CN103163511B

CN103163511B - Stepped frequency signal phase compensation method for digital array radar

Info

Publication number: CN103163511B
Application number: CN201310071217.7A
Authority: CN
Inventors: 刘海波; 龙腾; 姜菡
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2013-03-06
Filing date: 2013-03-06
Publication date: 2014-08-20
Anticipated expiration: 2033-03-06
Also published as: CN103163511A

Abstract

The invention discloses a digital array radar frequency step signal phase compensation method, which belongs to the field of digital signal processing. The method includes the following steps: 1. Each channel of the digital array radar transmits a series of frequency step signal sub-pulses to obtain video echo signals; 2. For the video callback signals of each sub-pulses in the channel, select the maximum The phase is linearly fitted, and the phase value at the specified time is compensated, so that the deviation between the slope of the fitted line and the ideal slope is zero, and the video echo compensation factor is obtained, and the compensated signal is subjected to IFFT to output a high-resolution range image; 3. Compensation for each channel The phase of the peak point of the high-resolution range image makes the phase difference of the peak point of the range image of each channel at the same distance Consistent with the ideal phase difference, the range image compensation factor is obtained; Fourth, the obtained video echo compensation factor and range image compensation factor are applied to the signal processing process of the digital array radar. The invention is suitable for signal processing of digital array radar.

Description

A Phase Compensation Method for Digital Array Radar Frequency Stepping Signal

技术领域 technical field

本发明属于雷达信号处理技术领域，特别适用于调频步进雷达体制中的目标高精度距离及角度测量。 The invention belongs to the technical field of radar signal processing, and is particularly suitable for measuring the high-precision distance and angle of a target in a frequency modulation stepping radar system. the

背景技术 Background technique

调频步进信号是一种具有高分辨能力的雷达信号，它发射一组脉间载频线性跳变、脉内线性调频的雷达脉冲，通过对各个子脉冲回波进行脉内脉冲压缩和脉间逆傅立叶变换(IFFT)处理获得目标的距离高分辨像。调频步进信号用线性调频子脉冲代替了频率步进信号中的简单脉冲，因此克服了雷达作用距离和单脉冲距离分辨力之间的矛盾，又能够在保持距离分辨力不变的条件下减少脉冲数，提高数据率，降低对系统处理带宽和采样率的要求。 The frequency modulation step signal is a radar signal with high resolution capability. It transmits a group of radar pulses with inter-pulse carrier frequency linear jump and intra-pulse linear frequency modulation. By performing intra-pulse pulse compression and inter-pulse The inverse Fourier transform (IFFT) process obtains the range high-resolution image of the target. The frequency modulation step signal replaces the simple pulse in the frequency step signal with a linear frequency modulation sub-pulse, so it overcomes the contradiction between the radar range and the single pulse distance resolution, and can reduce the distance while keeping the distance resolution unchanged. Increase the number of pulses, increase the data rate, and reduce the requirements for system processing bandwidth and sampling rate. the

对于目前广泛应用的数字阵列雷达，其存在多个通道，若将调频步进信号运用于数字阵列雷达，则不仅每个通道内相位均会导致调频步进信号各频点相位非线性的情况，而且存在多个通道间相位误差特性不一致的情况。 For the digital array radar widely used at present, there are multiple channels. If the FM step signal is applied to the digital array radar, not only the phase in each channel will lead to nonlinearity of the phase of each frequency point of the FM step signal, Moreover, there are situations where phase error characteristics among multiple channels are not consistent. the

由于通道内频点相位非线性会带来一维距离像主瓣展宽、幅度下降等问题，进而导致目标的一维距离像失真。而通道间相位误差特性不一致则会造成合成方向图波束指向偏移，旁瓣升高，影响测角质量。 Due to the phase nonlinearity of the frequency point in the channel, the main lobe broadening and amplitude drop of the one-dimensional range image will be caused, which will lead to the distortion of the one-dimensional range image of the target. The inconsistency of the phase error characteristics between channels will cause the beam pointing deviation of the synthetic pattern, the side lobe will increase, and the angle measurement quality will be affected. the

为了解决这个问题，就必须选择合适的时间点进行相位补偿，现有的针对频率步进信号的相位补偿技术仅仅针对单通道的情况进行线性相位校正，但并没有考虑到数字阵列雷达在多通道的情况下存在校正后其各通道线性特征曲线斜率不一致对测角带来误差。 In order to solve this problem, it is necessary to select the appropriate time point for phase compensation. The existing phase compensation technology for frequency step signal only performs linear phase correction for single channel, but it does not take into account the digital array radar in multi-channel In the case of correction, the slopes of the linear characteristic curves of each channel are inconsistent, which will bring errors to the angle measurement. the

