path difference determination unit 54 is referred to as "path difference determination process."

Specifically, the route difference determination unit 54 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), receives input of the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i for each GNSS satellite S_i.

The route difference determination unit 54 also determines the combination of two GNSS antennas (any two of 3A, 3B, and 3C) that are classified as time synchronization abnormal in the time synchronization determination process at the relevant processing time. The combination of two GNSS antennas (any two of 3A, 3B, and 3C) that are obtained from the synchronization determination unit 52 and classified as having an abnormal number of satellites in the determination process of the number of satellites at the relevant processing time are Obtained from the satellite number determination unit 53.

The path difference determination unit 54 then determines whether two GNSS antennas are classified as either time synchronization abnormality or satellite number abnormality among the path difference C_iXY between the GNSS antennas X and Y of the input GNSS satellite S_i. The following processing is performed using the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i for each GNSS satellite S_i in the combination (any two of 3A, 3B, and 3C).

The path difference determination unit 54 determines the corresponding For each combination of two GNSS satellites S_i among the GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas at the processing time, the distance between the GNSS antennas X and Y of each of the two GNSS satellites S_i is When the absolute value of the difference between the track differences C_iXY at Always classify route differences. This process is performed for each combination of two GNSS antennas (any two of 3A, 3B, and 3C) of the GNSS satellite S_i that the two GNSS antennas are simultaneously tracking at the time of the process. This is done for all combinations of the two GNSS satellites S_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 antenna-to-antenna singlet difference P_iXY for each of the plurality of GNSS satellites S_i is usually different from each other, whereas a single transmitting antenna /If GNSS signals from a plurality of GNSS satellites are transmitted from the same point, the inter-antenna singlet difference P_iXY for each of the plurality of GNSS satellites S_i will be the same. Therefore, in the process of determining the path difference for each GNSS satellite S_i, the inter-antenna singlet difference P_iXY for each of the plurality of GNSS satellites S_i may be verified (see Equations 3 and 4 above).

When verifying the inter-antenna single difference P_iXY for each of the plurality of GNSS satellites S_i, the path difference determination unit 54 verifies the two GNSS antennas (which are not classified as either time synchronization abnormality or satellite number abnormality). 3A, 3B, and 3C), a combination of two GNSS satellites S_i among the GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas at the time of the processing. For each case, when the absolute value of the difference between the single antenna differences P_i is abnormal, and the two GNSS satellites S_i are classified as always having a 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 C_iXY between the antennas for the GNSS satellite S_i, which represents the difference in path from the GNSS satellite S_i to each GNSS antenna 3A, 3B, and 3C, used in the process of determining the path difference for each GNSS satellite S_i, and the single overlap between antennas. The difference P_iXY is called a "path difference index."

The path difference determination unit 54 outputs information regarding the GNSS satellite S_i classified as a path difference abnormality (in other words, an abnormality in the arrival direction of the GNSS signal).

The abnormality determination unit 55 receives the input of the information regarding the GNSS satellite S_i, which is always classified as a path difference output from the path difference determination unit 54 at the relevant processing time, and determines whether or not an abnormality has occurred in the GNSS signal. .

Specifically, the abnormality determination unit 55 counts the number of GNSS satellites S_i whose path difference is always classified based on the information regarding the GNSS satellite S_i whose path difference is always classified, which is output from the path difference determination unit 54, and calculates the number of GNSS satellites S_i whose path difference is always classified. It is determined whether the number is equal to or greater than a predetermined abnormality determination threshold.

The abnormality determination threshold is not limited to a specific value; for example, it takes into account the number of GNSS satellites expected when GNSS signals from multiple GNSS satellites are being transmitted from a single transmitting antenna/same point. After that, it is set to an appropriate value as appropriate. It is conceivable that the abnormality determination threshold value is set to any value within a range of about 3 to 5, for example.

The abnormality determination unit 55 determines that no abnormality has occurred in the GNSS signal when the number of GNSS satellites S_i whose path difference is always classified is less than the abnormality determination threshold, and when the number is equal to or greater than the abnormality determination threshold. It is determined that an abnormality has occurred in the GNSS signal.

If it is determined that an abnormality has occurred in the GNSS signal, the abnormality state occurs, and the GNSS satellite S_i, which is always classified as a path difference, receives positioning information from the positioning unit 6 (specifically, its own position, direction, GNSS signals transmitted from the excluded GNSS satellite S_i are not used in the calculation process of positioning information by the positioning unit 6.

