CN103018737A

CN103018737A - Method for utilizing frequency distribution array (FDA) radar to estimate object distance and azimuthal angle and FDA radar

Info

Publication number: CN103018737A
Application number: CN2012105091436A
Authority: CN
Inventors: 王文钦; 邵怀宗; 王永兵; 杨帆; 潘晔; 胡全
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2012-11-20
Filing date: 2012-11-20
Publication date: 2013-04-03
Anticipated expiration: 2032-11-20
Also published as: CN103018737B

Abstract

The invention belongs to the technical field of frequency diversity array (FDA) radar. The invention discloses a method for estimating target distance and azimuth angle with FDA radar, which comprises dividing the transmitting array elements of the radar into a first transmitting sub-array and a second transmitting sub-array with the same number of array elements, and generating two transmitting sub-arrays The step of transmitting a signal, estimating the azimuth and range of the target. This method can effectively utilize the distance-dependent characteristics of the FDA radar beam to jointly estimate the azimuth and distance of the target, and overcome the coupling problem existing in the estimation of the range and azimuth of the target by the FDA radar.

Description

A method for estimating target distance and azimuth angle with FDA radar and FDA radar

技术领域 technical field

本发明属于雷达技术领域，具体涉及频率分集阵列(FDA)雷达技术领域。The invention belongs to the technical field of radar, in particular to the technical field of frequency diversity array (FDA) radar.

背景技术 Background technique

相控阵雷达可以自由地实现波束的空间扫描，因而广泛地应用于雷达目标检测与成像。通常相控阵雷达每个阵元发射的是同一个信号，通过在每个阵元的输出端接入移相器来实现波束方向控制，调整移相器的相移量便可实现波束的空域扫描。然而，相控阵雷达在每一快拍内，波束指向在所有距离分辨单元上是恒定的，也就是说波束指向与距离是无关的，因而不能利用线性相控阵雷达实现目标距离和方位角的二维联合估计。但是在某些应用中，常常又期望阵列波束在同一快拍内能够以不同的角度指向不同的距离，这就需要波束的指向能够随距离的变化而变化。Phased array radar can freely realize the spatial scanning of the beam, so it is widely used in radar target detection and imaging. Usually, each array element of phased array radar emits the same signal, and the beam direction control is realized by connecting a phase shifter at the output end of each array element, and the beam space can be realized by adjusting the phase shift amount of the phase shifter. scanning. However, in each snapshot of phased array radar, the beam pointing is constant on all range resolution units, that is to say, the beam pointing has nothing to do with the distance, so the linear phased array radar cannot be used to achieve target range and azimuth angle The two-dimensional joint estimate of . However, in some applications, it is often expected that the array beam can point to different distances at different angles in the same snapshot, which requires that the beam pointing can change with the distance.

频率分集阵列(FDA，Frequency Diverse Array)雷达在同一时间对不同阵元施加不同的频偏，可以提供距离依赖性波束扫描功能，这和传统的相控阵和频率扫描天线都是不同的；频率扫描天线的频偏是在不同的时间施加的，而且所有阵元的频偏是相同的；FDA雷达发射和相控阵一样的相参信号，但是各阵元附加了不同的频偏Δf，因而辐射出去的信号频率是不同的。Frequency Diversity Array (FDA, Frequency Diverse Array) radar applies different frequency offsets to different array elements at the same time, which can provide distance-dependent beam scanning function, which is different from traditional phased array and frequency scanning antennas; frequency The frequency offset of the scanning antenna is applied at different times, and the frequency offset of all array elements is the same; the FDA radar transmits the same coherent signal as the phased array, but each array element has a different frequency offset Δf, so The radiated signal frequency is different.

现有技术分析了FDA雷达波束的距离依赖特性，但是没有回答如何有效地利用这种距离依赖特性，也没有解决FDA雷达在对目标距离向和方位角向进行估计时存在的耦合问题，即：发射波束不能聚焦在期望的目标点上，而是分布成一条距离向和方位角向相耦合的“峰脊”上，如图1所示。The existing technology analyzes the distance-dependent characteristics of the FDA radar beam, but does not answer how to effectively use this distance-dependent characteristic, nor solve the coupling problem existing in the FDA radar when estimating the target range and azimuth, namely: The transmit beam cannot be focused on the desired target point, but is distributed into a "peak and ridge" coupled in the range and azimuth directions, as shown in Figure 1.