发明内容 Contents of the invention

有鉴于此，本发明提供了一种数字阵列雷达频率步进信号相位补偿方法，能够在数字阵列雷达应用中，消除通道间的相位误差给调频步进信号带来的影响，从而提高测距和测角精度。 In view of this, the present invention provides a digital array radar frequency step signal phase compensation method, which can eliminate the influence of the phase error between channels on the frequency modulation step signal in the application of digital array radar, thereby improving the ranging and angle measurement accuracy. the

为达到上述目的，本发明的技术方案为：该方法包括如下步骤： In order to achieve the above object, the technical solution of the present invention is: the method may further comprise the steps:

第一步、数字阵列雷达具有多个通道，每个通道由1个天线阵元和1路接收机组成；每个通道发射一串频率步进信号子脉冲，并接收各子脉冲的目标回波信号；对目标回波信号进行处理，获得各子脉冲的视频回波信号； The first step, the digital array radar has multiple channels, each channel is composed of an antenna element and a receiver; each channel transmits a series of frequency step signal sub-pulses, and receives the target echo of each sub-pulse signal; process the target echo signal to obtain the video echo signal of each sub-pulse;

第二步、获得每个通道的视频回波补偿因子，具体为： The second step is to obtain the video echo compensation factor of each channel, specifically:

针对每个通道，在该通道中，每个子脉冲的视频回波信号的各采样点中选取一个对应相位最大值的点作为该子脉冲的相位采样点，对于每个子脉冲的相位采样点及其对应相位值进行线性拟合得到当前通道的相位拟合直线； For each channel, in this channel, select a point corresponding to the maximum value of the phase in each sampling point of the video echo signal of each sub-pulse as the phase sampling point of the sub-pulse, for the phase sampling point of each sub-pulse and its Perform linear fitting on the corresponding phase value to obtain the phase fitting straight line of the current channel;

选取一个通道的相位拟合直线的斜率作为标准值，调整各通道相位拟合直线的斜率与标准值一致； Select the slope of the phase fitting line of a channel as the standard value, and adjust the slope of the phase fitting line of each channel to be consistent with the standard value;

对于每个通道，在调整后的相位拟合直线中，获取相位采样点对应的值，并在调整前的相位拟合直线中，同样获取相位采样点对应的值，二者之差作为该通道的视频回波补偿因子，对该通道视频回波信号的相位采样点使用该补偿因子进行补偿，补偿后的信号进行逆傅里叶变换IFFT输出高分辨距离像； For each channel, in the adjusted phase fitting straight line, obtain the value corresponding to the phase sampling point, and in the phase fitting straight line before adjustment, also obtain the corresponding value of the phase sampling point, and the difference between the two is used as the channel The compensation factor of the video echo is used to compensate the phase sampling point of the channel video echo signal, and the compensated signal is subjected to inverse Fourier transform IFFT to output a high-resolution range image;

第三步、获得每个通道的距离像补偿因子，具体为： The third step is to obtain the range image compensation factor of each channel, specifically:

对经第二步补偿后的各通道高分辨距离像，取峰值点的相位进行补偿，补偿值由各通道高分辨距离像在相同距离上的峰值点的相位差与理想相位差之间的差值确定，补偿后与理想相位差之间的差值为0，记录对应数字阵列雷达的多个通道的一组补偿值，即为距离像补偿因子； For the high-resolution range image of each channel after the second step of compensation, the phase of the peak point is taken for compensation, and the compensation value is determined by the phase difference of the peak point of the high-resolution range image of each channel at the same distance The difference between the ideal phase difference is determined, after compensation The difference between the ideal phase difference and the ideal phase difference is 0, and a set of compensation values corresponding to multiple channels of the digital array radar is recorded, which is the range image compensation factor;

第四步、在数字阵列雷达的信号处理过程中，在获得视频回波信号之后，使用所述视频回波补偿因子对视频回波信号各采样点的相位进行补偿；对补偿后的视频回波信号进行IFFT，获得高分辨距离像，使用所述距离像补偿因子对各通道高分辨距离像峰值点的相位进行补偿。 The fourth step, in the signal processing process of the digital array radar, after obtaining the video echo signal, use the video echo compensation factor to compensate the phase of each sampling point of the video echo signal; The signal is subjected to IFFT to obtain a high-resolution range image, and the phase of the peak point of the high-resolution range image of each channel is compensated by using the range image compensation factor. the

进一步地，第一步中，通道发射的信号为一串线性调频Chirp子脉冲。 Further, in the first step, the signal transmitted by the channel is a series of chirp sub-pulses. the

有益效果： Beneficial effect:

利用本发明所述补偿步骤得到补偿因子，不仅能够对线性调频步进回波信号进行合成高分辨前的通道内相位误差补偿，而且对合成高分辨像进行通道间相位误差补偿，理论上可形成目标的无展宽、主瓣幅度无下降的真实的一维高分辨距离像；解决了由于通道内相位误差及通道间相位误差带来的对测距及测角的影响，尤其适用于调频步进体制雷达对角度的高精度测量。 Using the compensation step of the present invention to obtain the compensation factor can not only compensate the phase error in the channel before the high-resolution synthesis of the linear frequency modulation step echo signal, but also perform inter-channel phase error compensation on the high-resolution synthesis image, which can theoretically form The true one-dimensional high-resolution range image with no broadening of the target and no decline in the amplitude of the main lobe; solves the impact on ranging and angle measurement due to phase errors within and between channels, especially suitable for FM stepping High-precision measurement of angles by institutional radar. the

附图说明 Description of drawings

图1是本发明在工程上实际实施的信号处理流程图； Fig. 1 is the signal processing flowchart that the present invention actually implements in engineering;

图2是补偿前后的各通道高分辨距离像对比图； Figure 2 is a comparison diagram of the high-resolution range image of each channel before and after compensation;

图3是补偿前后的合成方向图对比图。 Figure 3 is a comparison diagram of the synthetic direction map before and after compensation. the

具体实施方式 Detailed ways

下面结合附图并举实施例，对本发明进行详细描述。 The present invention will be described in detail below with reference to the accompanying drawings and examples. the

如图1所示，本方法包括如下步骤： As shown in Figure 1, this method includes the following steps:

第一步、数字阵列雷达具有多个通道，每个通道由1个天线阵元和1路接收机组成；每个通道发射一串频率步进信号子脉冲，并接收各子脉冲的目标回波信号；对目标回波信号进行处理，获得各子脉冲的视频回波信号。其中对目标回波信号所进行的处理包括信号的采样。 The first step, the digital array radar has multiple channels, each channel is composed of an antenna element and a receiver; each channel transmits a series of frequency step signal sub-pulses, and receives the target echo of each sub-pulse signal; the target echo signal is processed to obtain the video echo signal of each sub-pulse. The processing of the target echo signal includes signal sampling. the

本实施例中以线性调频Chirp子脉冲串为例进行叙述，则第一步具体包括如下步骤： In this embodiment, the Chirp sub-pulse train is used as an example to narrate, then the first step specifically includes the following steps:

步骤101，假设数字阵列雷达具有M个通道，每个通道由1个天线阵元和1路接收机组成，对于通道m，其天线阵元Z_m的发射信号为一串频率步进信号子脉冲，1≤m≤M。 Step 101, assuming that the digital array radar has M channels, each channel is composed of one antenna element and one receiver, for channel m, the transmitted signal of its antenna element Z _m is a series of frequency stepping signal sub-pulses , 1≤m≤M.

本实施例中所采用的频率步进信号为线性调频Chirp子脉冲串，该Chirp子脉冲串进行载频线性跳变，对其进行采样处理后获得线性调频Chirp子脉冲的一般数学模型，Chirp子脉冲表示为下式： The frequency stepping signal adopted in this embodiment is chirp sub-pulse train, and the chirp sub-pulse train undergoes carrier frequency linear hopping, and the general mathematical model of chirp sub-pulse is obtained after sampling processing. Chirp sub-pulse The pulse is expressed as the following formula:

$x x ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} rect rect ((\frac{t t - - {iT i}_{r r}}{{T T}_{p p}})) exp exp {{j j [[22 π π (({f f}_{00} + + iΔf iΔf)) t t + + πK πK {((t t - - {iT i}_{r r}))}^{22}]]}},, - - - - - - ((11))$

t∈(0，NT_r) t ∈ (0, NT _r )

其中，T_p为子脉冲宽度，T_r为脉冲重复周期，f₀为每个子脉冲的载频分量，Δf为脉间载频增量，f₀+iΔf为第i+1个子脉冲的载频的中心频率，i取值为0、1、2...N-1，N为脉组内子脉冲个数，K为子脉冲的调频斜率。 Among them, T _p is the sub-pulse width, T _r is the pulse repetition period, f ₀ is the carrier frequency component of each sub-pulse, Δf is the inter-pulse carrier frequency increment, f ₀ +iΔf is the carrier frequency of the i+1th sub-pulse The center frequency of i, the value of i is 0, 1, 2...N-1, N is the number of sub-pulses in the pulse group, and K is the frequency modulation slope of the sub-pulses.

