CN112014807A - An adaptive clutter suppression method for frequency agile radar - Google Patents
An adaptive clutter suppression method for frequency agile radar Download PDFInfo
- Publication number
- CN112014807A CN112014807A CN202010824214.6A CN202010824214A CN112014807A CN 112014807 A CN112014807 A CN 112014807A CN 202010824214 A CN202010824214 A CN 202010824214A CN 112014807 A CN112014807 A CN 112014807A
- Authority
- CN
- China
- Prior art keywords
- clutter
- clu
- target
- doppler
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000001629 suppression Effects 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000003044 adaptive effect Effects 0.000 title claims description 16
- 239000011159 matrix material Substances 0.000 claims abstract description 32
- 238000001228 spectrum Methods 0.000 claims abstract description 19
- 238000012545 processing Methods 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims abstract description 15
- 230000001427 coherent effect Effects 0.000 claims abstract description 10
- 238000013499 data model Methods 0.000 claims abstract description 6
- 238000001514 detection method Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 230000003595 spectral effect Effects 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 230000006835 compression Effects 0.000 claims description 4
- 238000007906 compression Methods 0.000 claims description 4
- 238000005314 correlation function Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 claims description 2
- 238000004364 calculation method Methods 0.000 claims 1
- 238000004088 simulation Methods 0.000 description 14
- 238000013461 design Methods 0.000 description 11
- 230000004044 response Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000000342 Monte Carlo simulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000002592 echocardiography Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
- G01S7/414—Discriminating targets with respect to background clutter
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
Description
技术领域technical field
本发明涉及雷达信号处理技术领域,具体涉及一种频率捷变雷达的自适应杂波抑制方法。适用于杂波环境下,频率捷变雷达的目标一维成像和检测。The invention relates to the technical field of radar signal processing, in particular to an adaptive clutter suppression method for a frequency agile radar. It is suitable for one-dimensional imaging and detection of targets of frequency agile radar in clutter environment.
背景技术Background technique
雷达对抗是电子对抗的一个重要组成部分,频率捷变技术是雷达实现主动抗干扰的有效措施;在频率捷变信号中,各个发射脉冲的载频以随机或者预定的方式在较宽的频带内作较大范围捷变,具备低截获概率的特性,可以有效抑制瞄准式、压制式、欺骗式等多种主幅瓣干扰形式。Radar countermeasures are an important part of electronic countermeasures. Frequency agility technology is an effective measure for radar to achieve active anti-jamming. In frequency agile signals, the carrier frequency of each transmitted pulse is randomly or predetermined in a wide frequency band. It has the characteristics of low probability of interception and can effectively suppress various forms of main lobe interference such as aiming, suppressing, and deception.
频率捷变雷达由于其优异的抗干扰和距离维高分辨能力而受到广泛关注。但由于各个脉冲发射载频的不一致,频率捷变雷达与传统的雷达动目标检测(MTD)技术不兼容,使得杂波抑制问题成为频率捷变雷达用于实际工程的一大阻碍。Frequency-agile radars have received extensive attention due to their excellent anti-jamming and range-dimensional high resolution capabilities. However, due to the inconsistency of the carrier frequencies of each pulse transmission, the frequency agile radar is incompatible with the traditional radar moving target detection (MTD) technology, which makes the clutter suppression problem a major obstacle for the frequency agile radar to be used in practical engineering.
目前适用于频率捷变雷达在杂波环境下的相参处理算法有两种。一种是先利用一次相参处理时间内的同频脉冲信号实现杂波抑制,然后再利用异频脉冲回波实现带宽合成,输出经过杂波抑制后的目标高分辨一维距离像;这种方法的缺陷在于,杂波抑制时无法利用所有脉冲提供的自由度,因此其杂波抑制性能受到限制,若要保持足够高的杂波处理增益,需要雷达发射多组同频脉冲,由此又会增加发射波形的规律性,降低频率捷变雷达的抗干扰性能。另一种方法是利用频率捷变雷达一次CPI内发射的所有脉冲实现杂波抑制和带宽合成处理,这种算法实现了异频杂波抑制,可以使用一次CPI内的所有脉冲提供的自由度实现杂波抑制,目前唯一的例子是瑞典国防研究所的S.R.J.Axelsson于2007年在IEEETrans on GRS期刊发表了subtraction算法,该算法是频率捷变雷达杂波抑制的一大进步,标志着异频杂波抑制的可行性,但该算法仅能对完全静止的杂波起到良好的抑制作用,而通常由于风速的影响,杂波的功率谱具有一定的谱宽,即杂波散射体不会是完全静止的,因此该算法在实际工程中的应用大为受限。At present, there are two kinds of coherent processing algorithms suitable for frequency agile radar in clutter environment. One is to first use the same-frequency pulse signal within a coherent processing time to achieve clutter suppression, and then use different-frequency pulse echoes to achieve bandwidth synthesis, and output a high-resolution one-dimensional range image of the target after clutter suppression; The disadvantage of this method is that the degree of freedom provided by all the pulses cannot be used in clutter suppression, so its clutter suppression performance is limited. It will increase the regularity of the transmitted waveform and reduce the anti-jamming performance of the frequency agile radar. Another method is to use all the pulses transmitted in one CPI of the frequency agile radar to achieve clutter suppression and bandwidth synthesis processing. This algorithm achieves inter-frequency clutter suppression and can be implemented using the degrees of freedom provided by all pulses in one CPI. Clutter suppression, the only example at present is that S.R.J.Axelsson of the Swedish National Defense Research Institute published the subtraction algorithm in the IEEETrans on GRS journal in 2007. This algorithm is a major advance in frequency agile radar clutter suppression, marking the difference between frequency clutter. However, the algorithm can only suppress the completely static clutter, and usually due to the influence of wind speed, the power spectrum of the clutter has a certain spectral width, that is, the clutter scatterer will not be completely static, so the application of this algorithm in practical engineering is greatly limited.