发明内容 Contents of the invention

为了解决现有技术在用FDA雷达对目标距离向和方位角向进行估计时存在的技术问题，本发明提出了一种用FDA雷达估计目标距离和方位角的方法，能够有效地解决上述现有技术中存在的问题。In order to solve the technical problems existing in the prior art when using the FDA radar to estimate the target range and azimuth, the present invention proposes a method for estimating the target distance and azimuth with the FDA radar, which can effectively solve the above-mentioned existing problems. problems in technology.

为了解决这个技术问题，本发明的第一方面在于提供一种用FDA雷达估计目标距离和方位角的方法，包括如下步骤：In order to solve this technical problem, a first aspect of the present invention is to provide a method for estimating target distance and azimuth with FDA radar, comprising the steps:

1)将雷达的发射阵元分成阵元个数相等第一发射子阵列和第二发射子阵列；1) Dividing the transmitting array elements of the radar into a first transmitting sub-array and a second transmitting sub-array with equal numbers of array elements;

2)产生两个子阵列的发射信号：2) Generate the emission signals of the two subarrays:

第一发射子阵列中的每个阵元的发射信号的频率为The frequency of the transmit signal of each array element in the first transmit subarray is

f_c1，i＝f₀+(i-1)·Δf₁，i＝1，2，....M；f _{c1, i} =f ₀ +(i-1)·Δf ₁ , i=1, 2, ... M;

第二发射子阵列中的每个阵元的发射信号的频率为The frequency of the transmit signal of each array element in the second transmit sub-array is

f_c2，i＝f₀+(i-1)·Δf₂，i＝1，2，....Mf _{c2, i} =f ₀ +(i-1)·Δf ₂ , i=1, 2, ... M

M为子阵列中阵元的总数，f₀为雷达系统载频，Δf₁为预先设定的第一发射子阵列的载频增量，Δf₂为预先设定的第二发射子阵列的载频增量；M is the total number of array elements in the subarray, f ₀ is the carrier frequency of the radar system, Δf ₁ is the preset carrier frequency increment of the first transmitting subarray, and Δf ₂ is the preset carrier frequency of the second transmitting subarray. frequency increment;

3)估计目标的方位角和距离：3) Estimate the azimuth and distance of the target:

$((\overset{^^}{θ θ},, \overset{^^}{r r})) = = \underset{θ θ,, r r}{max max} J J ((θ θ,, r r)) = = \underset{θ θ,, r r}{max max} {| | {w w}^{H h} ((θ θ,, r r)) y the y | |}^{22}$

其中，w(θ，r)表示接收信号的导向矢量，θ为接收信号波束的所有可能的方位角，r为接收信号波束的所有可能的距离值，y是接收到的信号，(·)^H表示共轭转置，

为估计出的目标的方位角和距离。where w(θ, r) represents the steering vector of the received signal, θ is all possible azimuth angles of the received signal beam, r is all possible distance values of the received signal beam, y is the received signal, ( ) ^H represents the conjugate transpose,

is the estimated azimuth and distance of the target.

为了解决这个技术问题，与上述第一方面相结合，本发明的第二方面在于提供一种用FDA雷达估计目标距离和方位角的方法，当所述的发射阵元的个数为奇数时，则以阵列的中间阵元为中点，将阵列分成阵元个数相等第一发射子阵列和第二发射子阵列。In order to solve this technical problem, in combination with the above-mentioned first aspect, the second aspect of the present invention is to provide a method for estimating target distance and azimuth with FDA radar, when the number of the transmitting array elements is an odd number, Then, the array is divided into a first emitting sub-array and a second emitting sub-array with the same number of array elements by taking the middle element of the array as the midpoint.

为了解决这个技术问题，与上述第一方面相结合，本发明的第三方面在于提供一种用FDA雷达估计目标距离和方位角的方法，所述的接收信号的导向矢量等于发射信号的导向矢量。In order to solve this technical problem, in combination with the above-mentioned first aspect, the third aspect of the present invention is to provide a method for estimating target distance and azimuth with FDA radar, the steering vector of the received signal is equal to the steering vector of the transmitted signal .

