KR102198297B1 - Method for directional processing of multiple GNSS ionosphere measurement for ionosphere disturbance monitoring and system thereof - Google Patents

Abstract

An embodiment of the present invention includes a signal receiver configured to receive a satellite navigation signal and determine a time-specific gradient total electron quantity (STEC) from the received satellite navigation signal; A three-dimensional numerical differential processing unit that differentiates the detected total amount of gradient electrons by a third order at fixed time intervals, and specifies at least two or more time points at which the disturbance of the microionized layer occurs from the result of the third order differential; A time-varying data processing unit that calculates three-dimensional time-varying data for disturbances of the micro-ionization layer by performing third-order differentiation according to at least two time intervals based on the result of the third-order differentiation; And a time-varying data analysis unit that analyzes the calculated 3D time-varying data according to a change in time interval, and determines a point of disturbance of the micro-ionospheric layer due to a cause of the ground among the specified at least two viewpoints from the analyzed result. Disclosed is an apparatus for analyzing a disturbance point of a micro-ionization layer, including.

Description

[Method for directional processing of multiple GNSS ionosphere measurement for ionosphere disturbance monitoring and system thereof]

The present invention relates to a method and system for directivity processing of a plurality of satellite navigation ionosphere measurements, and more specifically, a directivity processing method capable of selectively processing disturbances arriving in a specific direction by combining a plurality of satellite navigation ionosphere measurements And to the system.

The satellite navigation system including GPS in the United States consists of a number of satellites that transmit navigation signals. The general use of satellite navigation is for a user on the ground to receive a navigation signal and calculate its position. In this case, the ionosphere existing on the propagation path of the satellite signal is recognized as an error factor that causes the propagation delay of the satellite signal. For accurate estimation of the ionospheric error, the navigation satellite broadcasts signal sources at two frequencies, and the terrestrial satellite navigation receiver can estimate the amount of ionospheric delay and correct the error by using the difference in the delay generated at each frequency.

In addition to the original use of satellite navigation, there is a field of remote sensing in which the ionosphere is observed using a satellite navigation signal source. Taking GPS as an example, GPS signals are broadcast simultaneously at the L1 frequency (1575.42 MHz) and the L2 frequency (1227.60 MHz). Since the ionosphere has a characteristic of a dispersive medium, it causes a delay amount that is inversely proportional to the square of the frequency of the signal source passing through the ionosphere. Therefore, from the difference between the signals received at the two frequencies, it is possible to calculate the amount of ionospheric delay for the ionospheric pass point connecting the satellite and the user.

1 is a diagram showing an ionospheric passage point and an amount of ionospheric delay at the corresponding point.

FIG. 1 can be derived from the results of analyzing satellite navigation signals received from a plurality of GPS satellites by receivers in the observation reference station on the ground, and the actual ionosphere is distributed between an altitude of 80 km and 1000 km on the earth. In order to facilitate data processing, a specific point was set as the ionosphere concentration altitude, and the point passing through the altitude was defined as the ionospheric passage point. Referring to FIG. 1, it can be seen that a plurality of observation reference station receivers exist in Japan and China, centering on the Korean Peninsula, and a smaller amount of ionospheric delay is observed in a receiver located at a point with a high latitude.

The field of satellite navigation ionosphere telemetry has been applied to observe various characteristics of the ionosphere. The ionosphere undergoes not only large-scale or medium-scale changes such as solar activity and Earth's geomagnetic change, but also subtle changes due to ground earthquakes, chemical explosions, and underground nuclear tests. Among these, the object of this patent is to detect minute disturbances in the ionosphere caused by terrestrial causes.

There have been a number of studies using satellite navigation to detect disturbances in micro-ionospheric layers caused by earthquakes, chemical explosions, and underground nuclear tests. In order to detect microscopic changes in the ionosphere, it is necessary to remove the main tendency, such as daily change in the ionosphere. There are two main ways to remove this tendency.

The first is a method of modeling the change in the amount of ionospheric delay according to the altitude angle change of the satellite with a specific function and to differentiate the change in the actual ionosphere from the modeling result. The actual ionosphere observation value has the advantage of being observed in the unit of TECU (Total Electron Content Unit), but there is a limit in which it is difficult to specify the time of occurrence of the ionosphere disturbance source.

The second method is to use the amount of change by numerically differentiating the observed values of the ionosphere. In a recent study, very minute ionosphere disturbances caused by underground nuclear tests have been detected by a method of third-order numerical differentiation of observations of the ionosphere. The numerical differential method has the advantage of being able to check the changes of the ionosphere disturbance sources in detail, but it is difficult to distinguish the disturbance sources because it is affected by a number of ionosphere disturbance sources.

The method of detecting micro-ionospheric disturbance according to numerical differentiation can be found in the reference paper (Jihye Park, Ph.D. Dissertation, Ohio State University, 2011).

1. Korean Patent Registration No. 10-1387659 (published on April 21, 2014) 2. Korean Patent Registration No. 10-1181443 (published on 2012.09.24 registration) 3. Korean Patent Registration No. 10-0305714 (published on September 26, 2001)

1.Ionospheric monitoring by the Global Positioning Satellite System (GNSS), Jihye Park, Ph.D. Dissertation, Ohio State University, 2012 2. GPS discrimination of traveling ionospheric disturbances from underground nuclear explosions and earthquakes, Jihye Park et. al., NAVIGATION: Journal of The Institute of Navigation, Vol 61, No.2, Summer 2014

The technical problem to be solved by the present invention is to improve the observational gain for ionospheric disturbances caused by ground causes in the detection of fine ionospheric disturbances (TID), thereby distinguishing from ionospheric disturbances caused by other causes. It is to provide a method and a system for implementing the method.

