Ionospheric Drift Detection Method and System Based on Phased Array Incoherent Scatter Radar

Abstract

The present invention belongs to the field of ionospheric drift detection, and specifically relates to a method and system for ionospheric drift detection based on a phased array incoherent scatter radar, aiming to solve the problem that there is currently no evaluation system for detecting ionospheric drift using an incoherent scatter radar operating normally at low latitudes, thus unable to select the optimal beam configuration to accurately detect ionospheric drift. The present invention includes: constructing a mapping relationship between the vector velocity in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction; for different beam configurations, performing forward and inverse modeling respectively to obtain the relative deviation and relative inversion error of the vector drift; selecting the beam configuration with a relative deviation less than a first set threshold and a relative inversion error less than a second set threshold as the optimal beam configuration for ionospheric drift detection; at the position where the optimal beam configuration is located, detecting the F-layer ionospheric drift through the optimal beam configuration. The present invention achieves high-precision and accurate detection of F-layer ionospheric drift.

Description

Background Art

[0002] The plasma drift velocity in the F layer of the ionosphere is one of the key parameters of the Earth's ionosphere. In the low-latitude ionosphere, it is related to most well-known features, such as the equatorial ionization anomaly (EIA), plasma irregularities, equatorial electrojet (EEJ), the F3 layer of the ionosphere, etc. The plasma drift velocity can provide intuitive kinetic and electrodynamic information, which helps to understand the behavior of the Earth's ionospheric plasma under geomagnetically quiet and disturbed conditions, and is conducive to revealing the physical mechanism of the coupling of the low-latitude ionosphere magnetosphere-ionosphere-thermosphere system.

[0003] The observation of the plasma drift velocity mainly comes from satellite in-situ measurements, incoherent / coherent scatter radar (ISR / CSR), and remote sensing detection by ionosondes, etc. Satellite detection can provide wide latitude and longitude coverage, but it has limitations in terms of altitude variation and time continuity. As an instrument with low cost and low operating cost, the ionosonde can provide long-term observations of the plasma drift velocity, but it is not reliable for the vertical drift of the daytime ionosphere. Among all ionospheric detection methods, the ground-based incoherent scatter radar is by far the most powerful detection method, which has many advantages such as strong detection function, many parameters (multiple fields and particle components), high accuracy, good resolution, and large altitude range coverage, and occupies a dominant position in ionospheric detection. During the detection process of the incoherent scatter radar, there are isotropic parameters represented by electron density, and anisotropic parameters represented by drift velocity.

[0004] As the only currently normally operating incoherent scatter radar in the low-latitudes, it has the advantages of long-term continuous operation, selectable working modes, and flexible operation, and can be used for the research of major scientific issues such as "low-latitude atmosphere-ionosphere-magnetosphere coupling". In the low-latitude region, the plasma drift is only a few meters to dozens of meters per second, which is comparable to the inversion error. Therefore, the configuration of the radar scanning beam has an important impact on the accuracy of the drift vector velocity inversion. Summary of the Invention

[0005] In order to solve the above problems in the prior art, that is, there is currently no evaluation system for detecting ionospheric drift using a normally operating incoherent scatter radar in the low-latitudes, and thus it is impossible to select the optimal beam configuration to accurately detect ionospheric drift, the present invention provides an ionospheric drift detection method based on a phased array incoherent scatter radar, and the ionospheric drift detection method includes:

[0006] Step S10, constructing a mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction based on the velocity in any line-of-sight direction of the incoherent scatter radar;

[0007] Step S20, for different beam configurations at each position in the all-sky scanning mode:

[0008] Forward model the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity in the radar beam direction respectively, and set the three components of the forward vector drift as the true values to obtain the line-of-sight velocity in the radar beam direction, so as to realize the simulation of radar-detected ionospheric drift;

[0009] Inverse model the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity in the radar beam direction respectively, and set the three components of the inverse vector drift as the inversion values;

[0010] Step S30, use the ratio between the value obtained by subtracting the true value from the inversion value and the true value as the relative deviation of the vector drift, and use the ratio between the inversion error and the true value as the relative inversion error of the vector drift; for the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimate;

[0011] Step S40, select the beam configuration with the relative deviation of the vector drift less than the first set threshold and the relative inversion error of the vector drift less than the second set threshold as the optimal beam configuration for ionospheric drift detection;

[0012] Step S50, at the position where the optimal beam configuration is located, perform F-layer ionospheric drift detection through the optimal beam configuration.

