ISAR radar multi-target echo simulation method and system

Abstract

The invention discloses an ISAR radar multi-target echo simulation method and system, and relates to the technical field of radar imaging. The method comprises the following steps: S1, constructing a radar multi-target imaging simulation scene; s2, determining a discrete sampling time sequence of single radar pulse echo sampling according to a radar multi-target imaging simulation scene; s3, establishing an echo model of a plurality of scattering points of the single target according to the emission signal model and the echo sampling time, and generating certain echo data of each scattering point of the single target; s4, traversing the remaining targets according to the step S3, and generating single pulse echo data of all the targets; s5, repeating the steps S2 to S4, and generating target echo data of all pulses during imaging; and S6, synthesizing an ISAR radar multi-target echo matrix according to the target echo data of all pulses in the imaging period. According to the method, echo data with multi-target characteristics can be reflected, and verification implementation of an ISAR multi-target imaging algorithm is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of radar imaging technology, and in particular to an ISAR radar multi-target echo simulation method and system. Background Art

[0002] Inverse Synthetic Aperture Radar (ISAR), an active detection device, uses imaging technology to process the echo data of moving targets to produce high-resolution images of them. ISAR imaging can reveal information such as the target's size, shape, and structure, and is widely used in both military and civilian applications.

[0003] During ISAR radar imaging, the simulation and generation of echo signals directly impacts the verification of imaging algorithm performance. Currently, multi-target radar echo simulation is limited to narrowband radars. Each target is treated as an independent scattering point during echo generation, making it unsuitable for ISAR imaging. However, ISAR radars offer high resolution in both range and directional dimensions, while traditional ISAR target echo simulations remain limited to single-target echoes. In modern warfare, multi-target situations, such as artillery swarms and drone swarms, are common, and single-target echoes are insufficient to verify the multi-target imaging performance of imaging algorithms. Multi-target echo simulation differs from single-target echoes in that it requires full consideration of the motion trajectories of different targets and the coherence of radar sampling during generation. It is not a simple superposition of single-target echo data. In general, there is a lack of multi-target echo simulation methods for broadband radar ISAR. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to provide an ISAR radar multi-target echo simulation method and system that can reflect the echo data of multi-target characteristics and facilitate the verification and implementation of ISAR multi-target imaging algorithm.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: an ISAR radar multi-target echo simulation method, comprising the following steps:

[0006] S1, build radar multi-target imaging simulation scene;

[0007] S2, according to the radar multi-target imaging simulation scenario, determine the discrete sampling time sequence of a single radar pulse echo sampling;

[0008] S3, based on the transmission signal model and the echo sampling time, establish an echo model of multiple scattering points of a single target, and generate a certain echo data of each scattering point of the single target;

[0009] S4, traversing the remaining targets according to step S3, generating single pulse echo data of all targets;

[0010] S5, repeating steps S2 to S4 to generate target echo data for all pulses during the imaging period;

[0011] S6, synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

[0012] The present invention also discloses an ISAR radar multi-target echo simulation system, comprising:

[0013] Simulation scene construction module, used to build radar multi-target imaging simulation scene;

[0014] A single discrete sampling time series acquisition module is used to determine the discrete sampling time series of a single radar pulse echo according to a radar multi-target imaging simulation scenario;

[0015] Single target scattering point echo data acquisition module: used to establish the echo model of multiple scattering points of a single target according to the transmission signal model and echo sampling time, and generate a certain echo data of each scattering point of a single target;

[0016] All target single pulse echo data acquisition module: used to traverse the remaining targets and generate single pulse echo data for all targets;

[0017] Each target echo data generation module is used to generate each target echo data of all pulses during imaging;

[0018] The multi-target echo matrix generation module is used to synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

[0019] The beneficial effects of the above-described technical solution are as follows: The method described herein, based on the practical application of multi-target echo generation in ISAR imaging, fully considers the motion trajectory characteristics, echo delay, and signal coherence of different targets, generating echo data that reflects the characteristics of multiple targets, facilitating the verification and implementation of ISAR multi-target imaging algorithms. The method utilizes the generation of K target echoes as a typical example to illustrate the implementation of the ISAR radar multi-target echo simulation method. The method is applicable to any number of targets and can also be used as a reference when the radar is deployed as a dual-base system, demonstrating its high versatility and scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 is a main flow chart of the method according to an embodiment of the present invention;

[0022] Figure 2Schematic diagram of a radar multi-target imaging simulation scenario in the method according to an embodiment of the present invention;

[0023] Figure 3 is a diagram showing the relationship between the radar transmission signal and the echo sampling time in the method according to an embodiment of the present invention;

