A method and apparatus for determining a high frequency skywave hybrid propagation path

Abstract

The application relates to the technical field of parameter estimation, and provides a method and device for determining a high-frequency sky-wave mixed propagation path. A first expression of an ionospheric reflection point coordinate is determined; a second expression of a sea surface scattering point coordinate is determined; a first candidate solution curve of an equal group path of an uplink length from a transmitting station to an ionospheric reflection point and a receiving length from a receiving station to a sea surface scattering point is determined according to the first expression, the second expression and an actual group path; a first-order sea clutter is used to determine an actual Bragg frequency, and a second candidate solution curve of an equal Bragg frequency of the uplink length and the receiving length is determined; and the mixed propagation path is solved according to the first candidate solution curve and the second candidate solution curve, so that the dependence on a background ionospheric model or prior propagation conditions in the prior art when determining the high-frequency sky-wave mixed propagation path is solved.

Description

Technical Field

[0001] This invention relates to the field of parameter estimation technology, and in particular to a method and apparatus for determining the mixed propagation path of high-frequency ground and earth waves. Background Technology

[0002] High-frequency hybrid skywave and groundwave propagation combines the long-range illumination of skywaves with stable groundwave reception, possessing the engineering advantages of both skywave's over-the-horizon coverage and the relatively stable groundwave receiving link. However, forward propagation in this system still requires traversing and relying on the ionosphere. The spatiotemporal fluctuations, tilt, and disturbances of ionospheric electron density significantly alter the incident path, reflection position, and wavefront phase. Therefore, while its propagation path reliability is superior to the two-way skywave link in a pure skywave system, it is still significantly lower overall than that of groundwave radar propagating from the ocean surface. Consequently, how to reliably determine the propagation path of skywave and groundwave radar under complex ionospheric conditions has become a crucial fundamental issue for this type of system, moving from mechanistic analysis to stable application.

[0003] However, existing technologies for determining the propagation path of mixed high-frequency ionospheric and ground waves often rely on high-precision ionospheric background models or valid propagation assumptions, making it difficult to reliably determine the propagation path in this scenario.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by this invention is that the determination of the propagation path of high-frequency terrestrial and ground waves often relies on high-precision ionospheric background models or effective propagation assumptions, which results in low reliability.

[0006] Firstly, a method for determining the propagation path of high-frequency terrestrial and atmospheric waves is provided, including: A first expression to determine the coordinates of the ionospheric reflection point; a second expression to determine the coordinates of the sea surface scattering point; Based on the first expression, the second expression, and the actual group path, determine the first candidate solution curve of the equal group path for the uplink length from the transmitter to the ionospheric reflection point and the receiving length from the receiver to the sea surface scattering point; The actual Bragg frequency is determined based on the first-order sea clutter, and a second candidate solution curve for the equal Bragg frequency of the uplink length and the receive length is determined based on the first expression and the second expression. Based on the first candidate solution curve and the second candidate solution curve, solve the first expression and the second expression to obtain the hybrid propagation path.

[0007] Further, the step of determining the actual Bragg frequency based on first-order sea clutter, and determining the second candidate solution curve of equal Bragg frequencies for the uplink length and the receive length based on the first expression and the second expression includes: Based on the spectral peak difference between positive first-order sea clutter and negative first-order sea clutter, the actual Bragg frequency obtained from the measurement is extracted. Based on the first expression and the second expression, determine the theoretical Bragg frequencies corresponding to the uplink length and the receive length; Based on the theoretical Bragg frequency, the solution space of the uplink length and the receive length is constrained using the actual Bragg frequency to obtain the second candidate solution curve.

[0008] Furthermore, the expression for the solution space of constraining the uplink length and the receive length using the actual Bragg frequency based on the theoretical Bragg frequency is as follows: ; in, This indicates the actual Bragg frequency. This represents the theoretical Bragg frequency.

