Delay-Doppler mapping simulation method and system for sea ice GNSS scattered signals

Abstract

The present invention provides a method and system for simulating delayed Doppler mapping of sea ice GNSS scattered signals, including: utilizing a scattering calculation module to determine the total scattering coefficient of each linearly polarized channel based on an electromagnetic scattering model; utilizing a GNSS scattered signal processing module to generalize the total scattering coefficient of each linearly polarized channel to obtain a fully polarized coherent model, thereby obtaining the dual-station radar cross sections for all polarized channels; and utilizing a fully polarized DDM waveform generation module to generate a DDM waveform based on GNSS signal parameters and the dual-station radar cross sections for all polarized channels. By combining the electromagnetic scattering model of sea ice with the DDM simulation of the GNSS system, the present invention overcomes the problem of the model having only a single polarization, clarifies the different polarization response characteristics of GNSS signal reflections from the sea ice surface and open water, and constructs a fully polarized DDM combination using a polarization coherence matrix, thus breaking through the limitation of traditional GNSS-R systems that only use left-hand circular polarization.

Description

Technical Field

[0001] The present invention belongs to the field of GNSS-R technology, and specifically relates to a Delay-Doppler Mapping simulation method and system for sea ice GNSS scattered signals. The method is used to generate Delay-Doppler Map (DDM) waveforms, especially DDM waveforms for different polarization channels in a reduced polarization mode. The simulation method is applicable to L / S / C multi-band GNSS or communication satellite signals. Background Art

[0002] In its initial applications, GNSS-R (Global Navigation Satellite System-Reflectometry) uses LHCP polarization antennas to receive surface reflection signals. Therefore, LR polarization is used in the process of ground object parameter inversion.

[0003] With the advancement of Global Navigation Satellite System (GNSS) technology, the reception and utilization of GNSS reflected signals are no longer limited to the original L / R polarization. R and L represent the RHCP (right-hand circular polarization) and LHCP (left-hand circular polarization) polarization states, respectively. Using antennas with other polarizations to receive reflected signals other than LHCP polarizations is a key trend in current and future receiver design.

[0004] For example, ESA's HydroGNSS, scheduled for launch in 2024, employs a dual-polarization design, employing both RHCP and LHCP receiver antennas to receive signals reflected from the Earth's surface. This means that during the inversion process, both RR and LR polarization reflectivity data will be combined to improve the accuracy of surface parameter inversion. While traditional GNSS-R uses left-hand circular polarization (LHCP) as a receiving antenna, existing technologies using other polarizations already exist.

[0005] However, in the field of sea ice, no one has yet focused on the simulation of GNSS scattered signals in polarization directions other than LHCP, nor has anyone considered how to use GNSS scattered signals in multiple polarization directions to improve sensitivity to sea ice. Summary of the Invention

[0006] The purpose of the present invention is to provide a delay-Doppler mapping simulation method and system for sea ice GNSS scattered signals to construct a full-polarization combined DDM.

[0007] To achieve the above objectives, the present invention provides a method for simulating delay-Doppler mapping of sea ice GNSS scattered signals, comprising:

[0008] S1: Based on the electromagnetic scattering model, the 4×4 full polarization scattering matrix of the sea ice GNSS scattered signal is calculated;

[0009] S2: Based on the full polarization scattering matrix, the bistatic radar cross section of any polarization channel is obtained using the electromagnetic wave polarization synthesis method;

[0010] S3: Generate DDM waveforms based on GNSS signal parameters and bistatic radar cross sections for all polarization channels using the full polarization DDM waveform generation module.

[0011] Step S1 specifically includes:

[0012] S11: Determine the total scattering coefficient of each linear polarization channel using a scattering calculation module according to an electromagnetic scattering model;

[0013] S12: Utilizing the GNSS scattered signal processing module, generalize a full polarization coherence model according to the total scattering coefficient of each linear polarization channel, wherein the full polarization coherence model includes a 4×4 full polarization scattering matrix.

[0014] When using the scattering calculation module to determine the total scattering coefficient of each linear polarization channel, the type of electromagnetic scattering model used is selected from the sea ice electromagnetic scattering model selection module according to user needs; the type of electromagnetic scattering model includes at least one of an improved integral equation model, a physical optics model, a small slope approximation model and a machine learning algorithm model.