In the method according to an embodiment of the present invention for solving the technical problem, the ionospheric passage point detection unit analyzes a communication result in which at least one observation reference station receiver receives a satellite navigation signal from a plurality of navigation satellites, and the An ionospheric passage point determination step of grasping ionospheric passage points located between the navigation satellites and the receiver at a predetermined reference altitude based on the analyzed result; A multidimensional vector calculation step of calculating, by the multidimensional vector calculation unit, information on a relative distance and direction between a disturbance source point on the reference altitude where an ionospheric disturbance signal is generated and the identified ionospheric passage point as one multidimensional vector; A weight application step of calculating, by a weight application unit, a weight for the disturbance source point based on the location information of the disturbance source point, and applying the calculated weight to the multidimensional vector; And a disturbance timing point determination step of determining, by the disturbance timing point determination unit, an ionospheric disturbance generated at the disturbance source point from a result of analyzing the applied multidimensional vector.

A system according to another embodiment of the present invention for solving the above technical problem analyzes a communication result in which at least one observation reference station receiver receives a satellite navigation signal from a plurality of navigation satellites, and based on the analyzed result. An ionospheric passage point grasping unit for grasping ionospheric passage points located between the navigation satellites and the receiver on a reference altitude set at a predetermined reference altitude; A multidimensional vector calculation unit that calculates information on a relative distance and direction between a disturbance source point at which the ionospheric disturbance signal is generated on the reference altitude and the identified ionospheric passage point as one multidimensional vector; A weight application unit that calculates a weight for the disturbance source point based on the location information of the disturbance source point and applies the calculated weight to the multidimensional vector; And a disturbance time point determination unit configured to determine ionospheric disturbance generated at the disturbance source point from a result of analyzing the applied multidimensional vector.

An embodiment of the present invention may provide a computer-readable recording medium storing a program for implementing the method.

Existing ionospheric disturbance detection techniques have limitations in detecting weak ionospheric disturbances caused by ground causes, because the main tendency observed at a single ionospheric passage point is removed, but the present invention has limitations in detecting weak ionospheric disturbances. By incorporating the measurements of the ionosphere at a point, we can improve the observational gain for ionospheric disturbances occurring in specific directions.

In addition, since remote monitoring of the ionosphere is applied to situations such as earthquakes and underground nuclear explosions, if the present invention is used to direct the direction of the event to be monitored, the utilization of remote monitoring of the ionosphere using satellite navigation is significantly improved. It is expected to be able to do it.

1 is a diagram showing an ionospheric passage point and an amount of ionospheric delay at the corresponding point.
2 is a diagram for describing a method of detecting fine ionospheric disturbance according to numerical differentiation.
FIG. 3 is a view for explaining a point of difficulty in distinguishing the disturbance of the micro-ionospheric layer caused by an event occurring on the ground in the method of detecting micro-ionospheric disturbance according to FIG.
4 is a view for explaining a process of integrating ionospheric measurements at ionospheric passage points observed by a plurality of observation reference stations from a plurality of navigation satellites.
5 is a diagram illustrating an example of a conceptual diagram for a satellite array antenna technology applied in an antenna system.
6 is a block diagram showing an example of a system for processing the directionality of a plurality of satellite navigation ionosphere measurements according to the present invention.
7 is a diagram schematically illustrating a process of obtaining location information of ionospheric passage points on a reference elevation.
8 shows a diagram necessary to model the received signal at the ionospheric passage point.
9 shows the structure of a general beamformer.
10A and 10B are diagrams for explaining another example of improving or attenuating an observation gain of a signal incident from a specific direction according to the present invention.
11 is a diagram showing an example for explaining a spatial signal processing technique in which the observation gain in the east direction is amplified and the observation gain in the north direction is attenuated.
12 shows an example of a simulation result of an observed value of an ionosphere disturbance received at each ionosphere pass point of FIG. 10B.
13 shows another example of a simulation result of an observed value of an ionospheric disturbance received at each ionospheric pass point of FIG. 10B.
14 is a diagram showing a flowchart of an example of a method of processing the directionality of an ionospheric measurement value according to the present invention.

Since the present invention can apply various transformations and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. Effects and features of the present invention, and a method of achieving them will be apparent with reference to the embodiments described later in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, the same or corresponding components are assigned the same reference numerals, and redundant descriptions thereof will be omitted. .

In the following embodiments, terms such as first and second are used for the purpose of distinguishing one component from other components, not for a limiting meaning.

In the following embodiments, a singular expression includes a plurality of expressions unless the context clearly indicates otherwise.

In the following embodiments, the terms include or have means that the features or elements described in the specification are present, and do not preclude the possibility of adding one or more other features or components in advance.

When a certain embodiment can be implemented differently, a specific process order may be performed differently from the described order. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order opposite to the described order.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

2 is a diagram for describing a method of detecting fine ionospheric disturbance according to numerical differentiation.

Referring to FIG. 2, the ionosphere observation results from 1 o'clock to 5 o'clock are shown as data observed in China, and based on the information on the underground nuclear test revealed by basic research by seismometers and related experts, 2 o'clock in FIG. It can be seen that the disturbance of the ionosphere generated in is confirmed by an underground nuclear test.

In order to detect minute disturbances in the ionosphere due to earthquakes, chemical explosions, and underground nuclear tests using satellite navigation, the main tendency such as daily change of the ionosphere is removed from the ionosphere measurements using satellite navigation, and irregular characteristics due to specific disturbance sources are determined. Should be detected. The present invention does not depend on the technique itself for removing the main tendency, and more specifically, proposes a technique applied to the ionospheric observation value after the tendency is removed.

In addition, for simplicity of the equation, it is assumed that GPS signals are processed, but all of them can be used in the same way through only the frequency conversion process for a satellite navigation signal source other than GPS.

The carrier measurement values at the GPS L ₁ , L _{2, and} 2 frequencies obtained from the satellite navigation receiver can be modeled as in Equations 1 and 2.

