KR101104452B1 - Ionosphere storm detection system and method using reference station oriented space-time differential based on gnss - Google Patents

Abstract

An ionospheric storm detection system and method using satellite navigation based reference station directed space-time difference is disclosed. The ionospheric storm detection system using space-time difference based on satellite navigation based reference station is a navigation satellite group consisting of a plurality of navigation satellites for transmitting location data using a predetermined code and navigation message, and transmits and receives the location data and is fixed. A plurality of terrestrial reference stations for transmitting position information, and a GPS receiver for transmitting and receiving the position data and the fixed position information with the navigation satellite group and the ground reference station. Therefore, it is possible to solve the problem of not detecting the ionospheric storm due to the space difference and to shorten the detection time, and also to reduce the data throughput and the time required.

GNSS, space-time differential, ionospheric storm, IONOSPHERE STORM DETECTION

Description

IONOSPHERE STORM DETECTION SYSTEM AND METHOD USING REFERENCE STATION ORIENTED SPACE-TIME DIFFERENTIAL BASED ON GNSS}

The present invention relates to an ionospheric storm detection system and method, and more particularly, to an ionospheric storm detection system and method using satellite navigation based reference station-oriented space-time difference that can solve the ionospheric storm detection problem and reduce the time required for detection. It is about.

As the spread of terminals with a single frequency navigation system and a global positioning system (GPS) has become more common, efforts are needed to reduce errors in positioning by reducing errors in observations.

However, the factors that reduce the accuracy of GPS positioning can be divided into three parts. First, the errors caused by structural factors include satellite time error, satellite position error, deflection of ionospheric and convective layers, noise, and multipath.

Secondly, there is a geometrical error due to satellite placement, and finally, SA (Selective Availability) is the biggest source of error. All of these factors potentially add up to a very large error, which is called UERE (User Equivalent Range Error). Each error varies greatly with time and place.

Here, the ground based augmentation system (GBAS) for aviation is used for reinforcing information generated using navigation satellite signals received from reference stations around the airport to support precise takeoff and landing of an aircraft. It is a satellite navigation ground reinforcement system that provides position correction information and integrity information) to users through VHF communication in real time.

Since the GBAS Category I system architecture currently uses L1 single frequency, it may not meet the system performance requirements in case of sudden error such as ionospheric storm. Indeed, in April 2000 and November 2003, ionospheric storms had an inclination of the ionospheric delay of 425 mm / km, causing the aircraft vertical position error to exceed the 10m vertical alert limit (VAL). Stable precision takeoff and landing using satellite navigation was not possible.

These special cases are very rare, but they can pose a significant risk to aircraft operations once they occur around the airport, especially when an ionospheric storm is approaching from behind the aircraft. Even higher.

In the United States, which experienced abnormal behavior of these satellite navigation systems due to the impact of ionosphere storms in the 2000s, many studies have been conducted to minimize the impact by detecting ionosphere storms in advance, and the ionosphere storm threats are mathematically modeled. A model (Ionospheric Threat Space Model) was developed. However, the results of applying the developed model to existing Code-Carrier Divergence Test (CCD) and Measurement Quality Monitoring (MQM), which are representative integrity monitoring techniques, do not satisfy the time-to-alert (TTA) requirements. In order to meet the demanding requirements of Category II / III, separate ionospheric storm detection on the aircraft was required.

An object of the present invention for solving the above-mentioned problems is an ionospheric storm detection system and method using satellite navigation based reference station-oriented space-time difference that can solve the ionospheric storm undetected problem and reduce the time required for detection according to the space difference phenomenon In providing.

Another object of the present invention is to provide an ionospheric storm detection system and method using satellite navigation-based reference station-oriented space-time difference that can provide an ionospheric storm detection technique that can satisfy time-to-alert (TTA) requirements. .

According to a preferred embodiment of the present invention for achieving the above object of the present invention, the ionospheric storm detection system using the satellite-based reference station-oriented space-time difference, a plurality of locations for transmitting position data using a predetermined code and navigation message Navigation satellite group consisting of a navigation satellite, a plurality of terrestrial reference station for transmitting and receiving the position data, and transmitting fixed fixed position information and transmitting and receiving the position data and the fixed position information with the navigation satellite group and the ground reference station It includes a GPS receiver. In this case, the GPS receiver is configured to generate a determination value through the space-time double difference between the position data and the fixed position information, and compare the determination value with a preset threshold to determine whether an ionospheric storm has occurred.