[0015] The step S1 specifically includes: for each linear polarization channel, selecting an electromagnetic scattering model or a combination of multiple electromagnetic scattering models to establish a calculation model for the total scattering coefficient of the linear polarization channel.

[0016] The full polarization coherence model includes a scattering matrix of circular polarization and the linear polarization scattering matrix S and the polarization coherence matrix T; the step S12 specifically includes:

[0017] S121: Total scattering coefficient of each linear polarization channel , construct the linear polarization scattering matrix S;

[0018] S122: Constructing a polarization coherence matrix T according to the linear polarization scattering matrix S;

[0019] S123: According to the linear polarization scattering matrix, a circular polarization scattering matrix is ​​obtained by transformation.

[0020] The bistatic radar cross section of an arbitrary polarization channel is obtained by multiplying the full polarization scattering matrix by the Stokes vector in the polarization direction on its left and right ends.

[0021] Based on the Zavorotny-Voronovich model framework, in the DDM waveform, the time delay and Doppler shift Scattered power distribution under for:

[0022] ,

[0023] in, is the coherent integration time, is the transmit power, are the transmitting and receiving antenna gains, is the signal wavelength, is the bistatic radar scattering coefficient, is the fuzzy function, is the distance from the transmitter and receiver to the surface scattering point, is the surface differential scattering area.

[0024] The GNSS signal parameters include carrier frequency, modulation mode, chip length information and corresponding coherent integration time from various GNSS systems. , transmit power , transmit and receive antenna gain , signal wavelength , fuzzy function , the distance between the transmitter and the receiver and the surface scattering point , and the GNSS system includes GPS, BDS, Galileo or GLONASS.

[0025] In another aspect, the present invention provides a delay-Doppler mapping simulation system for sea ice GNSS scattered signals, comprising:

[0026] a scattering calculation module configured to determine a total scattering coefficient for each linearly polarized channel based on an electromagnetic scattering model;

[0027] A GNSS scattered signal processing module is configured to generalize the total scattering coefficient of each linear polarization channel to obtain a fully polarized coherent model, thereby obtaining a bistatic radar cross section for all polarization channels;

[0028] The full polarization DDM waveform generation module is configured to generate DDM waveforms based on GNSS signal parameters and the bistatic radar cross sections of all polarization channels.

[0029] The delay-Doppler mapping simulation system for sea ice GNSS scattered signals further includes a sea ice electromagnetic scattering model selection module, which is used to provide the scattering calculation module with the electromagnetic scattering model required by the user.

[0030] This paper combines a sea ice electromagnetic scattering model (regardless of its specific implementation) with the DDM simulation of GNSS systems to overcome the problem of current sea ice GNSS-R scattering signal models being limited to a single polarization. This model identifies the different polarization responses of GNSS signals reflected by sea ice surfaces (smooth / rough ice, new ice / multi-year ice) and open water. Using a polarization coherence matrix, a fully polarization-combined DDM is constructed, breaking the limitation of traditional GNSS-R, which relies solely on left-hand circular polarization (LHCP). The electromagnetic scattering model is interchangeable and can be used to generate scattering coefficients for various polarization channels, including but not limited to physical, semi-empirical, and data-driven models. The polarization of the transmitted signal is RHCP, while the polarization of the received signal can be any combination of LHCP, H, V, RHCP, and other polarizations, providing new insights for GNSS-R receiver design and inversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the delay-Doppler mapping simulation method for sea ice GNSS scattered signals. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0033] The present invention is mainly based on the following principles:

[0034] This paper combines a sea ice electromagnetic scattering model (regardless of the specific implementation) with DDM simulation of GNSS systems to overcome the current single-polarization problem of sea ice GNSS-R scattering signal models. This model identifies the different polarization responses of GNSS signals to the reflection of sea ice surfaces (smooth / rough ice, new ice / multi-year ice) and open water. The L-band (GNSS frequency band) has a certain degree of penetration into sea ice (on the order of centimeters to meters). GNSS signals with different polarization orientations have different sensitivities to the internal structure of the ice layer. Combining multiple polarization parameters (such as polarization ratio and phase difference) to construct a machine learning classification model improves the accuracy of sea ice type identification (e.g., distinguishing between floating ice, ice ridges, and melt ponds). Polarization information can also be used for: Melt monitoring: Seawater meltout reduces surface roughness, significantly changing the polarization ratio (VV / HV), enabling real-time tracking of ice edge retreat. Ice ridge detection: The rough surface of ice ridges produces strong cross-polarization scattering, and polarization characteristics can be used for terrain reconstruction.

