阅读说明：本技术 多频带雷达融合成像方法、装置、设备及可读存储介质 (Multi-band radar fusion imaging method, device, equipment and readable storage medium ) 是由 吴宏林 赵淑珍 于 2019-11-20 设计创作，主要内容包括：本申请公开了一种多频带雷达融合成像方法、装置、设备及计算机可读存储介质。其中,方法包括获取已知频带的多部窄带雷达回波数据；根据两部雷达的回波数据进行融合初始化处理,并利用幅度相位估计方法得到未知频带回波数据的谱幅度和滤波器的初始估计值,基于已知频带的雷达回波数据和最小均方差准则,利用谱幅度和滤波器的初始估计值按照循环迭代方法以估计未知频带回波数据并优化滤波器；从而在已知窄带雷达回波情况下实现雷达目标回波数据的宽频带融合估计。本申请在目标先验知识未知且宽频带回波数据缺失场景中实现了多频带雷达融合成像,有效增强了雷达成像的距离分辨率。(The application discloses a multiband radar fusion imaging method, device and equipment and a computer readable storage medium. The method comprises the steps of obtaining multiple narrow-band radar echo data of known frequency bands; performing fusion initialization processing according to echo data of two radars, obtaining the spectral amplitude of the echo data of an unknown frequency band and the initial estimation value of a filter by using an amplitude phase estimation method, and estimating the echo data of the unknown frequency band and optimizing the filter by using the spectral amplitude and the initial estimation value of the filter according to a cyclic iteration method based on the radar echo data of a known frequency band and a minimum mean square error criterion; therefore, the broadband fusion estimation of the radar target echo data is realized under the condition of the known narrow-band radar echo. According to the method and the device, multi-band radar fusion imaging is realized in the scene that target priori knowledge is unknown and broadband echo data is lost, and the range resolution of radar imaging is effectively enhanced.)

1. A multi-band radar fusion imaging method, comprising:

acquiring radar echo data of a known frequency band, wherein the radar echo data of the known frequency band are a plurality of narrow-band radar echo data;

initializing radar echo data of an unknown frequency band, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band and an initial estimation value of a filter by using an amplitude phase estimation method;

estimating radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method by using the spectral amplitude and the initial estimated value of the filter based on the radar echo data of the known frequency band and a minimum mean square error criterion;

the filter is used for enabling signal frequency components in the radar echo data of the known frequency band to pass through without distortion, and enabling the similarity of the spectral contents of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band to be not lower than a preset threshold value.

2. The multiband radar fusion imaging method of claim 1, wherein the radar echo data of the unknown frequency band is estimated and the filter is optimized using the spectral magnitudes and the initial estimate of the filter according to a cyclic iterative method based on the radar echo data of the known frequency band and a minimum mean square error criterion as:

and estimating and obtaining the radar echo data of the unknown frequency band by using an optimized calculation relational expression, wherein the optimized calculation relational expression is as follows:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

3. The multiband radar fusion imaging method of claim 1, wherein the estimating radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method using the spectral magnitudes and an initial estimate of the filter based on the radar echo data of the known frequency band and a minimum mean square error criterion comprises:

s1031: calculating an estimated data of the radar echo data of the unknown frequency band based on a preset unknown data calculation relational expression by using the spectral amplitude and the initial estimated value of the filter;

s1032: filling the radar echo data of the unknown frequency band with the estimation data, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band filled with the estimation data and the secondary estimation value of a filter by using the amplitude phase estimation method;

s1033: and repeatedly executing S1031-S1032 until the amplitude phase estimation method is converged, and obtaining the final radar echo data of the unknown frequency band.

4. The multiband radar fusion imaging method of claim 3, wherein the unknown data calculation relationship is:

wherein R is_uFor the radar echo data of the unknown frequency band,

5. The multiband radar fusion imaging method according to claim 2, wherein the initializing of the radar echo data of the unknown frequency band is:

and performing zero filling processing on the radar echo data of the unknown frequency band to serve as an initial value of the radar echo data of the unknown frequency band.

