A target echo simulation method coupled with radar attitude

Abstract

The application relates to a target echo simulation method coupled with a radar posture, which comprises the following steps: obtaining a radar target relative angle under a radar relative target body coordinate system; obtaining a polarization scattering matrix of the target according to the radar target relative angle; performing radar target time-frequency feature simulation to generate horizontal polarization echo and vertical polarization echo of the target in real time; modulating the horizontal polarization echo and the vertical polarization echo of the target by using the polarization scattering matrix of the target to obtain polarization echo; adjusting and matching the polarization echo based on a roll angle of the radar to obtain polarization combined echo matched with a polarization receiving direction of the radar; and radiating the polarization combined echo to a microwave darkroom space through vertical and horizontal position control and a sky feed system to form simulated target echo signals. The application guarantees correct simulation of the polarization target signal when the roll angle changes.

Description

Technical Field

[0001] This invention relates to the field of radio frequency simulation technology, and in particular to a target echo simulation method coupled with radar attitude. Background Technology

[0002] Currently, most domestic radio frequency simulation systems radiate electromagnetic signals in the form of horizontal or vertical linear polarization, resulting in a single signal form and relatively simple implementation. To better study the target detection, identification, and tracking technology of the newly developed arbitrary polarization radar, it is necessary to simulate the target polarization scattering characteristics and target angular position tracking under arbitrary polarization in a laboratory environment, providing a semi-physical simulation environment for the design and development of homing system polarization radars.

[0003] For radar RF simulations on airborne and other moving platforms, when the radar roll angle changes drastically, the fixed polarization direction of the radiating antenna in existing RF simulation systems cannot accurately simulate polarized target signals, resulting in poor matching between the polarization radiation of the RF simulation system and the radar polarization reception. Furthermore, when the radar operates in single-polarization mode, the radiating antenna simulating the RF target signal and the radar receiving antenna will form cross-polarization, thus weakening the target signal strength detected by the radar and causing unstable target tracking. Therefore, how to simulate the polarization characteristics of the RF signal coupled with the radar attitude in the RF simulation system is a problem that urgently needs to be solved in the RF simulation and verification of radar systems with roll, especially under large roll conditions. Summary of the Invention

[0004] Based on the above analysis, this invention aims to disclose a target echo simulation method coupled with radar attitude, thereby solving the problem of target echo simulation under large roll conditions.

[0005] This invention discloses a target echo simulation method coupled with radar attitude, comprising the following steps:

[0006] Obtain the radar-target relative angle in the radar-target body coordinate system;

[0007] The polarization scattering matrix of the target is obtained based on the relative angle of the radar target;

[0008] The radar target time-frequency characteristics are simulated to generate the target's horizontal and vertical polarization echoes in real time; the target's polarization scattering matrix is ​​used to modulate the polarization characteristics of the target's horizontal and vertical polarization echoes to obtain the polarization echoes.

[0009] The polarization echo is adjusted and matched based on the radar roll angle to obtain a combined polarization echo that matches the radar polarization receiving direction.

[0010] The polarized echo is radiated into the microwave anechoic chamber space through vertical and horizontal precision control and the antenna feed system, forming a simulated target echo signal.

[0011] Furthermore, based on the current relative angle of the radar target, the corresponding polarization scattering matrix is ​​retrieved from the established polarization scattering feature library corresponding to the relative angle of the radar target.

[0012] Furthermore, based on the simulated target time delay and Doppler information, and according to the operating sequence of the polarimetric radar, the radar target time-frequency characteristics are simulated, and the horizontal polarimetric echo S of the target is generated in real time. tr H and vertically polarized echo S tr V Then, the target's polarization scattering matrix is ​​used to analyze the target's horizontal polarization echo S. tr H and vertically polarized echo S tr V Polarization characteristic modulation is performed to obtain the polarization echo S. r H S r V ;

[0013]

[0014] Among them, S HH S is the complex scattering coefficient of the target when it is emitted and received in H polarization; HV S is the complex scattering coefficient of the target when it is emitted in H polarization and received in V polarization; VH S represents the complex scattering coefficient of the target when it is emitted in V-polarization and received in H-polarization; VV H represents the complex scattering coefficient of the target when it is emitting V-polarized and receiving V-polarized; H represents horizontal polarization and V represents vertical polarization.

[0015] Furthermore, the process of adjusting and matching the polarized target echo based on the radar roll angle includes:

[0016] 1) Based on the radar roll angle, establish a polarization radiation and polarization reception matching model;

[0017] 2) Based on this matching model, the polarization echo S r H S r V The amplitude is orthogonally calculated, attenuated, and phase compensated to obtain a polarized combined echo that matches the radar polarization receiving direction.

