CN113433512B - Method for suppressing interference on dense false targets of LFM pulse compression radar - Google Patents

Method for suppressing interference on dense false targets of LFM pulse compression radar Download PDF

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CN113433512B
CN113433512B CN202110695961.9A CN202110695961A CN113433512B CN 113433512 B CN113433512 B CN 113433512B CN 202110695961 A CN202110695961 A CN 202110695961A CN 113433512 B CN113433512 B CN 113433512B
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刘凯旋
彭晓燕
汪鹏
田勇
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University of Electronic Science and Technology of China
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/2813—Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2927—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods by deriving and controlling a threshold value
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/36—Means for anti-jamming, e.g. ECCM, i.e. electronic counter-counter measures
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Abstract

The invention belongs to the technical field of radar electronic countermeasure, and particularly relates to a method for suppressing interference of dense false targets for an LFM pulse compression radar. When the traditional dense false targets are used for suppressing interference, the distances and amplitudes of the false targets are mostly distributed in a disordered manner, and internal false targets or edge false targets in a generated false target group are often detected by a radar by using a constant false alarm algorithm of multi-target detection such as SO-CFAR, SO that the positions of the false target group and a real target are exposed, and the effect of suppressing interference is poor or completely ineffective. According to the method, by designing the relevant parameters of the sampled forwarded signals, the complete coverage of the false targets and the edge false targets in the false target group and the suppression interference on the real radar echo signals are realized under the SO-CFAR constant false alarm detection method, the potential danger brought to the real targets due to the exposure of the false target positions when the dense false targets perform the suppression interference is solved, the interference effect when the dense false targets perform the suppression interference is improved, and the method has good practicability.

Description

一种对LFM脉冲压缩雷达的密集假目标压制干扰方法A Dense False Target Suppression Jamming Method for LFM Pulse Compression Radar

技术领域technical field

本发明属于雷达电子对抗技术领域，具体涉及一种对LFM脉冲压缩雷达的密集假目标压制干扰方法。The invention belongs to the technical field of radar electronic countermeasures, in particular to a method for suppressing and jamming dense false targets of LFM pulse compression radar.

背景技术Background technique

脉冲压缩雷达能够利用雷达信号脉内或脉间的相干性，使得普通干扰信号无法在脉冲压缩时获得较高的匹配增益，大幅度降低了普通干扰的干扰效果。密集假目标干扰作为一种主要的干扰手段，利用了LFM脉冲压缩雷达接收机对雷达回波具有较高的频率增益和相位增益的特点，采用了DRFM数字存储技术对雷达信号进行存储转发，可以在雷达接收端产生多个虚假目标，实现对LFM脉冲压缩雷达的欺骗干扰或压制干扰。传统的密集假目标作压制干扰时，假目标的间距和幅度大多是无序分布的，其产生的假目标群中的内部假目标或边缘假目标，往往会被雷达使用SO-CFAR(最小选择恒虚警)这样针对多目标检测的恒虚警算法检测出来，从而会导致假目标群和真实目标位置的暴露，使得压制干扰效果变差或完全失效。因此，需要对密集假目标干扰信号的相关参数进行设计，实现对相对应的恒虚警检测算法下假目标群内部假目标与边缘假目标的完全遮盖以及对真实雷达回波信号的压制干扰。Pulse compression radar can make use of the coherence within or between pulses of radar signals, so that ordinary jamming signals cannot obtain higher matching gain during pulse compression, which greatly reduces the jamming effect of ordinary jamming. Dense false target jamming, as a main jamming method, takes advantage of the high frequency gain and phase gain of LFM pulse compression radar receivers to radar echoes, and uses DRFM digital storage technology to store and forward radar signals. Generate multiple false targets at the radar receiving end to achieve deception jamming or suppress jamming of LFM pulse compression radar. When the traditional dense false targets are used for suppressing interference, the spacing and amplitude of the false targets are mostly disorderly distributed, and the internal false targets or edge false targets in the false target group generated by them are often used by the radar using SO-CFAR (minimum selection). The constant false alarm algorithm for multi-target detection is detected, which will lead to the exposure of false target groups and real target positions, making the suppression and interference effect worse or completely invalid. Therefore, it is necessary to design the relevant parameters of the dense false target interference signal, so as to completely cover the false target inside the false target group and the false target on the edge under the corresponding constant false alarm detection algorithm, and suppress the interference to the real radar echo signal.