When it is determined that an abnormality has occurred in the GNSS signal, the abnormality occurrence state may be maintained for a predetermined abnormality retention time. While the abnormality occurrence state is maintained, the GNSS satellite S_i whose path difference is always classified is excluded from the satellite group used in the positioning information calculation process by the positioning unit 6.

The abnormality retention time is not limited to a specific length of time, and may be used, for example, to prevent a situation in which the number of normal GNSS satellites S_i (in other words, used for calculation processing of positioning information by the positioning unit 6) is extremely reduced. An appropriate time length is set as appropriate, taking into consideration the possibility of capturing the GNSS satellite S_i normally due to the movement of the mobile object on which the GNSS Compass 1 is mounted. .

If it is determined that an abnormality has occurred in the GNSS signal, or when the number of GNSS satellites S_i that are always classified as path differences becomes zero, the abnormality occurrence state is canceled, or the path difference is always classified as The abnormality occurrence state is canceled when the number of GNSS satellites S_i that have been classified becomes zero and the number of GNSS satellites S_i whose path difference is not always classified becomes a predetermined number (for example, 4) or more. Good too. In other words, a method for detecting an abnormality in a received signal and a device for detecting an abnormality in a received signal detect all signals transmitted from each of multiple GNSS satellites S_i when the determination that an abnormality has occurred in the GNSS signal is maintained. If it is determined that the path difference of the GNSS signals is normal, the determination that an abnormality has occurred in the GNSS signals may be canceled.

For example, if an output device (not shown) including a monitor and a speaker is attached to the GNSS compass 1, an abnormality in the GNSS signal can be detected by displaying an alarm screen on the output device's monitor or by displaying an alarm screen on the output device's monitor. The user may be notified by emitting an alarm from a speaker. 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 received signal abnormality detection method and GNSS compass 1 according to the embodiment, two antennas (any of 3A, 3B, and 3C) that are not classified as either time synchronization abnormality or satellite number abnormality For each combination of two GNSS satellites S_i of the GNSS satellites S_i that are simultaneously tracked by the two antennas, the path difference abnormality (in other words, the direction of arrival of the GNSS signal) is detected. Therefore, it is possible to improve the reliability of the detection process for abnormalities in received signals in GNSS without using the satellite direction estimated from the satellite position based on ephemeris.

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, according to the GNSS compass 1 described in the above embodiment, the time synchronization between the GNSS receivers 4A, 4B, and 4C may be insufficient, multipath or noise may occur 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 process of determining the path difference of the next cycle is executed using the first path difference threshold.

FIG. 4 is a flowchart showing the procedure of the above-mentioned path difference determination process. Specifically, the route difference determination unit 54 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), receives input of the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i for each GNSS satellite S_i.

The route difference determination unit 54 also determines the combination of two GNSS antennas (any two of 3A, 3B, and 3C) that are classified as time synchronization abnormal in the time synchronization determination process at the relevant processing time. The combination of two GNSS antennas (any two of 3A, 3B, and 3C) that are obtained from the synchronization determination unit 52 and classified as having an abnormal number of satellites in the determination process of the number of satellites at the relevant processing time are Obtained from the satellite number determination unit 53.

The path difference determination unit 54 then determines whether two GNSS antennas are classified as either time synchronization abnormality or satellite number abnormality among the path difference C_iXY between the GNSS antennas X and Y of the input GNSS satellite S_i. The following processing is performed using the path difference C_iXY between the GNSS antennas X and Y of the GNSS satellite S_i for each GNSS satellite S_i in the combination (any two of 3A, 3B, and 3C).

The path difference determination unit 54 determines the corresponding For each combination of two GNSS satellites S_i among the two GNSS satellites S_i that are simultaneously tracked by the two GNSS antennas at the time of the relevant processing, determine whether the trajectory difference is always classified as a satellite based on the determination of the immediately preceding cycle. (Step S1).

If the path difference determining unit 54 confirms in step S1 that the satellite is not always classified as having a path difference (NO in step S1), the path difference determining unit 54 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 54 checks whether the satellite is always classified as having a track difference in the determination 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 and the second path difference threshold to perform path difference determination processing, it is possible to suppress misjudgments that occur due to minute variations or offsets in path differences. It is possible to do so.

Further, in the above embodiment, the 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.