Equations 1 and 2 refer to equations used for modeling a carrier measurement value at two frequencies greater than or equal to L ₁ and L ₂ obtained from a satellite navigation receiver. In Equations 1 and 2, subscript 1 denotes an L ₁ band frequency, subscript 2 denotes an L ₂ band frequency, and superscript i denotes an arbitrary visible satellite. In addition, in Equations 1 and 2, L is the carrier measurement, d is the actual distance between the reception and the satellite, δR is the scalar distance measurement error caused by the three-dimensional position error of the satellite, b is the satellite clock error, and I is the ionosphere delay. Error, T is convective layer delay error, B is receiver clock error, λ is carrier phase, N is unspecified number, and ε is measurement noise. The estimated gradient ionization layer delay may be calculated by differentiating the double frequency measurements of Equations 1 and 2.

는 경사전리층 지연 추정값, f는 주파수, bias는

에 해당하는 값으로 임의의 바이어스 상수값을 의미한다. 경사전리층 지연 추정값에는 경사전리층 지연량, 위성 및 수신기의 하드웨어 지연, 측정 잡음 등이 포함되어 있다. Equation 3 represents an equation for the estimated delay of the gradient ionosphere. In Equation 3

Is the gradient ionospheric delay estimate, f is the frequency, and the bias is

It is a value corresponding to and means an arbitrary bias constant value. The gradient ionization layer delay estimate includes the gradient ionization layer delay amount, satellite and receiver hardware delay, and measurement noise.

Therefore, in order to estimate the amount of delay in the gradient ion layer from the estimated value of the gradient ion layer, the hardware delay and measurement noise of the satellite and receiver must be removed. The method of removing hardware delay and measurement noise of satellites and receivers is described in Ionospheric monitoring by the Global Positioning Satellite System (GNSS), Jihye Park, Ph.D.Dissertation, Ohio State University, 2012 or, GPS discrimination of traveling ionospheric disturbances from underground nuclear explosions and earthquakes, Jihye Park et.al., NAVIGATION: Journal of The Institute of Navigation, Vol 61, No.2, Summer 2014), so a detailed description is provided herein. It will be omitted, and the estimate of the gradient ionization layer delay assumes that the hardware delay and measurement noise have already been removed.

Since the gradient ionization layer delay amount has a tendency to be proportional to the gradient total electron quantity (STEC) and frequency, this proportional relationship can be expressed as Equation 4 below.

는 i번째 위성에서 관측한 경사총전자량, f₁은 L₁ 대역 주파수,

는 경사전리층 지연 추정값을 의미한다. 지상의 관측기준국의 수신기가 위성항법신호를 수신하고, 수신된 위성항법신호를 분석한 관측기준국의 메인프로세서(main processor)는, 수학식 4를 통해 시간별 경사총전자량(STEC)을 산출할 수 있다.Equation 4 is an equation representing the total amount of inclined electrons observed by the i-th satellite with respect to the GPS L ₁ frequency. In Equation 4

Is the total gradient of electrons observed from the i-th satellite, f ₁ is the frequency of the L ₁ band,

Denotes the estimated delay of the gradient ionosphere. The receiver of the ground observation reference station receives the satellite navigation signal, and the main processor of the observation reference station, which analyzes the received satellite navigation signal, calculates the slope total electron quantity (STEC) by time through Equation 4 can do.

Subsequently, the main processor differentiates the total amount of gradient electrons by a third order at fixed time intervals as in Equations 5 to 7.

Equations 5 to 7 are equations sequentially showing the result of dividing the total amount of gradient electrons into a third order value at 30 second intervals, which are fixed time intervals. If the ionosphere disturbance data due to an actual ground cause is applied to Equation 7, the result as shown in FIG. 2 can be obtained.

FIG. 3 is a view for explaining a point of difficulty in distinguishing the disturbance of the micro-ionospheric layer caused by an event occurring on the ground in the detection method of the micro-ionospheric disturbance according to FIG. 2 and the purpose of the present invention.

Referring to FIG. 3, it can be seen that the detection result of the ionospheric disturbance according to FIG. 2 is a result shown from 0 o'clock to 6:30 o'clock by further extending the time range. In FIG. 3, in addition to the ionospheric disturbance that occurred at 2 o'clock already described in FIG. 2, it is confirmed that there is a significant ionospheric disturbance between 0 o'clock and 1 o'clock and 6 o'clock to 6:30 o'clock. According to FIG. 3, it can be confirmed that disturbances of a larger magnitude than the ionosphere disturbance observed at 2 o'clock occurred several times before 1 o'clock and after 6 o'clock, and at that time, there were no specific events disturbing the ionosphere on the ground. Considering the point, it is assumed that it is not due to the cause of the ground, but due to irregular changes in the ionosphere that can occur routinely due to changes in the Earth's magnetic field or characteristics of solar activity (such as the period of sunspot movement).

As described in Fig. 3, according to the ionosphere disturbance detection technique using a method of simply applying numerical differentiation to the ionosphere measurements, a single satellite navigation observation reference station applies a method of extracting irregular changes by removing the main tendency of the ionosphere. In addition, the magnitude of the ionosphere disturbance obtained only by this method is very weak, and may be confused with disturbances other than the cause of the ground (for example, disturbances observed between 0 and 1 o'clock in FIG. 3 and after 6 o'clock). . As above, it is possible to check the fine disturbance of the ionosphere caused by ground causes by calculating the gradient total electron quantity (STEC) from the satellite navigation signal received by the receiver of the single satellite navigation observation reference station. Since ionospheric disturbances are also observed, there is a limit to post-processing in the field using the ionosphere disturbance detection technique using satellite navigation.

4 is a view for explaining a process of integrating ionospheric measurements at ionospheric passage points observed by a plurality of observation reference stations from a plurality of navigation satellites.