[0035] The electromagnetic scattering model is interchangeable and includes, but is not limited to, physical models, semi-empirical models, and data-driven models. It can also encompass subsequent derivative technologies such as AI alternative models and quantum computing acceleration. The electromagnetic scattering model can be replaced with any of the following: the IEM model, the PO model, the SSA model, and a machine learning model, as long as the electromagnetic scattering model can calculate the fully polarized bistatic scattering coefficient.

[0036] Furthermore, the present invention uses a polarization coherent matrix to construct a fully polarized DDM, breaking through the limitation of traditional GNSS-R, which only uses left-hand circular polarization (LHCP). The polarization direction of the transmitted signal is RHCP, and the polarization direction of the received signal is a variety of permutations and combinations of LHCP, H, V, RHCP, etc.

[0037] Furthermore, this invention implements signal processing in Compact Polarimetry (CP). Compact Polarimetry (CP) involves receiving signals from a subset of polarization channels (e.g., single circular polarization transmission and dual linear polarization reception) and reconstructing full polarization information using mathematical models. Its core approach is to reduce the number of polarization channels actually received (e.g., from four fully polarized channels to two) while simultaneously deriving key polarization parameters through algorithms, thereby reducing hardware complexity while preserving sufficient and comprehensive information.

[0038] like Figure 1 As shown, the delay Doppler mapping simulation method of sea ice GNSS scattered signals of the present invention specifically includes the following steps:

[0039] Step S1: Calculate and obtain a 4×4 full polarization scattering matrix based on the electromagnetic scattering model;

[0040] The step S1 specifically includes:

[0041] Step S11: using the scattering calculation module 20 to determine the total scattering coefficient of each linear polarization channel according to the electromagnetic scattering model;

[0042] When the total scattering coefficient of each linear polarization channel is determined by using the scattering calculation module 20, the type of electromagnetic scattering model used is Figure 1 The sea ice electromagnetic scattering model selection module 10 is selected according to user needs.

[0043] The electromagnetic scattering model is interchangeable and is used to generate scattering coefficients for various polarization channels. Types of electromagnetic scattering models include, but are not limited to, physical models, semi-empirical models, and data-driven models. Specifically, these include, but are not limited to, improved integral equation models (IEMs), physical optics models (POs), small slope approximation models (SSAs), and machine learning algorithm models. The polarization direction of the transmitted signal is RHCP, while the polarization direction of the received signal is LHCP, H, V, RHCP, and other permutations and combinations. This provides new insights into the design and inversion of GNSS-R receivers.

[0044] Table 1 shows the physical meaning of the various parameter symbols in the electromagnetic scattering model of sea ice. All physical parameters adopt the ISO standard naming convention.

[0045] Table 1: Parameter symbols and their physical meanings

[0046]

[0047] The step S1 specifically includes: for each linear polarization channel, selecting an electromagnetic scattering model or a combination of multiple electromagnetic scattering models to establish a calculation model for the total scattering coefficient of the linear polarization channel.

[0048] That is, the total scattering coefficient of different polarization channels pq (p,q represents the polarization directions of transmission and reception, here is a linear polarization channel, p,q ∈ {h,v}, h,v is the horizontal polarization direction and the vertical polarization direction) can be 、 ,or For the total scattering coefficient under each polarization channel, one scattering model or a superposition of multiple scattering models can be selected to calculate the total scattering coefficient under the polarization channel.