[0009] Further, determining the theoretical Bragg frequencies corresponding to the uplink length and the received length based on the first expression and the second expression includes: The difference between the second expression and the first expression is determined as the first intermediate quantity, the norm of the first intermediate quantity is determined as the second intermediate quantity, and the ratio of the first intermediate quantity to the second intermediate quantity is determined as the first unit vector in the direction of incident on the sea surface. The negative of the spherical tangential unit vector at the receiving station is determined as the second unit vector in the direction of return ground wave departure; The norm of the second expression is determined as the third intermediate quantity, and the ratio of the second expression to the third intermediate quantity is determined as the spherical unit normal vector at the sea surface scattering point. The theoretical Bragg frequency is determined based on the wave number of the electromagnetic wave, the first unit vector, the second unit vector, and the spherical unit normal vector.

[0010] Furthermore, the expression for the theoretical Bragg frequency is: ; in, It is the acceleration due to gravity. Let the wave number be the electromagnetic wave. Represents the first unit vector. This represents the second unit vector. This represents the unit normal vector of the sphere.

[0011] Further, the first candidate solution curve of the equal-group path for determining the uplink length from the transmitting station to the ionospheric reflection point and the receiving length from the receiving station to the sea surface scattering point based on the first expression, the second expression, and the actual group path includes: Obtain the actual group path obtained from the measurement; Based on the actual group path, using the first expression and the second expression, the solution space of the uplink length and the receiving length is constrained based on the equal group path to obtain the first candidate solution curve.

[0012] Further, the expression for the solution space of the uplink length and the receive length constrained by the equal-group path, using the first expression and the second expression according to the actual group path, is as follows: ; in, This indicates the length of the upstream line. Indicates the received length, For the first expression, For the second expression, This refers to the actual group path.

[0013] Further, the step of solving the first expression and the second expression based on the first candidate solution curve and the second candidate solution curve to obtain the hybrid propagation path includes: Based on the intersection of the first candidate solution curve and the second candidate solution curve, the first expression and the second expression are solved to obtain the unique solution for the uplink length and the unique solution for the receive length, so as to obtain the hybrid propagation path.

[0014] Secondly, an apparatus for determining a mixed propagation path of high-frequency ground and earth waves is provided, the apparatus comprising: a processor and a memory for storing processor-executable instructions; The processor is configured to execute the method for determining the mixed propagation path of high-frequency ground and earth waves.

[0015] Thirdly, a non-volatile computer storage medium is provided, the computer storage medium storing computer-executable instructions, which are executed by one or more processors to perform the method for determining the high-frequency ground wave hybrid propagation path described in the first aspect.

[0016] Fourthly, a computer program product containing instructions is provided, which, when executed on a computer or processor, causes the computer or processor to perform the method for determining a high-frequency terrestrial wave hybrid propagation path as described in the first aspect.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes first-order sea clutter and inverse constraints based on measured physical quantities to determine the mixed propagation path of high-frequency ground-to-surface waves, thereby achieving radar parameter estimation. First, expressions for two unknown coordinates are constructed using the geometric relationships between the transmitting station and the ionospheric reflection point, and between the receiving station and the sea surface scattering point. Then, a first candidate solution curve is formed using actual group paths, and a second candidate solution curve is formed using the Bragg frequency inherent in the first-order sea clutter and independent of the ionospheric state. The group path reflects time delay constraints, and the Bragg frequency reflects radial velocity constraints at the sea surface scattering point. Finally, based on these two factors, all necessary geometric and physical conditions satisfying the propagation path are determined, thus obtaining the mixed propagation path. This approach avoids reliance on high-precision ionospheric background models or valid propagation assumptions. It does not depend on ionospheric models or prior propagation conditions; the mixed propagation path of high-frequency ground-to-surface waves can be uniquely determined using only the first-order sea clutter of the radar echo, effectively improving reliability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a method for determining a mixed propagation path of high-frequency ground and earth waves provided in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating a specific example of a high-frequency ground-to-earth wave hybrid propagation path provided in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating a specific example of the overall flow of a method according to an embodiment of the present invention. Figure 4 This is a flowchart illustrating step 20 provided in an embodiment of the present invention; Figure 5 This is a flowchart illustrating step 30 provided in an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating a specific example of radar measurement of Bragg frequency provided in an embodiment of the present invention; Figure 7This is a schematic diagram illustrating a specific example of the intersection point of a candidate solution curve for an equal-group path and a candidate solution curve for an equal-Bragg frequency, provided in an embodiment of the present invention. Figure 8 This is a schematic diagram of a device for determining the mixed propagation path of high-frequency ground and earth waves provided in an embodiment of the present invention. Detailed Implementation

[0020] 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.