发明内容SUMMARY OF THE INVENTION
针对现有技术中存在的问题,本发明的目的在于提供一种频率捷变雷达的自适应杂波抑制方法,可利用频率捷变雷达一次CPI内发射的所有脉冲实现杂波抑制和相参处理,并且具有较强的适应性,即适用于杂波功率谱展宽的情况和不同的杂波起伏情况。In view of the problems existing in the prior art, the purpose of the present invention is to provide an adaptive clutter suppression method for a frequency agile radar, which can utilize all the pulses emitted in the primary CPI of the frequency agile radar to achieve clutter suppression and coherent processing , and has strong adaptability, that is, it is suitable for the situation of clutter power spectrum broadening and different clutter fluctuations.
为了达到上述目的,本发明采用以下技术方案予以实现。In order to achieve the above objects, the present invention adopts the following technical solutions to achieve.
一种频率捷变雷达的自适应杂波抑制方法,包括以下步骤:An adaptive clutter suppression method for frequency agile radar, comprising the following steps:
步骤1,建立频率捷变信号模型,构造频率捷变雷达在杂波背景下的回波数据模型,并对频率捷变雷达的回波数据依次进行下变频、低通滤波、脉冲压缩和目标采样,得到目标所在距离门的采样信号作为待处理输入信号;
步骤2,根据频率捷变信号模型设计广义多普勒窗函数,用于在步骤3中扩展杂波多普勒通道的多普勒覆盖范围;
步骤3,根据频率捷变雷达模型设计对应于杂波多普勒通道的距离匹配滤波器组;通过该距离匹配滤波器组和所述广义多普勒窗函数,计算所述待处理输入信号在杂波多普勒通道上的高分辨一维距离像,并据此估计强杂波散射点的距离和幅度信息;
步骤4,根据所述强杂波散射点的距离和幅度信息构造杂波加噪声协方差矩阵R;
步骤5,根据频率捷变信号模型、杂波协方差矩阵R和目标的跟踪速度,设计对应于目标多普勒通道的杂波抑制滤波器组;并利用该杂波抑制滤波器组对待处理输入信号进行杂波抑制,得到杂波抑制后的目标高分辨一维距离像,完成频率捷变雷达的自适应杂波抑制。
与现有技术相比,本发明的有益效果为:Compared with the prior art, the beneficial effects of the present invention are:
(1)相对于利用一次相参处理时间内的同频脉冲信号实现杂波抑制的方法,本发明方法可使用所有脉冲提供的自由度来实现杂波抑制,因此具备更好的杂波抑制理论性能;由于本发明方法实现了异频杂波抑制,不需要一次相参处理时间内发射多个同频脉冲,可以保证发射信号有强随机性来降低截获概;此外,异频杂波抑制还意味着雷达可以保持在较大范围内随机捷变,不损失频率捷变雷达的高距离分辨性能。(1) Compared with the method of using the same frequency pulse signal in one coherent processing time to achieve clutter suppression, the method of the present invention can use the degrees of freedom provided by all pulses to achieve clutter suppression, so it has a better clutter suppression theory performance; because the method of the present invention realizes the suppression of inter-frequency clutter, it does not need to transmit multiple pulses of the same frequency within one coherent processing time, which can ensure that the transmitted signal has strong randomness to reduce the probability of interception; in addition, the inter-frequency clutter suppression also It means that the radar can maintain random agility in a large range without losing the high range resolution performance of frequency agile radar.
(2)与Subtraction算法相比,本发明设计了广义多普勒窗函数和杂波抑制滤波器的多普勒域展宽方法,使得本发明方法可适用于实际的杂波环境,即在杂波功率谱具有一定谱宽的情况下依然有效。(2) Compared with the Subtraction algorithm, the present invention designs the generalized Doppler window function and the Doppler domain broadening method of the clutter suppression filter, so that the method of the present invention can be applied to the actual clutter environment, that is, in the clutter environment It is still valid when the power spectrum has a certain spectral width.
