CN109856682A - A kind of sparse imaging method and system of millimeter wave based on thinned array - Google Patents
A kind of sparse imaging method and system of millimeter wave based on thinned array Download PDFInfo
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Abstract
The present invention provides a kind of sparse imaging method and system of the millimeter wave based on thinned array, the first electromagnetic field data of array the described method includes: the original electromagnetic field data that thinned array is acquired is gathered according to the variation of the first equivalence principle, first equivalence principle includes the equivalence changes for keeping sparse frequency point constant；It is the second electromagnetic field data gathered on frequency point that the original electromagnetic field data is changed according to the second equivalence principle, and second equivalence principle includes under different frequent points based on the variation under the densely covered array；It is imaged according to first electromagnetic field data and the second electromagnetic field data using millimeter wave holographic imaging algorithm.The present invention can be improved the imaging definition of long-distance millimeter-wave imaging system.
Description
Technical field
The present invention relates to holographic imaging technical field, in particular to the sparse imaging side of a kind of millimeter wave based on thinned array
Method and a kind of sparse imaging system of millimeter wave based on thinned array.
Background technique
In recent years, international and domestic anti-terrorism situation is increasingly severe, and safety problem becomes society, various countries question of common concern, special
It is not to check that pressure is huge in the personnel safeties of important events, such as station, airport, harbour, various regions clearance bayonet, large stadium
Rally also all suffers from the personnel's safety check pressure for needing fast passing.
The safety check of conventional is all the safety check towards single cooperative target personage, mainly checks portable small object
Product, such as lighter, pocket knife, liquid, than it is more typical be exactly airport and railway station entrance safety check.It is transported by the practice of many years
Row, this kind of safety check is extremely important, effectively prevents the personal event generation for carrying dangerous goods and entering important place.
It takes metal detection, infrared ray, X-ray, artificial hand traditional safety check means such as to touch and does not adapt to new security situation
Requirement.Traditional metal detector can only detect short distance small range target；The various rays such as X-ray can be to tested person
Body causes ionising radiation to injure；Infrared ray be based on body surface temperature imaging, in the case where there is fabric to block can not clearly at
Picture.And millimeter wave safety check imaging system not only can detect that and hide metal object under fabric, can also detect that plastics pistol, ceramics
The nonmetallic dangerous material such as cutter, explosive can obtain visual safety check image.
In the millimeter wave safety check imaging system of the prior art, the active 3D hologram imaging of human body safety check is all in low coverage
From realization, image-forming range is no more than 1m.In the world, U.S. L-3, Smith company, Britain and Germany Rohde&Schwarz dominate
External millimeter wave safety check imager market represents the highest level of millimeter wave safety check imaging technique, but this three sections of imagers are all
It is the safety check imaging system in face of short distance cooperative target.Wherein, L3 mm-wave imaging instrument product imaging (as shown in Figure 1) is differentiated
For rate less than 1cm, sweep time is 2s or so, and maximum feature is rotary machine scanning, and imaging algorithm is based on densely covered
The holographic imaging algorithm of the back scattering of battle array, when tested object is static, image artifact minor lobe is low, and image quality is high.But
Maximum problem lies also in it and uses mechanical scanning, and being detected personage must be static, otherwise image blur.German RS millimeter wave safety check
Imaging system (as shown in Figure 2), using the sparse front structure of the all-electronin of non-scan, imaging algorithm basic principle
It is analogous to the holographic imaging algorithm based on back scattering of L3 company.Although its image scanning mode is the scanning of electronics front,
The scanning collection time is very short, and substantially in hundred millimeter magnitudes, but its algorithm used is mainly the echo phase of substantially static target
Position is used as operating basis, therefore when target slightly moves even normal walking, and target echo phase will change acutely, Yuan Youzhen
To the imaging algorithm of cooperative target will sharply decline at the resolution ratio of image, can not be imaged for noncooperative target.For L3
With the mm-wave imaging instrument of RS, bandwidth of operation is no more than 10GHz, therefore its fore-and-aft distance resolution ratio is no more than 1.5cm, in reality
Border is not in application, since longitudinal resolution is high, to can seriously affect image when tested passenger wears more than one piece clothes or thick clothes
Resolution ratio.The image-forming principle of the mm-wave imaging instrument of Smiths Detection company and rudimentary algorithm and both of the aforesaid company phase
Closely.