Referring to FIG. 4, the present invention includes a Controlled Reception Pattern Antenna (CRPA) unit 410 for receiving a satellite navigation signal from the navigation satellites when a plurality of navigation satellites exist, and the reception pattern It can be seen that a structure in which the receiver 430 of the observation reference station receives the ionospheric measurements calculated from the control antenna unit 410 is used.

When explaining the difference between the method according to Figs. 2 and 3 and the method according to Fig. 4, the method according to Figs. 2 and 3 described above is the ionosphere disturbance by a single observation reference station receiving a satellite navigation signal from a navigation satellite. While the value is calculated, the method according to FIG. 4 has a plurality of navigation satellites and a plurality of observation reference stations, and a virtual plane between the navigation satellites and the observation reference station (meaning the reception pattern control antenna unit 410). The ionosphere disturbance value is considered to exist and is transmitted to the receiver 430 of the observation reference station on the ground after the ionospheric disturbance value is calculated on the plane, and finally the ionospheric disturbance value with improved observation gain is obtained.

According to the method according to FIG. 4, it is possible for a plurality of observation reference stations to integrate the ionosphere measurements at a plurality of ionospheric passage points observed from a plurality of navigation satellites, and thus the observation gain (detection) of the ionosphere disturbance caused by a ground cause of interest. Gain) can be improved. Specifically, the present invention improves the observation gain by selectively synchronously integrating ionospheric disturbances coming from a specific direction in the process of integrating a plurality of ionosphere observations in order to improve the observational gain of ionospheric disturbance, and Ionospheric disturbance allows for asynchronous integration.

5 is a diagram illustrating an example of a conceptual diagram for a satellite array antenna technology applied in an antenna system.

5 is a diagram schematically showing a concept of applying phase control to signals received from each antenna by using a plurality of antennas as reception points. Among the phased array antenna technology, the configuration utilized as a part of the present invention is to control the phase of the RF signal received from each antenna element by using an array antenna composed of a plurality of antennas to control the gain of the RF signal received in a specific direction. It improves and attenuates the gain of the signal received in other directions. In the present invention, in order to combine the phased array antenna technology as described above with a technology for improving the observation gain of the ionospheric disturbance value obtained through a satellite navigation signal, the ionospheric measurement value at a reference altitude through a series of equations described below is elaborated. We propose a modeling and application method.

Each antenna element of the phased array antenna in the antenna system is a device that receives an actual signal, and its position is fixed, but from the viewpoint of applying to the ionosphere observation as in the present invention, it is not the satellite navigation receiving antenna of the satellite navigation observation reference station. The passing point must be set as the destination point. In addition, each antenna element in FIG. 5 corresponds to each of the ionospheric passage points in FIG. 1, and an actual satellite navigation signal is received by a reception antenna of a satellite navigation observation reference station installed on the ground, but in the present invention, the amount of ionospheric delay is observed. It is distinguished from using the existing array antenna technology in that it defines the ionospheric passage point as the receiving point.

Since the ionospheric passage point continuously moves as the satellite moves, the plurality of ionospheric passage points have a characteristic that changes every hour, and the physical quantity observed at the ionosphere passage point is the ionosphere delay amount or the total amount of free electrons. In order to detect the micro-mobile ionospheric disturbance, the present invention performs an integrated process targeting the ionospheric measurement values from which the main tendency is removed, and in order to perform the processing on the ionospheric measurements from which the main tendency is removed, the above equation 1 to Equation 7 may be used.

6 is a block diagram showing an example of a system for processing the directionality of a plurality of satellite navigation ionosphere measurements according to the present invention.

6, the directivity processing system 600 according to the present invention includes an ionospheric pass point determination unit 610, a multidimensional vector calculation unit 630, a weight application unit 650, and a disturbance time point determination unit 670. I can see that.

The ionospheric passage point determination unit 610 analyzes the communication result of receiving a satellite navigation signal from at least one observation reference station receiver from a plurality of navigation satellites, and the navigation satellites and the receiver at a preset reference altitude based on the analyzed result. Identify the ionosphere transit points located in between.

The present invention is to improve the directivity gain with respect to the ionosphere measurement, and defines the ionosphere passage point observed by the plurality of navigation satellites at the ionosphere concentration altitude of 350 km. Therefore, the reference altitude preset in the ionospheric passage point determination unit 610 may be 350 km above sea level.

7 is a diagram schematically illustrating a process of obtaining location information of ionospheric passage points on a reference elevation.

In FIG. 7, the amount of ionospheric delay is observed on a path connecting the satellite and the observation reference station in a straight line, and the observed amount of delay is referred to as a slant delay. In the present invention, in order to integrate and process a plurality of ionospheric observations, the oblique ionospheric layer delay amount is converted into a vertical ionospheric layer delay amount. Accordingly, the gradient ionization layer delay amount calculated according to Equation 3 may be converted into a gradient total electron quantity STEC according to Equation 4, and may be converted into a vertical ionization layer delay amount VTEC (vertical TEC) according to Equation 8 to be described later. Referring to FIG. 7, slant delay and vertical delay have an angular deviation as much as β, and β may be determined when Rr, Rs, h, and el are given as shown in the equation shown in FIG. 7.

Equation 8 represents an equation for converting the total amount of gradient electrons into the amount of vertical ionospheric delay. In Equation 8, STEC is the total gradient of electrons, R _r is the distance from the center of the Earth to the observation reference station on the ground, and is the same as the radius of the Earth, R _s is the distance from the center of the Earth to the ionospheric passage point, and el is It means the elevation angle of the navigation satellite measured by the observation reference station. In Equation 8, h is a distance difference between the ground and the concentration of the ionosphere, which is 350 km, and i is regarded as a symbol for counting the ionosphere passage points individually.