附图说明Description of drawings
下面结合附图和具体实施例对本发明做进一步详细说明。The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
图1是本发明的实现流程图;Fig. 1 is the realization flow chart of the present invention;
图2(a)是本发明设计的广义多普勒窗函数的速度响应与普通矩形窗处理结果的对比图;Fig. 2 (a) is the contrast diagram of the speed response of the generalized Doppler window function designed by the present invention and the processing result of ordinary rectangular window;
图2(b)是图2(a)中3dB主瓣的局部放大图;Figure 2(b) is a partial enlarged view of the 3dB main lobe in Figure 2(a);
图3(a)是本发明中使用广义多普勒窗函数生成的对应于杂波多普勒通道的高分辨一维距离像结果图;Fig. 3 (a) is the high-resolution one-dimensional range image result map corresponding to clutter Doppler channel generated using generalized Doppler window function in the present invention;
图3(b)是使用普通矩形窗函数得到的对应于杂波多普勒通道的高分辨一维距离像结果图;Figure 3(b) is a high-resolution one-dimensional range image result corresponding to the clutter Doppler channel obtained by using an ordinary rectangular window function;
图4(a)是本发明设计的杂波抑制滤波器的距离-多普勒二维响应结果图;Fig. 4 (a) is the range-Doppler two-dimensional response result diagram of the clutter suppression filter designed by the present invention;
图4(b)是图4(a)结果中阻带的局部放大图;Fig. 4(b) is a partial enlarged view of the stop band in the result of Fig. 4(a);
图4(c)是图4(a)结果中通带的局部放大图;Fig. 4(c) is a partial enlarged view of the passband in the result of Fig. 4(a);
图5(a)是本发明设计的杂波抑制滤波器在杂波多普勒通道的距离响应结果图;Fig. 5 (a) is the range response result diagram of the clutter suppression filter designed by the present invention in the clutter Doppler channel;
图5(b)本发明实施例在通带所在距离单元的多普勒响应结果图;Fig. 5(b) Doppler response result diagram of the embodiment of the present invention in the distance unit where the passband is located;
图6(a)是使用距离匹配滤波器组得到的目标高分辨一维距离像结果图;Fig. 6 (a) is the result graph of the target high-resolution one-dimensional range image obtained using the range matched filter bank;
图6(b)是使用本发明的杂波抑制滤波器组得到的目标高分辨一维距离像结果图;Fig. 6 (b) is the result diagram of the target high-resolution one-dimensional range image obtained using the clutter suppression filter bank of the present invention;
图7(a)是本发明方法和subtraction算法随参数σc和v变化时的杂波抑制性能曲线对比图;Fig. 7 (a) is the clutter suppression performance curve comparison diagram when the method of the present invention and the subtraction algorithm change with the parameters σ c and v;
图7(b)本发明方法和subtraction算法随输入信杂噪比和参数v变化时的杂波抑制性能曲线对比图。FIG. 7(b) is a comparison diagram of the clutter suppression performance curves of the method of the present invention and the subtraction algorithm when the input signal-to-noise ratio and the parameter v change.
具体实施方式Detailed ways
下面将结合实施例对本发明的实施方案进行详细描述,但是本领域的技术人员将会理解,下列实施例仅用于说明本发明,而不应视为限制本发明的范围。The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.
参考图1,本发明提供的一种频率捷变雷达的自适应杂波抑制方法,包括以下步骤:Referring to FIG. 1 , an adaptive clutter suppression method for a frequency agile radar provided by the present invention includes the following steps:
步骤1,建立频率捷变信号模型,构造频率捷变雷达在杂波背景下的回波数据模型,并对频率捷变雷达的回波数据依次进行下变频、低通滤波、脉冲压缩和目标采样,得到目标所在距离门的采样信号作为待处理输入信号;
建立频率捷变信号模型:设一次相参处理时间(CPI)内发射N个独立的线性调频脉冲,脉冲重复间隔为Tr,各个脉冲的时宽和带宽分别为Tp和Bp,频率捷变间隔为Δf,fc为初始载频,则各个脉冲的载频可分别写为fc+niΔf,其中,i=0,1,…,N-1,ni为第i个随机频率调制编码。设M为可选频点个数,则有fc+niΔf∈[fc,fc+MΔf]。那么,第i个发射脉冲信号可以写为:Establish a frequency agile signal model: suppose that N independent chirp pulses are transmitted within a coherent processing time (CPI), the pulse repetition interval is Tr , the time width and bandwidth of each pulse are T p and B p respectively, and the frequency agility The variable interval is Δf, and f c is the initial carrier frequency, then the carrier frequency of each pulse can be written as f c +n i Δf, where i=0,1,...,N-1,n i is the i-th random Frequency Modulation Coding. Let M be the number of optional frequency points, then there is f c +n i Δf∈[f c ,f c +MΔf]. Then, the i-th transmitted pulse signal can be written as:
其中,t为时间,μ=Bp/Tp为调频斜率,rect(·)是矩形窗函数,Among them, t is the time, μ=B p /T p is the frequency modulation slope, rect( ) is the rectangular window function,
构造频率捷变雷达在杂波背景下的回波数据模型:设一个径向速度为Vtar的目标被雷达捕获并跟踪,该目标由K个散射点组成,各个目标散射点与雷达之间的初始距离分别为:Rtar(1),Rtar(2),…,Rtar(K);那么,在t时刻第k个散射点相对于雷达的距离为rtar(t,k)=Rtar(k)-Vtart。Construct the echo data model of frequency agile radar in the background of clutter: set a target whose radial velocity is V tar to be captured and tracked by the radar, the target consists of K scattering points, and the distance between each target scattering point and the radar is The initial distances are: R tar (1), R tar (2),…,R tar (K); then, the distance of the kth scattering point relative to the radar at time t is r tar (t,k)=R tar (k)-V tar t.