6. The multiband radar fusion imaging method according to claim 5, wherein the obtaining of the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by the amplitude phase estimation method is:

calculating to obtain the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using an amplitude phase estimation relational expression, wherein the amplitude phase estimation relational expression is as follows:

wherein the content of the first and second substances,l＝01, …, L-1, L ═ N-M +1, N is the total number of discrete frequency samples, M is the length of the filter, K is an integer multiple of N, h (ω [. omega. ]), and_k) In order for the filter to be a so-called filter,is the output of the filter, ω_kFrequency, β (ω)_k) Is the spectral amplitude.

7. A multiband radar fusion imaging apparatus, comprising:

the known frequency band data acquisition module is used for acquiring radar echo data of a known frequency band, wherein the radar echo data of the known frequency band are a plurality of narrow-band radar echo data;

the unknown frequency band data calculation module is used for carrying out initialization processing on the radar echo data of an unknown frequency band and obtaining the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using an amplitude phase estimation method; estimating radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method by using the spectral amplitude and the initial estimated value of the filter based on the radar echo data of the known frequency band and a minimum mean square error criterion; the filter is used for enabling signal frequency components in the radar echo data of the known frequency band to pass through without distortion, and enabling the similarity of the spectral content of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band to be not lower than a preset threshold value.

8. The multiband radar fusion imaging apparatus according to claim 7, wherein the unknown frequency band data calculation module is specifically configured to estimate the radar echo data of the unknown frequency band by using an optimized calculation relationship, where the optimized calculation relationship is:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

9. A multiband radar fusion imaging apparatus comprising a processor for implementing the steps of the multiband radar fusion imaging method according to any one of claims 1 to 6 when executing a computer program stored in a memory.

10. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a multiband radar fusion imaging program, which when executed by a processor implements the steps of the multiband radar fusion imaging method according to any one of claims 1 to 6.

Technical Field

The present application relates to the field of image fusion technologies, and in particular, to a multiband radar fusion imaging method, apparatus, device, and computer-readable storage medium.

Background

The radar high-resolution range profile can provide rich geometric characteristics of targets and has important value for improving detection or classification performance. The distance resolution of single radar imaging is difficult to meet actual requirements due to the restriction of bandwidth and hardware cost, and the data fusion technology can synthesize radar echo data of different frequency bands to enhance the imaging distance resolution to obtain high-precision imaging.

Under multi-radar observation, signals are usually incoherent, and coherent matching of radar data of different view angles and different frequency bands can be realized through coherent processing. The coherent data is fused to obtain a frequency response with a larger bandwidth, and the distance resolution of imaging is effectively improved. The multiband radar data fusion method includes a Band Width Extrapolation (BWE) method and a spectrum estimation method. The BWE method uses a linear prediction model to realize observation interval extrapolation, without target prior knowledge, but under the condition of a wide missing band, the error is large, resulting in artifacts. The spectral estimation method tries to estimate parameters of signals through parametric modeling, and then utilizes the parameters to obtain position and amplitude information of a target, and the method has low side lobes, but the resolution depends on the accuracy of parameter estimation, and the number of scattering points of the target needs to be observed in advance, which is difficult to realize in practice.

Therefore, the imaging resolution ratio of the single radar is difficult to meet the actual requirement, and the existing fusion method is difficult to adapt to the multi-radar signal fusion processing with missing frequency band; how to realize multiband radar fusion imaging in a scene with unknown target priori knowledge and missing broadband is a problem to be solved by a person skilled in the art.

Disclosure of Invention

The application provides a multiband radar fusion imaging method, device and equipment and a computer readable storage medium, which realize multiband radar fusion imaging in a scene with unknown target priori knowledge and broadband missing, and effectively enhance the range resolution of radar imaging.