[0013] In some preferred embodiments, the velocity in any line-of-sight direction of the incoherent scatter radar is:

[0014]

[0015] where k = [k e k n k z represents the direction vector of the beam, v = [v e v n v z represents the three components of the velocity, i represents the i-th line-of-sight direction, and [e n z] represent the eastward, northward, and zenith directions respectively in the radar center geodetic coordinate system. T In some preferred embodiments, the direction vector of the beam is:

[0016] where Dis represents the arc distance of the projection of the distance between the observation point and the incoherent scatter radar on the ground, and φ represents the azimuth angle,

[0017]

[0018] ​Let \(R\) represent the distance between the observation point and the incoherent scatter radar, and \([X\ Y\ Z]\) represent the projections of \(R\) in the zonal, meridional, and geodetic vertical directions. Let \(H = Z\) represent the projection of \(R\) in the geodetic vertical direction.

[0019] In some preferred embodiments, the projection of \(R\) in the geodetic vertical direction is calculated as follows:

[0020] (H + R E ) 2 = R E 2 + R 2 - 2R E R cos(90 + θ)

[0021] where \(R\) E represents the radius of the Earth, and θ represents the beam elevation angle of the incoherent scatter radar.

[0022] In some preferred embodiments, the arc distance on the ground of the projection of the distance between the observation point and the incoherent scatter radar is:

[0023]

[0024] where \(R\) E represents the radius of the Earth, and θ represents the beam elevation angle of the incoherent scatter radar.

[0025] In some preferred embodiments, the mapping relationship between the vector velocity in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction is:

[0026] v los = Av + e los

[0027] where \(n\) represents the number of line-of-sight velocities, \(v\) los is the vector velocity, \(e\) los is the error of the line-of-sight velocity, and \(A\) is the beam direction matrix.

[0028] In some preferred embodiments, the forward modeling method for the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity of the radar beam direction is:

[0029] Based on the vector velocity \(v\) and the beam direction matrix \(A\), obtain the error-free line-of-sight velocity:

[0030]

[0031] Add the error to the error-free line-of-sight velocity:

[0032]

[0033] Among them, α is a random number with a mean of 0 and a standard deviation of 1. e los is the line-of-sight velocity error.

[0034] In some preferred embodiments, the method for obtaining the line-of-sight velocity error is as follows:

[0035] Collect the measured values of the line-of-sight velocity error of the incoherent scatter radar for a set time period;

[0036] Perform gridding interpolation on the measured values of the line-of-sight velocity error for the set time period to obtain the line-of-sight velocity error.

[0037] In some preferred embodiments, the method for performing the inversion of the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity in the radar beam direction is as follows:

[0038] Based on the Bayesian estimation method, inversely obtain the vector velocity and covariance matrix:

[0039]

[0040] Among them, is the inversely estimated vector velocity, is the inversely estimated error covariance matrix, The diagonal elements of are the squared values of the inversion errors, Σ v and Σ e are the prior covariance matrices of velocity and error respectively.

[0041] On the other hand, the present invention proposes an ionospheric drift detection system based on a phased array incoherent scatter radar. The ionospheric drift detection system includes:

[0042] A mapping relationship construction module configured to construct a mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity in the radar beam direction based on the velocity in any line-of-sight direction of the incoherent scatter radar;

[0043] A forward modeling module configured to perform forward modeling of the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity in the radar beam direction for different beam configurations at each position in the full-sky scan mode, and set the three components of the forward modeled vector drift as the true values to obtain the line-of-sight velocity in the radar beam direction, thereby realizing the simulation of radar detection of ionospheric drift;

[0044] An inversion module configured to perform inversion of the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity in the radar beam direction for different beam configurations at each position in the full-sky scan mode, and set the three components of the inversely modeled vector drift as the inversion values;

[0045] An error acquisition module, configured to use the ratio between the inversion value minus the true value and the true value as the relative deviation of the vector drift, and use the ratio between the inversion error and the true value as the relative inversion error of the vector drift; the inversion error, the square value of which is the diagonal element of the error covariance matrix of the inversion estimate.