发明内容SUMMARY OF THE INVENTION

为了解决现有的密集假目标干扰技术存在的以上不足和缺陷，本发明提出了一种采用对雷达信号采样后进行有序转发的密集假目标干扰，其目的在于解决现有的密集假目标干扰在作压制干扰时容易被SO-CFAR(最小选择恒虚警)检测算法检测出假目标群内部假目标和边缘假目标的问题。In order to solve the above deficiencies and defects existing in the existing dense false target jamming technology, the present invention proposes a dense false target jamming which adopts orderly forwarding after sampling the radar signal, the purpose of which is to solve the existing dense false target jamming It is easy to be detected by SO-CFAR (Minimum Selection Constant False Alarm) detection algorithm when suppressing interference.

本发明的技术方案为：The technical scheme of the present invention is:

一种对LFM脉冲压缩雷达密集假目标压制干扰的方法，包括以下步骤：A method for suppressing jamming of dense false targets of LFM pulse compression radar, comprising the following steps:

S1、确定LFM脉冲压缩雷达回波的经脉冲压缩后的信噪比：S1. Determine the pulse-compressed signal-to-noise ratio of the LFM pulse-compressed radar echo:

Figure BDA0003127901690000011
Figure BDA0003127901690000011

其中Pt、Gt、Gr分别是雷达发射机的发射功率、发射天线和接收天线的增益，λ为雷达信号的波长，σ是目标的反射面积，Rt代表目标至雷达的距离，k、T0分别是玻尔兹曼常数和噪声温度，B为雷达信号的频率带宽，F是雷达接收机噪声系数，D是脉冲压缩比，M是相干积累的次数，γ是脉冲积累因子；Among them, Pt, Gt, and Gr are the transmit power of the radar transmitter, the gain of the transmitting antenna and the receiving antenna, respectively, λ is the wavelength of the radar signal, σ is the reflection area of the target, Rt is the distance from the target to the radar, and k and T0 are respectively Boltzmann constant and noise temperature, B is the frequency bandwidth of the radar signal, F is the radar receiver noise figure, D is the pulse compression ratio, M is the number of coherent accumulation, and γ is the pulse accumulation factor;

S2、确定在SO-CFAR检测下对真实目标回波以及干扰群内部假目标进行遮盖所需要的假目标的信噪比大小：S2. Determine the signal-to-noise ratio of the false target required to cover the real target echo and the false target inside the interference group under SO-CFAR detection:

Figure BDA0003127901690000021
Figure BDA0003127901690000021

其中χ是目标检测单元的信噪比，χi为参考窗内假目标信噪比，N为参考单元个数，

Figure BDA0003127901690000022
为想要达到的检测概率，
Figure BDA0003127901690000023
为虚警概率；where χ is the signal-to-noise ratio of the target detection unit, χ i is the signal-to-noise ratio of false targets in the reference window, N is the number of reference units,
Figure BDA0003127901690000022
is the desired detection probability,
Figure BDA0003127901690000023
is the false alarm probability;

S3、确定在SO-CFAR检测下干扰群边缘最小假目标信噪比χe：S3. Determine the minimum false target signal-to-noise ratio χ e at the edge of the interference group under SO-CFAR detection:

Figure BDA0003127901690000024
Figure BDA0003127901690000024

其中，in,

Figure BDA0003127901690000025
Figure BDA0003127901690000025

检测门限T的概率密度函数满足如下公式：The probability density function of the detection threshold T satisfies the following formula:

Figure BDA0003127901690000026
Figure BDA0003127901690000026

其中，α为门限阈值因子

Figure BDA0003127901690000027
β2为背景噪声的功率；where α is the threshold threshold factor
Figure BDA0003127901690000027
β 2 is the power of background noise;

S4、确定单个假目标群内的假目标个数n：S4. Determine the number n of false targets in a single false target group:

利用公式(2)进行迭代计算依次得出各假目标的信噪比，并且在干扰群的边缘干扰信号的信噪比需要满足下式：Use formula (2) to perform iterative calculation to obtain the signal-to-noise ratio of each false target in turn, and the signal-to-noise ratio of the interference signal at the edge of the interference group needs to satisfy the following formula:

χ≤χe (6)χ≤χ e (6)

当信噪比小于等于χe时累计的假目标个数就是一个干扰群中的假目标数量n；When the signal-to-noise ratio is less than or equal to χ e , the accumulated number of false targets is the number n of false targets in an interference group;

S5、确定采样信号的转发时间间隔：S5. Determine the forwarding time interval of the sampling signal:

Figure BDA0003127901690000028
Figure BDA0003127901690000028

其中L为雷达参考窗长度，c为光速；where L is the length of the radar reference window, and c is the speed of light;

S6、确定对雷达信号的采样周期：S6. Determine the sampling period of the radar signal:

Figure BDA0003127901690000031
Figure BDA0003127901690000031

其中T为雷达脉冲时长，n为所需假目标个数，B为雷达脉冲带宽；where T is the radar pulse duration, n is the required number of false targets, and B is the radar pulse bandwidth;

S7、确定采样信号的转发时长τ：S7. Determine the forwarding duration τ of the sampled signal:

假目标群内假目标之间的信噪比和转发采样目标的采样占空比

Figure BDA0003127901690000032
有关，且满足如下关系：Signal-to-noise ratio among false targets within false target group and sampling duty cycle of forwarding sampled targets
Figure BDA0003127901690000032
related and satisfy the following relationship:

Figure BDA0003127901690000033
Figure BDA0003127901690000033

其中τn、τm分别为第n个假目标和第m个假目标的采样时长，χn、χm分别为第n个假目标和第m个假目标的信噪比；where τ n and τ m are the sampling durations of the nth false target and the mth false target, respectively, and χ n and χ m are the signal-to-noise ratios of the nth false target and the mth false target, respectively;

S8、对接收的雷达信号每隔时间Ts进行一次采样，每次采样后根据步骤S4中得到的参数n进行n次不等时长的转发，每次转发的时间间隔由S5中得到的参数t决定，第n次转发的时长由步骤S7中得到的参数τn决定。S8. Sampling the received radar signal every time T s , and after each sampling, carry out n times of unequal time forwarding according to the parameter n obtained in step S4, and the time interval of each forwarding is determined by the parameter t obtained in S5 Decision, the duration of the n-th forwarding is determined by the parameter τ n obtained in step S7.

本发明结合经典的密集假目标产生方法，对接收的雷达信号进行采样并根据本发明设计的参数进行重复转发。转发信号将在雷达接收端产生一组由中心向两侧幅度有序递减且间距有序的假目标，使得SO-CFAR的每个参考窗内部都至少含有一个假目标，真实目标回波尽量位于这群假目标的中心，通过本发明的设计的参数，真实目标回波能够被主假目标压制，干扰群内部的内侧假目标可以被外侧的假目标压制，而干扰群最边缘的假目标可以通过环境噪声实现压制。The present invention combines the classical dense false target generation method to sample the received radar signal and repeat the forwarding according to the parameters designed by the present invention. The forwarding signal will generate a group of false targets with orderly decreasing amplitude and orderly spacing from the center to the two sides at the radar receiving end, so that each reference window of SO-CFAR contains at least one false target, and the echo of the real target is located as far as possible. At the center of this group of false targets, through the parameters designed by the present invention, the echo of the real target can be suppressed by the main false target, the inner false target inside the interference group can be suppressed by the outer false target, and the false target at the outermost edge of the interference group can be suppressed by the false target. Suppression by ambient noise.

附图说明Description of drawings

图1为本发明的压制干扰示意图；Fig. 1 is the suppression interference schematic diagram of the present invention;

图2为对雷达信号采样后无规律转发后经SO-CFAR检测后的结果图；Figure 2 is the result of SO-CFAR detection after sampling the radar signal irregularly and forwarding it;

图3为按照本发明中算法计算得出的参数进行转发后经SO-CFAR检测后的结果图。FIG. 3 is a result diagram of SO-CFAR detection after forwarding the parameters calculated by the algorithm in the present invention.