And can be carried out the passive imaging system being imaged at a distance all can only be at two-dimensional image, such as the Digital of Britain
Single steps target can be imaged in the remote human body imaging system of barriers TS4/TS5, use 0.25THz passive
Imaging, resolution ratio is greater than 5cm when remote, but due to imaging and passive imaging, for the acquisition of echo-signal only have amplitude information without
Phase information can not carry out three-dimensional imaging, can only be at the two-dimensional image of similar outline property；With above three sections of Active Imagings equipment phase
Than under same definition case, picture clarity is poor, is unfavorable for the image recognition in later period.Especially imaging needs indoors
There is auxiliary source irradiation, otherwise human body temperature and the temperature difference for carrying dangerous goods are little, cause institute very fuzzy at image.
Therefore for realizing high-resolution three-dimensional imaging at a distance, current imaging system is formed by the resolution of image
Rate and details are all far insufficient for application demand.Improving the image resolution ratio being imaged at a distance and rich image details has very greatly
Necessity.
Summary of the invention
The technical issues of technical solution of the present invention is solved are as follows: the imaging for how improving long-distance millimeter-wave imaging system is clear
Clear degree.
In order to solve the above-mentioned technical problem, it is sparse to provide a kind of millimeter wave based on thinned array for technical solution of the present invention
Imaging method, comprising:
By the original electromagnetic field data of thinned array acquisition according to the first electricity that the variation of the first equivalence principle is densely covered array
Magnetic field data, first equivalence principle include the equivalence changes for keeping sparse frequency point constant；
It is the second electromagnetic field data gathered on frequency point that the original electromagnetic field data is changed according to the second equivalence principle,
Second equivalence principle includes under different frequent points based on the variation under the densely covered array；
It is imaged according to first electromagnetic field data and the second electromagnetic field data using millimeter wave holographic imaging algorithm.
Optionally, the original electromagnetic field data by thinned array acquisition is battle array of gathering according to the variation of the first equivalence principle
Column the first electromagnetic field data include:
Using displaced phase center method, will be obtained in the original electromagnetic field data in the thinned array arbitrarily transmitting-receiving group
Electromagnetic field signal be equivalent to its and receive and dispatch the signal that obtains with position in transmitting-receiving array element alignment, to obtain the first electromagnetism number of fields
According to.
Optionally, the original electromagnetic field data by thinned array acquisition is battle array of gathering according to the variation of the first equivalence principle
First electromagnetic field data of column further include:
Before being changed to the original electromagnetic field data according to first equivalence principle, to the original electromagnetic field data
It is superimposed the first preset phase factor.
Optionally, the second original electromagnetic field data to be gathered according to the variation of the second equivalence principle on frequency point
Electromagnetic field data includes:
According to the sparse frequency point that the thinned array uses, echo reference signal is set；
Echo-signal in the original electromagnetic field data is sought cross-correlation with reference signal to estimate to obtain target range
It counts；
Bandpass filter is set to filter the echo-signal according to the Target Distance Estimation data；
Interpolation is carried out to the filtered echo-signal by Nonuniform fast Fourier transform；
By the echo-signal after interpolation multiplied by the preset second preset phase factor related with reference signal, to obtain
State the second electromagnetic field data.
Optionally, described to be calculated according to first electromagnetic field data and the second electromagnetic field data using millimeter wave holographic imaging
Method is imaged
Guarantee frequency to constant, based on first electromagnetic field data and the second electromagnetic field data at horizontal and vertical two
Orientation carries out two-dimensional space Fourier transformation to obtain transformation signal；
It converts in basis of signals multiplied by the third preset phase factor determined by wave number and image-forming range herein；
Above-mentioned transformation signal interpolation to equally spaced distance is handled into signal in wave number to be formed in frequency dimension；
Three-dimensional inverse Fourier transform is carried out to processing signal and obtains imaging results.
Optionally, first electromagnetic field data and the second electromagnetic field data include array spacings data and frequency point space-number
According to.