同理,设目标所在距离门内有L个杂波散射点,各个杂波散射点与雷达之间的初始距离分别为:Rclu(1),Rclu(2),…,Rclu(L),各个杂波散射点的速度分别为:Vclu(1),Vclu(2),…,Vclu(L),那么,在t时刻第l个杂波散射点相对于雷达的距离为rclu(t,l)=Rclu(l)-Vclu(l)t。那么,对应于该距离门的接收信号可写为:Similarly, suppose that there are L clutter scattering points in the range gate where the target is located, and the initial distances between each clutter scattering point and the radar are: R clu (1), R clu (2),…,R clu (L ), the speed of each clutter scattering point is: V clu (1), V clu (2),..., V clu (L), then, the distance of the lth clutter scattering point relative to the radar at time t is r clu (t,l)=R clu (l)-V clu (l)t. Then, the received signal corresponding to this range gate can be written as:
其中,w(t)是功率为σw 2的接收机噪声,γtar(k)和γclu(l)分别是第k个目标散射点和第l个杂波散射点的散射系数。where w(t) is the receiver noise with power σ w 2 , γ tar (k) and γ clu (l) are the scattering coefficients of the k-th target scattering point and the l-th clutter scattering point, respectively.
以上接收信号经过完整的线性调频信号处理流程,即下变频,低通滤波、脉冲压缩后再进行采样处理,得到第i个回波脉冲在目标所在距离门的采样信号写为:The above received signal undergoes a complete linear frequency modulation signal processing process, that is, down-conversion, low-pass filtering, and pulse compression before sampling processing, and the sampling signal of the i-th echo pulse at the distance gate where the target is located is written as:
s(i)=star(i)+sclu(i)+w(i)s(i)=s tar (i)+s clu (i)+w(i)
其中in
定义接收信号向量为s∈C1×N,s=[s(0),s(1),…,s(N-1)],有Define the received signal vector as s∈C 1×N , s=[s(0),s(1),...,s(N-1)], we have
s=star+sclu+ws=s tar +s clu +w
其中,star=[star(0),star(1),…,star(N-1)]表示目标的采样向量,sclu=[sclu(0),sclu(1),…,sclu(N-1)]表示杂波的采样向量,w=[w(0),w(1),…,w(N-1)]表示噪声的采样向量。则向量s作为待处理输入信号。Among them, s tar = [s tar (0), s tar (1),..., s tar (N-1)] represents the sampling vector of the target, s clu = [s clu (0), s clu (1), ...,s clu (N-1)] represents the sampling vector of clutter, and w=[w(0),w(1),...,w(N-1)] represents the sampling vector of noise. Then the vector s is used as the input signal to be processed.
步骤2,根据频率捷变信号模型设计广义多普勒窗函数,用于在步骤3中扩展杂波多普勒通道的多普勒覆盖范围;
广义多普勒窗函数用于展宽零多普勒通道的多普勒覆盖范围,根据频率捷变雷达回波模型中的目标采样数据的多普勒相位项,设计广义多普勒窗函数。由目标采样数据(star(i)的公式),设计一个速度为V0的杂波散射点对应的多普勒相位向量:The generalized Doppler window function is used to widen the Doppler coverage of the zero-Doppler channel. The generalized Doppler window function is designed according to the Doppler phase term of the target sampled data in the frequency-agile radar echo model. From the target sampled data (formula of s tar (i)), design a Doppler phase vector corresponding to the clutter scattering point with velocity V 0 :
同时,设计一个速度为V1的参考向量:At the same time, design a reference vector with velocity V 1 :
设广义多普勒窗函数为ω=[ω(0),ω(1),…,ω(N-1)],在使用该广义多普勒窗函数的基础上将杂波多普勒相位向量与参考向量进行互相关,得到两者的相关函数:Let the generalized Doppler window function be ω=[ω(0),ω(1),...,ω(N-1)], and on the basis of using the generalized Doppler window function, the clutter Doppler phase vector Cross-correlate with the reference vector to get the correlation function of the two:
其中,ΔV=V0-V1,⊙表示Hadamard积,[·]H表示共轭转置。Among them, ΔV=V 0 −V 1 , ⊙ represents the Hadamard product, and [·] H represents the conjugate transpose.
根据相关函数表示形式,基于传统窗函数设计广义多普勒窗函数。According to the representation of the correlation function, the generalized Doppler window function is designed based on the traditional window function.
由于广义多普勒窗函数用于展宽零多普勒通道的多普勒覆盖范围,该函数适宜基于大主瓣宽度窗函数进行设计,例如Blackman窗、Kaiser窗等等。示例性地,原始布莱克曼窗函数(Blackman窗)为:Since the generalized Doppler window function is used to widen the Doppler coverage of the zero-Doppler channel, the function is suitable to be designed based on a large main lobe width window function, such as Blackman window, Kaiser window and so on. Exemplarily, the original Blackman window function (Blackman window) is:
基于Blackman窗设计的广义多普勒窗函数可写为:The generalized Doppler window function based on Blackman window design can be written as:
步骤3,根据频率捷变信号模型设计对应于杂波多普勒通道的距离匹配滤波器组;通过该距离匹配滤波器组和所述广义多普勒窗函数,计算所述待处理输入信号在杂波多普勒通道上的高分辨一维距离像,并据此估计强杂波散射点的距离和幅度信息;
本发明通过生成对应于杂波多普勒通道的高分辨一维距离像来估计强杂波散射点的距离和幅度信息,以实现自适应杂波抑制。The present invention estimates the distance and amplitude information of strong clutter scattering points by generating a high-resolution one-dimensional range image corresponding to the clutter Doppler channel, so as to realize adaptive clutter suppression.