[0018] Furthermore, based on the radar roll angle, a polarization radiation and polarization reception matching model is established as follows:

[0019]

[0020] In the formula, S r H It is the matched horizontal polarization echo, S r V For the matched vertical polarization echo, and It is a set of polarization orthogonal unit vectors defined by the radar transmitting / receiving antenna; and S is a set of polarization orthogonal unit vectors defined by the dual-polarized antenna used for echo simulation; r H ⊥ The corresponding signal component of the horizontally polarized echo signal in the V channel of the target echo simulation, S r H || The corresponding signal component of the horizontally polarized echo signal in the H channel of the target echo simulation; S r V ⊥ The corresponding signal component of the vertically polarized echo signal in the V channel of the target echo simulation, S r V || The corresponding signal component of the horizontally polarized echo signal in the H channel of the target echo simulation; S r H ⊥ S r V ⊥ S r H || and S r V || Determined based on radar roll angle.

[0021] Furthermore, S is determined based on the radar roll angle γ(t). r H ⊥ S r V ⊥ S r H || and S r V || for:

[0022]

[0023] In the formula, δ H It is echo S r H ⊥ Advanced Sr H || Time phase angle; δ V It is echo S r V ⊥ Advanced S r V || Time phase angle;

[0024] in,

[0025] Furthermore, the polarization combined echo includes the V-channel vertical transmission combined echo and the H-channel horizontal transmission combined echo;

[0026] S r H ⊥ S r V ⊥ Two-in-one power combining is performed to obtain the V-channel vertical transmit-receive combined echo:

[0027] S r⊥ =S r H ⊥ +S r V ⊥

[0028] S r H || S r V || Two-in-one power combining is performed to obtain the horizontal transmit-receive combined echo of channel H:

[0029] S r|| =S r H || +S r V || .

[0030] Furthermore, after precisely controlling the vertical and horizontal positions of the combined vertical and horizontal echoes by means of the relative angle of the radar target, the signals are radiated into the microwave anechoic chamber through the antenna feed system to form a simulated target echo signal.

[0031] Furthermore, the antenna feed system is an array-type antenna feed system, which simulates the spatial angular position of the target signal through a three-element array with continuously changing angles.

[0032] Furthermore, before performing target echo simulation, the amplitude and phase differences between the horizontal and vertical channels are eliminated to ensure that the hardware electrical lengths of the horizontal and vertical frequency conversion and local oscillator signal distribution networks remain consistent.

[0033] This invention can achieve one of the following beneficial effects:

[0034] The target echo simulation method coupled with radar attitude disclosed in this invention establishes a polarization radiation and polarization reception matching model based on roll angle. This overcomes the deficiency of fixed polarization direction of radiating antenna in existing radio frequency simulation systems, and realizes the adjustment of polarization direction of triple radiating antenna to keep it consistent with the orthogonal coordinate system of transmitting / receiving antenna polarization when the radar has a roll angle. This ensures the matching of simulated polarized target echo with radar system polarization reception, and satisfies the optimal matching reception of target echo signal power for large dynamic radar under indoor conditions. It also realizes the correct simulation of polarized target signal when roll angle changes, and supports radio frequency simulation test verification of radar guidance system under large roll conditions. Attached Figure Description

[0035] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0036] Figure 1 This is a flowchart of the target echo simulation method coupled with radar attitude in an embodiment of the present invention;

[0037] Figure 2 This is an example diagram of an orthogonal coordinate system for the polarization radiation and polarization reception matching model in an embodiment of the present invention.

[0038] Figure 3 This is a flowchart illustrating the target channel consistency calibration process in an embodiment of the present invention. Detailed Implementation

[0039] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0040] One embodiment of the present invention discloses a target echo simulation method coupled with radar attitude, such as... Figure 1 As shown, it includes the following steps:

[0041] Step S1: Obtain the radar-target relative angle in the radar-target body coordinate system;

[0042] Step S2: Obtain the polarization scattering matrix of the target based on the relative angle of the radar target;

[0043] Step S3: Simulate the time-frequency characteristics of the radar target and generate the horizontal and vertical polarization echoes of the target in real time; use the target's polarization scattering matrix to perform polarization feature modulation on the horizontal and vertical polarization echoes of the target to obtain the polarization echoes.

[0044] Step S4: Adjust and match the polarization echo based on the radar roll angle to obtain a polarization combined echo that matches the radar polarization receiving direction.