When the navigation satellite and the observation reference station exist as shown in FIG. 7, the ionospheric passage point determination unit 610 determines the location information and the number of ionospheric passage points located between the navigation satellites and the receiver of the observation reference station. The location information of the children specifically refers to the latitude and longitude of the ionosphere passing points.

Equations 9 to 11 are math used by the ionospheric pass point determination unit 610 to calculate location information (latitude, longitude) of the ionospheric pass points when there are a plurality of navigation satellites and an observation reference station in FIG. This is an example of an equation. Referring to FIG. 7, in Equations 9 to 11, φ _r and λ _r are the latitude and longitude (degree units) of the observation reference station, respectively, and φ _pp and λ _pp are the latitude and longitude of the ionospheric passage point. Unit), and Az means the azimuth angle of the navigation satellite at the observation base station. In addition, in Equation 11, ψ _pp denotes the angular deviation between the observation reference station and the navigation satellite, based on the center of the earth.

The number of ionosphere crossing points may vary depending on the number of navigation satellites and the number of reference stations. For example, the number of navigation satellites may be 4, the number of observation reference stations on the ground that receive satellite navigation signals from the navigation satellites may be 3, and the number of ionosphere transit points may be 12.

The VTEC value calculated according to Equation 8 can be used as a measurement value capable of observing irregular changes in the ionosphere since the main tendency is removed by various methods. As an example, the numerical differentiation method according to Equations 5 to 7 may be applied to VTEC as it is. That is, since the method of removing the main tendency from the ionospheric measurement value (VTEC) can be independently applied, the VTEC from which the main tendency has been removed can be defined as δVTEC and used for subsequent calculation processing.

8 shows a diagram necessary to model the received signal at the ionospheric passage point.

More specifically, FIG. 8 schematically shows that the M ionospheric passage points by four navigation satellites and three satellite navigation observation reference stations are located on an imaginary plane above the ionosphere concentration altitude of 350 km. Here, M may be 12, and may vary depending on the number of navigation satellites and observation reference stations.

Each r _i (i=1, 2, 3, 4, ... M) in FIG. 8 represents the location of the ionosphere passing point generated at an altitude of 350 km on the radio transmission path of the navigation satellite observation reference station receiver and the navigation satellite. it means. The latitude φ _pp and the longitude λ _pp of the ionospheric passage point can be calculated through Equations 9 and 10. In the present invention, the concentration of the ionosphere at an altitude of 350 km above is assumed as a regional plane, and a regional coordinate system xy for a two-dimensional plane is defined. Therefore, the latitude and longitude coordinates of the ionospheric passage point can be converted into an xy coordinate system.

Equation 12 represents an equation for the result of converting the latitude and longitude coordinates of the ionospheric passage point into the xy coordinate system. In Equation 12, a _x and a _y are unit vectors for the xy coordinate system, respectively, and r _x and r _y indicate a size value for each coordinate.

Referring to FIG. 8, assuming a point 350 km above the ionosphere disturbance origin, it can be seen that the location of the disturbance origin is represented by a two-dimensional vector u. The 2D vector u for the ionospheric disturbance source may be expressed as Equation 13 for the incident angle θ.

In Equation 13, u denotes a two-dimensional vector of the origin of the ionospheric disturbance in the x-y coordinate system, and θ denotes the incidence angle of the origin of the ionospheric disturbance with respect to the origin of the x-y coordinate system.

Next, if the mobile ionospheric disturbance transmitted in the form of waves on the ionosphere by the ionospheric disturbance source is defined as the carriers of the input signals s(t) and wc, the reference signal x(t) received at an arbitrary reference ionospheric pass point is It can be modeled as in Equation 14.

Based on Equation 14, the ionospheric signal xi(t) received at an arbitrary i-th ionospheric pass point r _i can be modeled as in Equation 15.

는 전리층통과점의 위치에 따른 전리층 교란의 도달시간의 차이를 의미한다. 일반적인 배열안테나 기술에 따르면, 전리층 교란의 파동 s(t)를 단일 파동에 의한 협대역 신호라고 가정하여, s(t)와 s(t-τ)가 같다고 단순화시켜서, 반송파에 의한 지연값만을 고려하지만, 본 발명에서 대상으로 하는 전리층 교란의 파동은 반송파가 존재하지 않고, 전리층통과점간의 거리와 교란 발생 도달 거리를 고려할 때, s(t)를 협대역 신호로 가정할 수 없다. 그러므로, 반송파 주파수 w_c를 0으로 보고, s(t)의 파동을 정현파로 가정하면 수학식 15는 수학식 16과 같이 정리할 수 있다.In Equation 15, vTID refers to the propagation speed of a wave by mobile ionospheric disturbance in the ionosphere,

Denotes the difference in arrival time of the ionosphere disturbance according to the location of the ionosphere passage point. According to the general array antenna technology, it is assumed that the ionospheric disturbance wave s(t) is a narrowband signal by a single wave, simplifies that s(t) and s(t-τ) are the same, and only considers the delay value due to the carrier wave. However, the wave of ionospheric disturbance targeted by the present invention does not have a carrier, and s(t) cannot be assumed as a narrow-band signal when considering the distance between the ionospheric passage points and the distance to which the disturbance occurs. Therefore, assuming that the carrier frequency w _c is 0 and the wave of s(t) is a sine wave, Equation 15 can be summarized as Equation 16.

In Equations 16 and 17, w _s denotes the frequency of the ionospheric disturbance wave, and a _i (θ) is defined as an array steering vector for each passing point when the ionospheric passage point is assumed to be each array antenna. I can. If Equation 17 is expressed as a vector signal for M passing points, it is as Equation 18.

