A method for evaluating the effectiveness of GNSS interference

Abstract

This invention discloses a GNSS interference effectiveness evaluation method, comprising the following steps: Step 1, loading known interference radiation source signal characteristic parameters and affected frequencies; Step 2, analyzing the loss value along the electromagnetic wave propagation channel path using a radio wave propagation model; Step 3, calculating the grounding power of interference signals reaching the receiving point at all grid points within the selected area, combined with the interference source antenna gain; Step 4, calculating the signal strength at which the grounding power of interference signals at all grid points within the selected area exceeds the receiver sensitivity; Step 5, comparing all grid points within the selected area with the interference threshold to provide the regional influence range and intensity of interference effectiveness at all grid points within the selected area. The GNSS interference effectiveness evaluation method disclosed in this invention can quickly analyze the regional influence range and intensity of interference effectiveness.

Description

Technical Field

[0001] This invention belongs to the field of GNSS interference monitoring, and specifically relates to a GNSS interference effectiveness evaluation method in this field. Background Technology

[0002] With the rapid development of radio application systems, GNSS (Global Navigation Satellite System) has been widely used. However, due to the weak signal of GNSS, it is extremely susceptible to interference. The International Committee on Global Navigation Satellite Systems believes that electromagnetic interference has become a key factor restricting GNSS from achieving its intended functions and performance.

[0003] Currently, there is a serious lack of understanding regarding GNSS interference effectiveness. On the one hand, my country's research in the field of satellite navigation started relatively late, resulting in a superficial understanding of GNSS system interference detection and consequently insufficient evaluation and analysis of satellite navigation applications. On the other hand, electromagnetic interference mainly originates from the air and the ground, significantly impacting various types of GNSS receivers or user terminals equipped with GNSS modules. Correspondingly, GNSS system interference detection has not yet been developed into a large-scale or systematic, targeted, and professional technology, leading to a limited amount of research on GNSS interference effectiveness analysis and evaluation.

[0004] In response to the problem that satellite navigation signals are susceptible to intentional or unintentional interference, threatening the safe use of GNSS, there is an urgent need to conduct research on GNSS interference effectiveness assessment technology, and to develop a systematic interference assessment technology so that various satellite navigation applications can obtain rapid effect assessment and alarm response when facing GNSS interference. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a GNSS interference effectiveness evaluation method that can quickly analyze the influence range and intensity of interference effectiveness.

[0006] The present invention adopts the following technical solution:

[0007] An improved method for evaluating GNSS jamming effectiveness includes the following steps:

[0008] Step 1: Load information such as the characteristic parameters of known interfering radiation sources and the affected frequencies;

[0009] Step 2: Analyze the loss values ​​along the electromagnetic wave propagation channel path using an electromagnetic wave propagation model.

[0010] After being emitted from the transmitting antenna, interference signals are affected by natural environmental factors along the electromagnetic wave propagation path (such as surface vegetation type and reflection coefficient, ground transmission impedance, irregular terrain, climate type, atmospheric refractive index, etc.) and propagation distance, resulting in complex and variable attenuation during propagation. The specific propagation mode increases with the complexity of the electromagnetic wave environment. However, interference signals mainly propagate through free space, ground reflection, various diffractions, and tropospheric scattering. This step requires establishing a dedicated electromagnetic wave propagation model to analyze the attenuation values ​​along the electromagnetic wave propagation channel path.

[0011] Commonly used radio wave propagation models can be broadly categorized into three types: empirical models, semi-empirical-semi-deterministic models, and deterministic models. Empirical models are derived from extensive analysis of real-world test data; they are relatively simple, convenient to use, and have fewer constraints. Semi-empirical-semi-deterministic models are statistical models that apply deterministic methods to specific environments, typically used for analyzing and predicting radio wave propagation in specific terrain conditions. Deterministic models are based on electromagnetic theory and derived from Maxwell's equations; currently, most of these models are calculated using ray tracing of electromagnetic fields. Different radio wave propagation models have different applicability ranges, and their prediction results can vary significantly. Therefore, to accurately model complex electromagnetic environments, it is crucial to select the appropriate propagation model.

[0012] This invention uses a free-space propagation model as an example to introduce its calculation process. It is assumed that electromagnetic waves propagate in an isotropic, homogeneous, lossless infinite space, i.e., free space. In this free space, rays are straight lines, and the wave energy is unaffected by other factors, depending only on the propagation distance. Propagation loss is mainly caused by energy divergence during propagation.

[0013] The free space propagation model is defined as:

[0014] P loss =32.4 + 20lgd + 20lgf

[0015] In the above formula, P loss d represents the radio wave propagation loss value (unit: dB), d represents the radio wave propagation path length (unit: km), and f represents the frequency (unit: MHz).