步骤102，发射信号经目标反射后，天线阵元Z_m对应天线接收机J_m接收到目标回波信号为频率步进子脉冲延时τ_m(t)的信号。 Step 102, after the transmitted signal is reflected by the target, the antenna array element Z _m corresponding to the antenna receiver J _m receives the target echo signal as a signal with a frequency step sub-pulse delay τ _m (t).

本实施例中，目标回波信号Chirp子脉冲延时τ_m(t)的信号，表示为： In this embodiment, the signal of the target echo signal Chirp sub-pulse delay τ _m (t) is expressed as:

${x x}_{m m} ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} rect rect ((\frac{t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))}{{T T}_{p p}}))$

$exp exp {{j j 22 π π [[(({f f}_{00} + + iΔf iΔf)) ((t t - - {τ τ}_{m m} ((t t)))) + + \frac{11}{22} K K {((t t - - {τ τ}_{m m} ((t t)) - - {iT i}_{r r}))}^{22}]]}},, - - - - - - ((22))$

t∈(0，NT_r) t ∈ (0, NT _r )

其中τ_m(t)＝2R/c-(m-1)dsinθ/c，c为光速，R为目标与天线阵元Z_m的距离，θ为目标与通道法线之间的夹角，d为各相邻天线阵元之间的距离，其中与2R/c相比，(m-1)dsinθ/c量级较小可以忽略。 Where τ _m (t) = 2R/c-(m-1)dsinθ/c, c is the speed of light, R is the distance between the target and the antenna element Z _m , θ is the angle between the target and the channel normal, d is the distance between adjacent antenna elements, and compared with 2R/c, (m-1)dsinθ/c is small in magnitude and can be ignored.

步骤103，将通道m的目标回波信号和相参本振信号进行混频处理，获得视频回波。在本实施例中，所使用的相参本振信号为： Step 103, performing frequency mixing processing on the target echo signal of channel m and the coherent local oscillator signal to obtain video echo. In this embodiment, the coherent local oscillator signal used is:

$y the y ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} rect rect ((\frac{t t - - {iT i}_{r r}}{{T T}_{r r}})) exp exp {{j j 22 π π (({f f}_{00} + + iΔf iΔf)) \cdot \cdot t t]]}},, - - - - - - ((33))$

t∈(0，NT_r) t ∈ (0, NT _r )

将式(2)与相参本振信号进行混频得到的视频回波为： The video echo obtained by mixing the formula (2) with the coherent local oscillator signal is:

${x x}_{m m}^{' '} ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} rect rect ((\frac{t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))}{{T T}_{p p}})) \cdot \cdot exp exp {{j j 22 π π [[- - (({f f}_{00} + + iΔf iΔf)) {τ τ}_{m m} ((t t)) + + \frac{11}{22} K K {((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))}^{22}]]}},, - - - - - - ((44))$

t∈(0，NT_r) t ∈ (0, NT _r )

由于通道内相位误差，各脉冲最大值点的相位变化不是理想的线性直线，而是在直线上下波动。φ_i为各脉冲相位与理想值的差值。则式(4)变为： Due to the phase error in the channel, the phase change of each pulse maximum point is not an ideal linear straight line, but fluctuates up and down the straight line. φ _i is the difference between each pulse phase and the ideal value. Then formula (4) becomes:

${s the s}_{m m} ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} rect rect [[\frac{t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))}{{T T}_{p p}}]] \cdot &Center Dot; exp exp ((jπK jπK {((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))}^{22})) - - - - - - ((55))$

$\cdot &Center Dot; exp exp ((- - j j 22 π π {f f}_{00} {τ τ}_{m m} ((t t)))) \cdot \cdot exp exp ((- - j j 22 πiΔ πiΔ {fτ fτ}_{m m} ((t t)))) \cdot \cdot exp exp (({- - jφ jφ}_{i i}))$

对于频率步进信号的简单脉冲，所获的视频回波信号可以直接应用于以后各步骤，而本实施例中的频率步进信号为线性调频Chirp子脉冲串，则需要对视频回波信号进行脉冲压缩。 For the simple pulse of the frequency step signal, the video echo signal obtained can be directly applied to each step in the future, and the frequency step signal in the present embodiment is a chirp sub-pulse train of chirp, then the video echo signal needs to be processed pulse compression. the

其中脉冲压缩是基于匹配滤波理论，是对线性调频信号的一种处理形式，当子脉冲线性调频信号为： Among them, pulse compression is based on matched filter theory, which is a form of processing for chirp signals. When the sub-pulse chirp signal is:

$rect rect | | \frac{t t}{{T T}_{p p}} | | exp exp (({jπKt jπKt}^{22})) - - - - - - ((66))$

其脉冲压缩的输出结果应为： The output result of its pulse compression should be:

$rect rect | | \frac{t t}{{T T}_{p p}} | | \sqrt{{KT KT}_{p p}^{22}} \frac{sin sin (({πKT πKT}_{p p} t t))}{{πKT πKT}_{p p} t t} exp exp ((- - j j {πKt πKt}^{22})) exp exp ((jπ jπ / / 44)) - - - - - - ((77))$

则本实施例中对式(5)进行脉冲压缩后得到： Then in the present embodiment, formula (5) is obtained after pulse compression:

${s the s}_{m m}^{' '} ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} \sqrt{{KT KT}_{P P}} \cdot &Center Dot; rect rect ((\frac{t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))}{{T T}_{p p}})) \cdot \cdot \frac{sin sin {πKT πKT}_{p p} ((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))}{{πKT πKT}_{p p} ((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))} - - - - - - ((88))$

$\cdot \cdot exp exp ((jπ jπ / / 44)) exp exp {{- - jπK jπK ((t t - - {iT i}_{r r} - - {τ τ}_{m m} {((t t))}^{22}}} \cdot &Center Dot; exp exp {{- - j j 22 π π (({f f}_{00} + + iΔf iΔf)) {τ τ}_{m m} ((t t))}} \cdot \cdot exp exp (({- - jφ jφ}_{i i}))$

针对每个通道，在该通道中，每个子脉冲的视频回波信号的各采样点中选取一个对应相位最大值的点作为该子脉冲的相位采样点，对于每个子脉冲的相位采样点及其对应相位值进行线性拟合得到当前通道的相位拟合直线； For each channel, in this channel, a point corresponding to the maximum value of the phase is selected from each sampling point of the video echo signal of each sub-pulse as the phase sampling point of the sub-pulse, for the phase sampling point of each sub-pulse and its Perform linear fitting on the corresponding phase value to obtain the phase fitting straight line of the current channel;

对于每个通道，在调整后的相位拟合直线中，获取相位采样点对应的值，并在调整前的相位拟合直线中，同样获取相位采样点对应的值，二者之差作为该通道的视频回波补偿因子，对该通道视频回波信号的每个采样点均使用该补偿因子进行补偿，补偿后的信号进行逆傅里叶变换IFFT输出高分辨距离像。 For each channel, in the adjusted phase fitting straight line, obtain the value corresponding to the phase sampling point, and in the phase fitting straight line before adjustment, also obtain the corresponding value of the phase sampling point, and the difference between the two is used as the channel Each sampling point of the video echo signal of the channel is compensated by the compensation factor of the video echo, and the compensated signal is subjected to inverse Fourier transform IFFT to output a high-resolution range image. the

本实施例中第二步具体包括如下步骤 In this embodiment, the second step specifically includes the following steps

步骤201，对于通道m，在每个子脉冲的视频回波信号的所有的采样时刻点中，选取对应相位最大值的点作为该脉冲的相位采样点，由于子脉冲个数为N，则通道m具有N个相位采样点，将N个相位采样点及其对应相位值进行线性拟合得到通道m的相位拟合直线。本实施例中由于使用Chirp子脉冲进行处理，则取脉冲压缩后的视频回波信号的最大值点的相位，对其进行线性拟合。 Step 201, for channel m, in all sampling time points of the video echo signal of each sub-pulse, select the point corresponding to the phase maximum value as the phase sampling point of the pulse, since the number of sub-pulses is N, then channel m There are N phase sampling points, and linear fitting is performed on the N phase sampling points and their corresponding phase values to obtain a phase fitting straight line of channel m. In this embodiment, since Chirp sub-pulses are used for processing, the phase of the maximum value point of the pulse-compressed video echo signal is taken, and linear fitting is performed on it. the

此时则消除了单通道内通道相位误差造成的频点相位非线性。 At this time, the frequency-point phase nonlinearity caused by channel phase error within a single channel is eliminated. the

本实施例中，由式(8)可知，理想的线性相位直线应当是以2πΔfτ_m(t)为斜率，以i为变量的，而因为φ_i的引入，导致相位在理想直线上下波动，因此拟合后的斜率会存在与理想的线性相位直线的偏差，假设对于通道m，得到的各脉冲进行脉冲压缩后最大值点拟合相位直线可表示为： In this embodiment, it can be seen from formula (8) that the ideal linear phase line should have a slope of 2πΔfτ _m (t) and i as a variable, and because of the introduction of φ _i , the phase fluctuates up and down on the ideal line, so The fitted slope will deviate from the ideal linear phase line. Assuming that for channel m, the fitted phase line at the maximum point after each pulse is pulse compressed can be expressed as:

Φ_m为各脉冲进行脉冲压缩后最大值点相位，k_m为拟合相位直线的斜率，b_m 为拟合相位直线的截距，β_m为通道m的斜率与理想斜率值之差。 Φ _m is the phase of the maximum point after pulse compression for each pulse, km is the slope of the fitted phase line, b _m is the intercept of the fitted phase line, _{and β m} _is the difference between the slope of channel m and the ideal slope value.