1 GNSS compass 2 Control unit 3 GNSS antenna 3A, 3B, 3C GNSS antenna 4 GNSS receiver 4A, 4B, 4C GNSS receiver 5 Abnormality detection unit 51 Track difference calculation unit 52 Time synchronization determination unit 53 Number of satellites determination unit 54 Track difference Determination unit 55 Abnormality determination unit 6 Positioning unit

Claims (10)

Receiving GNSS signals transmitted from each of a plurality of satellites via at least three antennas,
For each combination of two receivers among the at least three receivers provided corresponding to each of the at least three antennas, the internal times of the two receivers are not synchronized with each other. Sometimes, the combination of two antennas corresponding to the two receivers in question is classified as a time synchronization abnormality,
For each combination of two antennas among the at least three antennas, when the number of satellites simultaneously tracked by the two antennas is less than a predetermined threshold, the combination of the two antennas is is classified as an abnormal number of satellites,
For each combination of two antennas that are not classified as either the time synchronization abnormality or the number of satellites abnormality, the combination of two of the satellites that are simultaneously tracked by the two antennas. For each case, when a track difference index representing the difference in track from each of the two satellites to each of the two antennas is less than or equal to a predetermined track difference threshold, the two satellites are always classified as having a track difference. ,
determining that an abnormality has occurred in the GNSS signal when the number of satellites that are always classified by the route difference is equal to or greater than a predetermined threshold;
A method for detecting an abnormality in a received signal, characterized in that: maintaining a determination that an abnormality has occurred in the GNSS signal for a predetermined time;
2. The method for detecting an abnormality in a received signal according to claim 1. When it is determined that the path differences of all the GNSS signals transmitted from each of the plurality of satellites are normal while the determination that an abnormality has occurred in the GNSS signal is maintained, the GNSS Release the judgment that an abnormality has occurred in the signal,
3. The method for detecting an abnormality in a received signal according to claim 2. A determination as to whether or not an abnormality has occurred in the GNSS signal is performed at a predetermined cycle, and the satellite whose path difference is always classified in the determination performed in the immediately preceding period is determined to have a path difference that is lower than the predetermined path difference threshold. performing the determination in the next cycle using a second path difference threshold having a large value;
The method for detecting an abnormality in a received signal according to any one of claims 1 to 3. If the trajectory difference of the satellite that is always classified is determined to be normal, executing the determination in the next cycle using the predetermined trajectory difference threshold;
5. The method for detecting an abnormality in a received signal according to claim 4. at least three receivers provided corresponding to each of the at least three antennas, which receive GNSS signals transmitted from each of the plurality of satellites via the at least three antennas;
For each combination of two receivers among the at least three receivers, when the internal times of each of the two receivers are not time synchronized, a time synchronization determination unit that classifies a combination of two corresponding antennas as a time synchronization abnormality;
For each combination of two antennas among the at least three antennas, when the number of satellites simultaneously tracked by the two antennas is less than a predetermined threshold, the combination of the two antennas is a satellite number determination unit that classifies the satellite number abnormality as a satellite number abnormality;
For each combination of two antennas that are not classified as either the time synchronization abnormality or the number of satellites abnormality, the combination of two of the satellites that are simultaneously tracked by the two antennas. For each case, when a track difference index representing the difference in track from each of the two satellites to each of the two antennas is less than or equal to a predetermined track difference threshold, the two satellites are always classified as having a track difference. A path difference determination unit;
an anomaly determining unit that determines that an anomaly has occurred in the GNSS signal when the number of satellites that are always classified as having a path difference is equal to or greater than a predetermined threshold;
A device for detecting an abnormality in a received signal, characterized in that: maintaining a determination that an abnormality has occurred in the GNSS signal for a predetermined time;
The apparatus for detecting an abnormality in a received signal according to claim 6. When it is determined that the path differences of all the GNSS signals transmitted from each of the plurality of satellites are normal while the determination that an abnormality has occurred in the GNSS signal is maintained, the GNSS Release the judgment that an abnormality has occurred in the signal,
The apparatus for detecting an abnormality in a received signal according to claim 7. A determination as to whether or not an abnormality has occurred in the GNSS signal is performed at a predetermined cycle, and the satellite whose path difference is always classified in the determination performed in the immediately preceding period is determined to have a path difference that is lower than the predetermined path difference threshold. performing the determination in the next cycle using a second path difference threshold having a large value;
The apparatus for detecting an abnormality in a received signal according to any one of claims 6 to 8. If the trajectory difference of the satellite that is always classified is determined to be normal, executing the determination in the next cycle using the predetermined trajectory difference threshold;
The apparatus for detecting an abnormality in a received signal according to claim 9.