具体地,定义对应于中心速度为V的多普勒通道的距离匹配滤波器矩阵为ΦV∈CN ×M,其中 根据匹配滤波原理可知,距离匹配滤波器矩阵中的元素为:Specifically, the range-matched filter matrix corresponding to the Doppler channel whose center velocity is V is defined as Φ V ∈ C N ×M , where According to the matched filtering principle, the elements in the distance matched filter matrix are:
由于杂波功率谱通常服从0均值高斯分布,定义Φ0为对应于杂波多普勒通道的距离匹配滤波器矩阵,其对应的中心速度为0m/s;接收信号向量s在该多普勒通道上生成的复高分辨一维距离像按如下公式计算:Since the clutter power spectrum usually obeys the 0-mean Gaussian distribution, Φ 0 is defined as the distance-matched filter matrix corresponding to the clutter Doppler channel, and its corresponding center velocity is 0 m/s; the received signal vector s is in the Doppler channel. The complex high-resolution one-dimensional distance image generated above is calculated according to the following formula:
则yclu对应的高分辨一维距离像为|·|为取模操作。Then the high-resolution one-dimensional distance image corresponding to y clu is |·| is the modulo operation.
对高分辨一维距离像进行门限检测,超过预设检测门限的杂波散射点为强杂波散射点,得到H个强杂波散射点,则第h个强杂波散射点的距离和散射系数估计值分别为和h=1,2,…,H,H>1。For high-resolution one-dimensional range images Perform threshold detection, the clutter scattering points exceeding the preset detection threshold are strong clutter scattering points, and H strong clutter scattering points are obtained, then the distance and the estimated value of the scattering coefficient of the h-th strong clutter scattering point are respectively and h=1,2,...,H,H>1.
步骤4,根据所述强杂波散射点的距离和幅度信息构造杂波加噪声协方差矩阵R;
杂波加噪声协方差矩阵用于使得杂波抑制滤波器在强杂波散射点位置处形成零陷,考虑到杂波功率谱扩展以及强杂波散射点距离信息估计误差,本发明在速度-距离二维同时进行零陷展宽以保持杂波抑制的稳健性。The clutter-plus-noise covariance matrix is used to make the clutter suppression filter form a null at the position of the strong clutter scattering point. Considering the clutter power spectrum expansion and the estimation error of the distance information of the strong clutter scattering point, the present invention is in the speed- Simultaneous null broadening in distance 2D to maintain robustness of clutter suppression.
具体地,根据雷达当前的工作环境,设定杂波抑制滤波器的零陷在速度维的展宽程度为DV,在距离维的展宽程度为DR;其中DV大于杂波谱宽度σc,DR大于频率捷变雷达的距离分辨率c/2MΔf;设第h个强杂波散射点的距离参数速度参数Vclu(h)~N(0,DV 2),那么,定义Rclu(h)和Vclu(h)的概率密度函数分别为和有:Specifically, according to the current working environment of the radar, the degree of broadening of the null trap of the clutter suppression filter in the velocity dimension is D V , and the degree of broadening in the distance dimension is D R ; where D V is greater than the clutter spectral width σ c , D R is greater than the range resolution c/2MΔf of the frequency agile radar; set the range parameter of the h-th strong clutter scattering point Velocity parameters V clu (h)~N(0,D V 2 ), then, the probability density functions of R clu (h) and V clu (h) are defined as and Have:
定义对应于第h个强杂波散射点的杂波协方差矩阵为Rh∈CN×N,其第α行第β列元素为[Rh]α,β,则:Define the clutter covariance matrix corresponding to the h-th strong clutter scattering point as R h ∈ C N×N , and its elements in the α-th row and β-column are [R h ] α,β , then:
当α=β时,When α=β,
[Rh]α,β=1[R h ] α, β = 1
当α≠β时,When α≠β,
其中,nα为第α个随机频率调制编码,nβ为第β个随机频率调制编码;Among them, n α is the α-th random frequency modulation code, and n β is the β-th random frequency modulation code;
由于Rclu(h)和Vclu(h)彼此间具有独立性,上式可重写为:Since R clu (h) and V clu (h) are independent of each other, the above equation can be rewritten as:
基于上式可求得第h个强杂波散射点的杂波协方差矩阵Rh的每个元素。Based on the above formula, each element of the clutter covariance matrix R h of the h-th strong clutter scattering point can be obtained.
那么,定义杂波加噪声协方差矩阵为R∈CN×N,有:Then, define the clutter plus noise covariance matrix as R∈C N×N , we have:
其中,为第h个强杂波散射点的距离估计值,I∈CN×N是单位矩阵。in, is the distance estimate of the h-th strong clutter scattering point, and I∈C N×N is the identity matrix.