In addition, by further expanding Equation 18, considering the wave generated by changes in the solar activity and magnetic field in addition to the wave caused by the ionosphere disturbance caused by the ground cause of interest, the ionosphere disturbance source s(t) A determinant including K signals s _i (t) and i = 1 to K arriving in K directions simultaneously, considering K random sources other than a single source, can be defined as in Equation 19. .

In Equation 19, A(θ) may be defined as an array steering vector composed of ionospheric passing points, and may be expressed as a multidimensional vector as shown in Equation 20. Finally, considering the reception noise n(t) in Equation 19, it can be seen that the modeling of the array received signal received at the ionospheric passage point of the reference altitude is completed as shown in Equation 21.

Hereinafter, description of FIG. 6 will be followed again.

The multidimensional vector calculation unit 630 converts information on the relative distance and direction between the source of the disturbance at which the ionospheric disturbance signal is generated and the ionospheric passage point grasping unit 610 on the reference altitude as one multidimensional vector. Calculate. Here, the multidimensional vector calculated by the multidimensional vector calculating unit 630 means an array steering vector composed of the ionospheric passing points as shown in Equation 20.

The weight application unit 650 calculates a weight for the disturbance source point based on the location information of the disturbance source point, and applies the calculated weight to the multidimensional vector.

Hereinafter, a process of calculating the weight for the disturbance source point by the weight application unit 650 will be described.

The present invention uses a method that proposes modeling of an array antenna assuming that the ionospheric pass points of Equations 12 to 21 are used as the receiving antenna and the ionospheric disturbance wave is the incident signal source. In accordance with the present invention, after the modeling is completed as shown in Equation 21, by applying various array antenna algorithms to the result of the modeling is completed, the observed value of the ionospheric disturbance observed at the ionospheric passage point is improved in a specific direction. Through this, it is possible to clearly identify the point in time when the ionosphere disturbance caused by a specific cause on the ground occurred.

As an example, a process of applying a conventional beamformer to a result modeled as in Equation 21 will be described.

9 shows the structure of a general beamformer.

In FIG. 9, the weight application unit 650 adjusts the weight w for each received signal in Equation 21 so that the output of the signal incident in a specific direction is maximized.

First, the weight application unit 650 calculates a weight to be applied to each received signal. The weight application unit 650 adjusts the size of w to improve the gain in a specific direction, and determines the steering of the beamformer shown in FIG. 8 in order to adjust the size of w.

Equation 22 represents a result signal in which the modeling of the received signal of the ionospheric passage point is completed as shown in Equation 21 and the observation gain for a specific direction is improved. As a method of determining the weight vector w, various beamforming techniques such as the aforementioned conventional beamformer and a minimum variance beam former may be used. In the present invention, the weight vector w through such a beamforming technique It is possible to determine and improve the observation gain in a specific direction because the modeling was performed under the assumption that the point 350km above the sky was set as the reference altitude, and the ionospheric passage point was assumed to be an array antenna lying in the xy coordinate system of the reference altitude.

The weight application unit 650 applies the calculated weight to the multidimensional vector, thereby calculating a final signal y(t) for analyzing the result of the ionospheric disturbance.

Subsequently, the disturbance time point determination unit 670 analyzes the multidimensional vector to which the weight is applied, and determines the ionospheric disturbance generated at the disturbance source point from the analysis result.

As an example, the weight application unit 650 uses a conventional beamformer to maximize the output of the disturbing source signal incident in a specific direction θ, and calculates the optimal weight w to maximize the signal-to-noise ratio (SNR). It can be determined through Equation 23.

Equation 23 is an equation for calculating the weight of the disturbing source signal incident in a specific direction θ by the weight application unit 650 using a conventional beamformer technique. When Equation 23 is applied to Equation 22, the final signal y In (t), a result of improved observation gain in a specific direction θ can be observed. That is, the weight application unit 650 may calculate the weight w based on the angle (incidence angle) information measured based on the origin in the 2D coordinate system in which the ionospheric passage points exist.

Referring to FIG. 3 as an example, the observation gain of the ionospheric disturbance at 2 o'clock is significantly improved by the weight application unit 650, which is greater than the magnitude of the ionospheric disturbance between 0 and 1 o'clock and after 6 o'clock. As a result, the disturbance time point determination unit 670 can more clearly distinguish the ionosphere disturbance caused by the ground. In the present invention, the disturbance time point determination unit 670 is able to clearly distinguish ionospheric disturbances caused by ground causes, considering a plurality of ionospheric passage points on the reference altitude as array antennas, and modeling for applying the array antenna technique In addition to performing the modeling result, the weight w is defined as a function of the incident angle θ and the final signal y(t) is calculated as shown in Equation 22 based on the weight.

10A and 10B are diagrams for explaining another example of improving or attenuating an observation gain of a signal incident from a specific direction according to the present invention.

First, FIG. 10A intuitively shows the point of passage of the ionosphere for one of the ground observation reference stations and any navigation satellite. Specifically, in FIG. 10A, the eight black circles located on the Korean peninsula mean eight ground observation reference stations located on the Korean peninsula, and the blue stars located northwest of the Korean Peninsula represent the ionosphere passage points for the designated navigation satellites. do. In FIG. 10A, for convenience of explanation, only one navigation satellite and eight observation reference stations communicating with the navigation satellite have been described, but in a situation where the present invention is actually implemented, navigation from a plurality of navigation satellites and each of the navigation satellites There may be a number of ionospheric pass points by a plurality of reference stations receiving signals.

In the present invention, since each ionosphere passing point is assumed to be a sensor that observes ionospheric disturbance, after the ionosphere passing point existing at a specific height between the navigation satellite and the ground observation reference station is specified, after that, the ground observation reference station is excluded. Signal processing is performed using only the ionospheric passage point, and the ionospheric passage point of FIG. 10A may be illustrated as shown in FIG. 10B using a local coordinate system.