由于式(8)中因偏差exp(-jφ_i)的引入，拟合后的线性相位直线的斜率为2πΔf(τ_m(t)+β_m)，式(8)变为： Due to the introduction of the deviation exp(-jφ _i ) in formula (8), the slope of the fitted linear phase line is 2πΔf(τ _m (t)+β _m ), and formula (8) becomes:

${s the s}_{m m}^{' '} ((t t)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} \sqrt{{KT KT}_{P P}} \cdot \cdot rect rect ((\frac{t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))}{{T T}_{p p}})) \cdot &Center Dot; \frac{sin sin π π {KT KT}_{p p} ((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))}{{πKT πKT}_{p p} ((t t - - {iT i}_{r r} - - {τ τ}_{m m} ((t t))))} - - - - - - ((1010))$

$\cdot \cdot exp exp ((jπ jπ / / 44)) exp exp {{- - jπK jπK ((t t - - {iT i}_{r r} - - {τ τ}_{m m} {((t t))}^{22}}} \cdot &Center Dot; exp exp {{- - j j 22 π π (({f f}_{00} + + iΔf iΔf)) [[{τ τ}_{m m} ((t t)) + + {β β}_{m m}]]}}$

步骤202，本实施例使用Chirp子脉冲，则取脉冲压缩后的视频回波信号即式(10)进行处理。 In step 202, this embodiment uses Chirp sub-pulses, and the pulse-compressed video echo signal, namely Equation (10), is used for processing. the

本实施例经计算验证，为获取脉冲回波信号最大值点相位，应选取时刻为t＝iT_r+τ_m(t)，由此可得采样后第i个脉冲的回波输出为： This embodiment has been verified by calculation. In order to obtain the phase of the maximum point of the pulse echo signal, the time t=iT _r +τ _m (t) should be selected, so that the echo output of the i-th pulse after sampling can be obtained as:

${s the s}_{c c}^{' '} ((i i)) = = \sqrt{{KT KT}_{p p}^{22}} \cdot \cdot exp exp ((jπ jπ / / 44)) \cdot \cdot exp exp [[- - j j 22 π π (({f f}_{00} + + iΔf iΔf)) (({τ τ}_{m m} ((t t)) + + {β β}_{m m}))]] - - - - - - ((1111))$

令各通道相位拟合直线的斜率偏差β_m＝0得到： Let the slope deviation β _m of each channel phase fitting line = 0 to get:

${s the s}_{c c}^{' '} ((i i)) = = \sqrt{{KT KT}_{p p}^{22}} \cdot \cdot exp exp ((jπ jπ / / 44)) \cdot &Center Dot; exp exp [[- - j j 22 π π (({f f}_{00} + + iΔf iΔf)) {τ τ}_{m m} ((t t))]] - - - - - - ((1212))$

则β₁～β_m作为视频回波补偿因子。上式(12)即为补偿之后t时刻第i个脉冲的视频回波信号，对上式进行IFFT输出高分辨距离像为： Then β ₁ ~ β _m are used as video echo compensation factors. The above formula (12) is the video echo signal of the i-th pulse at time t after compensation, and IFFT is performed on the above formula to output a high-resolution range image as:

${| | y the y ((l l)) | |}_{m m} = = \sqrt{{KT KT}_{p p}^{22}} \cdot &Center Dot; exp exp ((- - jπ jπ / / 44)) \cdot \cdot exp exp ((- - j j 22 {πf πf}_{00} \cdot \cdot {τ τ}_{m m} ((t t)))) \cdot \cdot | | \frac{sin sin π π ((l l - - NΔf NΔf \cdot \cdot ((22 R R / / c c))))}{N N sin sin \frac{π π}{N N} ((l l - - NΔf NΔf \cdot \cdot ((22 R R / / c c))))} | | - - - - - - ((1313))$

其中l＝0、1、......、N-1。 where l=0, 1, . . . , N-1. the

对于每个通道均进行上述步骤的补偿并进行IFFT获得各通道的高分辨距离像。 For each channel, the compensation of the above steps is performed and IFFT is performed to obtain a high-resolution range image of each channel. the