Optionally, the sparse imaging method of the millimeter wave further include:
Select the thinned array and sparse frequency point；
Echo is received according to the thinned array and sparse frequency point to form the original electromagnetic field data.
In order to solve the above-mentioned technical problem, it is dilute to additionally provide a kind of millimeter wave based on thinned array for technical solution of the present invention
Dredge imaging system, comprising:
First equivalent unit, the original electromagnetic field data suitable for acquiring thinned array are according to the variation of the first equivalence principle
First electromagnetic field data of densely covered array, first equivalence principle includes the equivalence changes for keeping sparse frequency point constant；
Second equivalent unit is suitable for the original electromagnetic field data according to the variation of the second equivalence principle on densely covered frequency point
The second electromagnetic field data, second equivalence principle includes under different frequent points based on the variation under the densely covered array；
Imaging unit is suitable for using millimeter wave holographic imaging according to first electromagnetic field data and the second electromagnetic field data
Algorithm imaging.
Optionally, first equivalent unit includes:
It is superimposed subelement, is suitable for before being changed to the original electromagnetic field data according to first equivalence principle, to institute
It states original electromagnetic field data and is superimposed the first preset phase factor；
Equivalent subelement, be suitable for use displaced phase center method, by the original electromagnetic field data in the Sparse Array
It arranges the electromagnetic field signal that any transmitting-receiving group obtains and is equivalent to its signal obtained in transmitting-receiving array element alignment transmitting-receiving with position, to obtain
First electromagnetic field data.
Optionally, second equivalent unit includes:
Subelement is set, suitable for the sparse frequency point used according to the thinned array, echo reference signal is set；
Related subelement, suitable for by the original electromagnetic field data echo-signal and reference signal ask cross-correlation to
Obtain Target Distance Estimation data；
Filtering subunit is believed suitable for bandpass filter is arranged according to the Target Distance Estimation data with filtering the echo
Number；
Subelement is converted, is suitable for carrying out interpolation to the filtered echo-signal by Nonuniform fast Fourier transform；
Algorithm subelement, suitable for by the echo-signal after interpolation multiplied by preset the second default phase related with reference signal
Location factor, to obtain second electromagnetic field data.
The beneficial effect of technical solution of the present invention at least that:
Technical solution of the present invention can be applied to long-distance millimeter-wave safety check imaging system, holographic with original short distance millimeter wave
Human body imaging system is similar, two and three dimensions imaging is realized using two-dimensional surface aperture, using based on target back scattering
(BP) non-focusing coherent wave different on two-dimensional surface aperture can be passed through digital focus principle by millimeter wave holographic imaging algorithm
It focuses on the imaging plane of some distance, is then calculated by space inversion, reflection and the scattering for recovering imaging region are special
Property distribution, obtain the relatively sharp millimeter wave hologram image of imaging region.The present invention can be to remote noncooperative target people
Object is imaged, image-forming range 1m-10m.Technical solution of the present invention can detect the explosion carried with noncooperative target personage
Object and controlled knife, specific imaging resolution can be reduced with image-forming range and be improved.Technical solution of the present invention may be implemented in
The restructural sparse imaging of remote high-resolution three-dimension.
Technical solution of the present invention can greatly reduce transceiver channels number under same scan aperture using thinned array
Amount reduces transceiver quantity than densely covered battle array when keeping identical theoretical resolution.Pass through theory reckoning and Electromagnetic Simulation, this hair
Bright technical solution is based on different sparse subarray configurations, to force down artifact minor lobe, reduces image blur, improves image resolution
Rate.Technical solution of the present invention uses compressive sensing theory, and introducing frequency point is sparse, its effect for being equivalent to densely covered frequency point by algorithm
Fruit, while realizing the long-distance millimeter-wave self adaptive imaging algorithm to target range dynamic self-adapting, it is final more clear to obtain
Clear imaging results.