Here, the GPS receiver and the ground reference station are preferably provided to use the same positional data of the same navigation satellite group, and the selection of the reference station for receiving the fixed position information from the GPS receiver is the GPS. More preferably, it is selected according to the position of the receiver or the arrangement of the navigation satellite group.

The reference station may be selected as a reference station for receiving the position data from the same navigation satellite group as the navigation satellite group for transmitting the position data received by the GPS receiver.

In addition, the threshold value is preferably calculated in consideration of false alarm probability and degree of freedom (dof).

In addition, according to another preferred embodiment of the present invention for achieving the above object of the present invention, the ionospheric storm detection method using a satellite navigation-based reference station-oriented space-time difference is a navigation method for transmitting position data from the GPS receiver to the ground reference station Selecting a satellite group, transmitting position data using a predetermined code and a navigation message in the selected navigation satellite group, receiving the position data from the ground reference station, calculating and transmitting fixed position information Receiving the position data and the fixed position information at the GPS receiver, generating a determination value through space-time double difference between the position data and the fixed position information, and comparing the determination value with a threshold value to the ionospheric layer. Determining whether a storm has occurred.

In this case, the generating of the discrimination value may include comparing the pseudoranges with the same navigation satellite group for each of the GPS receiver and the ground reference station, and calculating the discrimination value from the compared pseudoranges. It is preferable to include.

The determining of whether the ionosphere storm is generated may further include generating the threshold value according to a false alarm probability and a degree of freedom.

According to the present invention, there is an effect that can solve the problem of not detected ionospheric storm due to the space difference phenomenon and shorten the time required for detection.

In addition, there is an advantage that can satisfy the time-to-alert (TTA) requirements.

In addition, by selecting the ground reference station 200 to be used as a user center having the GPS receiver 300 has the effect of reducing the data throughput and the time required, according to the navigation satellites such as aviation, land, sea There is an advantage that can be applied to various fields of navigation using reference station correction data.

In addition, since the Parity Vector RAIM method is used, the ionospheric storm can be detected relatively faster than the conventional sensor method regardless of the rate of change of the ionospheric delay value, and it is also applicable to the detection of the relatively slow ionostorm. There is this.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. Note that, in the following description, components that are substantially the same in structure and function and can be handled identically can be identified by the same reference numerals.

Referring to FIG. 1, an ionospheric storm detection system using satellite navigation based reference station-oriented space-time difference according to a preferred embodiment of the present invention will be described. 1 is a conceptual diagram illustrating an ionospheric storm detection system using a satellite navigation based reference station directed space-time difference according to a preferred embodiment of the present invention.

As shown here, the ionospheric storm detection system includes a navigation satellite group 100, a ground reference station 200, and a GPS receiver.

The navigation satellite group 100 includes a plurality of navigation satellites for transmitting data using a preset code and a navigation message. At this time, the navigation satellite group 100 may be provided as a navigation satellite commonly used in a global navigation satellite system (GNSS), the satellite positioning system using a satellite orbiting the orbit Refers to a system that provides location information of ground objects.

The ground reference station 200 is provided in plural to transmit and receive the position data and to transmit the fixed position information to the GPS receiver 300 which will be described later.

The GPS receiver 300 is preferably provided as a GPS terminal commonly used to transmit and receive the position data and the fixed position information with the navigation satellite group 100 and the ground reference station, but is not limited thereto. Preferably, the GPS receiver 300 may receive the position data at a single frequency, and the fixed position information may be provided using a wireless communication network.

Here, the ionospheric storm detection system generates a determination value through the space-time double difference between the position data and the fixed position information in the GPS receiver 300, and compares the determination value and a predetermined threshold value of the ionospheric storm Determine the occurrence.

Therefore, there is an effect that can solve the problem of not detected ionospheric storm due to the space difference phenomenon and shorten the time required for detection.

Here, before describing the operation of the ionospheric storm detection system, a brief description of the modeling of the ionospheric storm is as follows. 2 is an exemplary diagram for explaining the mathematical modeling of the ionosphere storm.