具体实施方式Detailed ways

本发明具体参数的计算，包括以下步骤：The calculation of the specific parameters of the present invention comprises the following steps:

步骤一：确定LFM脉冲压缩雷达的雷达回波的信噪比Step 1: Determine the signal-to-noise ratio of the radar echo of the LFM pulse compression radar

其信噪比可由如下公式确定：Its signal-to-noise ratio can be determined by the following formula:

Figure BDA0003127901690000041
Figure BDA0003127901690000041

其中Pt、Gt、Gr分别是是雷达发射机的发射功率，发射天线和接收天线的增益，λ为雷达信号的波长，σ是目标的反射面积，Rt代表目标至雷达的距离，k、T0分别是玻尔兹曼常数和噪声温度，B为雷达信号的频率带宽，F是雷达接收机噪声系数，D是脉冲压缩比，M是相干积累的次数，γ是脉冲积累因子。Among them, Pt, Gt and Gr are the transmit power of the radar transmitter, the gain of the transmitting antenna and the receiving antenna, λ is the wavelength of the radar signal, σ is the reflection area of the target, Rt is the distance from the target to the radar, k and T0 are respectively is the Boltzmann constant and noise temperature, B is the frequency bandwidth of the radar signal, F is the radar receiver noise figure, D is the pulse compression ratio, M is the number of coherent accumulations, and γ is the pulse accumulation factor.

步骤二：确定在SO-CFAR检测下对真实目标回波以及干扰群内部假目标进行压制所需要假目标的信噪比大小Step 2: Determine the signal-to-noise ratio of the false target required to suppress the real target echo and the false target inside the interference group under SO-CFAR detection

为保证在SO-CFAR检测下，主假目标能够对真实目标回波进行遮盖以及假目标能够被次级假目标遮盖，需要计算遮盖信号与被遮盖信号的信噪比关系。在假目标群内部，目标单元的参考窗内都至少分布一个假目标干扰，现只对参考窗内存在一个假目标干扰这种情况做分析，得到SO-CFAR恒虚警检测下目标单元的信噪比和参考窗内干扰的信噪比需满足：In order to ensure that the main false target can cover the real target echo and the false target can be covered by the secondary false target under SO-CFAR detection, it is necessary to calculate the signal-to-noise ratio relationship between the masked signal and the masked signal. In the false target group, at least one false target interference is distributed in the reference window of the target unit. Now we only analyze the situation that there is a false target interference in the reference window, and obtain the signal of the target unit under SO-CFAR constant false alarm detection. The noise ratio and the signal-to-noise ratio of the interference in the reference window must satisfy:

Figure BDA0003127901690000042
Figure BDA0003127901690000042

其中χ是目标检测单元的信噪比，χi为参考窗内假目标信噪比，N为参考单元个数，

Figure BDA0003127901690000043
为想要达到的检测概率，
Figure BDA0003127901690000044
为虚警概率。where χ is the signal-to-noise ratio of the target detection unit, χ i is the signal-to-noise ratio of false targets in the reference window, N is the number of reference units,
Figure BDA0003127901690000043
is the desired detection probability,
Figure BDA0003127901690000044
is the false alarm probability.

步骤三：确定在SO-CFAR检测下干扰群边缘最小假目标信噪比χe Step 3: Determine the minimum false target signal-to-noise ratio χ e at the edge of the interference group under SO-CFAR detection

由于SO-CFAR其算法自身独有的特点，处于某个干扰群的边缘假目标的检测门限将由其外侧的环境噪声决定，且边缘假目标的SO-CFAR参考窗为白噪声，在平方率检波器的情况下，检测门限T的概率密度函数满足如下公式：Due to the unique characteristics of the SO-CFAR algorithm itself, the detection threshold of the false target at the edge of a certain interference group will be determined by the ambient noise outside it, and the SO-CFAR reference window of the false target at the edge is white noise, and the detection threshold of the false target at the square rate is white noise. In the case of the detector, the probability density function of the detection threshold T satisfies the following formula:

Figure BDA0003127901690000045
Figure BDA0003127901690000045

其中N为参考单元数，α为门限阈值因子，β2为背景噪声的功率。在对一个检测单元做检测时，该单元的平均检测概率表达式如下：where N is the number of reference units, α is the threshold threshold factor, and β 2 is the power of the background noise. When detecting a detection unit, the average detection probability of the unit is expressed as follows:

Figure BDA0003127901690000046
Figure BDA0003127901690000046

同时，在噪声背景为白噪声的情况下

Figure BDA0003127901690000047
At the same time, when the noise background is white noise
Figure BDA0003127901690000047