[0021] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0022] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0023] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling," "wireless connection," etc. The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0024] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Regarding the background technical issues, existing technologies can be broadly divided into two categories: The first type of method relies on empirical ionospheric models. Some schemes combine international reference ionospheric models with three-dimensional ray tracing to numerically calculate the propagation path of high-frequency radio waves in the ionosphere. This approach is relatively complete in its mechanism and can provide a unique estimate of the propagation path, thus it is widely used in high-frequency radar propagation prediction, reflection point analysis, and path visualization. However, its accuracy is highly dependent on the background ionospheric model. When the ionosphere has local tilt, fine-scale irregularities, or rapid time-varying perturbations, even if the ray tracing algorithm itself is accurate, ray tracing based on the background ionospheric model may not be sufficient to support high-precision path reconstruction, thus limiting the applicability of this type of method in real-time, accurate path determination.

[0026] The second type of method tends to transform the originally complex hybrid propagation process into an analytical or low-dimensional solvable geometric problem by setting several propagation preconditions. For example, some schemes use a single-station wide-beam ground-to-surface wave system to locate sea surface scattering points, which usually requires first defining the propagation geometry and then combining observations to complete the inversion. Other schemes use propagation preconditions such as a plane parallel ionosphere, an inclined plane ionosphere, specular reflection, and a fixed reflection height to solve for propagation parameters and subsequently locate the point. The advantage of this type of method is its computational simplicity, ease of implementation, and ability to provide a unique propagation path under specific conditions. However, if the actual propagation environment deviates from the preset preconditions, the propagation path estimation may produce a non-negligible model mismatch error.

[0027] Therefore, overcoming the shortcomings of existing technologies and solving their dependence on background ionospheric models or a priori propagation conditions is a problem to be solved in this technical field.

[0028] To address the problems of existing technologies, this embodiment proposes a method for determining the mixed propagation path of high-frequency ground and earth waves. In one embodiment, such as... Figure 1 As shown, it includes: Step 10: Determine the first expression for the coordinates of the ionospheric reflection point; determine the second expression for the coordinates of the sea surface scattering point.

[0029] like Figure 2 The diagram illustrates a specific example of a hybrid high-frequency skywave-ground wave propagation path. The transmitting station, typically using skywave mode with the antenna elevation pointing towards the ionosphere, is the site that transmits high-frequency electromagnetic waves. The receiving station, typically using groundwave mode with the antenna pointing towards the sea surface, is the site that receives the sea-reflected echo. The ionospheric reflection point is the point where the ray path changes from rising to falling as the radio wave propagates in the ionosphere (for perpendicular incidence, it is the reflection point; for oblique incidence, it is the highest point). Since the ionosphere is a continuous refractive medium, the ionospheric reflection point is often defined as the location corresponding to the maximum virtual height in the group path integral. The sea-reflection point is the location where the radio wave interacts with the sea surface, resulting in backscattering (e.g., first-order Bragg scattering). In the hybrid system, the sea-reflection point is the target point of the skywave illumination and also the starting point of the groundwave echo. In a high-frequency hybrid system of skywave and groundwave, the skywave is emitted and then scattered by the sea surface, and then the groundwave is received. A complete signal path is as follows: the transmitting station reaches the ionospheric reflection point through the skywave, then reaches the sea surface scattering point through the skywave, and then the groundwave reaches the receiving station.

[0030] like Figure 3 As shown, firstly, the length from the transmitting station to the ionospheric reflection point is set. Based on the transmitting azimuth and elevation angles measured by the transmitting array, the coordinates of the ionospheric reflection point are obtained. In one embodiment, a first expression for the coordinates of the ionospheric reflection point can be determined based on the transmitting azimuth and elevation angles measured by the transmitting array. Secondly, the length from the receiving station to the sea surface scattering point is set. Based on the receiving azimuth angle measured by the receiving array, the coordinates of the sea surface scattering point are obtained. In one embodiment, a second expression for the coordinates of the scattering point can be determined based on the receiving azimuth angle measured by the receiving array.