Detailed description of the invention
Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other features of the invention,
Objects and advantages will become more apparent upon:
Fig. 1 is a kind of applicable cases schematic diagram of millimeter wave safety check imaging system in the prior art；
Fig. 2 is the applicable cases schematic diagram of another millimeter wave safety check imaging system in the prior art；
Fig. 3 is a kind of active MMW imaging safety check instrument structural schematic diagram for cooperative human body safety check；
Fig. 4 is a kind of three-dimensional densely covered battle array imaging system structural schematic diagram；
Fig. 5 is a kind of hologram three-dimensional imaging algorithm schematic diagram in technical solution of the present invention；
Fig. 6 is a kind of holographic imaging algorithm schematic diagram based on back scattering in technical solution of the present invention；
Fig. 7 is a kind of sparse front structural schematic diagram in technical solution of the present invention；
Fig. 8 is the sparse imaging method process signal of a kind of millimeter wave based on thinned array that technical solution of the present invention provides
Figure；
Fig. 9 is that another sparse imaging method process of millimeter wave based on thinned array that technical solution of the present invention provides is shown
It is intended to；
Figure 10 is that the sparse imaging system structure of a kind of millimeter wave based on thinned array that technical solution of the present invention provides is shown
It is intended to；
Figure 11 is another sparse imaging system structure of millimeter wave based on thinned array that technical solution of the present invention provides
Schematic diagram.
Specific embodiment
In order to preferably technical solution of the present invention be made clearly to show, the present invention is made into one with reference to the accompanying drawing
Walk explanation.
Millimeter wave safety check imaging system, i.e., the master of a kind of active MMW imaging safety check instrument for cooperative human body safety check
Structure is wanted as shown in figure 3, the system is combined using electronic array scanning with mechanical scanning, core is the millimeter of 2 × 80 array elements
Wave receives and dispatches imaging front linear array, and horizontal direction is scanned by imaging front linear array by switching, and vertical direction passes through
The vertical mechanical moving sweep of imaging front linear array all carries out multifrequency spot scan in conjunction with every row horizontal sweep, thus obtain at
As the space-frequency 3 D electromagnetic echo data of target area.From the point of view of imaging algorithm, which be can be regarded as shown in Figure 4
Three-dimensional gather battle array imaging system.
In conjunction with Fig. 4, it is assumed that target (" target ") is an individual goal (" target point "), one in the body target
A strong reflection spot coordinate is (x, y, z), the scanning for being covered with transceiver realized by electronic switch switching and vertical mechanical scanning
Plane (" scanned aperture ") is still located in z=Z1Plane on, the position of a transceiver on the plane of scanning motion
Set (" transceiver position ") be (x ', y ', Z1)。
When system work is in a wide frequency band rather than when a frequency point, for the reflection characteristic function f (x, y, z) of target
Carrying out integral can be obtained some transceiver in the reception response of frequency point ω=kc, and k is wave function.
By the rudimentary algorithm principle formula for converting the available system are as follows:
By algorithmic formula as it can be seen that active MMW safety check imaging needs to collect the echo complex signal of each scanning element, i.e.,
The amplitude and phase of echo can restore image scene image.
It applied to the active 3D hologram imaging of human body safety check is realized in short distance at present, image-forming range is no more than
1m.And can be carried out the passive imaging system being imaged at a distance all can only be at two-dimensional image, the resolution ratio and details of image are all remote insufficient
To meet application demand.Therefore high-resolution three-dimensional imaging is being realized at a distance, improve image resolution ratio and rich image is thin
Section has very big necessity.
Hologram three-dimensional imaging system depends on system bandwidth of operation in the image resolution ratio of depth dimension.In bandwidth of operation one
In the case where fixed, according to Nyquist's theorem, in order to guarantee not to be overlapped in depth dimension (Z axis of Fig. 5) image, system is in frequency domain
On sampling number need to meet formula (1) requirement.Therefore when image-forming range reaches 10m, the sampling number needed on frequency domain reaches
To 334, in the application of actual system, this frequency points is not to be able to satisfy system index, is mainly manifested in two aspects:
1) frequency points, which increase, can bring the elongated of imaging time, linear to insert because of the Fourier transformation in imaging algorithm
The duration that value etc. calculates step is strictly dependent on frequency points；
2) frequency points, which increase, will lead to becoming larger for data volume, this parameter restricts between imaging front and computer
Transmission medium.So based on the above issues, needing to look for and reducing frequency points but will not still bring imaging results aliasing
Method.