所以将上述三式结合可得，Therefore, combining the above three formulas, we can get,

Figure BDA0003127901690000051
Figure BDA0003127901690000051

步骤四：确定单个假目标群内的假目标个数nStep 4: Determine the number n of false targets in a single false target group

利用公式(2)进行迭代计算可以依次得出各假目标的信噪比，并且在干扰群的边缘干扰信号的信噪比需要满足下式：Using formula (2) for iterative calculation, the signal-to-noise ratio of each false target can be obtained in turn, and the signal-to-noise ratio of the interference signal at the edge of the interference group needs to satisfy the following formula:

χ≤χe (6)χ≤χ e (6)

当信噪比小于等于χe时累计的假目标个数就是一个干扰群中的假目标数量n；When the signal-to-noise ratio is less than or equal to χ e , the accumulated number of false targets is the number n of false targets in an interference group;

步骤五：确定采样信号的转发时间间隔Step 5: Determine the forwarding time interval of the sampled signal

要保证检测单元前后半个参考窗范围内都至少存在一个假目标用于提升真目标所处单元的检测门限，则转发间隔时间t的应满足：To ensure that there is at least one false target within the reference window before and after the detection unit to improve the detection threshold of the unit where the true target is located, the forwarding interval t should satisfy:

Figure BDA0003127901690000052
Figure BDA0003127901690000052

其中L为雷达参考窗长度，c为光速。where L is the length of the radar reference window and c is the speed of light.

步骤六：确定对雷达信号的采样周期Step 6: Determine the sampling period of the radar signal

对雷达信号的采样周期会影响到干扰群的间距，错误的采样周期会使得干扰群之间相互影响导致压制干扰失败。为保证干扰群间无重叠，对雷达信号的干扰采样周期Ts应满足：The sampling period of the radar signal will affect the spacing of the interference groups, and the wrong sampling period will make the interference between the interference groups fail to suppress the interference. In order to ensure that there is no overlap between interference groups, the interference sampling period T s for the radar signal should satisfy:

Figure BDA0003127901690000053
Figure BDA0003127901690000053

其中T是雷达脉冲时间宽度，B是雷达脉冲带宽，n是一个干扰群中所需的假目标个数，t是采样信号转发间隔。where T is the radar pulse time width, B is the radar pulse bandwidth, n is the number of false targets required in an interference group, and t is the sampling signal forwarding interval.

步骤七：确定采样信号的转发时长τStep 7: Determine the forwarding duration τ of the sampled signal

假目标群内假目标之间的信噪比和转发采样目标的采样占空比

Figure BDA0003127901690000054
有关，且满足如下关系：Signal-to-noise ratio among false targets within false target group and sampling duty cycle of forwarding sampled targets
Figure BDA0003127901690000054
related and satisfy the following relationship:

Figure BDA0003127901690000055
Figure BDA0003127901690000055

其中τn、τm分别为第n个假目标和第m个假目标的采样时长，χn、χm分别为第n个假目标和第m个假目标的信噪比。Among them, τ n and τ m are the sampling durations of the n-th false target and the m-th false target, respectively, and χ n and χ m are the signal-to-noise ratios of the n-th false target and the m-th false target, respectively.

步骤八：对接收的雷达信号每隔时间Ts进行一次采样，每次采样后根据步骤S4中得到的参数n进行n次不等时长的转发，每次转发的时间间隔由S5中得到的参数t决定，第n次转发的时长由步骤S7中得到的参数τn决定。Step 8: The received radar signal is sampled every time T s , and after each sampling, n times of unequal duration forwarding is performed according to the parameter n obtained in step S4, and the time interval of each forwarding is determined by the parameter obtained in S5. t is determined, and the duration of the n-th forwarding is determined by the parameter τ n obtained in step S7.

压制干扰示意图如图1所示，转发信号将在雷达接收端产生一组由中心向两侧幅度有序递减且间距有序的假目标Si，使得SO-CFAR的每个参考窗内部都至少含有一个假目标，真实目标回波S尽量位于这群假目标的中心，真实目标回波S被主假目标S0压制，干扰群内部的内侧假目标Si可以被外侧的假目标Si+1压制，而干扰群最边缘的假目标可以通过环境噪声实现压制。The schematic diagram of suppressing interference is shown in Figure 1. The forwarding signal will generate a group of false targets Si with orderly decreasing amplitude and orderly spacing from the center to the two sides at the radar receiving end, so that each reference window of SO-CFAR has at least Contains a false target, the real target echo S is located in the center of the group of false targets as much as possible, the true target echo S is suppressed by the main false target S 0 , and the inner false target Si inside the interference group can be suppressed by the outer false target Si + 1 to suppress, and the false target at the edge of the interference group can be suppressed by environmental noise.