In order to solve the above technical problems, embodiments of the present invention provide the following technical solutions:

the embodiment of the invention provides a multiband radar fusion imaging method on one hand, which comprises the following steps:

acquiring radar echo data of a known frequency band, wherein the radar echo data of the known frequency band are a plurality of narrow-band radar echo data;

initializing radar echo data of an unknown frequency band, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band and an initial estimation value of a filter by using an amplitude phase estimation method;

estimating radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method by using the spectral amplitude and the initial estimated value of the filter based on the radar echo data of the known frequency band and a minimum mean square error criterion;

the filter is used for enabling signal frequency components in the radar echo data of the known frequency band to pass through without distortion, and enabling the similarity of the spectral contents of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band to be not lower than a preset threshold value.

Optionally, the estimating the radar echo data of the unknown frequency band and optimizing the filter based on the radar echo data of the known frequency band and the minimum mean square error criterion by using the spectral amplitude and the initial estimation value of the filter according to a loop iteration method are as follows:

and estimating and obtaining the radar echo data of the unknown frequency band by using an optimized calculation relational expression, wherein the optimized calculation relational expression is as follows:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

R_ufor radar echo data of said unknown frequency band, h (ω)_k) Is a vector of the filter in question,

is the output of the filter, ω_kIs the frequency, R_aFor the radar echo data of the known frequency band, β (ω)_k) And the spectrum amplitude is calculated, N is the total number of discrete frequency sampling points, M is the length of the filter, and K is an integral multiple value of N.

Optionally, the estimating the radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method by using the spectral amplitude and the initial estimation value of the filter based on the radar echo data of the known frequency band and the minimum mean square error criterion includes:

s1031: calculating an estimated data of the radar echo data of the unknown frequency band based on a preset unknown data calculation relational expression by using the spectral amplitude and the initial estimated value of the filter;

s1032: filling the radar echo data of the unknown frequency band with the estimation data, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band filled with the estimation data and the secondary estimation value of a filter by using the amplitude phase estimation method;

s1033: and repeatedly executing S1031-S1032 until the amplitude phase estimation method is converged, and obtaining the final radar echo data of the unknown frequency band.

Optionally, the unknown data calculation relationship is:

wherein R is_uFor the radar echo data of the unknown frequency band,

for the estimated filter, ω_kIs the frequency, R_aFor the radar echo data of the known frequency band,

for estimating the spectral amplitude, L is N-M +1, N is the total number of discrete frequency samples, M is the length of the filter, and K is NThe integer multiple value.

Optionally, the initializing the radar echo data of the unknown frequency band includes:

and performing zero filling processing on the radar echo data of the unknown frequency band to serve as an initial value of the radar echo data of the unknown frequency band.

Optionally, the obtaining of the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using the amplitude phase estimation method is as follows:

calculating to obtain the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using an amplitude phase estimation relational expression, wherein the amplitude phase estimation relational expression is as follows:

wherein the content of the first and second substances,

n is the total number of discrete frequency sampling points, M is the length of the filter, K is the integral multiple of N, h (omega)_k) In order for the filter to be a so-called filter,

is the output of the filter, ω_kFrequency, β (ω)_k) Is the spectral amplitude.

Another aspect of an embodiment of the present invention provides a multiband radar fusion imaging apparatus, including:

the known frequency band data acquisition module is used for acquiring radar echo data of a known frequency band, wherein the radar echo data of the known frequency band are a plurality of narrow-band radar echo data;

the unknown frequency band data calculation module is used for carrying out initialization processing on the radar echo data of an unknown frequency band and obtaining the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using an amplitude phase estimation method; estimating radar echo data of the unknown frequency band and optimizing the filter according to a loop iteration method by using the spectral amplitude and the initial estimated value of the filter based on the radar echo data of the known frequency band and a minimum mean square error criterion; the filter is used for enabling signal frequency components in the radar echo data of the known frequency band to pass through without distortion, and enabling the similarity of the spectral content of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band to be not lower than a preset threshold value.