[0024] Figure 4 It is a principle block diagram of the system described in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Overall, such as Figure 1 As shown, the embodiment of the present invention discloses an ISAR radar multi-target echo simulation method, comprising the following steps:

[0028] S1, build radar multi-target imaging simulation scene;

[0029] S2, according to the radar multi-target imaging simulation scenario, determine the discrete sampling time sequence of a single radar pulse echo sampling;

[0030] S3, based on the transmission signal model and the echo sampling time, establish an echo model of multiple scattering points of a single target, and generate a certain echo data of each scattering point of the single target;

[0031] S4, traversing the remaining targets according to step S3, generating single pulse echo data of all targets;

[0032] S5, repeating steps S2 to S4 to generate target echo data for all pulses during the imaging period;

[0033] S6, synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

[0034] The following is a detailed description of the above steps based on the specific content:

[0035] Furthermore, the constructed imaging simulation scene includes the number of targets, target patterns, target motion parameters, the positional relationship between the radar and the target, and the imaging arc. Constructing the imaging simulation scene includes the following steps:

[0036] 1) Establish an arbitrary rectangular coordinate system, the position relationship diagram of the radar and the target is as follows Figure 2 As shown. Assume that the number of targets is K, and the number of scattering points contained in the kth target is I k , the target motion trajectory is freely set, and the coordinate of the radar in the rectangular coordinate system is R(X,Y).

[0037] 2) To achieve imaging, the radar continuously detects multiple targets and receives echoes. Assume that during the imaging period, the number of radar transmit / receive pulses is N, the imaging start time is recorded as T1, and the imaging end time is recorded as T N , the cumulative imaging angle is θ. To ensure imaging quality, the cumulative imaging angle θ is generally not less than 1°, and the number of pulses N is not less than 128.

[0038] Furthermore, the discrete sampling time series of a single radar pulse echo sampling is determined:

[0039] 1) According to the simulation scenario, calculate the single pulse echo time of each target. For the nth pulse time, the distance between each target and the radar can be calculated through the target motion model. The schematic diagram of the time relationship between the radar transmission signal and the echo signal is as follows: Figure 3 shown.

[0040] 2) Determine the gate size for echo sampling. The gate size for echo sampling is determined based on the duration and width of the nth pulse echo for each target, ensuring that all echoes are within the sampling gate. Considering the motion characteristics of different targets and to facilitate subsequent imaging processing, all pulse-echo matrices must have the same dimensions. The sampling gate time should be the maximum of the N pulse gate lengths; otherwise, some target echoes will be outside the gate.

[0041] 3) Determine the echo sampling time sequence. For the nth pulse moment, the echo sampling start time is recorded as t n0 =nT PRT +τ n0 ,(n=0,1,...,N-1), where T PRT is the radar transmit pulse repetition period, τ n0 is the delay of the sampling gate relative to the transmitted pulse. Assuming the number of echo samples per time is M and the sampling interval is Δt, to satisfy the Nyquist sampling theorem, Δt should be less than or equal to the inverse of the radar transmit signal bandwidth. The time series of the nth pulse echo sampling is:

[0042] t n_s =t n0+(0,1,...,M-1)×Δt (1)

[0043] The time series is a 1×M matrix.

[0044] Furthermore, the method for generating single pulse echo data of each scattering point of a single target includes the following steps:

[0045] 1) Radar transmission signal model

[0046] Assume that the radar transmits a linear frequency modulation signal with a pulse repetition period of T PRT , the emission signal of the nth pulse can be expressed as

[0047]

[0048] Where rect(·) is a rectangular window. When |·|≤0.5, rect(·)=1, and when |·|>0.5, rect(·)=0. For fast time, t n =nT PRT (n=0,1,2,...,N) is the time when the radar transmits the nth pulse, called slow time, and t is the total time. The relationship between the three is: f c is the carrier frequency, T p is the pulse width, μ is the modulation frequency.