步骤5,根据频率捷变信号模型、杂波协方差矩阵R和目标的跟踪速度,设计对应于目标多普勒通道的杂波抑制滤波器组;并利用该杂波抑制滤波器组对待处理输入信号进行杂波抑制,得到杂波抑制后的目标高分辨一维距离像,完成频率捷变雷达的自适应杂波抑制。
设目标的跟踪速度为该估计值由雷达目标跟踪模块给出。对应于目标所在的多普勒通道的距离匹配滤波器矩阵为 可由步骤3中公式(I)计算得到。Let the target tracking speed be This estimate is given by the radar target tracking module. The range-matched filter matrix corresponding to the Doppler channel where the target is located is It can be calculated by formula (I) in
设该多普勒通道对应的杂波抑制滤波器矩阵为 通过下式计算得到:Let the clutter suppression filter matrix corresponding to the Doppler channel be It is calculated by the following formula:
由拉格朗日乘子法可知:According to the Lagrange multiplier method:
利用杂波抑制滤波器矩阵对待处理输入信号s进行杂波抑制,得到杂波抑制后的目标复高分辨一维距离像:Utilize the clutter suppression filter matrix Perform clutter suppression on the input signal s to be processed, and obtain a complex high-resolution one-dimensional range image of the target after clutter suppression:
对其中的各个元素取模值即可得到频率捷变雷达杂波抑制后的目标高分辨一维距离像: The high-resolution one-dimensional range image of the target after frequency agile radar clutter suppression can be obtained by taking the modulo value of each element:
本发明为实现频率捷变雷达的自适应杂波抑制,首先利用频率捷变信号回波做出对应于杂波多普勒通道的高分辨一维距离像,用于估计强杂波散射点的距离和幅度信息;考虑到实际杂波的功率谱是扩展的,即杂波径向速度在以0为中心的小范围内随机变化,本发明方法设计了广义多普勒窗函数用于在杂波距离像成像过程中扩展杂波多普勒通道的覆盖范围。其次是根据强杂波散射点的距离和幅度估计信息设计杂波加噪声协方差矩阵,并以此计算具有距离-多普勒二维特性的杂波抑制滤波器组;该协方差矩阵用于使得杂波抑制滤波器在强杂波散射点位置处(距离-多普勒二维)形成零陷,考虑到强杂波散射点距离估计误差以及功率谱扩展情况,本发明方法可通过对协方差矩阵的调整使得杂波抑制滤波器的零陷在距离和速度维进行同时展宽,以增强方法的稳健性。最后,利用杂波抑制滤波器组取代距离匹配滤波器组以得到杂波抑制后的目标高分辨一维距离像。In order to realize the adaptive clutter suppression of the frequency agile radar, the present invention first uses the frequency agile signal echo to make a high-resolution one-dimensional range image corresponding to the clutter Doppler channel, which is used to estimate the distance of the strong clutter scattering point and amplitude information; considering that the power spectrum of the actual clutter is expanded, that is, the radial velocity of the clutter changes randomly in a small range centered at 0, the method of the present invention designs a generalized Doppler window function to be used in the clutter Extends the coverage of the clutter Doppler channel during range imaging. Secondly, the clutter plus noise covariance matrix is designed according to the distance and amplitude estimation information of the strong clutter scattering points, and the clutter suppression filter bank with the two-dimensional range-Doppler characteristic is calculated based on this; the covariance matrix is used for Make the clutter suppression filter form a zero trap at the position of the strong clutter scattering point (distance-Doppler two-dimensional), taking into account the distance estimation error of the strong clutter scattering point and the power spectrum expansion, the method of the present invention can pass the coordination The adjustment of the variance matrix allows the nulls of the clutter suppression filter to be broadened simultaneously in the distance and velocity dimensions to enhance the robustness of the method. Finally, the clutter suppression filter bank is used to replace the range-matched filter bank to obtain a high-resolution one-dimensional range image of the target after clutter suppression.
本发明方法能够利用频率捷变雷达一次CPI发射的所有脉冲实现杂波抑制,并在杂波功率谱展宽的情况下依旧适用,在实现异频杂波抑制并考虑实际杂波特性的基础上解决了频率捷变与杂波抑制的兼容问题。The method of the invention can realize the clutter suppression by using all the pulses transmitted by the primary CPI of the frequency agile radar, and is still applicable in the case of widening the clutter power spectrum, on the basis of realizing the different frequency clutter suppression and considering the actual clutter characteristics Solved the compatibility problem of frequency agility and clutter suppression.
仿真实验Simulation
为了证明本发明的有效性,采用以下仿真对比试验进一步说明。In order to prove the effectiveness of the present invention, the following simulation comparison test is used to further illustrate.