为了解决这个技术问题，与上述第三方面相结合，本发明的第四方面在于提供一种用FDA雷达估计目标距离和方位角的方法，所述的发射信号的导向矢量为In order to solve this technical problem, in combination with the above-mentioned third aspect, the fourth aspect of the present invention is to provide a method for estimating target distance and azimuth with FDA radar, and the steering vector of the transmitted signal is

$a a ((θ θ,, r r)) = = {[[11,, {e e}^{- - j j {ω ω}_{11}},, . . . . . . {e e}^{- - j j ((M m - - 11)) {ω ω}_{11}},, 11,, {e e}^{- - j j {ω ω}_{22}},, . . . . . . {e e}^{- - j j ((M m - - 11)) {ω ω}_{22}}]]}^{T T}$

[·]^T为向量的转置运算，ω₁表示第一发射子阵列中相邻两个阵元发射信号的相位差，ω₂表示第二发射子阵列中相邻两个阵元发射信号的相位差。[·] ^T is the transposition operation of the vector, ω ₁ represents the phase difference of the transmitted signals of two adjacent array elements in the first transmitting subarray, and ω ₂ indicates the phase difference of the transmitted signals of two adjacent array elements in the second transmitting subarray Phase difference.

为了解决这个技术问题，与上述第四方面相结合，本发明的第五方面在于提供一种用FDA雷达估计目标距离和方位角的方法，所述的ω₁和ω₂由下式计算得到：In order to solve this technical problem, in combination with the above-mentioned fourth aspect, the fifth aspect of the present invention is to provide a method for estimating target distance and azimuth with FDA radar, and described ω ₁ and ω ₂ are calculated by the following formula:

${ω ω}_{11} = = \frac{22 π π {f f}_{00} d d sin sin θ θ}{{c c}_{00}} - - \frac{22 πΔ πΔ {f f}_{11} r r}{},,$ ${ω ω}_{22} = = \frac{22 π π {f f}_{00} d d sin sin θ θ}{{c c}_{00}} - - \frac{22 πΔ πΔ {f f}_{22} r r}{}$

其中，θ为接收信号波束的所有可能的方位角，r为接收信号波束的所有可能的距离值，d为相邻阵元的间距，c₀为光速。Among them, θ is all possible azimuth angles of the received signal beam, r is all possible distance values of the received signal beam, d is the distance between adjacent array elements, and c ₀ is the speed of light.

为了解决这个技术问题，与上述第一方面相结合，本发明的第六方面在于提供一种用FDA雷达估计目标距离和方位角的方法，所述的Δf₁和Δf₂的取值方法是：其中任意一个取正数，另一个取负数。In order to solve this technical problem, in combination with the above-mentioned first aspect, the sixth aspect of the present invention is to provide a method for estimating target distance and azimuth angle with FDA radar, and the value method of described Δf ₁ and Δf ₂ is: Any one of them takes a positive number, and the other takes a negative number.

本发明还提供一种新的FDA雷达，包括第一发射子阵列和第二发射子阵列，所述的第一发射子阵列中的每个阵元的发射信号的频率为：The present invention also provides a new FDA radar, comprising a first transmitting subarray and a second transmitting subarray, the frequency of the transmitting signal of each array element in the first transmitting subarray is:

第二发射子阵列中的每个阵元的发射信号的频率为：The frequency of the transmitting signal of each array element in the second transmitting sub-array is:

f_c2，i＝f₀+(i-1)·Δf₂，i＝1，2，....M；f _{c2, i} =f ₀ +(i-1)·Δf ₂ , i=1, 2, ... M;

M为子阵列中阵元的总数，f₀为雷达系统载频，Δf₁为预先设定的第一发射子阵列的载频增量，Δf₂为预先设定的第二发射子阵列的载频增量。M is the total number of array elements in the subarray, f ₀ is the carrier frequency of the radar system, Δf ₁ is the preset carrier frequency increment of the first transmitting subarray, and Δf ₂ is the preset carrier frequency of the second transmitting subarray. frequency increment.

本发明的有益技术效果是：The beneficial technical effect of the present invention is:

1、能够有效地利用FDA雷达波束的距离依赖特性，对目标的方位角和距离进行联合估计；1. It can effectively use the distance-dependent characteristics of the FDA radar beam to jointly estimate the azimuth and distance of the target;

2、克服了FDA雷达在对目标距离向和方位角向进行估计时存在的耦合问题。2. Overcome the coupling problem of FDA radar when estimating the target range and azimuth.

附图说明 Description of drawings

图1是现有的FDA雷达的发射-接收波束辐射图；Figure 1 is a transmit-receive beam radiation diagram of an existing FDA radar;

图2是本发明提出的FDA雷达的发射-接收波束辐射图；Fig. 2 is the transmit-receive beam radiation pattern of FDA radar that the present invention proposes;

图3是本发明提出的一种用FDA雷达估计目标距离和方位角的方法的总体流程图；Fig. 3 is a kind of general flowchart of the method for estimating target range and azimuth angle with FDA radar that the present invention proposes;

图4是本发明提出的FDA雷达的Δf₁和Δf₂取不同值时对目标距离和方位角估计的性能对比图。Fig. 4 is a performance comparison chart of estimation of target distance and azimuth angle when Δf ₁ and Δf ₂ of the FDA radar proposed by the present invention take different values.