[0031] Step 20: Based on the first expression, the second expression, and the actual group path, determine the first candidate solution curve of the equal group path for the uplink length from the transmitting station to the ionospheric reflection point and the receiving length from the receiving station to the sea surface scattering point.

[0032] Then, based on the group path measured by the radar, the candidate solution curves of the equal group path with the previously set uplink length and receive length are obtained (i.e., the first candidate solution curve).

[0033] In this invention, the length from the transmitting station to the ionospheric reflection point is the uplink group path, which is the equivalent vacuum distance traveled by the radio wave along the actual curved path from the transmitting station to the ionospheric reflection point. The length from the receiving station to the sea surface scattering point is the ground wave path length or the receiving ground wave distance, which is the great circle arc distance along the Earth's surface from the sea surface scattering point to the receiving station. In this invention, this is called the receiving length. Since the refraction effect in ground wave propagation is negligible, its group path and geometric distance are almost equal. The great circle arc distance refers to the arc length of the shortest path between two points on a sphere (e.g., the Earth's surface). This path follows the minor arc of the great circle formed by the intersection of the plane passing through the center of the sphere and the plane at these two points.

[0034] Group propagation refers to the set of all possible paths from radar pulse transmission, through their propagation path to the sea surface target, and back to the radar receiver, with the same total propagation time (i.e., group delay). In traditional skywave radar, the group propagation corresponds to an ellipse, with the radar station and the equivalent receiving point as the foci. However, in hybrid systems, the downlink skywave path and the uplink groundwave path are asymmetrical, and the group propagation becomes a more complex oval shape. The group path refers to the total virtual path length of the radio wave propagating along its actual curved path. The actual group path is the group path data actually measured by the radar.

[0035] Step 30: Determine the actual Bragg frequency based on the first-order sea clutter, and determine the second candidate solution curve of the equal Bragg frequency of the uplink length and the receive length based on the first expression and the second expression.

[0036] Then, based on the measured Bragg frequency extracted from the first-order sea clutter, candidate Bragg frequency curves (i.e., the second candidate solution curve) for the previously set uplink and receive lengths are obtained. The specific method for extracting the measured Bragg frequency from the first-order sea clutter is determined by those skilled in the art based on the specific application scenario; a specific example will be provided below.

[0037] In this embodiment of the invention, the first-order sea clutter refers to the first-order sea clutter of the radar echo. The Bragg frequency refers to the Doppler shift of this echo relative to the radar carrier when the wavelength of the high-frequency radar wave is twice the wavelength of the sea surface capillary wave, resulting in coherent resonant scattering and a strong backscattered echo. The actual Bragg frequency is the Bragg frequency data obtained from actual measurements. The Bragg frequency is determined solely by the radar operating frequency and is independent of the propagation path and ionospheric state. In ground-wave radar, "equal Bragg" refers to the contour lines (i.e., rings) formed by all points on the sea surface that produce the same radial velocity (i.e., Doppler) of the Bragg echo. In hybrid systems, when a skywave path exists, the geometry of the "equal Bragg" may be distorted due to additional Doppler shift or path stretching caused by ionospheric reflection; however, the equal Bragg is still a set of sea surface scattering points that can produce the same observed Doppler shift.

[0038] Step 40: Based on the first candidate solution curve and the second candidate solution curve, solve the first expression and the second expression to obtain the hybrid propagation path.

[0039] Finally, the previously set uplink length and receive length are determined based on the intersection of the candidate solution curves for equal-group paths and the candidate solution curves for equal-Bragg frequencies, thereby achieving a unique determination of the high-frequency hybrid propagation path for both ground and air waves. The specific solution method should be determined by those skilled in the art based on the specific application scenario; a specific example will be provided below.