[0016] Step 3: Calculate the ground power P of the interference signal reaching the receiving point from all grid points within the selected area, based on the antenna gain of the interference source. s (Unit: dBm)

[0017] Assuming there is only one independent interference source within the area, that the interference source emits an interference signal with a certain transmission power, and that the antenna gain is the same in all directions (i.e., omnidirectional transmission), the ground power of the interference signal reaching the receiving point is P. s The entire physical process can be described using the following model:

[0018] P s =P J +P gain -P loss

[0019] In the above formula, P J P represents the emitted power (in dBm) of a known interfering radiation source. gain P represents the gain (in dBi) of the transmitting antenna of the interference source. loss This represents the radio wave propagation loss value (in dB); the above formula is used to calculate the ground power P of the interference signal at a single grid point reaching the receiving point. s Then, the power of the interference signal reaching the receiving point at each grid point within the selected area is calculated by traversing the area.

[0020] Step 4: Calculate the signal strength P where the ground power of the interference signal at all grid points within the selected area exceeds the receiver sensitivity. b (Unit: dB)

[0021] P b =P s -P rec

[0022] In the above formula, P rec Represents GNSS receiver sensitivity (GNSS receiver threshold, unit dBm);

[0023] Step 5: Compare all grid points P within the selected area. b With interference threshold P c Give the influence range and intensity P of the interference effectiveness of all grid points within the selected area. eff (Interference effectiveness, in dB):

[0024] The interference threshold is reflected both in the anti-interference capability of the satellite telemetry and control link's spread spectrum system itself, and also in the different anti-interference capabilities of different types of receivers, resulting in different interference thresholds. Therefore, P c (Unit dB) is defined as:

[0025] P c =P e +P r

[0026] P eP represents the anti-interference capability (in dB) of the spread spectrum system of the satellite telemetry, tracking, and command (TT&C) link itself, with a value range of 36 dB to 42 dB. r This represents the receiver's own interference immunity (unit: dB).

[0027] P eff =P b -P c

[0028] The next step is to determine whether the interfering radiation source affects the GNSS receiver:

[0029] When P eff A value greater than 0 indicates that the range and intensity of the interference effect area exceed the interference threshold. In this case, the receiver will be affected by the interference radiation source, potentially impacting positioning and timing. eff The larger the value, the greater the range and intensity of the interference effect area;

[0030] When P eff ≤0 means that the range and intensity of the interference effectiveness area are lower than or equal to the interference threshold. At this time, the interference signal strength is not enough to affect the receiver performance, so it will not have any impact on the receiver.

[0031] Calculate all grid points P within the selected region. eff Statistical analysis of all P eff For grids with values ​​greater than 0, the range and intensity of interference within the selected area are obtained.

[0032] Furthermore, the characteristic parameters of the interference radiation source signal in step 1 include information such as the interference source's transmission power, location, interference antenna transmission gain, and the GNSS frequency being interfered with.

[0033] The beneficial effects of this invention are:

[0034] The GNSS interference effectiveness assessment method disclosed in this invention can quickly analyze the influence range and intensity of interference effectiveness. This invention combines radio wave propagation model analysis and interference effectiveness assessment methods. The radio wave propagation model can calculate the attenuation value along the electromagnetic wave propagation channel path, and it comprehensively considers the changes in interference characteristics along the entire electromagnetic wave propagation link from transmission to reception, conforming to the natural laws of GNSS signal interference. This invention predicts the spatial distribution characteristics of the interference signal, solving the problem of GNSS interference effectiveness assessment.

[0035] The GNSS interference effectiveness evaluation method disclosed in this invention, based on the characteristics of GNSS interference signals and the acquisition of interference radiation source information, fully considers the changes in interference characteristics of the interference source throughout the entire electromagnetic wave propagation link from transmission to reception. It uses an electromagnetic wave propagation model to estimate the attenuation of electromagnetic waves during channel propagation, thereby achieving an accurate evaluation of the coverage and intensity of GNSS interference. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the method of the present invention;

[0037] Figure 2 This is a schematic diagram of the selected area in Example 1;

[0038] Figure 3 This is a schematic diagram showing the location of interference sources within the selected area in Example 1;

[0039] Figure 4 This is a schematic diagram of the interference effectiveness evaluation results of Example 1. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] Example 1: This example discloses a GNSS interference effectiveness evaluation method, the process of which is as follows: Figure 1 As shown, the selected area range is as follows Figure 2 As shown, a rectangular region is selected, with a horizontal range (X-direction) of 0m to 78000m and a vertical range (Y-direction) of 0m to 33000m; the interference radiation source has an emission power of 1W, i.e., the interference emission power P. J The gain is 30dBm; the transmitting antenna is omnidirectional, and the gain P is... gain 3dBi; such as Figure 3 As shown, the coordinates of the interference source are (35000m, 17000m); the interference frequency f is 1575.42MHz.