具体实施方式 Detailed ways

下面结合附图具体说明本发明技术方案的实施方式。The implementation manner of the technical solution of the present invention will be specifically described below in conjunction with the accompanying drawings.

本具体实施方式以一个X波段FDA雷达为例，其载波频率f₀＝10Hz，频偏Δf₁＝30kHz，Δf₂＝10kHz。假设一个均匀线性阵列有10个发射阵元和10个接收阵元，阵元之间的间隔为半个波长(λ＝c₀/f₀)，目标位于方位角θ＝10°和距离r＝10km。This specific embodiment takes an X-band FDA radar as an example, its carrier frequency f ₀ =10 Hz, frequency offset Δf ₁ =30 kHz, Δf ₂ =10 kHz. Suppose a uniform linear array has 10 transmitting array elements and 10 receiving array elements, the interval between the array elements is half a wavelength (λ=c ₀ /f ₀ ), the target is located at the azimuth angle θ=10° and the distance r= 10km.

如图3所示，本发明提出的一种用FDA雷达估计目标距离和方位角的方法包括如下步骤：As shown in Figure 3, a kind of method that the present invention proposes uses FDA radar to estimate target distance and azimuth angle and comprises the steps:

1)将雷达的发射阵元分成阵元个数相等第一发射子阵列和第二发射子阵列，当所述的发射阵元的个数为奇数时，则以阵列的中间阵元为中点，将阵列分成阵元个数相等第一发射子阵列和第二发射子阵列；1) Divide the transmitting array elements of the radar into the first transmitting sub-array and the second transmitting sub-array with the same number of array elements. When the number of the transmitting array elements is an odd number, take the middle array element of the array as the midpoint , divide the array into a first emitting sub-array and a second emitting sub-array with equal numbers of array elements;

2)产生两个发射子阵列的发射信号：2) Generate transmit signals of two transmit subarrays:

is the estimated azimuth and distance of the target.

接收信号的导向矢量w(θ，r)可以认为等于发射信号的导向矢量，而发射信号的导向矢量为：The steering vector w(θ, r) of the received signal can be considered equal to the steering vector of the transmitted signal, and the steering vector of the transmitted signal is:

其中，[·]^T表示向量的转置运算，ω₁表示第一发射子阵列中相邻两个阵元发射信号的相位差，ω₂表示第二发射子阵列中相邻两个阵元发射信号的相位差。为了减少运算量，ω₁和ω₂可以近似的由下式计算得到：Among them, [ ] ^T represents the transposition operation of the vector, ω ₁ represents the phase difference between the transmitted signals of two adjacent array elements in the first transmitting subarray, and ω ₂ represents the phase difference between the transmitted signals of two adjacent array elements in the second transmitting subarray. The phase difference of the signal. In order to reduce the amount of computation, ω ₁ and ω ₂ can be approximated by the following formula:

图4显示了在不同信噪比(横轴表示)条件下本发明提出的FDA雷达的Δf₁和Δf₂取若干组不同值时，采用本方法来对目标距离和方位角进行估计的估计误差

(纵轴表示)，该估计误差指的是对目标距离和方位角估计得总的估计方差，是分别计算目标距离和方位角克拉美-罗下限CRB_r和cRB_θ后得到的，即：

根据求出的方差可以看出，当FDA雷达的Δf₁和Δf₂中的任意一个取正数，另一个取负数时，估计误差较小。Fig. 4 shows when Δf ₁ and Δf ₂ of the FDA radar proposed by the present invention take several groups of different values under different signal-to-noise ratios (horizontal axis represents), adopt this method to estimate the estimation error of target distance and azimuth angle

(indicated by the vertical axis), the estimation error refers to the total estimated variance of the estimated target distance and azimuth angle, which is obtained after calculating the Cramer-Rao lower bounds CRB _r and cRB _θ of the target distance and azimuth angle respectively, namely:

According to the calculated variance, it can be seen that when any one of Δf ₁ and Δf ₂ of the FDA radar takes a positive number and the other takes a negative number, the estimation error is small.