[0049] In this embodiment, for each polarization channel pq (p, q represents the polarization directions of transmission and reception, here is a linear polarization channel, p, q ∈ {h, v}, h, v are the horizontal polarization direction and the vertical polarization direction), the total scattering coefficient of the polarization channel is Equal to the surface scattering component , volume scattering component and the bottom transmission component The sum (i.e. = + + ), where the surface scattering component Represents the surface scattering component of the uppermost layer of sea ice, the volume scattering component Represents the volume scattering component of the middle part of the sea ice and the bottom transmission component Represents the transmission component of the lowest layer of sea ice.

[0050] In this embodiment, the total scattering coefficients of all polarization channels are calculated using an improved integral equation model (IEM) to calculate their surface scattering components, and the layered Born approximation is used to calculate the volume scattering components.

[0051] Therefore, based on the improved integral equation model (IEM), the surface scattering component for:

[0052]

[0053] Where m represents the order of expansion, which is used to describe the contribution of different orders in the surface scattering process; is the wave vector, , is the wave vector component; is the polarization coupling coefficient, dimensionless; is the surface power spectral density.

[0054] wave vector components , for:

[0055]

[0056] in, is the wave vector, is the angle of incidence, is the scattering angle, is the relative azimuth.

[0057] Polarization coupling coefficient for:

[0058]

[0059] in, and is the polarization coupling function, representing the incident angle and scattering angle Next, polarization channel The coupled response to the scattered signal. Its specific form is related to the polarization characteristics, Fresnel reflection coefficient and geometric factors.

[0060] Based on the layered Born approximation, excluding the top and bottom layers, the scattering component of the sea ice in the nth layer for:

[0061]

[0062] Among them, z represents the vertical position coordinate, is the wave vector, is the volume scattering amplitude function, dimensionless; is the angle of incidence, is the attenuation coefficient of the nth layer, is the volume scattering element density of the nth layer, is the thickness of the nth layer, in m.

[0063] Among them, the volume scattering amplitude function for:

[0064] ,

[0065] in, is the complex dielectric constant of the nth layer, is the polarization-dependent scattering phase function, which is used to describe the incident wave (polarization ) and scattered waves (polarization ) is the phase response of volume scattering caused by the fluctuation of dielectric constant inside the medium, dimensionless, is the geometric correction factor, is the anisotropy parameter of the nth layer, is the angle of incidence, is the scattering angle, is the relative azimuth, is the principal axis direction of the material in the nth layer, where n is the layer number.

[0066] Bottom layer transmission component for:

[0067]

[0068] in, is the transmission coefficient from the medium of layer 0 to the medium of layer 1, which characterizes the ability of electromagnetic waves to penetrate the interface. It is dimensionless. Here, the medium of layer 0 and the medium of layer 1 are air and sea ice respectively. is the reflection coefficient of the bottom layer, which represents the reflection intensity of electromagnetic waves at the bottom interface and is dimensionless; is the bottom-layer interface roughness correction factor, which is used to describe the attenuation effect of surface roughness on the transmission signal and is dimensionless; H is the total vertical thickness of sea ice in meters; is the angle of incidence, is the total attenuation coefficient.

[0069] Among them, the transmission coefficient from the medium of the 0th layer to the medium of the 1st layer is , the reflection coefficient of the bottom layer It can be calculated by Fresnel transmission and reflection formula. The transmission coefficient from the medium of layer 0 to the medium of layer 1 is , the reflection coefficient of the bottom layer The bottom layer interface roughness correction factor is related to the incident angle and the dielectric constant of the materials on both sides of the interface. Calculated based on surface roughness statistical models (such as RMS height, correlation length), or calibrated through experiments.

[0070] Complex permittivity of the nth layer , the attenuation coefficient of the nth layer , surface power spectral density The specific calculation method of these layer parameters, such as the transmission coefficient from the medium of the nth layer to the medium of the n+1th layer, is shown in Table 2.

[0071] Table 2: Calculation of stratification parameters

[0072]

[0073] Total attenuation coefficient for:

[0074] ,

[0075] Where n is the layer number, is the total number of layers, is the attenuation coefficient of the nth layer, is the thickness of the nth layer in meters, and H is the total vertical thickness of the sea ice in meters.