Optionally, the unknown frequency band data calculation module is specifically configured to estimate and obtain radar echo data of the unknown frequency band by using an optimized calculation relation, where the optimized calculation relation is:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

R_ufor radar echo data of said unknown frequency band, h (ω)_k) Is a vector of the filter in question,

is the output of the filter, ω_kIs the frequency, R_aFor the radar echo data of the known frequency band, β (ω)_k) And the spectrum amplitude is calculated, N is the total number of discrete frequency sampling points, M is the length of the filter, and K is an integral multiple value of N.

An embodiment of the present invention further provides a multiband radar fusion imaging apparatus, including a processor, where the processor is configured to implement the steps of the multiband radar fusion imaging method according to any one of the foregoing embodiments when executing a computer program stored in a memory.

Finally, an embodiment of the present invention provides a computer-readable storage medium, on which a multiband radar fusion imaging program is stored, and when executed by a processor, the multiband radar fusion imaging program implements the steps of the multiband radar fusion imaging method according to any one of the foregoing embodiments.

The technical scheme provided by the application has the advantages that the middle unknown frequency band signal is obtained from the known frequency band data through the spectrum estimation of the self-adaptive filtering, so that the whole frequency band data is obtained, the method is suitable for any scene with missing frequency band bandwidth, the number of scattering points of a target does not need to be known, the fusion of multiband radar data is realized under the condition of no need of target priori knowledge, the distance resolution of radar imaging is enhanced, and the image similarity of fusion imaging and ideal full-frequency band imaging is improved.

In addition, the embodiment of the invention also provides a corresponding implementation device, equipment and a computer readable storage medium for the multiband radar fusion imaging method, so that the method has higher practicability, and the device, the equipment and the computer readable storage medium have corresponding advantages.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the related art, the drawings required to be used in the description of the embodiments or the related art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic flow chart of a multi-band radar fusion imaging method according to an embodiment of the present invention

Fig. 2 is a schematic frequency band diagram of an exemplary embodiment provided by an embodiment of the present invention;

fig. 3 is a schematic flowchart of an embodiment of S103 according to the present invention;

FIG. 4 is a schematic diagram of initial radar echo data provided by an embodiment of the present invention;

FIG. 5 is a diagram illustrating a radar echo imaging of a known frequency band 1 according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating a radar echo imaging of a known frequency band 2 according to an embodiment of the present invention;

fig. 7 is a schematic diagram of a multiband estimation result according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of an ideal full-band radar echo imaging provided by an embodiment of the present invention;

fig. 9 is a schematic diagram of a multiband fusion imaging result according to an embodiment of the present disclosure;

fig. 10 is a structural diagram of an embodiment of a multiband radar fusion imaging apparatus according to an embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "first," "second," "third," "fourth," and the like in the description and claims of this application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may include other steps or elements not expressly listed.

Having described the technical solutions of the embodiments of the present invention, various non-limiting embodiments of the present application are described in detail below.

Referring to fig. 1, fig. 1 is a schematic flow chart of a multiband radar fusion imaging method according to an embodiment of the present invention, where the embodiment of the present invention includes the following:

s101: radar echo data of a known frequency band is acquired.

In the present application, the radar echo data of the known frequency band may be narrowband radar echo data of a plurality of frequency bands, for example, 2 narrowband radar echo data shown in fig. 2, where frequency band 1 and frequency band 2 are two radars operating in different frequency bands, and there is an unknown frequency band data region between frequency band 1 and frequency band 2. If only echo data of a single radar is used for imaging an observation target, the range resolution is limited by the bandwidth of each frequency band radar. The multi-band radar fusion imaging can estimate the middle unknown frequency band data as accurately as possible through a fusion method on the basis of the known frequency band radar echo data, thereby achieving the purposes of widening the frequency band and improving the distance resolution.