As shown, mathematical modeling for ionospheric storms is required to analyze, detect in advance, and minimize the effects of ionospheric storms on aircraft takeoff and landing. The Ionospheric Wave Front Model (IWFM), as shown in FIG. Suggested. The IWFM is defined by various parameters representing the shape and characteristics of the ionosphere storm. In this specification, three main parameters such as Front Width (W), Gradient (G), and Front Speed (V_front) are considered and the parameter ranges are shown in Table 1. Is the same as

Threat Parameter Min Max Step W (Km) 15 200 3-15 V_front (m / s) 0 1000 0.1-100 G (mm / km) 30 500 7.5-30 D_front (0) (km) -195 526 0.1-2 D_air (0) (km) 5 45 0.1-2 Max Delay (m) - 25 -

to be.

The parameter ranges presented here may be different from those in Korea as a result of analyzing US data.

As described above, the ionospheric storm detection system utilizes the position data received from the GPS receiver 300 and the fixed position information to generate a false alarm probability requested by a test statistic generated through space-time double difference. (False Alarm Probability) and Deviation of Freedom (DOF), etc. Compared with the threshold calculated (Threshold) to detect the ionosphere storm, Parity Vector RAIM method is basically adopted for satellite identification.

Here, the comparison operation between the determination value and the threshold value will be described in more detail with reference to an example in an aircraft.

In general, in the ground system of GBAS, reinforcement information is broadcast to the aircraft through the VDB antenna, which reaches about 45km. The difference in pseudo distance from the ground system when the aircraft first receives the reinforcement information is as shown in Equation 1 below, and as the aircraft approaches the ground system, as shown in Equation 2, the pseudo distance in Decision Height (DH) is doubled. A difference value can be generated.

to be.

는 항공기, 즉 상기 GPS 수신기(300)에서 최초로 상기 지상 기준국(200)으로부터 보강 정보를 수신하는 시점(t=0)에서의 상기 GPS 수신기(300)에서의 가시위성 i에 대한 의사거리이며

는 동일 시점, 동일 위성에 대한 상기 지상 기준국(200)에서의 의사거리를 의미한다.here,

Is the pseudorange with respect to the visible satellite i in the GPS receiver 300 at the time point t = 0 at the time of receiving the reinforcement information from the ground reference station 200 in the aircraft, i.e., the GPS receiver 300

Denotes a pseudo distance from the ground reference station 200 with respect to the same satellite.

At this time, the GPS receiver 300 and the ground reference station 200 are provided to use the position data of the same navigation satellite group 100. That is, the selection of the reference station 200 for receiving the fixed position information in the GPS receiver 300 is selected according to the position of the GPS receiver 300 or the arrangement of the navigation satellite group 100.

In other words, the reference station 200 selected by the GPS receiver 300 has the same navigation satellite group 100 as the navigation satellite group 100 that transmits the position data received by the GPS receiver 300. Is determined by the reference station 200 that receives the location data.

Therefore, by selecting the ground reference station 200 which is used as a user center having the GPS receiver 300, the data throughput and the time required can be shortened. There is an advantage that can be applied to various fields of navigation using reference station correction data.

Equation 1, 2, and Equation 3 obtained from the Residual Vector from the Line of Sight Unit Vector (LOS) are as follows.

to be.

는 t = 0 시점과 t = t_D 시점에서의 항공기의 위치차분 벡터값 이고 υ는 시계 바이어스를 의미하고, 상기

는 수학식 4와 같다.here,

Is the position difference vector value of the aircraft at time t = 0 and time t = t _D , and υ denotes a clock bias.

Is the same as Equation 4.

to be.

는 다음의 수학식 5를 항으로 가지는 직교 가중치행렬이다.Where Equation 4

Is an orthogonal weight matrix having the following Equation 5 as a term.

는

의 표준편차이며, 두 번째 항은 공간 차에 따른 전리층 지연값의 표준편차를 의미한다. 상기 수학식 1내지 5로부터 다음의 수학식 6과 같은 판별값(Test Statistic)을 계산할 수 있다. 상기 판별값(Test Statistic)을 나타내는 수학식 6은 다음과 같다.Lt; / RTI >

Is

Is the standard deviation of, and the second term is the standard deviation of the ionospheric delay according to the space difference. From the Equations 1 to 5, a test statistic can be calculated as shown in Equation 6 below. Equation 6 representing the test value is as follows.

to be.