[0076] Step S12: Using the GNSS scattered signal processing module 30, according to the total scattering coefficient of each linear polarization channel To generalize the full polarization coherence model, the full polarization coherence model includes a 4×4 full polarization scattering matrix;

[0077] The full polarization coherence model includes a circularly polarized scattering matrix And the linear polarization scattering matrix S, polarization coherence matrix T, polarization coherence matrix T is a 4×4 full polarization scattering matrix.

[0078] The step S12 specifically includes:

[0079] Step S121: Based on the total scattering coefficient of each polarization channel , construct the linear polarization scattering matrix S;

[0080] The linear polarization scattering matrix S is:

[0081] ,

[0082] in, is the bistatic radar cross section in m², pq is the polarization channel, p,q represents the polarization direction of transmission and reception, p,q ∈ {h,v}, h,v are the horizontal polarization direction and the vertical polarization direction, is the vertical polarization scattering phase, is the horizontal polarization scattering phase, 、 is the cross-polarization scattering phase, in radians.

[0083] Among them, the total scattering coefficient of each polarization channel is Directly as the scattering matrix The elements in . That is: , = , .

[0084] Total scattering coefficient of polarization channel pq is a complex number and can be expressed as:

[0085]

[0086] in, is the amplitude of the total scattering coefficient of polarization channel pq, corresponding to the scattering intensity; is the phase of the total scattering coefficient of the polarization channel pq, corresponding to the phase delay caused by the difference in the electromagnetic wave propagation path.

[0087] The phase constraints are satisfied:

[0088] .

[0089] Step S122: constructing a polarization coherence matrix T according to the linear polarization scattering matrix S;

[0090] Among them, the polarization coherence matrix T is:

[0091]

[0092] in, is the total scattering coefficient of polarization channel pq, where p,q represent the polarization directions of transmission and reception, p,q ∈ {h,v}, h,v are the horizontal polarization directions and the vertical polarization directions; is the polarization scattering vector.

[0093] Therefore, the obtained polarization coherence matrix T is a 4×4 matrix.

[0094] Step S123: transforming the linear polarization scattering matrix to obtain a circular polarization scattering matrix.

[0095] Among them, according to the circularly polarized Stokes vector, the circularly polarized scattering matrix is ​​established With the linear polarization scattering matrix The conversion formula of is used to obtain the circularly polarized scattering coefficient.

[0096] The Stokes vector of circular polarization is expressed as:

[0097] Left-hand circular polarization (L):

[0098] Right-hand circular polarization (R):

[0099] Therefore, the circular polarization scattering matrix With the linear polarization scattering matrix The conversion formula is:

[0100]

[0101] in, is the linear polarization scattering matrix, is the circular polarization scattering matrix, is the transformation matrix.

[0102] The transformation matrix U is:

[0103] ,

[0104] Circular polarization scattering matrix for:

[0105] = ,

[0106] in, is the circular polarization scattering coefficient of polarization channel pq, where p and q represent the polarization directions of transmission and reception, For left-hand polarization and right-hand polarization.

[0107] Thus, the circular polarization scattering matrix is ​​obtained.

[0108] Step S2: Using the GNSS scattered signal processing module, according to the full polarization scattering matrix, the electromagnetic wave polarization synthesis method is used to obtain the dual-station radar scattering cross section of any polarization channel;

[0109] The polarization synthesis formula used in the method of electromagnetic wave polarization synthesis is well known in the art.

[0110] Among them, the dual-station radar scattering cross section (RCS) of any polarization channel is calculated using the full polarization scattering matrix (i.e., the polarization coherence matrix ), which is obtained by multiplying the left and right ends by the Stokes vector in the polarization direction. The Stokes vector in the polarization direction is obtained by the ellipticity angle and the ellipticity angle in the polarization direction.

[0111] For example, according to the polarization coherence matrix And the circularly polarized Stokes vector, directly calculate the circularly polarized bistatic radar cross section :

[0112]

[0113] in, is the polarization channel, p and q represent the polarization directions of transmission and reception, are the left-hand polarization direction and the right-hand polarization direction, is the Stokes vector of the polarization direction of the received signal, is the Stokes vector of the polarization direction of the transmitted signal.