[0046] An optimal beam configuration selection module, configured to select the beam configuration where the relative deviation of the vector drift is less than a first set threshold and the relative inversion error of the vector drift is less than a second set threshold as the optimal beam configuration for ionospheric drift detection.

[0047] A detection module, configured to perform F-layer ionospheric drift detection through the optimal beam configuration at the position where the optimal beam configuration is located.

[0048] Advantages of the present invention:

[0049] The ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention combines forward and inversion methods, can evaluate different experimental schemes before actual experiments, and at the same time the evaluation results can guide the design and improvement of the experimental scheme, improve the experimental effect and efficiency, so as to perform high-precision and accurate detection of F-layer ionospheric drift through the optimal beam configuration at the position where the optimal beam configuration is located. Description of the drawings

[0050] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present application will become more obvious:

[0051] Figure 1 is a forward and inversion schematic diagram of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention;

[0052] Figure 2 is a schematic diagram of the line-of-sight velocity error value in the forward process of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention;

[0053] Figure 3 is the simulation result under the east-west scan of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention;

[0054] Figure 4 is the simulation result under the north-south scan of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention;

[0055] Figure 5 is the evaluation result of the full-sky 5-beam detection of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention;

[0056] Figure 6 It is the evaluation result of the all-sky 10-beam detection in an embodiment of the ionospheric drift detection method based on the phased array incoherent scatter radar of the present invention;

[0057] Figure 7 It is the evaluation result of the north-south scanning detection of 21 beams on the north side in an embodiment of the ionospheric drift detection method based on the phased array incoherent scatter radar of the present invention;

[0058] Figure 8 It is the evaluation result of the north-south scanning detection of 21 beams on the south side in an embodiment of the ionospheric drift detection method based on the phased array incoherent scatter radar of the present invention. Detailed implementation manners

[0059] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the sake of description, only parts related to the relevant invention are shown in the drawings.

[0060] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0061] The present invention provides an ionospheric drift detection method based on a phased array incoherent scatter radar. This method includes a forward modeling module and an inversion module, and defines two indicators: the relative deviation of the vector velocity and the relative inversion error. Finally, the detection scheme is evaluated by analyzing these two indicators, specifically including:

[0062] Forward modeling module: The line-of-sight velocity is calculated by given three components of the vector drift, the azimuth and elevation angles of the beam, and the error of the line-of-sight velocity to simulate the observation of the radar.

[0063] Inversion module: Using the line-of-sight velocity obtained by the forward modeling module, as well as the azimuth and elevation angles of the beam and the error of the line-of-sight velocity, the three components of the vector drift are obtained through a certain inversion method.

[0064] Two indicators: The three components of the vector drift given in the forward modeling module are called the true values, and the three components of the vector drift obtained in the inversion module are called the inversion values. Define and

[0065] An ionospheric drift detection method based on a phased array incoherent scatter radar according to the present invention, the ionospheric drift detection method includes:

[0066] Step S10: Based on the velocity in any line-of-sight direction of the incoherent scatter radar, construct the mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction.

[0067] Step S20: For different beam configurations at various positions in the full-sky scanning mode:

[0068] Respectively perform the forward modeling of the mapping relationship between the vector velocity and the line-of-sight velocity of the radar beam direction for any beam configuration, and set the three components of the vector drift in the forward modeling as the true values to obtain the line-of-sight velocity of the radar beam direction, thereby realizing the simulation of the radar detection of ionospheric drift.

[0069] Respectively perform the inversion of the mapping relationship between the vector velocity and the line-of-sight velocity of the radar beam direction for any beam configuration, and set the three components of the vector drift in the inversion as the inversion values.

[0070] Step S30: Use the ratio of the difference between the inversion value and the true value to the true value as the relative deviation of the vector drift, and use the ratio of the inversion error to the true value as the relative inversion error of the vector drift; for the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimate.

[0071] Step S40: Select the beam configuration with the relative deviation of the vector drift less than the first set threshold and the relative inversion error of the vector drift less than the second set threshold as the optimal beam configuration for ionospheric drift detection.