FIG. 10B is a diagram illustrating the conversion of the ionospheric passage points in FIG. 10A into a regional coordinate system. According to FIG. 10A, it can be seen that the eight ionospheric passage points are expressed in km in the regional coordinate system. In FIG. 10B, for convenience of explanation, only one navigation satellite and eight observation reference stations communicating with the navigation satellite were described, but in a situation in which the present invention is actually implemented, the number of navigation satellites and the ground observation standard as shown in FIG. It will be obvious to those skilled in the art that the number of ionospheric passage points multiplied by the number of stations can be expressed in a regional coordinate system.

In the system for directivity processing of a plurality of satellite navigation ionosphere measurements according to the present invention, when the ionospheric passage point is set through a local coordinate system as shown in FIG. 10B, the modeling of Equations 12 to 21 is applied to the set ionospheric passage point. . The directivity processing system of a plurality of satellite navigation ionosphere measurements according to the present invention amplifies the observation gain of a signal incident from a specific direction (eg, direction A), and amplifies the observation gain of a signal incident from another specific direction (eg, direction B). An array antenna algorithm for attenuating the observed gain of the signal is applied, and the conventional beamformer of Equation 23 has been described as an example as described above.

11 is a diagram showing an example for explaining a spatial signal processing technique in which the observation gain in the east direction is amplified and the observation gain in the north direction is attenuated.

More specifically, FIG. 11 shows a technique of amplifying the observation gain in the east direction corresponding to an azimuth angle of 90 degrees and attenuating the observation gain in the north direction corresponding to an azimuth angle of 0 degrees. Is shown. In FIG. 11, it can be seen that the reception gain of the azimuth angle of 0 degrees differs by about 25 dB compared to the azimuth angle of 90 degrees (the gain is 0 dB when the azimuth angle is 90 degrees, and the gain is -25 dB when the azimuth angle is 0 degrees). In the present invention, as described above, by applying various beamforming algorithms such as MVDR in addition to the conventional beamformer, an observation gain for a signal in a specific direction can be amplified or attenuated, and the ionospheric disturbance to be specified according to the applied algorithm can be amplified or attenuated. You will be able to see more clearly.

12 shows an example of a simulation result of an observed value of an ionosphere disturbance received at each ionosphere pass point of FIG. 10B.

More specifically, Figure 12 assumes that the disturbance observed in the 1000 to 1200th samples is received in the east direction (azimuth angle 90 degrees), and the disturbance observed in the 200 to 400th samples is received in the north direction (azimuth angle 0 degrees). This is the result calculated in one state.

Referring to FIG. 12 in connection with FIG. 3, first, the ionospheric disturbance at the point that the user wants to observe is the ionospheric disturbance at the point of view 2 in FIG. 3, and at the same time, the ionospheric disturbance received from the east direction of FIG. 12. In addition, the ionosphere disturbance acting as an obstacle in observing the ionosphere disturbance at the point the user wants to observe is the ionosphere disturbance between 0 and 1 o'clock in FIG. 3 or after 6 o'clock, and at the same time in the north direction of FIG. It is the incoming ionosphere disturbance. 3 and 12 are situations observed at a single ionospheric passage point. In this case, according to the conventional method, the user can observe the ionosphere disturbance at the point and direction to be observed from the output result of the system and the ionosphere disturbance acting as an obstacle. Cannot be distinguished from each other.

13 shows another example of a simulation result of an observed value of an ionospheric disturbance received at each ionospheric pass point of FIG. 10B.

More specifically, FIG. 13 shows the results of amplifying the ionospheric disturbance received in the east direction and attenuating the ionospheric disturbance received in the north direction by applying the present invention. FIG. 13 is a result of applying the conventional beamforming algorithm described in FIG. 11 by integrating all observations of ionospheric disturbance received at the eight ionospheric passage points of FIG. 10B. In FIG. 12, the 200 to 400th samples (north direction) and Not only the 1000 to 1200th samples (east direction) cannot be distinguished from each other, the size of the 200th to 400th samples (north direction) is larger than that of the 1000th to 1200th samples (east direction), but in FIG. As the amplification or attenuation of the observed gain for is applied, it can be seen that compared to other samples, only the size of the 1000th to 1200th sample (eastward direction) differs from that of the other samples.

The beamformer technique applied in the communication system estimates the angle θ at which the maximum signal gain is obtained in consideration of an arbitrary direction, but the present invention needs to improve the observation gain by aiming at the ionosphere disturbance caused by a specific cause. Therefore, it is superior to the conventional micro-ionospheric disturbance detection technique in that the value of θ is set as a region of interest to improve (amplify) the observation gain for a specific ionosphere disturbance.

14 is a diagram showing a flowchart of an example of a method of processing the directionality of an ionospheric measurement value according to the present invention.

14 may be implemented by the system 600 for directivity processing of ionospheric measurements according to FIG. 6, and will be described below with reference to FIG. 6, and descriptions overlapped with those described in FIG. 6 will be omitted.

The ionospheric passage point determination unit 610 identifies location information of a plurality of ionospheric passage points on the reference elevation (S1410).

The multidimensional vector calculation unit 630 calculates information on the distance and direction between the identified ionospheric passage points and the ionospheric disturbance point as one multidimensional vector (S1430).

The weight application unit 650 calculates a weight for the disturbance source point based on the location information of the disturbance source point, and applies the calculated weight to the multidimensional vector calculated in step S1430 (S1450).

The disturbance time point determination unit 670 determines the ionospheric disturbance generated at the source of disturbance from the result of analyzing the multidimensional vector to which the weight is applied (S1470), where the ionospheric disturbance determined by the disturbance time point determination unit 670 is, It may be a concept including both the time point and the magnitude of the occurrence of the magnitude of the ionosphere disturbance.

