Method for GNSS interference detection based on sky plot carrier-to-noise ratio statistics

Abstract

The application provides a data transmission network system, comprising: receiving the carrier-to-noise ratio, the elevation angle and the azimuth angle information of different satellites and different frequencies from GNSS navigation reception; dividing the star map into different regions by using the azimuth angle and the elevation angle; obtaining the standard value by statistically processing the carrier-to-noise ratio values of the same satellite and the same frequency in different regions; and establishing a historical template by using the standard value as the reference for judging the GNSS interference detection. The application uses the frequency, angle and carrier-to-noise ratio information collected by the GNSS receiver to calculate the historical carrier-to-noise ratio values of different regions of the star map, and provides the basis for subsequent interference judgment.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation interference detection technology, and specifically to a method for GNSS interference detection based on the carrier-to-noise ratio statistics of star charts. Background Technology

[0002] Traditional GNSS interference detection methods are quite complex, and in practical interference detection, especially in high-real-time scenarios, a simpler and faster detection method is needed. Therefore, this invention utilizes the output information of the navigation receiver to propose a method for detecting and identifying weak suppression interference in satellite navigation based on the carrier-to-noise ratio (C / N0).

[0003] However, in practice, the carrier-to-noise ratio (CNR) can be low due to environmental obstructions, leading to misinterpretation of CNR fluctuations as interference. Therefore, this invention proposes a GNSS interference detection method based on CNR statistics from star charts. The star chart is divided into different regions, and the CNR values ​​for individual satellites and frequencies are statistically analyzed and stored. While a region may have a low CNR due to obstructions, its CNR will continue to decrease under weak suppression interference; therefore, this value can be used as a criterion for judgment. Summary of the Invention

[0004] The purpose of this invention is to provide a method for GNSS interference detection based on the statistical carrier-to-noise ratio of star charts, in order to solve the technical problems existing in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The purpose of this invention is to provide a method for GNSS interference detection based on the carrier-to-noise ratio statistics of star charts, which can solve the problem of misjudgment of weak suppression interference caused by low carrier-to-noise ratio due to obstructed environment.

[0007] The present invention solves the above problems through the following technical solution:

[0008] Methods for GNSS interference detection based on star chart carrier-to-noise ratio statistics include:

[0009] Step S1: Set standard values ​​for carrier-to-noise ratio for different areas based on experience;

[0010] Step S2: Use the carrier-to-noise ratio standard value to determine whether the data received per second is interfered with;

[0011] Step S3: Process the data based on the judgment result of S2;

[0012] Step S4: Establish a template for the average historical carrier-to-noise ratio of the region and use S2 and S3 to keep the database updated; repeat S2-S3, and after a certain amount of data from a single satellite at a single frequency point has accumulated, calculate and save the statistical value of the carrier-to-noise ratio of a single satellite at a single frequency point in each region of the star map.

[0013] Let A° be a granularity, and divide the entire pitch angle [0°-90°] region into... The granularity A value can be determined based on the actual application scenario for each pitch angle interval. Then, based on engineering experience, a standard carrier-to-noise ratio value under normal conditions is set for each pitch angle interval. After collecting satellite data at a specific moment, the measured carrier-to-noise ratio (CNR) of the region for all satellites at a given frequency is compared with the standard value for the corresponding elevation angle region. If the CNR of a satellite's region is lower than the standard value by a certain margin, that region is considered abnormal. The number of abnormal regions at that frequency and the total number of regions containing all satellites at that frequency at that moment are counted. These two values ​​are compared; if the difference exceeds a certain threshold, the data for that frequency at that moment is considered interfered with, and the data is replaced with the standard value for that region to ensure that the CNR used to calculate the regional statistical average is as unaffected as possible.

[0014] Step S1 specifically involves:

[0015] Step S11: Divide the pitch angle into n intervals with A° as the granularity: [0, [90 / A, 2*90 / A]... [(n-1)*90 / A, n*90 / A], and collect satellite data for a certain period of time.

[0016] Step S12: For a certain pitch angle range ( The average value is calculated by taking the middle 90% of all satellite carrier-to-noise ratio data at a single frequency point. . Number of frequency points

[0017] Step S13: Calculate the average carrier-to-noise ratio (CNR) of all frequency points in the pitch angle range based on step S12, and then perform another average calculation to obtain the standard value for the pitch angle range. .

[0018] Right now:

[0019] .

[0020] Step S2 specifically includes:

[0021] Step S21: Receive real-time satellite data from GNSS every second, and extract satellite frequency, elevation angle, azimuth angle, and carrier-to-noise ratio information.