[0072] Step S50: At the position where the optimal beam configuration is located, perform F-layer ionospheric drift detection through the optimal beam configuration.

[0073] To more clearly illustrate the ionospheric drift detection method based on the phased array incoherent scatter radar of the present invention, the following combines Figure 1 to elaborate on each step in the embodiments of the present invention.

[0074] The ionospheric drift detection method based on the phased array incoherent scatter radar in the first embodiment of the present invention includes Step S10 - Step S50, and each step is described in detail as follows:

[0075] Step S10: Based on the velocity in any line-of-sight direction of the incoherent scatter radar, construct the mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction.

[0076] The velocity in any line-of-sight direction of the incoherent scatter radar is shown in Equation (1):

[0077]

[0078] where k = [k e k n kz represents the direction vector of the beam, v = [v e v n v z T represents the three velocity components, i represents the i-th line-of-sight direction, and [e n z] represent the eastward, northward, and zenith directions respectively in the radar center geodetic coordinate system.

[0079] In the radar center geodetic coordinate system, the direction vector k of the beam can be expressed as Equation (2):

[0080] k = [k e k n k z = [X Y Z]R -1 (2)

[0081] Wherein, represents the distance between the observation point and the incoherent scatter radar, and [X Y Z] represents the projections of R in the latitudinal, meridional, and geodetic vertical directions.

[0082] Thus, the direction vector k of the beam can be expressed as Equation (3):

[0083]

[0084] Wherein, Dis represents the arc distance of the projection of the distance between the observation point and the incoherent scatter radar on the ground, φ represents the azimuth angle, and H = Z represents the projection of R in the geodetic vertical direction.

[0085] H can be obtained by solving Equation (4):

[0086] (H + R E ) 2 = R E 2 + R 2 - 2R E Rcos(90 + θ) (4)

[0087] Wherein, R E represents the radius of the earth, and θ represents the beam elevation angle of the incoherent scatter radar.

[0088] The arc distance of the projection of the distance between the observation point and the incoherent scatter radar on the ground can be obtained by Equation (5):

[0089]

[0090] When the vector velocity is the three components v pe (eastward perpendicular to the magnetic field line), v pn (northward perpendicular to the magnetic field line), v ap ​For the (anti-parallel magnetic field lines), the beam vector k also needs to be correspondingly converted to Equation (6):

[0091] k = [k pe k pn k ap = [k e k n k z × R geo2gmag (6)

[0092] where R geo2gmag is the transformation matrix, as shown in Equation (7):

[0093]

[0094] where D is the magnetic declination and I is the magnetic inclination angle.

[0095] Thus, for a certain specific spatial point (or spatial volume), the mapping relationship between the vector velocity in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction is as shown in Equation (8):

[0096] v los = Av + e los (8)

[0097] where n represents the number of line-of-sight velocities, v los is the vector velocity, e los is the error of the line-of-sight velocity, and A is the beam direction matrix.

[0098] Expanding Equation (8) gives Equation (9):

[0099]

[0100] From Equation (8), it can be seen that given the line-of-sight velocity v los , the beam direction matrix A and the line-of-sight velocity error e los , the vector velocity v can be inversely obtained. Given the vector velocity v, the beam direction matrix A and the line-of-sight velocity error e los , the line-of-sight velocity v los can be directly obtained. Thus, as Figure 1 shown, the present invention combines forward and inverse operations, and finally evaluates and assists in designing different experimental schemes by comparing the inverse value and the true value of the vector velocity.

[0101] Step S20, for different beam configurations at each position in the all-sky scanning mode:

[0102] Forward the mapping relationship between the vector velocity and the line-of-sight velocity of the radar beam direction for any beam configuration respectively, and set the three components of the forward vector drift as the true values to obtain the line-of-sight velocity of the radar beam direction, so as to realize the simulation of radar detection of ionospheric drift:

[0103] Based on the vector velocity v and the beam direction matrix A, the error-free line-of-sight velocity is obtained, as shown in Equation (10):

[0104]

[0105] Add errors to the error-free line-of-sight velocity, as shown in Equation (11):

[0106]

[0107] where α is a random number with a mean of 0 and a standard deviation of 1. e los is the line-of-sight velocity error.