若各通道相位直线斜率不同，则所对应的距离不同，而在合成天线方向图过程中，需要相同距离点上提取相位信息，因此各通道相位直线斜率若不一致会对合成天线方向图造成困难。调整相位拟合直线斜率一致之后，则消除了引入合成高分辨像的误差，从而消除了合成方向图的误差，能够提高测角精度。 If the slopes of the phase lines of each channel are different, the corresponding distances are different. In the process of synthesizing the antenna pattern, phase information needs to be extracted at the same distance points. Therefore, if the slopes of the phase lines of each channel are inconsistent, it will cause difficulties in synthesizing the antenna pattern. After adjusting the slope of the phase fitting line to be consistent, the error introduced into the synthetic high-resolution image is eliminated, thereby eliminating the error of the synthetic direction map and improving the accuracy of angle measurement. the

可以看出，第二步共进行了两处相位补偿，一处是步骤201中针对通道中各脉冲视频回波信号的最大值点相位进行拟合得线性直线，此处消除了单通道内通道相位误差造成的频点相位非线性；另一处是步骤202中，调整各通道相位拟合直线的斜率一致，并对通道中视频回波信号的每个采样点均进行补偿，此处消除了各通道相位直线斜率不一致对合成天线方向图造成的影响。 It can be seen that in the second step, a total of two phase compensations are carried out, one is a linear straight line fitted in step 201 to the phase of the maximum point of each pulse video echo signal in the channel, and the channel within a single channel is eliminated here. The frequency point phase nonlinearity caused by the phase error; the other is that in step 202, the slope of the phase fitting line of each channel is adjusted to be consistent, and each sampling point of the video echo signal in the channel is compensated. Here, the The influence of the inconsistency of the slopes of the phase lines of each channel on the synthetic antenna pattern. the

对经第二步补偿后的各通道高分辨距离像，取峰值点的相位进行补偿，补偿值由各通道高分辨距离像在相同距离上的峰值点的相位差与理想相位差之间的差值确定，补偿后与理想相位差之间的差值为0，记录对应数字阵列雷达的多个通道的一组补偿值，即为距离像补偿因子。 For the high-resolution range image of each channel after the second step of compensation, the phase of the peak point is taken for compensation, and the compensation value is determined by the phase difference of the peak point of the high-resolution range image of each channel at the same distance The difference between the ideal phase difference is determined, after compensation The difference between the ideal phase difference and the ideal phase difference is 0, and a set of compensation values corresponding to multiple channels of the digital array radar is recorded, which is the range image compensation factor.

本实施例中，对于数字阵列雷达，各相邻通道之间理想相位差为： In this embodiment, for the digital array radar, the ideal phase difference between adjacent channels is:

λ为波长。 λ is the wavelength. the

实际在频率步进数字阵列雷达中，由于通道间特性不一致，即各通道相位误差不同，会对后续测角及合成方向图造成影响。若各通道间特性不一致，每个通道引入相位误差α_m，则有 In fact, in the frequency stepping digital array radar, due to the inconsistency of channel characteristics, that is, the phase error of each channel is different, it will affect the subsequent angle measurement and synthetic pattern. If the characteristics of each channel are inconsistent, and each channel introduces a phase error α _m , then there is

$| | {y the y}_{cm cm} ((l l)) | | = = \sqrt{{KT KT}_{p p}^{22}} \cdot \cdot exp exp ((- - jπ jπ / / 44)) \cdot \cdot exp exp ((- - j j 22 {πf πf}_{00} \cdot &Center Dot; {τ τ}_{m m} ((t t))))$

$\cdot &Center Dot; | | \frac{sin sin π π ((l l - - NΔf NΔf \cdot &Center Dot; 22 R R / / c c))}{N N sin sin \frac{π π}{N N} ((l l - - NΔf NΔf \cdot &Center Dot; 22 R R / / c c))} | | \cdot &Center Dot; exp exp (({jα jα}_{m m})) - - - - - - ((1515))$

在本步骤进行时，可将标校物体放在法线方向，则各通道回波的理想相位差为0，根据第一步～第三步获取补偿后的高分辨距离像，对峰值点的相位进行补偿，使各通道之间的相位差Δφ为0，获取此时补偿因子。则使用该补偿因子对于通道间的不一致性可以进行较好的补偿。 During this step, the calibration object can be placed in the normal direction, then the ideal phase difference of the echoes of each channel is 0, according to the first to third steps to obtain the compensated high-resolution range image, the phase of the peak point is compensated, so that the phase difference Δφ between each channel is 0, and the compensation factor at this time is obtained. Then, the inconsistency between channels can be better compensated by using the compensation factor.