Since millimeter wave can not penetrate the characteristic of human skin, distance of the human body target in millimeter wave 3D hologram image
To presentation sparse characteristic.Three-dimensional echo data due to meeting nyquist sampling theorem has redundancy, in longitudinal dimension
Degree can also carry out high-resolution imaging by sparse frequency point data.In recent years, compressive sensing theory was widely used in radar
In imaging method, cardinal principle is signal in the case where meeting certain sparse characteristic, can be by being far below nyquist sampling rate
Data Exact Reconstruction original signal.Therefore in the technical solution of the present invention, it will focus on two of research based on compressive sensing theory
The millimeter wave remote three-dimensional imaging algorithm that the sparse and longitudinal dimension frequency-domain sparse of dimensional plane combines.
The sparse imaging method of the millimeter wave based on thinned array that technical solution of the present invention provides is, it can be achieved that remote millimeter
Wave safety check imaging, it is similar to original short distance millimeter wave holography human body imaging method, two peacekeepings are realized using two-dimensional surface aperture
Three-dimensional imaging, using based on target back scattering (BP) millimeter wave holographic imaging algorithm.Its basic physical significance is that two dimension is flat
Different non-focusing coherent waves, is focused on the imaging plane of some distance by digital focus principle, is then led on face diameter
Space inversion calculating is crossed, the reflection and scattering properties distribution of imaging region, i.e. the millimeter wave hologram image of imaging region are recovered.
As shown in Figure 6, it is assumed that target is a plane, in the plane being located at, be covered with the plane of scanning motion of transceiver then x/y plane on,
I.e. target is parallel with transceiver scans plane, and the two distance is a fixed value z0.
As shown in connection with fig. 6, the position of any of plane of scanning motion transceiver be (x ', y ', z0), the scattering point in target
(x,y,0).Then to the reflection characteristic function f (x, y) of target carry out integral can be obtained some transceiver reception response s (x ',
y’)
Wherein, wave constant k, k=w/c, w are work angular frequency, and c is the light velocity.It is a series of by resolving into spherical wave
Plane wave component, and formula (4) can be obtained after transformation.
According to shown in formula (4), as long as the receiver in acquisition scans aperture plane responds, can recover on specific range
Scattering properties distribution function, i.e., the two-dimentional millimeter-wave image on imaging plane.For sparse front as shown in Figure 7, tool
The rudimentary algorithm principle of body imaging is still similar to the holographic imaging of densely covered battle array, carries out X-Y scheme using based on back scattering algorithm
As restoring.
Wherein s (t, r) is the reception signal that some receiver corresponds to some transmitter.Using thinned array, same
Under the scan aperture of sample, transceiver channels quantity can be greatly reduced, i.e., reduced when keeping identical theoretical resolution than densely covered battle array
Transceiver quantity.It in the technical solution of the present invention, is exactly by theoretical reckoning and Electromagnetic Simulation, the different sparse submatrix knots of research
Structure reduces image blur to force down artifact minor lobe, improves image resolution ratio.The above are to remote non-cooperation personage mesh
Target two-dimensional imaging principle, due to the two-dimensional image of only one frequency point, its image information is few, and resolution ratio is poor, and three-dimensional image then can be more
The information of the tested personage of good reduction.But the frequency point number for needing to acquire when reaching high-resolution at three-dimensional image when remote
Very much, it is unfavorable for realizing fast imaging.And for conventional Sparse Array imaging, according to formula (4) when algorithm fixation is latter
As the target of some closer distance (Z0) can only be imaged, and cannot achieve and the target of dynamically changeable distance is carried out
Imaging.Therefore in the technical solution of the present invention, using compressive sensing theory, introducing frequency point is sparse, and by algorithm, it is equivalent to close
The effect of cloth frequency point, while realizing the long-distance millimeter-wave self adaptive imaging algorithm to target range dynamic self-adapting.