[0108] The line-of-sight velocity error e los is mainly determined by the signal-to-noise ratio of the echo signal, and the signal-to-noise ratio is mainly affected by the elevation angle of the beam, the distance of the observation point and the electron density.

[0109] As Figure 2 shown, it is a schematic diagram of the line-of-sight velocity error value in the forward process of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention. Collect the line-of-sight velocity error measurement values of the incoherent scatter radar in a set time period (the line-of-sight velocity error between 12:00 - 15:00 LT during 12 days of radar observation) and perform grid interpolation on the line-of-sight velocity error measurement values in the set time period to obtain the line-of-sight velocity error. It can be seen from Figure 2 that the error increases with the decrease of the elevation angle and the increase of the distance. When the elevation angle is lower than 50° or the distance exceeds 500 km, the line-of-sight velocity error increases sharply, exceeding 50 m / s, and the error in other ranges is basically within 10 m / s; the error is relatively small at about 100 - 200 km and 300 - 400 km in altitude because these two altitude ranges correspond to the E layer and F layer of the ionosphere with relatively large electron density.

[0110] As Figure 3 and Figure 4 shown, they are respectively the simulation results under the east-west scan and the north-south scan of an embodiment of the ionospheric drift detection method based on a phased array incoherent scatter radar of the present invention: The beam is set to start from an elevation angle of 55°, with an interval of 3.5°, and 21-beam scans are respectively from east to west and from north to south. The distance range is 100 km - 600 km, the step size is 10 km, and the vector velocity is set to be uniform in the whole space: v pe =-51 m / s, v pn =23 m / s, vap = -45 m / s (the same for the following tests). In the upper sub - figure, the red dots represent the azimuth and elevation angles of the experimental beam, and the blue hexagons represent the radar non - grating lobe scanning range. In the lower sub - figure, the left - hand sub - figure is the distribution of the line - of - sight velocity v los 0 in longitude / latitude and altitude. In Figure 3 , it can be seen that on the west side of the radar, the vector velocity projection in the beam line - of - sight direction shows as moving away, being positive. As the beam elevation angle increases, the projection component gradually decreases and becomes negative on the east side of the radar. In Figure 4 , the vector velocity projection on the north side of the radar in the beam line - of - sight direction is positive, and on the south side is negative. The right - hand sub - figure is the line - of - sight velocity v los after adding errors according to formula (11). It can be seen that there are more chaotic features in details, but overall, below a distance of 500 km, it still shows the same distribution trend as . Above a distance of 500 km, the line - of - sight velocity information is completely submerged by the errors, which is relatively close to the actual observations.

[0111] Invert the mapping relationship between the vector velocity of any beam configuration and the line - of - sight velocity in the radar beam direction respectively, and set the three components of the inverted vector drift to the inversion values:

[0112] Based on the Bayesian estimation method, the vector velocity and covariance matrix are inversely obtained, as shown in equations (12) and (13):

[0113]

[0114] where is the inversely estimated vector velocity, is the inversely estimated error covariance matrix, the diagonal elements of are the squared values of the inversion errors, Σ v and Σ e are the prior covariance matrices of velocity and error respectively.

[0115] The prior covariance matrix provides prior information for the inversion to balance the weights of observations (data) and experience (given prior standard deviations). Both are diagonal matrices with their respective variances as diagonal elements. The former is the variance of the three components of the vector velocity given according to experience, and the variance of the latter takes the error of the line - of - sight velocity. Here, the values of the variances of the three components of the vector velocity are given according to experience, and the prior standard deviations of the three components of the vector velocity in this paper are all taken as 500 m / s.

[0116] Step S30: Use the ratio between the difference of the inversion value minus the true value and the true value as the relative deviation of the vector drift, and use the ratio between the inversion error and the true value as the relative inversion error of the vector drift. For the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimation.

[0117] The relative deviation of the vector drift is shown in Equation (14):

[0118]

[0119] The relative inversion error of the vector drift is shown in Equation (15):

[0120]

[0121] Step S40: Select the beam configuration where the relative deviation of the vector drift is less than the first set threshold and the relative inversion error of the vector drift is less than the second set threshold as the optimal beam configuration for ionospheric drift detection.