(1)仿真条件:(1) Simulation conditions:
频率捷变信号的波形参数设置如下:初始频率fc=8GHz,一次CPI的发射脉冲个数N=256,可选频点个数M=128,脉冲重复间隔Tr=100us,脉冲宽度Tp=100us,脉冲带宽Bp=10MHz,频率捷变间隔Δf=10MHz,接收机噪声功率σw 2=0dB,载频调制编码ni(i=0,1,…,M-1)服从{0,1,…,M-1}上的离散均匀分布且彼此独立。在仿真2~4中,给定了一个固定的目标场景,其中目标速度为40m/s,该目标由三个散射点组成,其距离参数分别为Rtar(1)=1508m,Rtar(2)=1509m,Rtar(3)=1510m,它们的散射系数分别为γtar(1)=1dB,γtar(2)=3dB,γtar(3)=2dB。目标所在距离门中有三个强杂波散射点和若干弱杂波散射点,弱杂波回波总功率与目标回波功率一致,三个强杂波散射点的距离参数分别为Rclu(1)=1503m,Rclu(2)=1507m,Rclu(3)=1509m,其散射系数分别为γclu(1)=20dB,γclu(2)=22dB,γclu(3)=19dB,为了模拟杂波功率谱扩展情况,设置三个强杂波散射点的速度参数分别为Vclu(1)=0.169m/s,Vclu(2)=-0.028m/s,Vclu(3)=0.483m/s,在仿真5中,目标场景根据不同的场景参数随机设置。The waveform parameters of the frequency agile signal are set as follows: the initial frequency f c =8GHz, the number of transmit pulses for one CPI = 256, the number of optional frequency points M = 128, the pulse repetition interval Tr = 100us , the pulse width T p =100us, pulse bandwidth B p =10MHz, frequency agility interval Δf=10MHz, receiver noise power σ w 2 =0dB, carrier frequency modulation code ni (i=0,1,...,M-1) obeys {0 ,1,…,M-1} are discrete uniform distributions and independent of each other. In
(2)仿真内容及结果:(2) Simulation content and results:
仿真1,仿真本发明方法步骤2中的广义多普勒窗函数的特性,并将结果与普通矩形窗函数进行对比,两种窗函数的多普勒响应结果如图2(a)所示,图2(b)为图2(a)中3dB主瓣的局部放大图;从图2(a)中可以看出,广义多普勒窗函数可显著增大杂波多普勒通道的速度覆盖范围,从图2(b)中可以看出,矩形窗的3dB多普勒主瓣宽度为0.60m/s,而广义多普勒窗函数则为1.04m/s。
仿真2,仿真本发明方法步骤3生成的对应于杂波多普勒通道的高分辨一维距离像,并将结果与使用普通矩形窗函数时进行对比;仿真结果如图3所示,其中图3(a)是使用广义多普勒窗函数得到的结果,图3(b)是使用普通矩形窗函数得到的结果。从图3(a)中可以看出,当不使用广义多普勒窗函数时,第三个强杂波散射点无法从杂波一维距离像中被检测并估计信息,继而该强杂波散射点无法有效抑制;从图3(b)中可以看出,当使用广义多普勒窗函数时,三个强杂波散射点均可被检测,其距离参数估计分别为: 散射系数估计分别为
仿真3,仿真本发明方法步骤5产生的杂波抑制滤波器的距离-多普勒二维响应,仿真结果如图4(a)所示,其中,图4(b)是图4(a)结果中阻带的局部放大图,图4(c)是图4(a)结果中通带的局部放大图;从图4(a)、4(b)、4(c)中可以看出,本发明方法设计的杂波抑制滤波器具备二维特性,该杂波抑制滤波器在目标所在的多普勒通道上形成通带,在杂波所在多普勒通道上形成零陷,且零陷位置对应于各强波散射点。该杂波抑制滤波器的在杂波多普勒通道的距离响应以及在通带所在距离单元的多普勒响应结果分别如图5(a)和5(b)所示;从图5(a)、5(b)中可以看出,零陷在距离和速度维是同时展宽的,在距离维的展宽可以降低强杂波散射点距离信息估计误差引发的杂波抑制性能下降,而速度维的展宽可以应对杂波功率谱扩展带来的影响。
仿真4,仿真本发明方法步骤5产生杂波抑制后的目标高分辨一维距离像,并与普通相参处理结果进行对比,仿真结果如图6所示,其中图6(a)是使用距离匹配滤波器组得到的结果,图6(b)是使用本发明的杂波抑制滤波器组得到的结果。从图6(a)中可以看出,在传统相参处理得到的一维距离像中,目标被杂波所形成的噪底所淹没;从图6(b)中可以看出,利用本发明方法设计的杂波抑制滤波器得到的一维距离像中,目标的三个散射点形成的尖峰均可见,且尖峰位置正确对应于三个目标散射点的距离参数。
仿真5,仿真本发明方法在不同输入信杂噪比、不同的杂波谱宽度以及不同的杂波起伏模型下的性能,并将结果与subtraction算法进行对比;其中输入信杂比从-30dB到-10dB变化,杂波功率谱服从谱宽σc(标准差)从0到0.5m/s变化的高斯分布,不同杂波起伏模型服从尺度参数α=1,形状参数v分别为1、2、4的K分布;在各种情况下进行10000次蒙特卡洛实验,仿真结果如图7所示,在图7(a)中仿真了本发明方法随参数σc和v变化时的情况,输入信杂噪比固定为-20dB;在图7(b)仿真了本发明方法随输入信杂噪比和参数v变化时的情况,设置杂波功率谱宽度σc固定为0.22m/s。从图7(a)中可以看出,由于没有考虑杂波谱扩展的情况,Subtraction算法的性能随着杂波功率谱谱宽的增大而下降严重;而在本发明方法中,由于广义多普勒窗函数的使用,以及杂波抑制滤波器零陷在多普勒维的展宽,该方法在杂波功率谱展宽的情况下依然适用;对比图7(a)和7(b)中可以看出,不同的杂波起伏模型对算法性能也会带来一定影响,但影响很小,这是因为本发明方法采用自适应杂波抑制体制,对不同的杂波起伏模型具有适应性。
虽然,本说明书中已经用一般性说明及具体实施方案对本发明作了详尽的描述,但在本发明基础上,可以对之作一些修改或改进,这对本领域技术人员而言是显而易见的。因此,在不偏离本发明精神的基础上所做的这些修改或改进,均属于本发明要求保护的范围。Although the present invention has been described in detail with general description and specific embodiments in this specification, some modifications or improvements can be made on the basis of the present invention, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the claimed protection of the present invention.