可以看出，第三步进行了一次补偿，能够很好地消除通道间的不一致性，因此使用本方法可以对频率步进信号进行三次补偿，则通道内及通道间的相位误差均得到了较好的补偿。 It can be seen that in the third step, one compensation is performed, which can well eliminate the inconsistency between channels. Therefore, this method can be used to compensate the frequency step signal three times, and the phase errors within and between channels are relatively reduced. good compensation. the

第四步、在数字阵列雷达的信号处理过程中，在获得视频回波信号之后，使用所述视频回波补偿因子对视频回波信号的相位进行补偿；对补偿后的视频回波信号进行傅里叶逆变换IFFT获得各通道的高分辨距离像之后，使用所述距离像补偿因子对各通道高分辨距离像峰值点的相位进行补偿。 In the fourth step, in the signal processing process of the digital array radar, after the video echo signal is obtained, the video echo compensation factor is used to compensate the phase of the video echo signal; After the high-resolution range image of each channel is obtained by IFFT, the phase of the peak point of the high-resolution range image of each channel is compensated by using the range image compensation factor. the

本实施例采用4通道数字阵列雷达，共有4个天线阵元。4个天线阵元对应4路接收机，目标在法线方向约50m处。如图2所示为补偿前后的各通道高分辨距离像对比图，如图3是补偿前后的合成方向图对比图，通过图2和图3对实测数据成像处理结果进行比对，可以发现实测数据处理结果显示补偿后的高分辨成像结果及测角结果远远高于未补偿时的结果。其原因是本发明技术方案中，通道内及通道间的相位误差得到了较好的补偿。 In this embodiment, a 4-channel digital array radar is used, and there are 4 antenna elements in total. 4 antenna elements correspond to 4 receivers, and the target is about 50m away from the normal direction. Figure 2 shows the comparison of high-resolution range images of each channel before and after compensation, and Figure 3 shows the comparison of synthetic direction maps before and after compensation. By comparing the imaging processing results of the measured data with Figure 3, it can be found The data processing results show that the high-resolution imaging results and angle measurement results after compensation are much higher than those without compensation. The reason is that in the technical solution of the present invention, phase errors within and between channels are better compensated. the

下面结合附图和实施例，对本发明技术方案做进一步解释。 The technical solutions of the present invention will be further explained below in conjunction with the accompanying drawings and embodiments. the

综上所述，以上仅为本发明的较佳实施例而已，并非用于限定本发明的保护范围。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。 To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims

1. a digital array radar frequency step signal phase compensation method, is characterized in that, comprises the steps:

The first step, the digital array radar has multiple channels, each channel is composed of an antenna element and a receiver; each channel transmits a series of frequency step signal sub-pulses, and receives the target echo of each sub-pulse signal; the target echo signal is processed to obtain the video echo signal of each sub-pulse;

The processing of the target echo signal specifically includes signal sampling and performing frequency mixing processing on the target echo signal and coherent local oscillator signal of each channel to obtain the video echo of each sub-pulse;

The second step is to obtain the video echo compensation factor of each channel, specifically:

For each channel, in this channel, select a point corresponding to the maximum value of the phase in each sampling point of the video echo signal of each sub-pulse as the phase sampling point of the sub-pulse, for the phase sampling point of each sub-pulse and its Perform linear fitting on the corresponding phase value to obtain the phase fitting straight line of the current channel;

Select the slope of the phase fitting line of a channel as the standard value, and adjust the slope of the phase fitting line of each channel to be consistent with the standard value;

For each channel, in the adjusted phase fitting straight line, obtain the value corresponding to the phase sampling point, and in the phase fitting straight line before adjustment, also obtain the corresponding value of the phase sampling point, and the difference between the two is used as the channel The compensation factor of the video echo is used to compensate the phase sampling point of the channel video echo signal, and the compensated signal is subjected to inverse Fourier transform IFFT to output a high-resolution range image;

The third step is to obtain the range image compensation factor of each channel, specifically:

For the high-resolution range image of each channel after the second step of compensation, the phase of the peak point is taken for compensation, and the compensation value is determined by the phase difference of the peak point of the high-resolution range image of each channel at the same distance The difference between the ideal phase difference is determined, after compensation The difference between the ideal phase difference and the ideal phase difference is 0, and a set of compensation values corresponding to multiple channels of the digital array radar is recorded, which is the range image compensation factor;

The fourth step, in the signal processing process of the digital array radar, after obtaining the video echo signal, use the video echo compensation factor to compensate the phase of each sampling point of the video echo signal; The signal is subjected to IFFT to obtain a high-resolution range image, and the phase of the peak point of the high-resolution range image of each channel is compensated by using the range image compensation factor.

2. a kind of digital array radar frequency stepping signal phase compensation method as claimed in claim 1, is characterized in that, in the first step, the signal that channel transmits is a series of linear frequency modulation Chirp sub-pulses, then in the first step After the target echo signal is processed to obtain the video echo signal, pulse compression is further performed on the video echo signal for the second step.