[0114] According to the above formula , the specific component expressions calculated are as follows:

[0115] Circular polarization (RR / LL):

[0116]

[0117] Crossed Circular Polarization (LR / RL):

[0118]

[0119] In addition, according to the polarization coherence matrix calculated above As well as the linearly polarized Stokes vector, the linearly polarized bistatic radar cross section can also be directly calculated :

[0120]

[0121] in, is the polarization channel, p and q represent the polarization directions of transmission and reception, are the horizontal polarization direction and the vertical polarization direction, is the Stokes vector of the polarization direction of the received signal, is the Stokes vector of the polarization direction of the transmitted signal.

[0122] Step S3: using the full-polarization DDM waveform generation module 40 to generate a DDM waveform according to the GNSS signal parameters and the bistatic radar cross section of the full-polarization channel.

[0123] Based on the Zavorotny-Voronovich model, in the DDM waveform, the delay and Doppler shift Scattered power distribution under for:

[0124]

[0125] The meaning of each parameter in the formula is shown in Table 3.

[0126] In the formula, for any polarization channel pq ( ), bistatic radar scattering coefficient The bistatic radar cross section can be calculated by step S2. and the GNSS signal ambiguity function χ(τ,f d )coupling.

[0127] Table 3: Meaning of the parameters in the DDM waveform formula

[0128]

[0129] Among them, GNSS signal parameters include carrier frequency, modulation mode, chip length information and corresponding coherent integration time from various GNSS systems , transmit power , transmit and receive antenna gain , signal wavelength , fuzzy function , the distance between the transmitter and the receiver and the surface scattering point , and the GNSS system includes GNSS systems such as GPS, BDS, Galileo, or GLONASS.

[0130] Based on the above-mentioned delay-Doppler mapping simulation method for sea ice GNSS scattered signals, the implemented delay-Doppler mapping simulation system for sea ice GNSS scattered signals includes:

[0131] a scattering calculation module 20 configured to determine a total scattering coefficient of each linear polarization channel according to an electromagnetic scattering model;

[0132] The steps executed by the scattering calculation module 20 are consistent with the above step S1.

[0133] a GNSS scattered signal processing module 30 configured to generalize the total scattering coefficient of each linear polarization channel to obtain a full polarization coherence model, thereby obtaining a bistatic radar cross section for all polarization channels;

[0134] The steps executed by the GNSS scattered signal processing module 30 are consistent with the above step S2.

[0135] The full polarization DDM waveform generation module 40 is configured to generate a DDM waveform according to GNSS signal parameters and bistatic radar cross sections of all polarization channels.

[0136] The steps performed by the full-polarization DDM waveform generation module 40 are consistent with the above step S3.

[0137] Furthermore, the present application may also include a sea ice electromagnetic scattering model selection module 10, which is used to provide the user's desired electromagnetic scattering model to the scattering calculation module 20. Electromagnetic scattering model types include, but are not limited to, physical models, semi-empirical models, and data-driven models. Specifically, they include, but are not limited to, improved integral equation models (IEMs), physical optics models (POs), small slope approximation models (SSAs), and machine learning algorithm models. The polarization direction of the transmitted signal is RHCP, while the polarization direction of the received signal is LHCP, H, V, RHCP, and other permutations and combinations. This provides new insights into the design and inversion of GNSS-R receivers.

[0138] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications are possible. Any simple, equivalent changes and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention is conventional technology.

Claims

1. A delay-Doppler mapping simulation method for sea ice GNSS scattered signals, characterized in that: include: Step S1: Calculate the 4×4 full polarization scattering matrix of the sea ice GNSS scattering signal based on the electromagnetic scattering model; Step S2: Based on the full polarization scattering matrix, the bistatic radar cross section of any polarization channel is obtained using the electromagnetic wave polarization synthesis method; Step S3: Generate a DDM waveform using the full polarization DDM waveform generation module based on the GNSS signal parameters and the dual-station radar cross sections of all polarization channels; Step S1 specifically includes: Step S11: using a scattering calculation module to determine the total scattering coefficient of each linear polarization channel according to an electromagnetic scattering model; Step S12: using the GNSS scattered signal processing module, generalizing the total scattering coefficient of each linear polarization channel to obtain a full polarization coherence model, wherein the full polarization coherence model includes a 4×4 full polarization scattering matrix; The full polarization coherence model includes a scattering matrix of circular polarization and the linear polarization scattering matrix S and the polarization coherence matrix T, where the polarization coherence matrix is ​​a full polarization scattering matrix; the step S12 specifically includes: Step S121: Based on the total scattering coefficient of each linear polarization channel , construct the linear polarization scattering matrix S; p, q represent the polarization directions of transmission and reception; Step S122: constructing a polarization coherence matrix T according to the linear polarization scattering matrix S; Step S123: transforming the linear polarization scattering matrix to obtain a circular polarization scattering matrix.