[0122] Fast and accurate scanning is a major advantage of phased array radar over traditional radar. The present invention can flexibly design the beam configuration according to the experimental purpose. The beam configuration has a certain impact on the detection effect, so how to design the radar beam configuration is very important. Using the above method combining forward and inverse inversion, not only can the experimental beam configuration scheme be evaluated, but also it can guide the design of a more perfect experimental scheme, improving the experimental effect and experimental efficiency.

[0123] Step S50: At the position of the optimal beam configuration, perform F-layer ionospheric drift detection through the optimal beam configuration.

[0124] The experimental mode design and evaluation process of the present invention is as follows:

[0125] I. All-sky scanning mode

[0126] The all-sky scanning mode is to obtain the distribution of vector velocity in altitude and time, so only several beams need to be set in the all-sky range. First, the present invention sets a 5-beam configuration symmetric about the radar, and the results are as Figure 5 shown. The points in the leftmost subfigure represent the elevation angles and azimuth angles of the five beams, which are (65°, 0°), (65°, 90°), (65°, 180°), (65°, 270°), (90°, 0°) respectively. The right subfigure is the result of evaluating the inversion method, showing the distribution of the two indicators of relative deviation and relative inversion error respectively above and below. It can be seen that the inversion result of v pe has almost no deviation, and the inversion result of v ap has a small deviation below 425 km, within 0.1, but the deviation increases sharply at higher altitudes, while for v pnThe deviation of the inversion result is significantly larger than that of the other two components and can exceed 0.1 at altitudes below 400 km. In fact, since v pn is the smallest among the three components, it will be the most significantly affected by errors, so the deviation of the inversion result will also be greater than that of the other two components. The relative inversion errors of the three components are mostly around 0.1 - 0.25 at most altitudes and are basically the same. Figure 6 is the improved 8-beam configuration. The elevation and azimuth angles of the 8 beams are (59°, 0°), (60°, 0°), (61°, 0°), (59°, 180°), (60°, 180°), (61°, 180°), (65°, 90°), (65°, 270°) respectively. Among them, the 1st - 3rd beams are close to the vertical magnetic field line, the 4th - 6th beams are as close as possible to the magnetic field line, and the 7th - 8th beams are as close as possible to the east - west direction of the vertical magnetic field line. It can be seen that the detection effects of v pe 、v pn and v ap are all relatively good. The relative deviations and relative inversion errors of v pe 、v pn and v ap are smaller than those of Figure 5 . Such a beam setting is more suitable for detecting the altitude profile of the drift velocity.

[0127] II. Single - station fine - scanning mode

[0128] Fine - scanning means setting the beams more densely within a certain spatial range, and the vector velocity distribution with altitude, time, and longitude - latitude can be inversely obtained. In Figure 7 and Figure 8 , the beams scanned along the north - south direction were tested in the northern and southern regions respectively. In this test, the beams were set as 3 columns of 7 - beam scans parallel in the north - south direction. The elevation and azimuth angles of the middle - column beams were (50°, 0°), (55°, 0°), (60°, 0°), (65°, 0°), (70°, 0°), (75°, 0°), (80°, 0°) and (80°, 180°), (75°, 180°), (70°, 180°), (65°, 180°), (60°, 180°), (55°, 180°), (50°, 180°) respectively. Such a 21 - beam scan can cover geographical latitudes from 18.5° to 21.7° and from 15° to 18.2°. The former obtained the two components of v pe and v pn . The relative inversion error of v pe is mostly around 0.5, and the relative inversion error of v pn is even smaller, mostly within 0.3. The latter obtained v pe and v apFor the two components, the relative inversion errors are mostly around 0.5. This indicates that for fine scanning, it is suitable to set dense beams in the north for detection.

[0129] In the above embodiments, although the steps are described in the above order, those skilled in the art can understand that in order to achieve the effects of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in reverse order, and these simple changes are within the protection scope of the present invention.