Based on the above principles, technical solution of the present invention provides a kind of sparse imaging side of the millimeter wave based on thinned array
Method, as shown in figure 8, including the following steps:
Step S100 changes the original electromagnetic field data of thinned array acquisition for the array that gathers according to the first equivalence principle
The first electromagnetic field data, first equivalence principle includes the equivalence changes for keeping sparse frequency point constant；
Step S101, the second electricity original electromagnetic field data to be gathered according to the variation of the second equivalence principle on frequency point
Magnetic field data, second equivalence principle include under different frequent points based on the variation under the densely covered array；
Step S102 uses millimeter wave holographic imaging algorithm according to first electromagnetic field data and the second electromagnetic field data
Imaging.
In above-mentioned steps process, the original electromagnetic field data of thinned array acquisition includes based on the dilute of thinned array acquisition
It dredges the electromagnetic field data (for executing step S100) of array and uses the electromagnetic field data of sparse frequency point based on thinned array
(for executing step S101).Thinned array is equivalent to the array that gathers by the first equivalence principle described in step S100, i.e., will
The electromagnetic field data that the electromagnetic field data of thinned array is equivalent to densely covered array (keeps frequency point constant, this time frequency point is when equivalent
Sparse)；Sparse frequency point is equivalent to the frequency point that gathers by the second equivalence principle described in step S102, i.e., by the electricity of sparse frequency point
Magnetic field data is equivalent to the electromagnetic field data gathered on frequency point (under different frequent points, data are all based on densely covered array).In step
In S102 can according to after equivalent array spacings and frequency point interval, be imaged using millimeter wave holographic imaging algorithm.
Specifically, the original electromagnetic field data by thinned array acquisition is according to the first equivalent original according to step S100
Then variation is that the first electromagnetic field data of densely covered array includes:
Using displaced phase center method, will be obtained in the original electromagnetic field data in the thinned array arbitrarily transmitting-receiving group
Electromagnetic field signal be equivalent to its and receive and dispatch the signal that obtains with position in transmitting-receiving array element alignment, to obtain the first electromagnetism number of fields
According to.
According to step S100, the original electromagnetic field data by thinned array acquisition is according to the variation of the first equivalence principle
First electromagnetic field data of densely covered array further include:
Before being changed to the original electromagnetic field data according to first equivalence principle, to the original electromagnetic field data
It is superimposed the first preset phase factor.
The original electromagnetic field data is gathered on frequency point according to the variation of the second equivalence principle according to step S101
The second electromagnetic field data include:
According to the sparse frequency point that the thinned array uses, echo reference signal is set；
Echo-signal in the original electromagnetic field data is sought cross-correlation with reference signal to estimate to obtain target range
It counts；
Bandpass filter is set to filter the echo-signal according to the Target Distance Estimation data；
Interpolation is carried out to the filtered echo-signal by Nonuniform fast Fourier transform；
By the echo-signal after interpolation multiplied by the preset second preset phase factor related with reference signal, to obtain
State the second electromagnetic field data.
It is described holographic using millimeter wave according to first electromagnetic field data and the second electromagnetic field data according to step S102
Imaging algorithm is imaged
Guarantee frequency to constant, based on first electromagnetic field data and the second electromagnetic field data at horizontal and vertical two
Orientation carries out two-dimensional space Fourier transformation to obtain transformation signal；
It converts in basis of signals multiplied by the third preset phase factor determined by wave number and image-forming range herein；
Above-mentioned transformation signal interpolation to equally spaced distance is handled into signal in wave number to be formed in frequency dimension；
Three-dimensional inverse Fourier transform is carried out to processing signal and obtains imaging results.
According to above-mentioned steps S100~S102, first electromagnetic field data and the second electromagnetic field data include array spacings
Data and frequency point interval data.In a kind of change case, first electromagnetic field data can be to be obtained based on step S100
Array spacings data, second electromagnetic field data can be the frequency point interval data obtained based on step S101.
In another change case of the present embodiment, a kind of sparse imaging method of millimeter wave based on thinned array, such as Fig. 9
It is shown, it can also include the following steps:
S200 selects the thinned array and sparse frequency point；
S201 receives echo according to the thinned array and sparse frequency point to form original electromagnetic field data；
S202 to S204 respectively corresponds the step process of S100 to S102.