[0045] Step S5: The polarized echo is radiated into the microwave anechoic chamber space through vertical and horizontal precision control and the antenna feed system to form a simulated target echo signal.

[0046] Specifically, in step S1, the origin of the target's coordinate system is the target's centroid, and the three axes can be determined as needed, using the northeast-sky coordinate system as the three axes. The relative angles of the radar target include the radar yaw angle and the radar elevation angle.

[0047] Specifically, in step S2, based on the real-time calculated relative angle of the radar target, the corresponding polarization scattering matrix S(t) is retrieved from the established polarization scattering feature library corresponding to the relative angle of the radar target.

[0048]

[0049] Among them, S HH S is the complex scattering coefficient of the target when it is emitted and received in H polarization; HV S is the complex scattering coefficient of the target when it is emitted in H polarization and received in V polarization; VH S represents the complex scattering coefficient of the target when it is emitted in V-polarization and received in H-polarization; VV H represents the complex scattering coefficient of the target when it is emitting V-polarized and receiving V-polarized; H represents horizontal polarization and V represents vertical polarization.

[0050] The polarization scattering feature library can be obtained through field measurement, compact field testing, or electromagnetic calculation simulation.

[0051] Specifically, in step S3, based on radar modulation information and the simulated target's time delay τ(t) and Doppler information f... d (t), based on the operating sequence of the polarimetric radar, radar target simulation is performed to generate the target's horizontal polarimetric echo S in real time. tr H and vertically polarized echo S tr V Then, the target's polarization scattering matrix is ​​used to analyze the target's horizontal polarization echo S. tr H and vertically polarized echo S tr V Polarization characteristic modulation is performed to obtain the polarization echo S.r H S r V ;

[0052]

[0053] Specifically, in step S4, the process of adjusting and matching the polarized target echo based on the radar roll angle includes:

[0054] 1) Based on the radar roll angle, establish a polarization radiation and polarization reception matching model;

[0055] Specifically, based on the radar roll angle, the polarization radiation and polarization reception matching model is established as follows:

[0056]

[0057] In the formula, S r H It is the matched horizontal polarization echo, S r V For the matched vertical polarization echo, and It is a set of polarization orthogonal unit vectors defined by the radar transmitting / receiving antenna; and S is a set of polarization orthogonal unit vectors defined by the dual-polarized antenna used for echo simulation; r H ⊥ The corresponding signal component of the horizontally polarized echo signal in the V channel of the target echo simulation, S r H || The corresponding signal component of the horizontally polarized echo signal in the H channel of the target echo simulation; S r V ⊥ The corresponding signal component of the vertically polarized echo signal in the V channel of the target echo simulation, S r V || The corresponding signal component of the horizontally polarized echo signal in the H channel of the target echo simulation; S r H ⊥ S r V ⊥ S r H || and S r V || Determined based on the radar roll angle γ(t).

[0058] like Figure 2As shown, an example of an orthogonal coordinate system for the polarization radiation and polarization reception matching model is given.

[0059] More specifically, S is determined based on the radar roll angle γ(t). r H ⊥ S r V ⊥ S r H || and S r V || for:

[0060]

[0061] In the formula, δ H It is echo S r H ⊥ Advanced S r H || Time phase angle; δ V It is echo S r V ⊥ Advanced S r V || Time phase angle;

[0062] in,

[0063] 2) Based on this matching model, the polarization echo S r H S r V The amplitude is orthogonally calculated, attenuated, and phase compensated to obtain a polarized combined echo that matches the radar polarization receiving direction.

[0064] The polarized echo S can be controlled by a high-precision digitally controlled attenuator and a digitally controlled phase shifter. r H S r V The echo signal amplitude is subjected to orthogonal decomposition, attenuation control, and phase compensation processing.

[0065] Specifically, based on the radar roll angle γ(t), amplitude and phase control is performed on four independent amplitude and phase control channels composed of high-precision numerically controlled attenuators and numerically controlled phase shifters to achieve polarized echo S. r H S r V Orthogonal decomposition of echo signal amplitude, attenuation control, and phase compensation processing:

[0066] ΔP H =P(S) r H ⊥ )-P(S r H || )=20lg(|sinγ(t)| / |cosγ(t)|)=20lg(|tan(γ(t))|)

[0067] ΔP V =P(S) r V ⊥ )-P(S r V || )=20lg(|cosγ(t)| / |sinγ(t)|)=20lg(|cot(γ(t))|)

[0068] When -π / 2≤γ(t<-π / 4, S r H ⊥ Branch power remains constant, S r H || The branch power attenuation is ΔP H Phase shift is 0; S r V ⊥ The branch power attenuation is ΔP V S r V || The branch power remains constant, and the phase shift is π.