[0040] like Figure 2 As shown, the objective of this embodiment of the invention is to uniquely determine the hybrid propagation path of high-frequency terrestrial and terrestrial waves, which is the length from the transmitting station to the ionospheric reflection point. (i.e., uplink length) and the length of the scattering point from the receiving station to the sea surface. (i.e., the receiving length). The receiving length is unknown; the uplink length and the receiving length are related to the location of the ionospheric reflection point, and are obtained by the inversion solution of the intersection of equal Bragg Doppler and equal group paths in the embodiment of the present invention.

[0041] Unlike existing technologies that determine propagation paths through forward modeling and prediction, this invention utilizes first-order sea clutter and solves for inverse constraints based on measured physical quantities to determine the high-frequency hybrid propagation path of ground and air waves, thereby achieving radar parameter estimation. First, expressions for two unknown coordinates are constructed using the geometric relationships between the transmitting station and the ionospheric reflection point, and between the receiving station and the sea surface scattering point. Then, a first candidate solution curve is formed using the actual group path, and a second candidate solution curve is formed using the Bragg frequency inherent in the first-order sea clutter and independent of the ionospheric state. The group path reflects the time delay constraint, and the Bragg frequency reflects the radial velocity constraint of the sea surface scattering point. Finally, based on these two factors, all necessary geometric and physical conditions satisfying the propagation path are determined, thus obtaining the hybrid propagation path. Compared to existing technologies that rely on models such as the international reference ionosphere for ray tracing, this invention does not require assumptions about ionospheric electron density profiles, irregular body structures, or perturbation models. Therefore, it maintains robustness even when the ionosphere has local tilt, rapid time-varying characteristics, or fine-scale irregularities, avoiding path deviations caused by model mismatch. Compared to existing technologies that rely on simplified conditions such as a pre-set planar ionosphere, specular reflection, or fixed reflection height, this invention does not introduce any artificial propagation prerequisites. Instead, it determines the actual path based on the actual group delay and Bragg frequency measured in real time, thereby eliminating model mismatch errors. This invention avoids reliance on high-precision ionospheric background models or propagation assumptions of validity. It does not depend on ionospheric models or prior propagation conditions, and can uniquely determine the high-frequency mixed propagation path of ground and sky waves using only the first-order sea clutter of radar echoes, effectively improving reliability.

[0042] The method for determining the high-frequency terrestrial wave hybrid propagation path according to embodiments of the present invention will now be further described: like Figure 3 As shown, the first step of this embodiment of the invention is: in step 10, the first expression for the coordinates of the ionospheric reflection point is determined.

[0043] Specifically, in one embodiment, the first expression for obtaining the reflection point of the ionosphere is: ; in, The coordinates of the reflection point of the ionosphere. This refers to the set path length of the first segment of the terrestrial wave, i.e., the uplink length from the transmitting station to the ionospheric reflection point. To represent the three-dimensional coordinate vector of the transmitting array, The unit vector in the direction of launch; in, It can be calculated using the following formula: ; in, The azimuth angle measured by the transmitting array. The launch elevation angle measured by the launch array. The eastward unit vector at the launch station can be calculated using the following formula: ; The northward unit vector at the launch station can be calculated using the following formula: ; Let be the unit vector in the zenith direction at the launch station, which can be calculated using the following formula: ; in, The latitude of the launch station's geographical coordinates. The longitude is the geographical coordinate of the launch station.

[0044] like Figure 3 As shown, the second step in this embodiment of the invention is: in step 10, a second expression for the coordinates of the sea surface scattering point is determined.

[0045] Specifically, in one embodiment, the second expression for obtaining the coordinates of the sea surface scattering point is: ; in, The coordinates of the scattering point on the sea surface; The set path length for the third segment of the terrestrial wave is the length from the receiving station to the scattering point on the sea surface (i.e., the receiving length). For the Earth's radius, Let be the spherical unit normal vector at the receiving station. Let be the spherical tangential unit vector at the receiving station.

[0046] In one embodiment, the spherical unit normal vector It can be calculated using the following formula: ; in, The latitude of the seaside receiving station. This refers to the longitude of the geographical coordinates of the receiving station at the seaside.