此外，与图1相比，如图2所示，本发明提出的FDA雷达的发射波束能够较好的聚焦在期望的目标点上，而不是分布成一条距离向和方位角向相耦合的“峰脊”上。In addition, compared with Fig. 1, as shown in Fig. 2, the transmitting beam of the FDA radar proposed by the present invention can be better focused on the desired target point, instead of being distributed into a "coupling" in the range direction and the azimuth direction. on the ridge".

Claims

1. A method for estimating target distance and azimuth with FDA radar, comprising the steps:

1) Dividing the transmitting array elements of the radar into a first transmitting sub-array and a second transmitting sub-array with equal numbers of array elements;

2) Generate transmit signals of two transmit subarrays:

The frequency of the transmit signal of each array element in the first transmit subarray is

f _{c1, i} =f ₀ +(i-1)·Δf ₁ , i=1, 2, ... M;

The frequency of the transmit signal of each array element in the second transmit sub-array is

f _{c2, i} =f ₀ +(i-1)·Δf ₂ , i=1, 2, ... M

M is the total number of array elements in the subarray, f ₀ is the carrier frequency of the radar system, Δf ₁ is the preset carrier frequency increment of the first transmitting subarray, and Δf ₂ is the preset carrier frequency of the second transmitting subarray. frequency increment;

3) Estimate the azimuth and distance of the target:

((\overset{^^}{θ θ},, \overset{^^}{r r})) = = \underset{θ θ,, r r}{max max} J J ((θ θ,, r r)) = = \underset{θ θ,, r r}{max max} {| | {w w}^{H h} ((θ θ,, r r)) y the y | |}^{22}

where w(θ, r) represents the steering vector of the received signal, θ is all possible azimuth angles of the received signal beam, r is all possible distance values of the received signal beam, y is the received signal, ( ) ^H represents the conjugate transpose,

is the estimated azimuth and distance of the target.

2. the method for estimating target distance and azimuth angle with FDA radar according to claim 1, when the number of described transmitting array element is an odd number, then take the middle array element of array as midpoint, array is divided into array The number of elements is equal to the first emitting subarray and the second emitting subarray.

3. The method for estimating target distance and azimuth with FDA radar according to claim 1, wherein the steering vector of the received signal is equal to the steering vector of the transmitted signal.

4. the method for estimating target distance and azimuth angle with FDA radar according to claim 3, the steering vector of described transmission signal is:

a a ((θ θ,, r r)) = = {[[11,, {e e}^{- - j j {ω ω}_{11}},, . . . . . . {e e}^{- - j j ((M m - - 11)) {ω ω}_{11}},, 11,, {e e}^{- - j j {ω ω}_{22}},, . . . . . . {e e}^{- - j j ((M m - - 11)) {ω ω}_{22}}]]}^{T T}

[·] ^T is the transposition operation of the vector, ω ₁ represents the phase difference of the transmitted signals of two adjacent array elements in the first transmitting subarray, and ω ₂ indicates the phase difference of the transmitted signals of two adjacent array elements in the second transmitting subarray Phase difference.

5. the method for estimating target distance and azimuth with FDA radar according to claim 4, described ω ₁ and ω ₂ are calculated by following formula:

{ω ω}_{11} = = \frac{22 π π {f f}_{00} d d sin sin θ θ}{{c c}_{00}} - - \frac{22 πΔ πΔ {f f}_{11} r r}{{c c}_{00}},,

{ω ω}_{22} = = \frac{22 π π {f f}_{00} d d sin sin θ θ}{{c c}_{00}} - - \frac{22 πΔ πΔ {f f}_{22} r r}{{c c}_{00}}

Among them, θ is all possible azimuth angles of the transmitted signal beam, r is all possible distance values of the transmitted signal beam, d is the distance between adjacent array elements, and c ₀ is the speed of light.

6. the method for estimating target distance and azimuth with FDA radar according to claim 1, the value method of described Δf ₁ and Δf ₂ is: wherein any one takes a positive number, and another takes a negative number.

7. An FDA radar, comprising a first transmitting subarray and a second transmitting subarray, the frequency of the transmitting signal of each array element in the first transmitting subarray is:

f _{c1, i} =f ₀ +(i-1)·Δf ₁ , i=1, 2, ... M;

The frequency of the transmitting signal of each array element in the second transmitting sub-array is:

f _{c2, i} =f ₀ +(i-1)·Δf ₂ , i=1, 2, ... M;

M is the total number of array elements in the subarray, f ₀ is the carrier frequency of the radar system, Δf ₁ is the preset carrier frequency increment of the first transmitting subarray, and Δf ₂ is the preset carrier frequency of the second transmitting subarray. frequency increment.