[0069] When -π / 4 ≤ γ(t) < 0, S r H ⊥ The branch power attenuation is ΔP H S r H || Branch power remains constant, and phase shift is 0; S r V ⊥ Branch power remains constant, S r V || The branch power attenuation is ΔP V The phase shift is π;

[0070] When 0 ≤ γ(t) < π / 4, S r H ⊥ The branch power attenuation is ΔP H Sr H || Branch power remains constant, and phase shift is π; S r V ⊥ Branch power remains constant, S r V || The branch power attenuation is ΔP V The phase shift is 0;

[0071] When π / 4 ≤ γ(t) < π / 2, S r H ⊥ Branch power remains constant, S r H || The branch power attenuation is ΔP H The phase shift is π; S r V ⊥ The branch power attenuation is ΔP V S r V || The branch power remains constant and the phase shift is 0.

[0072] Specifically, the polarization combined echo includes a V-channel vertical transmission combined echo and an H-channel horizontal transmission combined echo.

[0073] S r H ⊥ S r V ⊥ Two-in-one power combining is performed to obtain the V-channel vertical transmit-receive combined echo:

[0074] S r⊥ =S r H ⊥ +S r V ⊥ ;

[0075] S r H || S r V || Two-in-one power combining is performed to obtain the horizontal transmit-receive combined echo of channel H:

[0076] S r|| =S r H || +S r V|| .

[0077] Specifically, in step S5, after performing vertical and horizontal precision control on the vertical and horizontal transmitted combined echoes by means of the relative angle of the radar target, the signals are radiated into the microwave anechoic chamber space through the antenna feed system to form a simulated target echo signal.

[0078] Specifically, the antenna feed system is an array-type antenna feed system, which simulates the spatial angular position of the target signal through a three-element array with continuously changing angles. The spatial angular position of the target signal simulated by the target echo simulation method in this embodiment is consistent with the roll angle of the radar antenna feed system, ensuring the correct simulation of the polarized target signal when the roll angle changes, and supporting the radio frequency simulation test verification of the radar guidance system under large roll conditions.

[0079] Preferably, the target echo simulation method coupled with radar attitude in this embodiment further includes eliminating the amplitude and phase difference between the horizontal and vertical channels before performing target echo simulation, so as to ensure that the hardware electrical lengths of the horizontal and vertical frequency conversion and local oscillator signal distribution networks are consistent.

[0080] Specifically, the process of eliminating amplitude and phase differences in the horizontal and vertical channels includes:

[0081] 1) Channel calibration;

[0082] First, measure the electrical length and phase relationship of each antenna element and its feeding system in the horizontal channel to generate a path table; the path table includes the amplitude and phase information of each antenna horn channel; then perform in-channel calibration based on the path table.

[0083] 2) Attenuator calibration;

[0084] Three attenuation tables were obtained by testing attenuators A, B, and C in the center triplet of the horizontal channel array; the attenuation tables include the correspondence between attenuation codes and attenuation amounts.

[0085] 3) Phase shifter calibration;

[0086] Three attenuation tables were obtained by testing phase shifters A, B, and C in the center triplet of the horizontal channel array; the attenuation tables include the correspondence between phase shift codes and phase shift amounts.

[0087] 4) Repeat steps 1-3) to eliminate amplitude and phase differences in the vertical channel.

[0088] 5) Phase difference compensation between H and V channels;

[0089] The phase difference between the H and V channels is measured using a vector network analyzer, and then compensation is performed in the fine control of the H channel to eliminate the phase difference between the channels.

[0090] like Figure 3 As shown, a specific target channel consistency calibration workflow is presented.