[0047] In one embodiment, the spherical tangential unit vector It can be calculated using the following formula: ; in, To receive the azimuth angle, The eastward unit vector at the receiving station can be calculated using the following formula: ; The northward unit vector at the receiving station can be calculated using the following formula: .

[0048] After obtaining the first and second expressions, in one embodiment, as follows: Figure 4 As shown, step 20 includes: Step 201: Obtain the actual group path obtained from the measurement.

[0049] Step 202: According to the actual group path, using the first expression and the second expression, based on the equal group path constraints of the solution space of the uplink length and the receiving length, to obtain the first candidate solution curve.

[0050] like Figure 3 As shown, the third step in this embodiment of the invention is: constraining the uplink length using equigroup path constraints. and receive length In one embodiment, the solution space is... and The solution satisfies the following expression: ; in, This indicates the length of the upstream line. Indicates the received length, For the first expression, For the second expression, The actual group path can be the group distance measured by radar in step 201. This yields... Candidate solution curves of equigroup paths in the plane .

[0051] In one embodiment, such as Figure 5 As shown, step 30 includes: Step 301: Extract the actual Bragg frequency obtained from the measurement based on the spectral peak difference between the positive first-order sea clutter and the negative first-order sea clutter.

[0052] like Figure 6 The diagram shows a specific example of radar measurement of Bragg frequency. A set of specific examples of positive first-order sea clutter and negative first-order sea clutter are shown in the figure.

[0053] Step 302: Determine the theoretical Bragg frequencies corresponding to the uplink length and the receive length based on the first expression and the second expression.

[0054] Step 303: Based on the theoretical Bragg frequency, use the actual Bragg frequency to constrain the solution space of the uplink length and the receive length to obtain the second candidate solution curve.

[0055] like Figure 3 As shown, the fourth step in this embodiment of the invention is: using Bragg frequency constraints. and In one embodiment, in step 303, the expression for the solution space of constraining the uplink length and the receive length using the actual Bragg frequency based on the theoretical Bragg frequency is: ; in, The actual Bragg frequency can be obtained from radar measurements. The theoretical Bragg frequency can be represented by a given... and Calculated.

[0056] By applying constraints to the above expression, we obtain... The plane satisfies the second candidate solution curve with equal Bragg frequency. .

[0057] Specifically, in one embodiment, according to step 301, It can be calculated using the following formula:

[0058] in, The Doppler frequency of the first-order sea clutter is... It is the Doppler frequency of the negative first-order sea clutter.

[0059] Specifically, in one embodiment, to illustrate the process of calculating the theoretical Bragg frequency, step 302 includes: The difference between the second expression and the first expression is determined as a first intermediate quantity, the norm of the first intermediate quantity is determined as a second intermediate quantity, and the ratio of the first intermediate quantity to the second intermediate quantity is determined as a first unit vector in the direction of incidence on the sea surface. In one embodiment, The calculation formula is as follows: ; in, This represents the second expression. This represents the first expression. express norm, Indicates the first intermediate quantity. This indicates the second intermediate quantity.

[0060] The negative of the spherical tangential unit vector at the receiving station is determined as the second unit vector in the direction of return ground wave departure. In one embodiment, The calculation formula is as follows: ; in, This represents the spherical tangential unit vector at the receiving station.

[0061] The norm of the second expression is determined as the third intermediate quantity, and the ratio of the second expression to the third intermediate quantity is determined as the spherical unit normal vector at the sea surface scattering point. In one embodiment, The calculation formula is as follows: ; in, This represents the second expression. express norm, This indicates the third intermediate quantity.

[0062] The theoretical Bragg frequency is determined based on the wave number of the electromagnetic wave, the first unit vector, the second unit vector, and the spherical unit normal vector. In one embodiment, the expression for the theoretical Bragg frequency is: ; in, It is the acceleration due to gravity. Let the wave number be the electromagnetic wave. Represents the first unit vector. This represents the second unit vector. This represents the unit normal vector of the sphere.