이며, W와 G는 IWFM에서 전리층 폭풍의 두께와 기울기를 나타내고

는 지상시스템과 DH간의 거리로 본 실시예에서는 5km로 구비되는 것으로 예시하나 이에 한정되는 것은 아니다.here,

W and G represent the thickness and slope of the ionosphere storm in the IWFM.

Is the distance between the ground system and the DH is illustrated as being provided with 5km in this embodiment, but is not limited thereto.

The threshold value for detecting the ionosphere storm, that is, the reference value, is determined by the required Alarm Alarm Probability and the Degree of Freedom (DOF) having a probability distribution as shown in Equation (7). Equation 7 representing the threshold is as follows.

to be.

3 illustrates an example of the threshold value change according to the false alarm probability and the degree of freedom. 3 is a graph showing threshold values according to degrees of freedom and false alarm probabilities.

The occurrence of the ionospheric storm is determined by comparing the determination value and the threshold calculated as described above.

Here, the ionospheric storm detection method using the satellite navigation-based reference station-oriented space-time difference according to another preferred embodiment of the present invention using the ionospheric storm detection system is as follows. 4 is a flowchart illustrating an ionospheric storm detection method using a satellite navigation-based reference station directed space-time difference according to another preferred embodiment of the present invention in order. For convenience of description, description will be made with reference to the reference numerals of the components shown in FIG. 1, and descriptions of the same or similar components will be omitted.

As shown in the figure, the ionospheric storm detection method first goes through the step (P1) of selecting a navigation satellite group 100 for transmitting position data to the ground reference station 200 in the GPS receiver.

Next, the navigation satellite group 100 composed of a plurality of navigation satellites is subjected to a step (P2) of transmitting location data using a preset code and a navigation message.

Next, the ground reference station 200 receives the position data, calculates and transmits fixed position information (P3).

Next, the GPS receiver receives the location data and the fixed location information (P4). In this case, as described above, the location data and the fixed location information are provided to be transmitted and received through the above-described GNSS, but is not limited thereto.

In addition, the GPS receiver and the ground reference station 200 to receive the position data from the same navigation satellite group 100 selected in the screening step (P1).

Next, a determination value is generated through a space-time double difference between the position data and the fixed position information (P5). In this case, the determination value is preferably calculated by Equations 1 to 6 as described above, which will be described below with reference to FIG. 5 to explain this in more detail. 5 is a flowchart illustrating the steps of generating the discrimination value in more detail.

As shown in the drawing, the step of generating the determination value (P5), first, compares the pseudo-distance with the same navigation satellite group 100 for each of the GPS receiver 300 and the ground reference station 200. The process goes to step (P51). In this case, the ground reference station 200 and the navigation satellite group 100 may vary according to the position of the GPS receiver 300 or the arrangement of the navigation satellites.

Next, the determination value is generated by going through step P52 of calculating the determination value from the compared pseudo ranges.

Next, the operation of the ionospheric storm detection method is completed by comparing the determination value with a predetermined threshold value and determining whether an ionospheric storm has occurred (P6).

At this time, as described above, the step (P6) of determining whether the ionospheric storm occurs, preferably further comprises the step of generating a threshold value according to the false alarm probability and the degree of freedom according to equation (7).

Comparative example

Here, simulated data reflecting the impact of the ionosphere storm was generated using the landing data collected directly from the IWFM and a specific airport in Korea for performance analysis of the ionosphere storm detection system and method according to the preferred embodiment of the present invention.

Assuming that the signal from satellite PRN 3 is affected by the ionosphere storm, simulation sample data are extracted from the range of Table 1. 6 shows an example of an elevation angle of the PRN satellite 3 and a delay value due to an applied ionospheric storm. FIG. 6 is an exemplary graph illustrating elevation of the PRN 3 satellite and an applied ionospheric storm delay value (PRN 3).

As a comparative example, the Code-Carrier Divergence Test algorithm used in the GBAS Category I system was used as a comparative example for the performance comparison of the ionospheric storm detection system and method of the present invention. Equation 8 representing the Code-Carrier Divergence Test algorithm used in the current GBAS Category I system is as follows.

to be.