Claims (8)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202010824214.6A CN112014807B (en) | 2020-08-17 | 2020-08-17 | Self-adaptive clutter suppression method for frequency agile radar |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202010824214.6A CN112014807B (en) | 2020-08-17 | 2020-08-17 | Self-adaptive clutter suppression method for frequency agile radar |
Publications (2)
Publication Number | Publication Date |
---|---|
CN112014807A true CN112014807A (en) | 2020-12-01 |
CN112014807B CN112014807B (en) | 2024-03-26 |
Family
ID=73504766
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN202010824214.6A Active CN112014807B (en) | 2020-08-17 | 2020-08-17 | Self-adaptive clutter suppression method for frequency agile radar |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN112014807B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112731301A (en) * | 2020-12-29 | 2021-04-30 | 北京环境特性研究所 | Interference suppression method and device for disc-shaped clutter analog measurement |
CN112965069A (en) * | 2021-03-21 | 2021-06-15 | 南京大学 | Frequency domain ground object suppression method for dual-polarization radar |
CN115510920A (en) * | 2022-10-17 | 2022-12-23 | 广东工业大学 | High-sea-condition sea clutter suppression method based on deep learning |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4727311B2 (en) * | 2005-06-15 | 2011-07-20 | 三菱電機株式会社 | Radar equipment |
CN104931938B (en) * | 2015-05-07 | 2017-07-28 | 清华大学 | Coherent frequency-agile radar clutter suppression method and system |
CN109061589B (en) * | 2018-07-06 | 2022-08-26 | 西安电子科技大学 | Target motion parameter estimation method of random frequency hopping radar |
-
2020
- 2020-08-17 CN CN202010824214.6A patent/CN112014807B/en active Active
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112731301A (en) * | 2020-12-29 | 2021-04-30 | 北京环境特性研究所 | Interference suppression method and device for disc-shaped clutter analog measurement |
CN112731301B (en) * | 2020-12-29 | 2023-06-09 | 北京环境特性研究所 | Interference suppression method and device for disc-shaped clutter simulation measurement |
CN112965069A (en) * | 2021-03-21 | 2021-06-15 | 南京大学 | Frequency domain ground object suppression method for dual-polarization radar |
CN115510920A (en) * | 2022-10-17 | 2022-12-23 | 广东工业大学 | High-sea-condition sea clutter suppression method based on deep learning |
Also Published As
Publication number | Publication date |
---|---|
CN112014807B (en) | 2024-03-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN111965615B (en) | A radar target detection method based on pre-detection estimation | |
CN108037494B (en) | Radar target parameter estimation method under impulse noise environment | |
CN112346030B (en) | Super-resolution direction-of-arrival estimation method for UAV swarms | |
CN112014807A (en) | An adaptive clutter suppression method for frequency agile radar | |
CN106546965A (en) | Based on radar amplitude and the space-time adaptive processing method of Doppler-frequency estimation | |
CN107490790B (en) | Simulation method of continuous multi-pulse coherent sea clutter | |
CN113376601B (en) | Sidelobe Suppression Method for Frequency-Agile Radar Based on CLEAN Algorithm | |
Sun et al. | A novel weighted mismatched filter for reducing range sidelobes | |
CN113835068B (en) | A Blind Source Separation Real-Time Anti-mainlobe Interference Method Based on Independent Component Analysis | |
CN113391286B (en) | Virtual aperture MIMO radar target detection method based on two-dimensional block sparse recovery | |
CN107329115A (en) | LFM modulated parameter estimating methods based on GCRBF networks | |
Xiong et al. | Radar high-speed target coherent detection method based on modified radon inverse Fourier transform | |
CN113238211A (en) | Parameterized adaptive array signal detection method and system under interference condition | |
Lu et al. | An efficient method for single-channel SAR target reconstruction under severe deceptive jamming | |
CN116248457A (en) | Orthogonal LFM-PC Doppler tolerance expansion-based inter-pulse forwarding interference resistant waveform optimization method | |
Zhang et al. | Range-velocity jamming suppression algorithm based on adaptive iterative filtering | |
CN118169686B (en) | SA-ISAR imaging and azimuth calibration method based on SCICPF method | |
Chen et al. | Anti-jamming approach based on radar transmitted waveform matching | |
Tian et al. | Joint Iterative Adaptive Approach for sidelobe suppression and migration correction of migrating targets | |
CN114966598B (en) | Method and device for adaptively suppressing strong ground clutter of low, slow and small radar | |
Malik et al. | Adaptive pulse compression for sidelobes reduction in stretch processing based MIMO radars | |
CN111025258B (en) | Joint mismatch filter for radar waveform diversity and design method thereof | |
CN114280532A (en) | A radar target angle estimation method and system based on in-band conjugate dot product | |
Corsini et al. | Signal-to-noise ratio and autocorrelation function of the image intensity in coherent systems. Sub-Rayleigh and super-Rayleigh conditions | |
CN114296039B (en) | LFMCW radar target constant false alarm detection method and device based on sparse reconstruction |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
GR01 | Patent grant | ||
GR01 | Patent grant |