[0091] In summary, the target echo simulation method coupled with radar attitude disclosed in this invention establishes a polarization radiation and polarization reception matching model based on roll angle. This overcomes the deficiency of fixed polarization direction of radiating antenna in existing RF simulation systems, and realizes the adjustment of the polarization direction of the triplet radiating antenna, ensuring consistency with the orthogonal coordinate system of the transmitting / receiving antenna polarization when the radar has a roll angle. This guarantees the matching between the simulated polarized target echo and the radar system's polarization reception, and satisfies the optimal matching reception of target echo signal power by a large dynamic radar under indoor conditions. It also achieves correct simulation of polarized target signals when the roll angle changes, supporting RF simulation test verification of radar guidance systems under large roll conditions.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A target echo simulation method coupled with radar attitude, characterized in that, Includes the following steps: Obtain the radar-target relative angle in the radar-target body coordinate system; The polarization scattering matrix of the target is obtained based on the relative angle of the radar target; The radar target time-frequency characteristics are simulated to generate the target's horizontal and vertical polarization echoes in real time; the target's polarization scattering matrix is ​​used to modulate the polarization characteristics of the target's horizontal and vertical polarization echoes to obtain the polarization echoes. The polarization echo is adjusted and matched based on the radar roll angle to obtain a combined polarization echo that matches the radar polarization receiving direction. The polarized combined echo is radiated into the microwave anechoic chamber space through vertical and horizontal precision control and the antenna feed system to form a simulated target echo signal. The process of adjusting and matching the polarized target echo based on the radar roll angle includes: 1) Based on the radar roll angle, establish a polarization radiation and polarization reception matching model; 2) Based on this matching model, polarization echo , The amplitude is orthogonally calculated, attenuated, and phase compensated to obtain a polarized combined echo that matches the radar polarization receiving direction.

2. The target echo simulation method coupled with radar attitude according to claim 1, characterized in that, Based on the current relative angle of the radar target, the corresponding polarization scattering matrix is ​​retrieved from the established polarization scattering feature library corresponding to the relative angle of the radar target.

3. The target echo simulation method coupled with radar attitude according to claim 1, characterized in that, Based on simulated target time delay and Doppler information, and according to the operating sequence of the polarimetric radar, the radar target time-frequency characteristics are simulated, and the horizontal polarimetric echo of the target is generated in real time. and vertical polarization echo ; Then, the target's horizontal polarization echo is obtained by using the target's polarization scattering matrix. and vertical polarization echo Polarization feature modulation is performed to obtain the polarization echo. , ; ； in, The complex scattering coefficient of the target when it is emitting H polarization and receiving H polarization; The complex scattering coefficient of the target when it is emitted in H polarization and received in V polarization; The complex scattering coefficient of the target when it is emitted in V-polarization and received in H-polarization; H represents the complex scattering coefficient of the target when it is emitting V-polarized and receiving V-polarized; H represents horizontal polarization and V represents vertical polarization.

4. The target echo simulation method coupled with radar attitude according to claim 1, characterized in that, Based on the radar roll angle, the polarization radiation and polarization reception matching model is established as follows: ； In the formula, It is the matched horizontal polarization echo. For the matched vertical polarization echo, and It is a set of polarization orthogonal unit vectors defined by the radar transmitting / receiving antenna; and It is a set of polarization orthogonal unit vectors defined by the dual-polarized antenna performing echo simulation; The signal components of the V channel corresponding to the horizontally polarized echo signal in the target echo simulation. The signal components of the horizontally polarized echo signal in the H channel of the target echo simulation; The signal components of the vertically polarized echo signal in the V channel of the target echo simulation. The signal components of the vertically polarized echo signal in the H channel of the target echo simulation; , , and Determined based on radar roll angle.

5. The target echo simulation method coupled with radar attitude according to claim 4, characterized in that, According to radar roll angle Definite , , and for: ； In the formula, It's an echo. Advanced Time phase angle; It's an echo. Advanced Time phase angle; in, .

6. The target echo simulation method coupled with radar attitude according to claim 5, characterized in that, The polarization combined echo includes the V-channel vertical transmission combined echo and the H-channel horizontal transmission combined echo; Will Two-in-one power combining is performed to obtain the V-channel vertical transmit-receive combined echo: Will Two-in-one power combining is performed to obtain the horizontal transmit-receive combined echo of channel H: 。 7. The target echo simulation method coupled with radar attitude according to claim 6, characterized in that, After precise vertical and horizontal positioning control of the vertical and horizontal transmitted combined echoes by means of the relative angle of the radar target, the signals are radiated into the microwave anechoic chamber through the antenna feed system to form simulated target echo signals.

8. The target echo simulation method coupled with radar attitude according to any one of claims 1-7, characterized in that, The antenna feed system is an array-type antenna feed system that simulates the spatial angular position of the target signal through a three-element array with continuously changing angles.

9. The target echo simulation method coupled with radar attitude according to claim 8, characterized in that, Before performing target echo simulation, the amplitude and phase differences between the horizontal and vertical channels are eliminated to ensure that the hardware electrical lengths of the horizontal and vertical frequency conversion and local oscillator signal distribution networks remain consistent.

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