Corresponding with above-mentioned steps process, it is sparse that technical solution of the present invention provides a kind of millimeter wave based on thinned array
Imaging system 1, comprising:
First equivalent unit 10, is adapted for carrying out step S100；
Second equivalent unit 11, is adapted for carrying out step S101；
Imaging unit 12 is adapted for carrying out step S102.
In a kind of example, the first equivalent unit 10 may include:
It is superimposed subelement, is suitable for before being changed to the original electromagnetic field data according to first equivalence principle, to institute
It states original electromagnetic field data and is superimposed the first preset phase factor；
Equivalent subelement, be suitable for use displaced phase center method, by the original electromagnetic field data in the Sparse Array
It arranges the electromagnetic field signal that any transmitting-receiving group obtains and is equivalent to its signal obtained in transmitting-receiving array element alignment transmitting-receiving with position, to obtain
First electromagnetic field data.
Second equivalent unit 11 may include:
Subelement is set, suitable for the sparse frequency point used according to the thinned array, echo reference signal is set；
Related subelement, suitable for by the original electromagnetic field data echo-signal and reference signal ask cross-correlation to
Obtain Target Distance Estimation data；
Filtering subunit is believed suitable for bandpass filter is arranged according to the Target Distance Estimation data with filtering the echo
Number；
Subelement is converted, is suitable for carrying out interpolation to the filtered echo-signal by Nonuniform fast Fourier transform；
Algorithm subelement, suitable for by the echo-signal after interpolation multiplied by preset the second default phase related with reference signal
Location factor, to obtain second electromagnetic field data.
Imaging unit 12 may include:
Interaction subelement is adapted to ensure that frequency to constant, is based on first electromagnetic field data and the second electromagnetic field data
Two-dimensional space Fourier transformation is carried out in horizontal and vertical two orientations to obtain transformation signal；
Multiplication subunit presets phase multiplied by the third determined by wave number and image-forming range in basis of signals suitable for converting herein
Location factor；
Difference subelement, be suitable in frequency dimension by above-mentioned transformation signal interpolation to equally spaced distance in wave number with shape
At processing signal；
Inversion subelement obtains imaging results suitable for carrying out three-dimensional inverse Fourier transform to processing signal.
Corresponding with above-mentioned steps process, it is dilute that technical solution of the present invention additionally provides a kind of millimeter wave based on thinned array
Dredge imaging system 2, comprising:
Selecting unit 20 is adapted for carrying out step S200；
Receiving unit 21 is adapted for carrying out step S201；
First equivalent unit 22, is adapted for carrying out step S202；
Second equivalent unit 23, is adapted for carrying out step S203；
Imaging unit 24 is adapted for carrying out step S204.
In relation to the first equivalent unit 22, the second equivalent unit 23, imaging unit 24 specific implementation result can refer to it is related
The description of first equivalent unit 10, the second equivalent unit 11, imaging unit 12.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow
Ring substantive content of the invention.
Claims (10)
1. a kind of sparse imaging method of millimeter wave based on thinned array characterized by comprising
The original electromagnetic field data of thinned array acquisition is changed according to the first equivalence principle as the first electromagnetic field of the array that gathers
Data, first equivalence principle include the equivalence changes for keeping sparse frequency point constant；
It is the second electromagnetic field data gathered on frequency point that the original electromagnetic field data is changed according to the second equivalence principle, described
Second equivalence principle includes under different frequent points based on the variation under the densely covered array；
It is imaged according to first electromagnetic field data and the second electromagnetic field data using millimeter wave holographic imaging algorithm.
2. the sparse imaging method of millimeter wave as described in claim 1, which is characterized in that described by the original of thinned array acquisition
Electromagnetic field data changes according to the first equivalence principle includes: for the first electromagnetic field data of the array that gathers
Using displaced phase center method, the electricity that will be obtained in the original electromagnetic field data in the thinned array arbitrarily transmitting-receiving group
Magnetic field signal is equivalent to it and receives and dispatches the signal obtained with position in transmitting-receiving array element alignment, to obtain first electromagnetic field data.