[0063] Finally, as Figure 3 As shown, the fifth step of this embodiment of the invention: obtaining and The intersection point uniquely determines the uplink length. and receive length This determines the high-frequency hybrid propagation path of the ground and solar waves. In one embodiment, step 40 includes: based on the intersection of the first candidate solution curve and the second candidate solution curve, solving the first expression and the second expression to obtain a unique solution for the uplink length and a unique solution for the received length, thereby obtaining the hybrid propagation path. Figure 7The diagram illustrates a specific example of the intersection of candidate solution curves with equal group paths and candidate solution curves with equal Bragg frequencies. The first candidate solution curve reflects the time delay constraint through the group path, while the second candidate solution curve reflects the radial velocity constraint of the scattering point on the sea surface through the Bragg frequency. Ultimately, the intersection of the two naturally satisfies all the necessary geometric and physical conditions for the propagation path. This embodiment of the invention transforms the originally complex and underdetermined hybrid propagation path inversion problem into a problem of solving the intersection of two measured constraint curves, thus avoiding the influence of ionospheric uncertainties.

[0064] This invention determines hybrid propagation paths using a reverse constraint inversion method. It utilizes the known Bragg frequency of sea clutter and the precisely measured group delay by radar (i.e., the group path is known) to form two independent spatial surface constraints; the intersection of these two constraints significantly narrows the range of possible paths. Then, the true path can be located using only the most basic ionospheric refraction continuity (rather than a complete model). Relying on the stability of the Bragg frequency and the precise measurability of the group path, it achieves the unique determination of the uplink and receive lengths, overcoming the dependence of traditional methods on ionospheric models or prior propagation conditions. This lays a crucial foundation for subsequent sea state inversion and target localization, and possesses high value for widespread application.

[0065] It should be noted that, unless there is a conflict, the various features in the embodiments of the present invention can be combined with each other, all of which are within the protection scope of the present invention. Furthermore, although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed differently from the module division in the device or the order in the flowchart. The above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0066] The foregoing embodiments provided a method for determining a mixed propagation path of high-frequency ground and earth waves. In this embodiment, another apparatus for determining a mixed propagation path of high-frequency ground and earth waves will be proposed. The apparatus for determining a mixed propagation path of high-frequency ground and earth waves includes: a processor and a memory for storing processor-executable instructions; wherein the processor is configured to execute the method for determining a mixed propagation path of high-frequency ground and earth waves as described in the foregoing embodiments.

[0067] like Figure 8 As shown, the device for determining the mixed propagation path of high-frequency ground and earth waves includes a processor 21 and a memory 22, wherein the processor 21 and the memory 22 can be connected by a bus or other means.

[0068] Processor 21 can be a CPU. Processor 21 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0069] The memory 22, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the method for determining the mixed propagation path of high-frequency earth and sky waves in the aforementioned embodiments. The processor executes various functional applications and training processes by running the non-transitory software programs, instructions, and modules stored in the memory.

[0070] The memory 22 may include a program storage area and a training storage area. The program storage area may store the operating system and applications required for at least one function; the training storage area may store training data created by the processor. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 22 may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The one or more modules stored in the memory 22, when executed by the processor 21, perform the method for determining the mixed propagation path of high-frequency ground and earth waves as shown in the embodiments of the present invention. Specific details of the method for determining the mixed propagation path of high-frequency ground and earth waves can be understood by referring to the corresponding descriptions and effects in the embodiments of the present invention, and will not be repeated here.

[0071] This embodiment also provides a computer storage medium storing a computer program that can be executed by a processor to complete the method for determining the mixed propagation path of high-frequency ground and earth waves as described in the foregoing embodiments.

[0072] The computer storage medium stores computer-executable instructions, which can execute the method for determining the high-frequency terrestrial wave hybrid propagation path in any of the above method embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0073] The specific steps of the method for determining the mixed propagation path of high-frequency ground and earth waves are described in the foregoing embodiments, and will not be repeated in this embodiment.