下面仿真实验，对本发明的技术效果作进一步展示和说明。The following simulation experiments further demonstrate and illustrate the technical effects of the present invention.

1.仿真条件和内容：1. Simulation conditions and content:

仿真实验通过MATLAB仿真软件实现，雷达信号采用线性调频信号，雷达信号发射功率为106W，雷达收发天线增益均为30dB,目标反射面积为10m2,雷达信号的脉宽T＝100us,信号带宽为10MHz,,波长为0.1m，LFM信号调制斜率k＝B/T,干扰机对雷达信号的采样频率为48Mhz，目标距离雷达40km,干扰机相对于目标前突1km，参考单元个数为8，雷达参考窗长度为300m，恒虚警概率PFA＝10-6,设定对检测单元的检测概率Pd＝0.1。The simulation experiment is realized by MATLAB simulation software. The radar signal adopts the linear frequency modulation signal, the radar signal transmit power is 10 6 W, the radar transceiver antenna gain is 30 dB, the target reflection area is 10 m 2 , the radar signal pulse width T=100us, the signal bandwidth is 10MHz, the wavelength is 0.1m, the LFM signal modulation slope k=B/T, the sampling frequency of the jammer to the radar signal is 48Mhz, the target distance from the radar is 40km, the jammer protrudes 1km relative to the target, and the number of reference units is 8 , the radar reference window length is 300m, the constant false alarm probability P FA =10 -6 , and the detection probability P d =0.1 for the detection unit is set.

仿真1，对雷达信号采样并进行无规律转发后形成的密集假目标干扰经过SO-CFAR恒虚警检测后的结果图，如图2所示。Simulation 1, the result of SO-CFAR constant false alarm detection of dense false target interference formed by sampling radar signals and forwarding irregularly is shown in Figure 2.

仿真2，对雷达信号采样并按照本发明中算法计算得出的参数进行转发后形成的密集假目标干扰经过SO-CFAR恒虚警检测后的结果图，如图3所示。Simulation 2, the result of SO-CFAR constant false alarm detection of the dense false target interference formed after sampling the radar signal and forwarding the parameters calculated by the algorithm in the present invention is shown in Figure 3.

2.仿真结果分析：2. Analysis of simulation results:

参照图2所示，对采样后的雷达信号进行无规律的转发，在SO-CFAR的检测下，虽然能够提升真实目标回波所在的检测单元的阈值从而实现对真实目标的压制干扰，但在干扰群边缘处的假目标由于信噪比较大，不能够被环境噪声遮盖，从而导致假目标被检测出来，给真实目标带来了位置暴露的风险。Referring to Fig. 2, the sampled radar signal is forwarded irregularly. Under the detection of SO-CFAR, although the threshold of the detection unit where the real target echo is located can be increased to achieve suppression of interference to the real target, but in the case of SO-CFAR Due to the large signal-to-noise ratio of the false targets at the edge of the interference group, they cannot be covered by the environmental noise, which leads to the detection of false targets and brings the risk of location exposure to the real targets.

参照图3所示，图3为按照本发明设计的参数进行有规律转发后，经SO-CFAR恒虚警检测后的结果图。按照本发明中的算法设置了转发信号的相关参数，使得在SO-CFAR检测下，干扰群内的干扰信号能够成功被次级干扰信号压制，干扰群边缘干扰信号能够被环境白噪声压制，从而在对真实目标回波进行成功压制干扰的基础上，实现了对整个干扰群的遮盖，避免了因假目标位置暴露而给真实目标带来的风险。Referring to FIG. 3 , FIG. 3 is a result diagram of SO-CFAR constant false alarm detection after the parameters designed according to the present invention are regularly forwarded. According to the algorithm in the present invention, the relevant parameters of the forwarding signal are set, so that under SO-CFAR detection, the interference signal in the interference group can be successfully suppressed by the secondary interference signal, and the interference signal at the edge of the interference group can be suppressed by the environmental white noise, thereby On the basis of successfully suppressing the interference of the real target echo, the entire interference group is covered, and the risk to the real target caused by the exposure of the false target position is avoided.