S102: and initializing the radar echo data of the unknown frequency band, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter by using an amplitude phase estimation method.

The frequency value of the radar echo data of the unknown frequency band may be within a frequency band formed by the minimum frequency and the maximum frequency of the radar echo data of the known frequency band, as shown in fig. 2. It can be understood that when calculating the spectral amplitude and the filter of the radar echo data of the unknown frequency band using the amplitude phase estimation method, i.e., the APES method, a numerical value based on the radar echo data of the unknown frequency band is required. Therefore, the radar echo data of the unknown frequency band can be initialized, and for convenience of subsequent data processing, for example, zero padding processing can be performed on the radar echo data of the unknown frequency band to serve as an initial value of the radar echo data of the unknown frequency band. Of course, other initialization processes may be performed, which do not affect the implementation of the present application. The filter is used for enabling the signal frequency component in the radar echo data of the known frequency band to pass without distortion, and enabling the radar echo data of the unknown frequency band and the radar echo of the known frequency bandThe similarity of the spectral content of the data is not lower than a preset threshold, that is, the frequency in the data of the known frequency band is made to be omega_kCan pass through the filter without distortion while bringing the unknown data as close as possible to the spectral content of the known data. The higher the similarity of the spectral content of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band is, the higher the accuracy and the trueness of the radar echo data of the unknown frequency band estimated by using the technical scheme provided by the application are, and a proper threshold value can be selected according to an actual application scene, which is not limited by the application.

S103: and based on the radar echo data of the known frequency band and the minimum mean square error criterion, estimating the radar echo data of the unknown frequency band and optimizing the filter by using the spectral amplitude and the initial estimated value of the filter according to a loop iteration method.

In the present application, radar echo data of a known frequency band, for example, echo data of two frequency bands shown in fig. 2, may be used to estimate intermediate unknown frequency band data according to a loop iteration using a minimum mean square error criterion, and the obtained data characteristics of the unknown frequency band are made to approach the characteristics of the known frequency band as much as possible, that is, the radar echo data of the unknown frequency band and the radar echo data of the known frequency band have similar spectral contents.

In the technical scheme provided by the embodiment of the invention, the middle unknown frequency band signal is obtained from the known frequency band data through the spectrum estimation of the self-adaptive filtering, so that the whole frequency band data is obtained, the method is suitable for any scene with missing frequency band bandwidth, the number of scattering points of a target does not need to be known, the fusion of multiband radar data is realized under the condition of no need of target priori knowledge, the distance resolution of radar imaging is enhanced, and the image similarity of the fusion imaging and the ideal full-frequency band imaging is improved.

It is understood that for radar imaging, after the signal is demodulated, envelope-aligned and self-focused, the one-dimensional echo at a certain view angle can be represented as:

R(f)＝∫_xσ(x)·exp{-j4πfx/C}dx； (1)

where R (f) is the echo scattered field, σ is the scattering intensity, and x is the reference coordinate system distance. Discretizing the frequency to obtain a discrete form of the echo model as follows:

R(f_n)＝∫_xσ(x)·exp{-j4πf_nx/C}； (2)

in the formula (f)_n＝f₀+n·df，f₀Indicating the full band start frequency and df the frequency sampling interval. For scattered echo data, a full-band discrete echo signal composed of N discrete frequency sampling points isKnown echo data of, for example, band 1 and band 2 constitute the available data vector R in R_aI.e. R_aFor multiple pieces of radar echo data of known frequency bands, the data vector of the unknown frequency band is R_uI.e. R_uFor radar echo data of an unknown frequency band, the data of the unknown frequency band needs to be estimated through the technical scheme provided by the application. The technical scheme includes that a filter is designed to enable the frequency in the known frequency band radar echo data to be omega_kThe sinusoidal components of (a) can be passed through the filter without distortion while bringing the unknown data as close as possible to the spectral content of the known data. After the initialization processing is performed on the unknown band data, as an initial value, taking zero padding on the unknown band data as an initial value, the following specific processing steps of obtaining an estimated value of the unknown band data according to the loop iteration method may be as follows:

zero-filling is performed on the echo data of the unknown frequency band as an initial value, and the spectral amplitude and the initial value of the filter, i.e., { β (ω), are estimated by the amplitude phase estimation method_k)，h(ω_k)}. More specifically, let