[0049] 2) Single pulse echo signal model of each scattering point of a single target

[0050] Assume that there are I on the kth target k scattering points, for the nth pulse moment, the scattering coefficient of the i-th scattering point P is recorded as σ k_i , the distance between the scattering point and the radar is recorded as R k_i , then the nth pulse echo signal received by the radar is

[0051]

[0052] The echo is coherently mixed to obtain the baseband echo signal, which can be expressed as:

[0053]

[0054] Assume that there are I on the kth target k scattering points, then I k The echo of a scattering point can be expressed as

[0055]

[0056] 3) Discretize the echo signal and generate the echo matrix

[0057] According to the sampling time series of formula (1), t n_s Replace the formula (5) The single pulse echo sequence of each scattering point of a single target is obtained. The sequence is a 1×M matrix, denoted as s k_n ,Right now

[0058]

[0059] Furthermore, the method for generating single pulse echo data of all targets includes the following steps:

[0060] 1) Discrete representation of a single pulse echo signal of a single target

[0061] According to formula (6), let k=1 in formula (6) and obtain the n-th pulse echo data of target 1:

[0062]

[0063] Similarly, the n-th pulse echo data of target 2 is:

[0064]

[0065] The n-th pulse echo data of target K is:

[0066]

[0067] 2) Synthesize single pulse echo signals of all targets

[0068] The nth pulse echo signal of all targets is recorded as s n , s n is the sum of the echo matrices of each target, that is:

[0069]

[0070] s n is a 1×M matrix.

[0071] Furthermore, generating target echo data for all pulses during imaging includes the following steps:

[0072] According to formula (10), the first pulse echo data is generated by step 2 as follows:

[0073]

[0074] Similarly, repeat step 2 to generate the second pulse echo data as follows:

[0075]

[0076] The Nth pulse echo data is:

[0077]

[0078] Furthermore, the method for synthesizing imaging echo data includes the following steps:

[0079] Based on the target echo data of all pulses during the imaging period (Equations (11) to (13)), the ISAR radar multi-target echo matrix s is synthesized as follows:

[0080]

[0081] s is an N×M matrix, and each row contains one pulse echo data.

[0082] Corresponding to the method, Figure 4 As shown, the embodiment of the present invention further discloses an ISAR radar multi-target echo simulation system, comprising:

[0083] A simulation scene construction module 101 is used to construct a radar multi-target imaging simulation scene;

[0084] The single discrete sampling time series acquisition module 102 is used to determine the discrete sampling time series of a single radar pulse echo according to the radar multi-target imaging simulation scenario;

[0085] The single target scattering point echo data acquisition module 103 is used to establish an echo model of multiple scattering points of a single target according to the transmission signal model and the echo sampling time, and generate a certain echo data of each scattering point of the single target;

[0086] All target single pulse echo data acquisition module 104, used to traverse the remaining targets and generate single pulse echo data of all targets;

[0087] Each target echo data generating module 105 is used to generate each target echo data of all pulses during the imaging period;

[0088] The multi-target echo matrix generation module 106 is used to synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

[0089] The specific implementation methods of the corresponding modules in the system can refer to the aforementioned ISAR radar multi-target echo simulation, which will not be described in detail here.

[0090] This method, based on the practical application of multi-target echo generation in ISAR imaging, fully considers the characteristics of different targets' motion trajectories, echo delays, and signal coherence. It generates echo data that reflects these characteristics, facilitating the verification and implementation of ISAR multi-target imaging algorithms. Furthermore, the method can also be used as a reference when the radar is deployed in a bistatic configuration, demonstrating its high versatility and scalability.

Claims

1. A method for simulating multi-target echoes of an ISAR radar, characterized in that The steps include: S1, build radar multi-target imaging simulation scene; S2, according to the radar multi-target imaging simulation scenario, determine the discrete sampling time sequence of a single radar pulse echo sampling; S3, based on the transmission signal model and the echo sampling time, establish an echo model of multiple scattering points of a single target, and generate a certain echo data of each scattering point of the single target; S4, traversing the remaining targets according to step S3, generating single pulse echo data of all targets; S5, repeating steps S2 to S4 to generate target echo data for all pulses during the imaging period; S6, synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

2. A method for simulating multi-target ISAR radar echoes according to claim 1, characterized in that In step S1: the radar multi-target imaging simulation scenario includes the number of targets, target patterns, target motion parameters, the positional relationship between the radar and the targets, and the imaging arc.

3. The ISAR radar multi-target echo simulation method according to claim 1, wherein: The method for constructing a radar multi-target imaging simulation scene in step S1 comprises the following steps: S1-1, establish an arbitrary rectangular coordinate system, set the number of targets to be K, and the number of scattering points of the kth target to be I k , the target motion trajectory is freely set, and the coordinates of the radar in the rectangular coordinate system are R(X,Y); S1-2, the radar continuously detects multiple targets and receives echoes. During the imaging period, the number of radar transmitted / received pulses is N, the imaging start time is T1, and the imaging end time is T N , the cumulative imaging angle is θ.

4. The ISAR radar multi-target echo simulation method according to claim 3, wherein: In step S1 , the imaging cumulative rotation angle θ is not less than 1°, and the number of pulses N is not less than 128.