[0130] The ionospheric drift detection system based on a phased array incoherent scatter radar according to the second embodiment of the present invention, the ionospheric drift detection system includes:

[0131] A mapping relationship construction module configured to construct a mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity of the radar beam direction based on the velocity in any line-of-sight direction of the incoherent scatter radar;

[0132] A forward modeling module configured to perform forward modeling of the mapping relationship between the vector velocity and the line-of-sight velocity of the radar beam direction for any beam configuration at each position in the full-sky scanning mode, and set the three components of the forward modeled vector drift as the true values to obtain the line-of-sight velocity of the radar beam direction, thereby realizing the simulation of the radar detection of ionospheric drift;

[0133] An inversion module configured to perform inversion of the mapping relationship between the vector velocity and the line-of-sight velocity of the radar beam direction for any beam configuration at each position in the full-sky scanning mode, and set the three components of the inverted vector drift as the inversion values;

[0134] An error acquisition module configured to use the ratio of the difference between the inversion value and the true value to the true value as the relative deviation of the vector drift, and use the ratio of the inversion error to the true value as the relative inversion error of the vector drift; for the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimate;

[0135] An optimal beam configuration selection module configured to select the beam configuration with the relative deviation of the vector drift less than the first set threshold and the relative inversion error of the vector drift less than the second set threshold as the optimal beam configuration for ionospheric drift detection;

[0136] A detection module configured to perform F-layer ionospheric drift detection through the optimal beam configuration at the position where the optimal beam configuration is located.

[0137] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related explanations of the above-described system can refer to the corresponding process in the foregoing method embodiments and will not be elaborated here.

[0138] It should be noted that the ionospheric drift detection system based on phased array incoherent scatter radar provided in the above embodiments is only illustrated by dividing the above functional modules. In practical applications, the above functions can be allocated to different functional modules according to needs, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be combined into one module, or further split into multiple sub-modules to complete all or part of the functions described above. For the names of the modules and steps involved in the embodiments of the present invention, they are only used to distinguish each module or step, and are not regarded as improper limitations of the present invention.

[0139] An electronic device according to a third embodiment of the present invention includes:

[0140] At least one processor; and

[0141] A memory communicatively connected to at least one of the processors; wherein,

[0142] The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned ionospheric drift detection method based on phased array incoherent scatter radar.

[0143] A computer-readable storage medium according to a fourth embodiment of the present invention stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned ionospheric drift detection method based on phased array incoherent scatter radar.

[0144] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes and related descriptions of the above-described storage device and processing device can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0145] Those skilled in the art should be able to realize that the modules and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of both. The programs corresponding to the software modules and method steps can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the technical field. To clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in the form of electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0146] The terms "first", "second", etc. are used to distinguish similar objects, rather than to describe or represent a specific order or sequence.

[0147] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, so that a process, method, article, or device / equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes the elements inherent in these processes, methods, articles, or devices / equipment.

[0148] So far, the technical solution of the present invention has been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An ionospheric drift detection method based on phased array incoherent scatter radar, characterized in that, The ionospheric drift detection method includes: Step S10: Based on the velocity in any line-of-sight direction of the incoherent scatter radar, construct a mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity in the radar beam direction; Step S20: For different beam configurations at each position in the full-sky scanning mode: Respectively perform the forward modeling of the mapping relationship between the vector velocity and the line-of-sight velocity in the radar beam direction for any beam configuration, and set the three components of the forward modeled vector drift as the true values to obtain the line-of-sight velocity in the radar beam direction, so as to realize the simulation of the radar detecting ionospheric drift; Respectively perform the inverse modeling of the mapping relationship between the vector velocity and the line-of-sight velocity in the radar beam direction for any beam configuration, and set the three components of the inverse modeled vector drift as the inversion values; Step S30: Use the ratio of the difference between the inversion value and the true value to the true value as the relative deviation of the vector drift, and use the ratio of the inversion error to the true value as the relative inversion error of the vector drift; for the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimate; Step S40: Select the beam configuration with the relative deviation of the vector drift less than the first set threshold and the relative inversion error of the vector drift less than the second set threshold as the optimal beam configuration for ionospheric drift detection; Step S50: At the position where the optimal beam configuration is located, perform the F-layer ionospheric drift detection through the optimal beam configuration.

2. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 1, characterized in that The velocity in any line-of-sight direction of the incoherent scatter radar is: Among them, k = [k e k n k z represents the direction vector of the beam, v = [v e v n v z T represents the three velocity components, i represents the i-th line-of-sight direction, and [e n z] represent the eastward, northward, and zenith directions respectively in the radar center geodetic coordinate system.​ 3. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 2, wherein The direction vector of the beam is: where Dis represents the arc distance of the projection of the distance between the observation point and the incoherent scatter radar on the ground, and φ represents the azimuth angle. represents the distance between the observation point and the incoherent scatter radar, [X Y Z] represents the projections of R in the zonal, meridional, and geodetic vertical directions, and H = Z represents the projection of R in the geodetic vertical direction.

4. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 3, characterized in that The projection of R in the geodetic vertical direction, its calculation method is: (H + R E ) 2 = R E 2 + R 2 - 2R E R cos(90 + θ) where R E represents the radius of the Earth, and θ represents the beam elevation angle of the incoherent scatter radar.

5. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 4, wherein The arc distance on the ground of the projection of the distance between the observation point and the incoherent scatter radar is: where R E represents the radius of the Earth, and θ represents the beam elevation angle of the incoherent scatter radar.

6. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 5, characterized in that, The mapping relationship between the vector velocity in the geomagnetic coordinate system and the line-of-sight velocity in the radar beam direction is: v los = Av + e los where n represents the number of line-of-sight velocities, v los is the vector velocity, e los is the error of the line-of-sight velocity, is the beam direction matrix.

7. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 6, wherein The method for performing the forward modeling of the mapping relationship between the vector velocity and the line-of-sight velocity in the radar beam direction for any beam configuration is: Based on the vector velocity v and the beam direction matrix A, obtain the error-free line-of-sight velocity: Add errors to the error-free line-of-sight velocity: where α is a random number with a mean of 0 and a standard deviation of 1, and e los is the line-of-sight velocity error.

8. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 7, characterized in that, The method for obtaining the line-of-sight velocity error is: Collect the line-of-sight velocity error measurement values of the incoherent scatter radar for a set time period; Perform grid interpolation on the line-of-sight velocity error measurement values of the set time period to obtain the line-of-sight velocity error.

9. The ionospheric drift detection method based on phased array incoherent scatter radar according to claim 6, characterized in that, The method for performing the inverse modeling of the mapping relationship between the vector velocity and the line-of-sight velocity in the radar beam direction for any beam configuration is: Based on the Bayesian estimation method, inversely obtain the vector velocity and the covariance matrix; Among them, is the vector velocity of the inversion estimation, is the error covariance matrix of the inversion estimation, The diagonal elements of are the squared values of the inversion errors, Σ v and Σ e are the prior covariance matrices of velocity and error respectively.

10. An ionospheric drift detection system based on a phased array incoherent scatter radar, characterized in that, The ionospheric drift detection system includes: A mapping relationship construction module, configured to construct a mapping relationship between the vector velocity of a set spatial point in the geomagnetic coordinate system and the line-of-sight velocity in the radar beam direction based on the velocity in any line-of-sight direction of the incoherent scatter radar; A forward modeling module, configured to respectively perform the forward modeling of the mapping relationship between the vector velocity and the line-of-sight velocity in the radar beam direction for any beam configuration at each position in the full-sky scanning mode, and set the three components of the forward modeled vector drift as the true values to obtain the line-of-sight velocity in the radar beam direction, so as to realize the simulation of the radar detecting ionospheric drift; An inversion module, configured to perform inversion of the mapping relationship between the vector velocity of any beam configuration and the line-of-sight velocity of the radar beam direction for different beam configurations at each position in the full-sky scanning mode, respectively, and set the three components of the inversion vector drift as the inversion values; An error acquisition module, configured to use the ratio between the inversion value minus the true value and the true value as the relative deviation of the vector drift, and use the ratio between the inversion error and the true value as the relative inversion error of the vector drift; for the inversion error, the square value is the diagonal element of the error covariance matrix of the inversion estimate; An optimal beam configuration selection module, configured to select the beam configuration with the relative deviation of the vector drift less than a first set threshold and the relative inversion error of the vector drift less than a second set threshold as the optimal beam configuration for ionospheric drift detection; A detection module, configured to perform F-layer ionospheric drift detection through the optimal beam configuration at the position where the optimal beam configuration is located.

Images