A data vector representing an M × 1 dimensional forward sliding overlay, with length L equal to N-M +1, and M being the filter length. The output of the filter can be expressed as

The M-tap filter can be represented as h (ω)_k)＝[h₀(ω_k),h₁(ω_k),…,h_M-1(ω_k)]^TFirst estimate { β (ω) using radar echo data for a known band of available data_k),h(ω_k) An initial estimate of. The objective of the amplitude phase estimation method is to design a filter in the least-squares sense to output a sinusoidal signal as close as possible to the frequency of interest and constant amplitude, i.e. to solve the optimization problem of the following amplitude phase estimation relation, which can be expressed as:

s.t.h^H(ω_k)α(ω_k)＝1

wherein the content of the first and second substances,

h(ω_k) In order to be a filter, the filter is,

being the output of the filter, ω_kFrequency, β (ω)_k) Is the spectral amplitude. Definition of

Is composed ofNormalized fourier transform of (a):

order toThen the optimization problem of the amplitude phase estimation relation can be solved, that is, the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter obtained in S102 can be as follows:

after obtaining the spectral amplitude of the radar echo data of the unknown frequency band and the initial estimation value of the filter, the initial estimation value is used

To estimate the unknown data vector R_uThat is, the following least squares problem is solved:

if it is

The objective function of the least squares problem described above can be written in matrix form:

is defined by H (ω)_k) The resulting matrix A (ω)_k)_L×gAnd B (ω)_k)_L×(N-g)The following equation holds:

while if d (ω)_k)＝η(ω_k)-A(ω_k)R_αThen the objective function of the least squares problem can be written as:

the objective function pair R_uMinimization, one can obtain:

that is, the calculation relational expression 11 is used for an unknown data calculation relational expression as estimation data for calculating radar echo data of an unknown frequency band based on a spectral width and an initial estimation value of a filter, an estimation value of radar echo data of the unknown frequency band is obtained by the calculation relational expression, and the estimated value is estimatedFilling unknown frequency band data and re-estimating { β (omega)_k),h(ω_k) And repeating the steps until the algorithm converges. One embodiment of S103 can be shown in fig. 3:

s1031: calculating an estimation data of radar echo data of an unknown frequency band based on a preset unknown data calculation relational expression by using the spectral amplitude and the initial estimation value of the filter;

s1032: and filling the radar echo data of the unknown frequency band with the estimation data, and obtaining the spectral amplitude of the radar echo data of the unknown frequency band filled with the estimation data and the secondary estimation value of the filter by using an amplitude phase estimation method.

S1033: judging whether convergence is carried out, if not, repeatedly executing S1021-S1022 until the amplitude phase estimation method is converged to obtain the final radar echo data of the unknown frequency band; and if so, estimating the data as radar echo data of an unknown frequency band of the unknown frequency band.

Cyclically executing that is, after step S1032, the quadratic estimate is then reused by the minimization equation

Re-estimating echo data R of unknown frequency band_u. Echo data R of unknown frequency band obtained by using latest estimation_uFilling the radar echo data of unknown frequency band and re-estimating by amplitude phase estimation methodTo obtain { β (ω)_k)，h(ω_k)}. And sequentially and circularly executing until the algorithm converges.