[0042] Assuming that the signal is within line-of-sight during the transmission of the interference radiation source, and that the energy loss is mainly caused by the energy divergence during propagation, the wave propagation loss value P at each grid point is calculated according to the free space propagation model formula (1). loss :

[0043] P loss =32.4+20lg d+20lg f (1)

[0044] Calculated Ploss The range is 96.40 dB to 129.70 dB.

[0045] Next, following step 3, calculate the grounding power P of the interference signal at all grid points within the selected area, using the parameters mentioned above. s :

[0046] P s =P J +P gain -P loss (2)

[0047] Calculated P s The range is -63.40dBm to -96.70dBm.

[0048] GNSS receiver threshold P rec Generally, -125dBm is selected, and the signal strength P at all grid points where the ground power of the interference signal exceeds the receiver sensitivity is calculated. b :

[0049] P b =P s -P rec (3)

[0050] Calculated P b The range is 28.30dB to 61.60dB.

[0051] The satellite telemetry and control link itself has a spread spectrum system with high anti-interference capability (P). e In this embodiment, 36dB is used; and a common receiver is selected, therefore P r The value is 0, according to formula (4):

[0052] P c =P e +P r (4)

[0053] Get P c The value is 36dB.

[0054] Interference effectiveness intensity P eff for:

[0055] P eff =P b -P c (5)

[0056] P was calculated eff The range is -7.70dB to 25.60dB.

[0057] Statistical analysis of all P eff The location and number of grid points greater than 0 determine the interference coverage area, and P on each grid point is given.eff The value represents the interference effectiveness strength.

[0058] The schematic diagram of the interference effectiveness evaluation results in this embodiment is shown below. Figure 4 As shown, the area within the black circle represents the interference range, that is, the region where the interference signal can affect the receiver. Centered on the interference radiation source, it spreads outward in a circular radial pattern, which is consistent with the calculation characteristics of the model of this invention. At the same time, spatially, the closer to the center, the higher the interference effectiveness, and the farther away from the center, the lower the interference effectiveness, until the interference signal can no longer affect the receiver performance. This is also consistent with the natural laws and spatial distribution characteristics of interference effectiveness.

[0059] In summary, the GNSS interference effectiveness evaluation method disclosed in this invention provides the spatial distribution characteristics of interference signals, which is of great value in the field of GNSS interference monitoring.

Claims

1. A method for evaluating the effectiveness of GNSS interference, characterized in that, Includes the following steps: Step 1: Load the characteristic parameters of the known interfering radiation source signal and the information of the affected frequencies; Step 2: Analyze the loss values ​​along the electromagnetic wave propagation channel path using an electromagnetic wave propagation model. P loss =32.4+20lg d+20lg f In the above formula, P loss d represents the radio wave propagation loss value, d represents the radio wave propagation path length, and f represents the frequency. Step 3: Calculate the ground power P of the interference signal reaching the receiving point from all grid points within the selected area, based on the antenna gain of the interference source. s : P s =P J +P gain -P loss In the above formula, P J P represents the emitted power of a known interfering radiation source. gain P represents the gain of the transmitting antenna of the interference source. loss This represents the radio wave propagation loss value; the ground power P of the interference signal at a single grid point reaching the receiving point is calculated using the above formula. s Then, the power of the interference signal reaching the receiving point at each grid point within the selected area is calculated by traversing the area. Step 4: Calculate the signal strength P where the ground power of the interference signal at all grid points within the selected area exceeds the receiver sensitivity. b : P b =P s -P rec In the above formula, P rec This represents the sensitivity of the GNSS receiver; Step 5: Compare all grid points P within the selected area. b With interference threshold P c Give the influence range and intensity P of the interference effectiveness of all grid points within the selected area. eff : P c =P e +P r P e This represents the anti-interference capability of the satellite telemetry and control link's spread spectrum system, with a value ranging from 36dB to 42dB. r This represents the receiver's own anti-interference capability; P eff =P b -P c When P eff >0 indicates that the range and intensity of the interference effectiveness area exceed the interference threshold. At this time, the receiver will be affected by the interference radiation source. eff The larger the value, the greater the range and intensity of the interference effect area; When P eff ≤0 means that the range and intensity of the interference effectiveness area are lower than or equal to the interference threshold. At this time, the interference signal strength is not enough to affect the receiver performance, so it will not have any impact on the receiver. Calculate all grid points P within the selected region. eff Statistical analysis of all P eff For grids with values ​​greater than 0, the range and intensity of interference within the selected area are obtained.

2. The GNSS interference effectiveness evaluation method according to claim 1, characterized in that: The characteristic parameters of the interference radiation source signal in step 1 include the interference source's transmission power, location, interference antenna transmission gain, and the GNSS frequency being interfered with.

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