[0022] Step S22: For a single frequency point, calculate the carrier-to-noise ratio of a specific satellite at that frequency point. The standard value of its pitch angle region Compare the values. If the value is below a certain threshold of the standard value... ,Right now If so, the area is temporarily considered abnormal (possibly due to occlusion at its azimuth angle resulting in a relatively low noise level).

[0023] Step S23: Repeat step S22 until all satellite regions at this frequency have been checked. Calculate the following data for all satellites at this frequency at this moment: the number of abnormal regions K and the total number of regions N. If the ratio K / N is greater than or equal to a certain threshold... , Right now If the frequency is positive, then the frequency point is considered to be interfered with; otherwise, it is considered to be uninterrupted.

[0024] Step S24: Based on steps S22 and S23, determine the interference of all frequency points at this moment.

[0025] Step S3 specifically includes:

[0026] If step S2 determines that a certain frequency point is interfered with at that moment, then data replacement is performed for all satellites at that frequency point: based on their regional distribution in the star map at that moment, the corresponding elevation angle regional standard value is used to replace the measured carrier-to-noise ratio value at that moment in turn, and cache it in the program; if there is no interference, then the measured carrier-to-noise ratio value is cached in the program.

[0027] Step S4 specifically includes:

[0028] When the carrier-to-noise ratio (CNR) data for a single frequency point from a single satellite from step S3 has been cached to a certain quantity, this data is segmented according to the regions defined in the star map. For example, all relevant data for a single frequency point of a single satellite within the sub-regions of the star map in terms of azimuth [0°, 30°] and elevation [10°, 20°] are segmented. The average CNR of a single frequency point of a single satellite within this sub-region of the star map is then calculated. And record their maximum carrier-to-noise ratio values. Minimum carrier-to-noise ratio The satellite offset number (SV), frequency information, azimuth range, and elevation range of the star chart will be used. , , It is used as a historical statistical template for satellite star charts for recording.

[0029] Beneficial effects

[0030] (1) The present invention uses the carrier-to-noise ratio information output by the GNSS navigation receiver to make interference judgment, which simplifies the weak interference judgment method and enables a preliminary judgment of the current weak suppression interference.

[0031] (2) The present invention has better performance than the traditional method. After dividing the star map into different regions, when a certain region is occluded, its carrier-to-noise ratio (CNR) is correspondingly lower, which can reflect that the current region is occluded. Therefore, when subjected to weak suppression interference, the CNR of the region should be even lower, eliminating misjudgment caused by occlusion. Attached Figure Description

[0032] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0034] Conversely, this application covers any substitutions, modifications, equivalent systems, and solutions made within the spirit and scope of this application as defined in the claims. Furthermore, to provide the public with a better understanding of this application, certain specific details are described in detail below. However, this application can be fully understood by those skilled in the art even without these detailed descriptions.

[0035] Combined with appendix Figure 1 As shown, the GNSS interference detection method based on the carrier-to-noise ratio statistics of star charts includes:

[0036] Step S1: Set standard values ​​for carrier-to-noise ratio for different areas based on experience; specifically including:

[0037] Step S11: Divide the elevation angle into 8 intervals with a granularity of 10°: [10, 20], [20, 30], [30, 40], [40, 50], [50, 60], [60, 70], [70, 80], [80, 90], and collect satellite data for a certain period of time.

[0038] Step S12: For a certain elevation angle interval i, take the middle 90% of the satellite carrier-to-noise ratio data at a single frequency point and calculate the average value. . Number of frequency points

[0039] Step S13: Calculate the average carrier-to-noise ratio (CNR) of all frequency points in the pitch angle range based on step S12, and then perform another average calculation to obtain the standard value for the pitch angle range. .

[0040] Right now:

[0041] ;

[0042] Step S2: Determine whether the received data per second is interfered with using the carrier-to-noise ratio standard value; specifically including:

[0043] Step S21: Receive real-time satellite data from GNSS every second, and extract satellite frequency, elevation angle, azimuth angle, and carrier-to-noise ratio information.

[0044] Step S22: For a single frequency point, compare the carrier-to-noise ratio (CNR) of all satellites at that frequency point with the standard value of its elevation angle region. If the value is lower than a certain threshold, such as 5dB, the area is temporarily considered abnormal (possibly due to occlusion at its azimuth angle, resulting in a low carrier-to-noise ratio).

[0045] Step S23: Based on step S22, count the number of abnormal regions K, and count the number of regions N where all satellites of this frequency point are located at this moment. If the ratio is greater than a certain threshold of K / N, such as 75%, then this frequency point is considered to be interfered with.