Optionally, in the step S103, the radar echo data of the unknown frequency band is estimated by using an optimized calculation relation, where the optimized calculation relation is:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

R_ufor radar echo data of unknown frequency band, h (ω)_k) Is a vector of the filter and is,

being the output of the filter, ω_kIs the frequency, R_aFor radar echo data of a known frequency band, β (ω)_k) And the spectrum amplitude is N, the total number of discrete frequency sampling points, M is the length of the filter, and K is an integral multiple value of N.

That is, the step S103 can be decomposed into two steps, one of which is to obtain echo data R of an unknown frequency band with a least mean square criterion based on spectral magnitudes and a filter_uI.e. based on the calculation of relational expressions

Calculating echo data R of unknown frequency band_uThe two of which are according to R_uEstimation of spectral amplitude and filter of unknown frequency band by APES method, i.e. based on

The estimation results in { β (ω)_k)，h(ω_k)}. The fusion estimation of the unknown frequency band data is the solutionSolving the optimization problem of the relational expression 12, and calculating to obtain R_uNamely radar echo data of an unknown frequency band. Finally, multi-band fusion imaging can be performed by using the radar echo data of the known frequency band and the radar echo data of the unknown frequency band.

Finally, to prove the effectiveness of the solution provided by the present application, the present application also provides an illustrative example, which may include the following:

the ideal full-band radar data of a certain wave band has 96 sampling with equal interval frequency, and the sampling interval is 1 MHz. Suppose that two radars with a bandwidth of 32MHz simultaneously observe a target with three strong scattering points (50m, 98m and 102 m), the obtained echo data respectively constitute the first 32 frequency sampling points and the second 32 frequency sampling points of the full-band radar data, and the data with a bandwidth of 32MHz in the middle is unknown, as shown in fig. 4. The one-dimensional range images of the target obtained by pulse compressing the echo data of the frequency band 1 and the frequency band 2 are respectively shown as 5 and 6. The target has three strong scattering points, but the single radar imaging is limited by the bandwidth, and the imaging cannot distinguish two near strong scattering points of 98m and 102 m.

The technical scheme provided by the application is used for fusing the multiband radar data, and the result of fusion imaging is shown in fig. 7-9. Fig. 7 is a comparison between target real echo data and the result of fusion estimation in the present application (abbreviated as GAPES in the figure), and it can be seen that the present application can realize approximate estimation of RCS data with a larger bandwidth from a known frequency band; the one-dimensional distance image obtained by pulse compression of the full-band data obtained by fusion is shown in fig. 9, two adjacent scattering points near 100m can be clearly identified, the fusion imaging result is close to ideal full-band imaging, and the effectiveness of the technical scheme of the application is shown.

The embodiment of the invention also provides a corresponding implementation device for the multiband radar fusion imaging method, so that the method has higher practicability. The multiband radar fusion imaging device provided by the embodiment of the invention is described below, and the multiband radar fusion imaging device described below and the multiband radar fusion imaging method described above may be referred to correspondingly.

Referring to fig. 10, fig. 10 is a block diagram of a multi-band radar fusion imaging apparatus according to an embodiment of the present invention, in an implementation manner, where the apparatus may include:

a known frequency band data acquisition module 101, configured to acquire radar echo data of a known frequency band; the radar echo data of the known frequency band are multiple narrow-band radar echo data;

the unknown frequency band data calculation module 102 is configured to perform initialization processing on radar echo data of an unknown frequency band, and obtain a spectral amplitude of the radar echo data of the unknown frequency band and an initial estimation value of a filter by using an amplitude phase estimation method; based on the radar echo data of the known frequency band and the minimum mean square error criterion, estimating the radar echo data of the unknown frequency band and optimizing the filter by using the spectral amplitude and the initial estimation value of the filter according to a loop iteration method; the filter is used for enabling signal frequency components in the radar echo data of the known frequency band to pass through without distortion, and enabling the similarity of the spectral contents of the radar echo data of the unknown frequency band and the radar echo data of the known frequency band to be not lower than a preset threshold value.