3. the sparse imaging method of millimeter wave as claimed in claim 2, which is characterized in that described by the original of thinned array acquisition
Electromagnetic field data is the first electromagnetic field data of densely covered array according to the variation of the first equivalence principle further include:
Before being changed to the original electromagnetic field data according to first equivalence principle, the original electromagnetic field data is superimposed
The first preset phase factor.
4. the sparse imaging method of millimeter wave as described in claim 1, which is characterized in that described by the original electromagnetic field data
Include: for the second electromagnetic field data on frequency point of gathering according to the variation of the second equivalence principle
According to the sparse frequency point that the thinned array uses, echo reference signal is set；
Echo-signal in the original electromagnetic field data is sought into cross-correlation with reference signal to obtain Target Distance Estimation number
According to；
Bandpass filter is set to filter the echo-signal according to the Target Distance Estimation data；
Interpolation is carried out to the filtered echo-signal by Nonuniform fast Fourier transform；
By the echo-signal after interpolation multiplied by the preset second preset phase factor related with reference signal, to obtain described
Two electromagnetic field datas.
5. the sparse imaging method of millimeter wave as described in claim 1, which is characterized in that described according to the first electromagnetism number of fields
According to and the second electromagnetic field data using millimeter wave holographic imaging algorithm imaging include:
Guarantee frequency to constant, based on first electromagnetic field data and the second electromagnetic field data in horizontal and vertical two orientation
To progress two-dimensional space Fourier transformation to obtain transformation signal；
It converts in basis of signals multiplied by the third preset phase factor determined by wave number and image-forming range herein；
Above-mentioned transformation signal interpolation to equally spaced distance is handled into signal in wave number to be formed in frequency dimension；
Three-dimensional inverse Fourier transform is carried out to processing signal and obtains imaging results.
6. the sparse imaging method of millimeter wave as described in claim 1 to 5, which is characterized in that first electromagnetic field data and
Second electromagnetic field data includes array spacings data and frequency point interval data.
7. the sparse imaging method of millimeter wave as described in claim 1, which is characterized in that further include:
Select the thinned array and sparse frequency point；
Echo is received according to the thinned array and sparse frequency point to form the original electromagnetic field data.
8. a kind of sparse imaging system of millimeter wave based on thinned array characterized by comprising
First equivalent unit, it is densely covered that the original electromagnetic field data suitable for acquiring thinned array changes according to the first equivalence principle
First electromagnetic field data of array, first equivalence principle include the equivalence changes for keeping sparse frequency point constant；
Second equivalent unit, suitable for the original electromagnetic field data is gathered according to the variation of the second equivalence principle on frequency point the
Two electromagnetic field datas, second equivalence principle include under different frequent points based on the variation under the densely covered array；
Imaging unit is suitable for using millimeter wave holographic imaging algorithm according to first electromagnetic field data and the second electromagnetic field data
Imaging.
9. the sparse imaging system of millimeter wave as claimed in claim 8, which is characterized in that first equivalent unit includes:
It is superimposed subelement, is suitable for before being changed to the original electromagnetic field data according to first equivalence principle, to the original
Beginning electromagnetic field data is superimposed the first preset phase factor；
Equivalent subelement is suitable for using displaced phase center method, will appoint in the original electromagnetic field data in the thinned array
The electromagnetic field signal that meaning transmitting-receiving group obtains is equivalent to it and receives and dispatches the signal obtained with position in transmitting-receiving array element alignment, described in obtaining
First electromagnetic field data.
10. the sparse imaging system of millimeter wave as claimed in claim 8, which is characterized in that second equivalent unit includes:
Subelement is set, suitable for the sparse frequency point used according to the thinned array, echo reference signal is set；
Related subelement, suitable for the echo-signal in the original electromagnetic field data is sought cross-correlation with reference signal to obtain
Target Distance Estimation data；
Filtering subunit, suitable for bandpass filter is arranged to filter the echo-signal according to the Target Distance Estimation data；
Subelement is converted, is suitable for carrying out interpolation to the filtered echo-signal by Nonuniform fast Fourier transform；
Algorithm subelement, suitable for by the echo-signal after interpolation multiplied by preset the second preset phase related with reference signal because
Son, to obtain second electromagnetic field data.
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