5. The ISAR radar multi-target echo simulation method according to claim 1, wherein: The discrete sampling time sequence of a single radar pulse echo sampling is determined in step S2. S2-1, according to the simulation scenario, calculate the single pulse echo time of each target: for the nth pulse time, the distance between each target and the radar is calculated using the target motion model; S2-2, determine the gate size for echo sampling: Determine the gate size for echo sampling based on the time and echo width of the nth pulse echo of each target, so that all echoes are within the sampling gate; all pulse echo matrices have the same dimension, and the sampling gate time length is the maximum of the N pulse gate lengths; S2-3, determine the echo sampling time sequence: for the nth pulse moment, the echo sampling start time is recorded as t n0 =nT PRT +τ n0 ,(n=0,1,...,N-1), where T PRT is the radar transmit pulse repetition period, τ n0 is the delay of the sampling gate relative to the transmitted pulse; assuming the number of echo samples for each time is M, the sampling time interval is Δt, and Δt is less than or equal to the inverse of the radar transmission signal bandwidth, then the time series of the n-th pulse echo sampling is: t n_s =t n0 +(0,1,...,M-1)×Δt (1) The time series is a 1×M matrix.

6. The ISAR radar multi-target echo simulation method according to claim 5, wherein: The method for generating single pulse echo data of each scattering point of a single target in step S3 comprises the following steps: S3-1, radar transmission signal model Assume that the radar transmits a linear frequency modulation signal with a pulse repetition period of T PRT , the emission signal of the nth pulse is expressed as: Where rect(·) is a rectangular window. When |·|≤0.5, rect(·)=1, and when |·|>0.5, rect(·)=0. For fast time, t n =nT PRT (n=0,1,2,...,N) is the time when the radar transmits the nth pulse, is the slow time, and t is the total time. The relationship between the three is: f c is the carrier frequency, T p is the pulse width, μ is the modulation frequency; S3-2, single pulse echo signal model of each scattering point of a single target Suppose there are I on the kth target k scattering points, for the nth pulse moment, the scattering coefficient of the i-th scattering point P is recorded as σ k_i , the distance between the scattering point and the radar is R k_i , then the nth pulse echo signal received by the radar is: The echo is coherently mixed to obtain the baseband echo signal expressed as: Assume that there are I on the kth target k scattering points, then I k The echo of a scattering point is expressed as: S3-3, discretize the echo signal and generate the echo matrix: According to the sampling time series of formula (1), t n_s Replace the formula (5) The single pulse echo sequence of each scattering point of a single target is obtained. The sequence is a 1×M matrix, denoted as s k_n ,Right now 7. The ISAR radar multi-target echo simulation method according to claim 6, wherein: The method for generating single pulse echo data of all targets in step S4 comprises the following steps: S4-1, Discretization representation of a single pulse echo signal of a single target According to formula (6), let k=1 in formula (6) and obtain the n-th pulse echo data of target 1: Similarly, the n-th pulse echo data of target 2 is: The n-th pulse echo data of target K is: S4-2, synthesizes single pulse echo signals of all targets The nth pulse echo signal of all targets is recorded as s n , s n is the sum of the echo matrices of each target, that is s n is a 1×M matrix.

8. The ISAR radar multi-target echo simulation method according to claim 7, wherein: The method for generating target echo data of all pulses during imaging in step S5 comprises the following steps: According to formula (10), the first pulse echo data generated by step S4-2 is: Similarly, repeat step S4-2, and the second pulse echo data is: The Nth pulse echo data is:

9. The ISAR radar multi-target echo simulation method according to claim 7, wherein: The method for synthesizing imaging echo data in step S6 comprises the following steps: The ISAR radar multi-target echo matrix s is synthesized from the target echo data of all pulses during the imaging period: s is an N×M matrix, and each row contains one pulse echo data.

10. An ISAR radar multi-target echo simulation system, characterized in that include: Simulation scene construction module, used to build radar multi-target imaging simulation scene; A single discrete sampling time series acquisition module is used to determine the discrete sampling time series of a single radar pulse echo according to a radar multi-target imaging simulation scenario; Single target scattering point echo data acquisition module: used to establish the echo model of multiple scattering points of a single target according to the transmission signal model and echo sampling time, and generate a certain echo data of each scattering point of a single target; All target single pulse echo data acquisition module: used to traverse the remaining targets and generate single pulse echo data for all targets; Each target echo data generation module is used to generate each target echo data of all pulses during imaging; The multi-target echo matrix generation module is used to synthesize the ISAR radar multi-target echo matrix from the target echo data of all pulses during the imaging period.

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