Optionally, in a specific embodiment, the unknown frequency band data calculating module 102 is specifically configured to estimate radar echo data of an unknown frequency band by using an optimized calculation relation, where the optimized calculation relation is:

s.t.h^H(ω_k)α(ω_k)＝1，k＝1,2,…,K；

wherein the content of the first and second substances,

R_ufor radar echo data of unknown frequency band, h (ω)_k) Is a vector of the filter and is,

being the output of the filter, ω_kIs the frequency, R_aFor radar echo data of a known frequency band, β (ω)_k) Is the spectrum amplitude, N is the total number of discrete frequency sampling points, M is the length of the filter, and K is the integer multiple of N.

In some embodiments of this embodiment, the unknown frequency band data calculating module 102 may further include:

the initial data estimation submodule is used for calculating the estimation data of the radar echo data of the unknown frequency band based on a preset unknown data calculation relational expression by utilizing the spectral amplitude and the initial estimation value of the filter;

the parameter re-estimation submodule is used for filling the radar echo data of the unknown frequency band with the estimation data and obtaining the spectral amplitude of the radar echo data of the unknown frequency band filled with the estimation data and the secondary estimation value of the filter by using an amplitude phase estimation method;

and the cyclic iteration module is used for circularly executing all steps in the estimation data estimation submodule and the parameter re-estimation submodule until the amplitude phase estimation method converges to obtain the final radar echo data of the unknown frequency band.

In some embodiments of this embodiment, the initial data estimation submodule is specifically operable to utilize the spectral magnitudes and the initial estimate of the filter based on

Calculating to obtain estimation data of radar echo data of an unknown frequency band;

R_ufor radar echo data of an unknown frequency band,

for the estimated filter, ω_kIs the frequency, R_aFor radar echo data of a known frequency band,

to estimate the spectral amplitude, L is N-M +1, N is the total number of discrete frequency samples, M is the length of the filter, and K is an integer multiple of N。

The functions of the functional modules of the multiband radar fusion imaging device according to the embodiments of the present invention may be specifically implemented according to the method in the above method embodiments, and the specific implementation process may refer to the description related to the above method embodiments, which is not described herein again.

Therefore, the multi-band radar fusion imaging is realized in the situation that the target priori knowledge is unknown and the broadband is lost, and the range resolution of radar imaging is effectively enhanced.

The embodiment of the invention also provides a multiband radar fusion imaging device, which specifically comprises:

a memory for storing a computer program;

a processor for executing a computer program to implement the steps of the multi-band radar fusion imaging method according to any of the above embodiments.

The functions of the functional modules of the multiband radar fusion imaging device according to the embodiments of the present invention may be specifically implemented according to the method in the foregoing method embodiments, and the specific implementation process may refer to the related description of the foregoing method embodiments, which is not described herein again.

Therefore, the multi-band radar fusion imaging is realized in the situation that the target priori knowledge is unknown and the broadband is lost, and the range resolution of radar imaging is effectively enhanced.

The embodiment of the present invention further provides a computer-readable storage medium, which stores a multiband radar fusion imaging program, where the multiband radar fusion imaging program is executed by a processor, and the steps of the multiband radar fusion imaging method according to any one of the above embodiments are provided. The storage medium may be various media capable of storing program codes, such as a U disk, a removable hard disk, a read-only memory, a random access memory, a magnetic disk, or an optical disk.

The functions of the functional modules of the computer-readable storage medium according to the embodiment of the present invention may be specifically implemented according to the method in the foregoing method embodiment, and the specific implementation process may refer to the related description of the foregoing method embodiment, which is not described herein again.

Therefore, the multi-band radar fusion imaging is realized in the situation that the target priori knowledge is unknown and the broadband is lost, and the range resolution of radar imaging is effectively enhanced.

The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

A multi-band radar fusion imaging method, apparatus, device and computer readable storage medium provided by the present application are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present application.