[0074] 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 determining the mixed propagation path of high-frequency ground and sky waves, characterized in that, include: The first expression for determining the coordinates of the ionospheric reflection point; The second expression for determining the coordinates of the sea surface scattering point; Based on the first expression, the second expression, and the actual group path, determine the first candidate solution curve of the equal group path for the uplink length from the transmitter to the ionospheric reflection point and the receiving length from the receiver to the sea surface scattering point; The actual Bragg frequency is determined based on the first-order sea clutter, and a second candidate solution curve for the equal Bragg frequency of the uplink length and the receive length is determined based on the first expression and the second expression. Based on the first candidate solution curve and the second candidate solution curve, solve the first expression and the second expression to obtain the hybrid propagation path.

2. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 1, characterized in that, The step of determining the actual Bragg frequency based on first-order sea clutter, and determining the second candidate solution curve for the equal Bragg frequency of the uplink length and the receive length based on the first expression and the second expression includes: Based on the spectral peak difference between positive first-order sea clutter and negative first-order sea clutter, the actual Bragg frequency obtained from the measurement is extracted. Based on the first expression and the second expression, determine the theoretical Bragg frequencies corresponding to the uplink length and the receive length; Based on the theoretical Bragg frequency, the solution space of the uplink length and the receive length is constrained using the actual Bragg frequency to obtain the second candidate solution curve.

3. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 2, characterized in that, The expression for the solution space constraining the uplink length and the receive length using the actual Bragg frequency, based on the theoretical Bragg frequency, is as follows: ； in, This indicates the actual Bragg frequency. This represents the theoretical Bragg frequency.

4. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 2, characterized in that, The step of determining the theoretical Bragg frequency corresponding to the uplink length and the received length based on the first expression and the second expression includes: The difference between the second expression and the first expression is determined as the first intermediate quantity, the norm of the first intermediate quantity is determined as the second intermediate quantity, and the ratio of the first intermediate quantity to the second intermediate quantity is determined as the first unit vector in the direction of incident on the sea surface. The negative of the spherical tangential unit vector at the receiving station is determined as the second unit vector in the direction of return ground wave departure; The norm of the second expression is determined as the third intermediate quantity, and the ratio of the second expression to the third intermediate quantity is determined as the spherical unit normal vector at the sea surface scattering point. The theoretical Bragg frequency is determined based on the wave number of the electromagnetic wave, the first unit vector, the second unit vector, and the spherical unit normal vector.

5. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 4, characterized in that, The expression for the theoretical Bragg frequency is: ； in, It is the acceleration due to gravity. Let the wave number be the electromagnetic wave. Represents the first unit vector. This represents the second unit vector. This represents the unit normal vector of the sphere.

6. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 1, characterized in that, The first candidate solution curve of the equal-group path for determining the uplink length from the transmitting station to the ionospheric reflection point and the receiving length from the receiving station to the sea surface scattering point based on the first expression, the second expression, and the actual group path includes: Obtain the actual group path obtained from the measurement; Based on the actual group path, using the first expression and the second expression, the solution space of the uplink length and the receiving length is constrained based on the equal group path to obtain the first candidate solution curve.

7. The method for determining the mixed propagation path of high-frequency ground and sky waves according to claim 6, characterized in that, The expression for the solution space of the uplink length and the receiving length constrained by the equal-group path, based on the actual group path and using the first and second expressions, is as follows: ； in, This indicates the length of the upstream line. Indicates the received length, For the first expression, For the second expression, This refers to the actual group path.

8. The method for determining the mixed propagation path of high-frequency ground and sky waves according to any one of claims 1-7, characterized in that, The step of solving the first expression and the second expression based on the first candidate solution curve and the second candidate solution curve to obtain the hybrid propagation path includes: Based on the intersection of the first candidate solution curve and the second candidate solution curve, the first expression and the second expression are solved to obtain the unique solution for the uplink length and the unique solution for the receive length, so as to obtain the hybrid propagation path.

9. A device for determining the propagation path of a high-frequency terrestrial wave mixed with a ground wave, characterized in that, The device for determining the mixed propagation path of high-frequency ground and earth waves includes: a processor and a memory for storing processor-executable instructions; The processor is configured to perform the method for determining the high-frequency ground wave hybrid propagation path as described in any one of claims 1 to 8.

10. A non-volatile computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which are executed by one or more processors to perform the method for determining the high-frequency ground wave hybrid propagation path as described in any one of claims 1 to 8.

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