[0046] Step S24: Based on steps S22 and S23, determine the interference of all frequency points at this moment.

[0047] Step S3: Process the data based on the judgment result of S2. If S2 detects that a certain frequency point is interfered with, then for all satellites under that frequency point, find the standard elevation angle value set in S1 based on the elevation angle of the star map area where it is located, and replace the carrier-to-noise ratio at this moment with the standard carrier-to-noise ratio value; if there is no interference, no replacement operation is performed.

[0048] Step S4: Repeat S2-S3. When the carrier-to-noise ratio (CNR) data for a single frequency point from a single satellite from Step S3 has been cached to a certain quantity, this data is segmented according to the regions defined in the star chart. For example, all relevant data for a single frequency point of a single satellite within the sub-regions of the star chart in terms of azimuth [0°, 30°] and elevation [10°, 20°]. Calculate the average CNR of a single frequency point of a single satellite within that sub-region of the star chart. And record their maximum carrier-to-noise ratio values. Minimum carrier-to-noise ratio The satellite offset number (SV), frequency information, azimuth range, and elevation range of the star chart will be used. , , These values ​​are recorded as historical statistical templates for satellite star charts and can be used as a reference for subsequent weak interference detection.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for GNSS interference detection based on satellite image carrier-to-noise ratio statistics, characterized in that, include: Step S1: Set standard values ​​for carrier-to-noise ratio for different areas based on experience; Step S2: Determine whether the data received per second is subject to interference using the carrier-to-noise ratio standard value, specifically including: Step S21: Receive real-time satellite data from GNSS every second, and extract satellite frequency, elevation angle, azimuth angle, and carrier-to-noise ratio information; Step S22: For a single frequency point, calculate the carrier-to-noise ratio of a specific satellite at that frequency point. The standard value of its pitch angle region Compare the values; if the value is below a certain threshold of the standard value. ,Right now If so, the area will be temporarily considered abnormal; Step S23: Repeat step S22 until all satellite regions at this frequency have been checked; Calculate the following data for all satellites at this frequency at this moment: the number of abnormal regions K, the total number of regions N; if the ratio K / N is greater than or equal to a certain threshold rate, 0 < rate ≤ 1, i.e. If the frequency point is affected, it is considered to be interfered with; otherwise, it is considered to be unaffected. Step S24: Based on step S23, determine the interference at all frequencies at this moment; Step S3: Process the data based on the judgment result of S2; Step S4: Repeat S2-S3. After a certain amount of data has been accumulated for a single frequency point of a single satellite, calculate and save the carrier-to-noise ratio statistics for each region of the star map for a single frequency point of a single satellite.

2. The GNSS interference detection method based on star chart carrier-to-noise ratio statistics according to claim 1, characterized in that, Step S1 specifically involves: Step S11: Divide the pitch angle into n intervals with A° as the granularity: [0, [90 / A, 2*90 / A]…[(n-1)*90 / A, n*90 / A], and collect satellite data for a certain period of time; Step S12: For a certain pitch angle range For i=1,2,…,n; take the middle 90% of the satellite carrier-to-noise ratio data for a single frequency point and calculate the average value. , Number of frequency points; Step S13: Calculate the carrier-to-noise ratio (CNR) statistics for all frequency points in the elevation angle range based on step S12, and then perform an average calculation to obtain the standard value for the elevation angle range. ; Right now: 。 3. The GNSS interference detection method based on star chart carrier-to-noise ratio statistics according to claim 1, characterized in that, Step S3 specifically includes: If step S2 determines that a certain frequency point is interfered with at that moment, then data replacement is performed for all satellites at that frequency point: based on their regional distribution in the star map at that moment, the corresponding elevation angle regional standard value is used to replace the measured carrier-to-noise ratio value at that moment in turn, and cache it in the program; if there is no interference, then the measured carrier-to-noise ratio value is cached in the program.

4. The GNSS interference detection method based on star chart carrier-to-noise ratio statistics according to claim 1, characterized in that, Step S4 specifically includes: When the carrier-to-noise ratio (CNR) data of a single frequency point from a single satellite from step S3 has been cached to a preset quantity, this data is segmented according to the regions divided by the star map, and the average CNR of a single frequency point of a single satellite in that sub-region of the star map is calculated. And record their maximum carrier-to-noise ratio values. Minimum carrier-to-noise ratio ; This includes the satellite offset number (SV), frequency information, azimuth range, and elevation range of the star chart. , , It is used as a historical statistical template for satellite star charts for recording.

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