对比现有的密集假目标压制干扰技术，本发明的特点是在对真实目标回波进行压制干扰的基础上，通过对干扰信号相关参数的设计，使得假目标群中的假目标在SO-CFAR恒虚警检测下能实现相互遮盖，解决了密集假目标干扰常见的假目标暴露问题，避免了因为被雷达使用SO-CFAR恒虚警检测算法检测出假目标，而对真目标带来的潜在威胁。Compared with the existing dense false target suppression interference technology, the present invention is characterized in that, on the basis of suppressing interference on the echo of the real target, through the design of the relevant parameters of the interference signal, the false targets in the false target group are in SO-CFAR. Under the constant false alarm detection, it can achieve mutual coverage, solve the common false target exposure problem of dense false target interference, and avoid the potential for the real target caused by the false target detected by the radar using the SO-CFAR constant false alarm detection algorithm. threaten.

Claims (1)

1. A method for suppressing interference on dense false targets of an LFM pulse compression radar is characterized by comprising the following steps:
s1, determining the signal-to-noise ratio of the LFM pulse compression radar echo after pulse compression:
Figure FDA0003127901680000011
wherein Pt, Gt and Gr are respectively the transmitting power of a radar transmitter and the gains of a transmitting antenna and a receiving antenna, lambda is the wavelength of a radar signal, sigma is the reflection area of a target, Rt represents the distance from the target to the radar, k and T0 are respectively a Boltzmann constant and a noise temperature, B is the frequency bandwidth of the radar signal, F is the noise coefficient of the radar receiver, D is the pulse compression ratio, M is the number of coherent accumulation, and gamma is an accumulation factor;
s2, determining the signal-to-noise ratio of a false target required for covering the echo of the real target and the false target in the interference group under the SO-CFAR detection:
Figure FDA0003127901680000012
wherein χ is the signal-to-noise ratio of the target detecting unit i Is the signal-to-noise ratio of the false target in the reference window, N is the number of reference units,
Figure FDA0003127901680000013
to want to achieveThe probability of the detection of the arrival,
Figure FDA0003127901680000014
is the false alarm probability;
s3, determining the minimum false target signal-to-noise ratio chi of interference group edge under SO-CFAR detection e ：
Figure FDA0003127901680000015
Wherein,
Figure FDA0003127901680000016
the probability density function of the detection threshold T satisfies the following formula:
Figure FDA0003127901680000017
where α is a threshold factor
Figure FDA0003127901680000018
β 2 Power as background noise;
s4, determining the number n of false targets in a single false target group:
after the true echo signal-to-noise ratio is obtained by using the formula (1), iterative calculation is performed by using the formula (2) to sequentially obtain the signal-to-noise ratio of each false target, and the signal-to-noise ratio of the interference signal at the edge of the interference group needs to satisfy the following formula:
χ≤χ e (6)
when the signal-to-noise ratio is less than or equal to x e The number of the false targets accumulated in time is the number n of the false targets in one interference group;
s5, determining the forwarding time interval of the sampling signal:
Figure FDA0003127901680000021
wherein L is the radar reference window length and c is the speed of light;
s6, determining the sampling period of the radar signal:
Figure FDA0003127901680000022
wherein T is radar pulse duration, n is the number of the needed false targets, and B is radar pulse bandwidth;
s7, determining the forwarding time length tau of the sampling signal:
signal-to-noise ratio between decoys within a decoy group and sampling duty cycle of a forwarded sampling target
Figure FDA0003127901680000023
And satisfies the following relationship:
Figure FDA0003127901680000024
wherein τ is n 、τ m The sampling duration, χ, of the nth and mth decoys, respectively n 、x m The signal-to-noise ratios of the nth false target and the mth false target respectively;
s8, receiving radar signals at intervals of T s Sampling once, forwarding for n times of unequal duration according to the parameter n obtained in the step S4 after each sampling, wherein the time interval of each forwarding is determined by the parameter t obtained in the step S5, and the duration of the nth forwarding is determined by the parameter tau obtained in the step S7 n And (6) determining.
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