는 시정수(Time Constant)를 의미하는데 수학식 9의 조건에 의하여 결정되며

는 측정값 갱신 간격으로 본 실시예에서는 0.5초이다. 이 때, 시정수를 나타낸 수학식 9는 다음과 같다.here,

Means Time Constant, which is determined by the condition of Equation 9.

Is 0.5 seconds in this embodiment in the measured value update interval. At this time, Equation 9 representing the time constant is as follows.

to be.

The detection time according to the rate of change of the ionospheric delay value of the Code-Carrier Divergence Test algorithm, which is the comparative example, was compared through a simulation. 7 is a graph illustrating a comparison result of sensing time taken by each algorithm according to an ionospheric storm detection method and a comparative example according to a preferred embodiment of the present invention.

As shown in the figure, the value (B) representing the ionospheric storm detection delay rate of the Code-Carrier Divergence Test algorithm is first examined. It takes

On the other hand, when looking at the value (A) showing the ionospheric storm detection delay rate of the algorithm according to the ionospheric storm detection system and method of the present invention, since the Parity Vector RAIM method is used, regardless of the ionospheric delay change rate, It has fast detection performance and can detect even slow moving ionosphere storms.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

1 is a conceptual diagram illustrating an ionospheric storm detection system using a satellite navigation based reference station directed space-time difference according to a preferred embodiment of the present invention.

2 is an exemplary diagram for explaining the mathematical modeling of the ionosphere storm.

3 is a graph showing threshold values according to degrees of freedom and false alarm probabilities.

4 is a flowchart illustrating an ionospheric storm detection method using a satellite navigation-based reference station directed space-time difference according to another preferred embodiment of the present invention in order.

5 is a flowchart illustrating the steps of generating the discrimination value in more detail.

FIG. 6 is an exemplary graph illustrating elevation of the PRN 3 satellite and an applied ionospheric storm delay value (PRN 3).

7 is a graph illustrating a comparison result of sensing time taken by each algorithm according to an ionospheric storm detection method and a comparative example according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: navigation satellite group 200: reference station

300: GPS receiver

Claims (8)

A navigation satellite group including a plurality of navigation satellites for transmitting location data using a preset code and a navigation message; A plurality of terrestrial reference stations for transmitting and receiving the position data and transmitting fixed fixed position information; And A GPS receiver for transmitting and receiving the position data and the fixed position information with the navigation satellite group and the ground reference station; The GPS receiver generates a determination value through space-time double difference between the position data and the fixed position information, and compares the determination value with a preset threshold to determine whether an ionospheric storm has occurred. An ionospheric storm detection system using space-based difference based on reference station. The method of claim 1, And the GPS receiver and the ground reference station are space navigation based on satellite navigation based reference station using the same positional data of the same navigation satellite group. The method of claim 1, An ionospheric storm detection system using satellite navigation based reference station-oriented space-time difference is selected according to the position of the GPS receiver or the arrangement of the navigation satellite group. The method of claim 1, And the reference station is a reference station for receiving the position data in the same navigation satellite group as the navigation satellite group for transmitting the position data received by the GPS receiver. The method of claim 1, The threshold value is an ionospheric storm detection system using satellite navigation-based reference station-oriented space-time difference is calculated in consideration of false alarm probability and degree of freedom (DOF). Selecting a navigation satellite group for transmitting position data from the GPS receiver to the ground reference station; Transmitting location data using a predetermined code and a navigation message in the selected navigation satellite group; Receiving the position data at the ground reference station, calculating and transmitting fixed position information; Receiving the position data and the fixed position information at the GPS receiver; Generating a discrimination value through space-time double difference between the position data and the fixed position information; And Determining whether an ionospheric storm has occurred by comparing the determination value with a preset threshold value; An ionospheric storm detection method using satellite navigation based reference station-oriented space-time difference. The method of claim 6, Generating the determination value Comparing the pseudoranges with the same navigation satellite group for each of the GPS receiver and the ground reference station; And Calculating the discrimination value from the compared pseudoranges; An ionospheric storm detection method using satellite navigation based reference station-oriented space-time difference. The method of claim 6, The determining of whether an ionospheric storm is generated may include generating the threshold value according to a false alarm probability and a degree of freedom.

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