2. The method for simulating delay-Doppler mapping of sea ice GNSS scattered signals according to claim 1, characterized in that: When using the scattering calculation module to determine the total scattering coefficient of each linear polarization channel, the type of electromagnetic scattering model used is selected from the sea ice electromagnetic scattering model selection module according to user needs; The type of the electromagnetic scattering model includes at least one of an improved integral equation model, a physical optics model, a small slope approximation model and a machine learning algorithm model.

3. The method for simulating delay-Doppler mapping of sea ice GNSS scattered signals according to claim 2, characterized in that: The step S1 specifically includes: for each linear polarization channel, selecting an electromagnetic scattering model or a combination of multiple electromagnetic scattering models to establish a calculation model for the total scattering coefficient of the linear polarization channel.

4. The method for simulating delay-Doppler mapping of sea ice GNSS scattered signals according to claim 1, characterized in that: The bistatic radar cross section of an arbitrary polarization channel is obtained by multiplying the full polarization scattering matrix by the Stokes vector in the polarization direction on its left and right ends.

5. The method for simulating delay-Doppler mapping of sea ice GNSS scattered signals according to claim 1, characterized in that: Based on the Zavorotny-Voronovich model framework, in the DDM waveform, the time delay and Doppler shift Scattered power distribution under for: ， in, is the coherent integration time, is the transmit power, are the transmitting and receiving antenna gains, is the signal wavelength, is the bistatic radar scattering coefficient, is the fuzzy function, is the distance from the transmitter and receiver to the surface scattering point, is the surface differential scattering area; p and q represent the polarization directions of transmission and reception.

6. The method for simulating delay-Doppler mapping of sea ice GNSS scattered signals according to claim 1, characterized in that: The GNSS signal parameters include carrier frequency, modulation mode, chip length information and corresponding coherent integration time from various GNSS systems. , transmit power , transmit and receive antenna gain , signal wavelength , fuzzy function , the distance between the transmitter and the receiver and the surface scattering point , and the GNSS system includes GPS, BDS, Galileo or GLONASS.

7. A delay-Doppler mapping simulation system for sea ice GNSS scattered signals, characterized in that: include: a scattering calculation module configured to determine a total scattering coefficient for each linearly polarized channel based on an electromagnetic scattering model; a GNSS scattered signal processing module configured to generalize a full polarization coherence model based on the total scattering coefficient of each linear polarization channel, wherein the full polarization coherence model includes a 4×4 full polarization scattering matrix, and to obtain a bistatic radar cross section for all polarization channels based on the full polarization scattering matrix; A fully polarized DDM waveform generation module configured to generate DDM waveforms based on GNSS signal parameters and bistatic radar cross sections for all polarization channels; The full polarization coherence model includes a circularly polarized scattering matrix And the linear polarization scattering matrix S, polarization coherence matrix T, the polarization coherence matrix is ​​the full polarization scattering matrix; The full polarization coherence model is generalized based on the total scattering coefficient of each linear polarization channel, which includes: According to the total scattering coefficient of each linear polarization channel , construct the linear polarization scattering matrix S; p, q represent the polarization directions of transmission and reception; According to the linear polarization scattering matrix S, the polarization coherence matrix T is constructed; According to the linear polarization scattering matrix, the circular polarization scattering matrix is ​​transformed.

8. The delay-Doppler mapping simulation system for sea ice GNSS scattered signals according to claim 7, characterized in that: It also includes a sea ice electromagnetic scattering model selection module, which is used to provide the scattering calculation module with the electromagnetic scattering model required by the user.

Images