Existing ionospheric disturbance detection techniques have limitations in detecting weak ionospheric disturbances caused by ground causes, because the main tendency observed at a single ionospheric passage point is removed, but the present invention has limitations in detecting weak ionospheric disturbances. By incorporating the measurements of the ionosphere at a point, we can improve the observational gain for ionospheric disturbances occurring in specific directions.

The embodiment according to the present invention described above may be implemented in the form of a computer program that can be executed through various components on a computer, and such a computer program may be recorded in a computer-readable medium. In this case, the medium is a magnetic medium such as a hard disk, a floppy disk, and a magnetic tape, an optical recording medium such as a CD-ROM and a DVD, a magneto-optical medium such as a floptical disk, and a ROM. , A hardware device specially configured to store and execute program instructions, such as RAM, flash memory, and the like.

Meanwhile, the computer program may be specially designed and configured for the present invention, or may be known and usable to those skilled in the computer software field. Examples of the computer program may include not only machine language codes produced by a compiler but also high-level language codes that can be executed by a computer using an interpreter or the like.

The specific implementations described in the present invention are examples and do not limit the scope of the present invention in any way. For brevity of the specification, descriptions of conventional electronic configurations, control systems, software, and other functional aspects of the systems may be omitted. In addition, the connection or connection members of the lines between the components shown in the drawings exemplarily represent functional connections and/or physical or circuit connections. Connections, or circuit connections, may be represented. In addition, if there is no specific mention such as “essential” or “importantly”, it may not be an essential component for the application of the present invention.

In the specification of the present invention (especially in the claims), the use of the term “above” and a similar reference term may correspond to both the singular and the plural. In addition, when a range is described in the present invention, the invention to which an individual value falling within the range is applied (unless otherwise stated), and each individual value constituting the range is described in the detailed description of the invention. Same as Finally, if there is no explicit order or contrary to the steps constituting the method according to the present invention, the steps may be performed in a suitable order. The present invention is not necessarily limited according to the order of description of the steps. The use of all examples or illustrative terms (for example, etc.) in the present invention is merely for describing the present invention in detail, and the scope of the present invention is limited by the above examples or illustrative terms unless limited by the claims. It does not become. In addition, those skilled in the art can recognize that various modifications, combinations, and changes may be configured according to design conditions and factors within the scope of the appended claims or their equivalents.

Claims (9)

The ionospheric pass point determination unit analyzes a communication result in which at least one observation reference station receiver receives a satellite navigation signal from a plurality of navigation satellites, and the navigation satellites and the receiver at a reference altitude preset based on the analyzed result An ionospheric passage point identification step of identifying the ionospheric passage points located between;
A multidimensional vector calculation step of calculating, by the multidimensional vector calculation unit, information on a relative distance and direction between a disturbance source point on the reference altitude where an ionospheric disturbance signal is generated and the identified ionospheric passage point as one multidimensional vector;
A weight application step of calculating, by a weight application unit, a weight for the disturbance source point based on the location information of the disturbance source point, and applying the calculated weight to the multidimensional vector; And
A disturbance timing point determination step of determining, by a disturbance timing point determination unit, an ionospheric disturbance generated at the disturbance source point from a result of analyzing the applied multidimensional vector; Including,
The ionospheric disturbance determined by the disturbance point determination unit,
At least one of a time when the disturbance occurs at the source of disturbance and a magnitude of the ionospheric disturbance generated at the time point, the directivity processing method of a plurality of satellite navigation ionosphere measurements. The method of claim 1,
The location information of the ionospheric passage point,
A straight line connecting the navigation satellite and the receiver and a virtual plane on the reference altitude meet
Directional processing method of a plurality of satellite navigation ionosphere measurements, characterized in that information on the latitude and longitude of a location. The method of claim 1,
The reference altitude is,
Directivity processing method of a plurality of satellite navigation ionosphere measurements, characterized in that 350 km above sea level. The method of claim 1,
The weight application step,
The directivity processing method of a plurality of satellite navigation ionospheric measurements, characterized in that the weight is calculated with angle information measured based on an origin in a two-dimensional coordinate system in which the ionospheric passage points exist. A computer-readable recording medium storing a program for executing the method according to any one of claims 1 to 4. At least one observation reference station receiver analyzes a communication result of receiving a satellite navigation signal from a plurality of navigation satellites, and an ionospheric passage point located between the navigation satellites and the receiver on a reference altitude preset based on the analyzed result An ionosphere crossing point grasping unit;
A multidimensional vector calculation unit that calculates information on a relative distance and direction between a disturbance source point at which the ionospheric disturbance signal is generated on the reference altitude and the identified ionospheric passage point as one multidimensional vector;
A weight application unit that calculates a weight for the disturbance source point based on the location information of the disturbance source point and applies the calculated weight to the multidimensional vector; And
Including; a disturbance time point determination unit for determining the ionospheric disturbance generated at the disturbance source from the result of analyzing the applied multidimensional vector,
The ionospheric disturbance determined by the disturbance point determination unit,
The directivity processing system of a plurality of satellite navigation ionosphere measurements, which is at least one of a time point at which the disturbance occurs at the source of disturbance and a magnitude of the ionosphere disturbance generated at the time point. The method of claim 6,
The location information of the ionospheric passage point,
A straight line connecting the navigation satellite and the receiver and a virtual plane on the reference altitude meet
Directional processing system of a plurality of satellite navigation ionosphere measurements, characterized in that information on the latitude and longitude of a location. The method of claim 6,
The reference altitude is,
A directional processing system of a plurality of satellite navigation ionosphere measurements, characterized in that 350 km above sea level. The method of claim 6,
The weight application unit,
The directivity processing system of a plurality of satellite navigation ionosphere measurements, characterized in that the weight is calculated based on angle information measured based on an origin in a two-dimensional coordinate system in which the ionospheric passage points exist.

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