CN111505629B - Terahertz security inspection imaging system and method - Google Patents

Terahertz security inspection imaging system and method Download PDF

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CN111505629B
CN111505629B CN202010380622.7A CN202010380622A CN111505629B CN 111505629 B CN111505629 B CN 111505629B CN 202010380622 A CN202010380622 A CN 202010380622A CN 111505629 B CN111505629 B CN 111505629B
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terahertz
antenna
target
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data processing
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CN111505629A (en
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董晓
杨青山
张云华
张德海
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National Space Science Center of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/887—Radar or analogous systems specially adapted for specific applications for detection of concealed objects, e.g. contraband or weapons
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G01S13/9056—Scan SAR mode
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G01S13/9082—Rotating SAR [ROSAR]

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Abstract

The invention discloses a terahertz security inspection imaging system and a method thereof, wherein the system comprises: the terahertz transmitter-receiver comprises a rotating platform capable of vertically moving up and down, a motor, a terahertz transceiver channel and a data processing module arranged on an upper computer; the motor controls the horizontal rotation and the vertical movement of the rotary platform; the terahertz transceiving channel is arranged at the edge part of the rotary platform and can realize spiral scanning in the movement of the rotary platform; the terahertz transceiving channel is used for transmitting signals outwards, acquiring echo signals reflected by a target and sending the echo signals to the data processing module; and the data processing module is used for processing the echo signal and outputting a two-dimensional display image. The antenna of the system of the invention realizes omnidirectional observation by rotating and scanning, images a target in a range of 360 degrees, and can simultaneously carry out security inspection on a plurality of people.

Description

Terahertz security inspection imaging system and method
Technical Field
The invention relates to the technical field of radar systems and signal processing, in particular to a terahertz security inspection imaging system and method.
Background
The terahertz radar has the advantages of high imaging resolution, small size, light weight, strong penetrating power and no harm to a human body, and active terahertz imaging can effectively image the human body, discover forbidden articles and avoid invading privacy. The current security imaging system can be divided into a scanning type and a two-dimensional array type. A scanning type Imaging system realizes high resolution by a terahertz frequency band quasi-optical focusing mode, and simultaneously carries out point-by-point Imaging on a human body by two-dimensional mechanical scanning (document [1 ]: G.Timms, M.Brothers, J.Bunton, J.Archer, G.Rosolen, Y.Li, et al, 'Design and testing of an active 190-GHz millimeter-wave image, and' Journal of Electronic Imaging, vol.19, p.043019, 2010.); another scanning Imaging system is to perform a circular scan on a human body and perform three-dimensional Imaging by using a circular synthetic aperture radar (document [2 ]: d.mcmackin, d.sheen, t.hall, m.kennedy, and h.focus, "Biometric identification using a holographic radar Imaging technique," vol.6538: SPIE,2007.) a two-dimensional array Imaging system arranges a large number of array elements on a two-dimensional plane, and performs high-resolution three-dimensional Imaging by using an array to synthesize a narrow beam and combining large-bandwidth ranging (document [3 ]: s.ahmed, a.schiessl, f.gumbmann, m.tiout ebb, s.mathfe, and l.schmidt, "Advanced Microwave Imaging," IEEE Microwave magic, vol.13, pp.).
The scanning imaging mode depends on a mechanical scanning structure, is limited by the acceleration and deceleration processes of mechanical movement, and generally has difficulty in realizing high-speed scanning. To reduce the time for mechanical scanning, the number of antenna elements needs to be increased, which increases the complexity and cost of the system. The two-dimensional array mode is fast, but the number of array elements is large, the consistency of a plurality of receiving and transmitting channels is difficult to ensure, and the complex structure increases the system cost. The circular scanning method combines a real aperture method and a mechanical scanning method, a plurality of array elements are arranged in a vertical dimension, and the azimuth direction improves the resolution through the circular synthetic aperture imaging, and the method is successfully applied at present (document [4 ]: D.McMakin, D.Sheen, T.Hall, J.Tedeschi, and A.M.Jones, "New improvements to millimeter-wave body scanners," Proceedings of 3DBODY.TECH, 2017.). However, circular scanning requires surrounding a person in a circular scanning area, the range of action is limited, only one person can be detected at a time, and if a plurality of persons need to be imaged simultaneously, a new imaging mode needs to be sought.
Disclosure of Invention
The invention aims to solve the problem that a terahertz security inspection system simultaneously images a plurality of people, and provides a rotary type scanning terahertz security inspection imaging system.
In order to achieve the above object, embodiment 1 of the present invention provides a terahertz security inspection imaging system, including: the terahertz transmitter-receiver comprises a rotating platform capable of vertically moving up and down, a motor, a terahertz transceiver channel and a data processing module arranged on an upper computer;
the motor controls the horizontal rotation and the vertical movement of the rotary platform; the terahertz transceiving channel is arranged at the edge part of the rotary platform and can realize spiral scanning in the movement of the rotary platform;
the terahertz transceiving channel is used for transmitting signals outwards, acquiring echo signals reflected by a target and sending the echo signals to the data processing module;
and the data processing module is used for processing the echo signal and outputting a two-dimensional display image.
As an improvement of the above system, the terahertz transceiving channel is arranged on the rotary platform; the motor comprises a rotary control motor and a vertical motion control motor; the rotation control motor is used for controlling the rotating platform to rotate at a constant speed at a rotating speed omega; and the vertical motion control motor is used for controlling the rotating platform to move up and down at a vertical speed v.
As an improvement of the above system, the taihe z transceiving channels are one or more groups; the multiple sets of Taihe Z transceiving channels are fixed into a whole from top to bottom.
As an improvement of the above system, a set of terahertz transceiving channels includes: the terahertz antenna comprises a terahertz antenna, a transmitter and a plurality of receivers; the terahertz antenna is positioned at the edge of the rotating platform;
a transmitter for generating a transmission signal of a terahertz frequency band;
the terahertz antenna is used for transmitting the transmitted electromagnetic waves; receiving echo signals reflected by the target;
and the receiver is used for collecting echo signals reflected by the target and received by the terahertz antenna and then sending the echo signals to the data processing module.
As an improvement of the above system, the specific implementation process of the data processing module is as follows:
the echo signal reflected by the target is subjected to pulse compression to obtain distance direction compression data sr(ta,tr)：
Figure BDA0002481921990000021
Wherein t isrFor fast time within a single radar pulse, taSlow time formed for transmitting multiple radar pulses, p (x)P,yP,zP) To be located at (x)P,yP,zP) Scattering coefficient of target, B is transmission signal bandwidth, fcIs the carrier frequency, c is the speed of light, RP(ta) Distance of target from antenna:
Figure BDA0002481921990000031
(xa(ta),ya(ta),za(ta) Is t)aThree-dimensional coordinates of the antenna phase center at time:
Figure BDA0002481921990000032
wherein, omega is the horizontal rotating speed of the rotating platform; r is the radius of the antenna phase center from the center of the circle of the rotary platform; v is the vertical linear motion speed of the rotary platform;
dividing a target area into three-dimensional discrete pixel points (x)i,yi,zi) The target center position is (x)i0,yi0,zi0) For each pixel point, calculate (x)i,yi,zi) To the antenna (x)a(ta),ya(ta),za(ta) A distance delay t ofri：
Figure BDA0002481921990000033
Then to sr(ta,tr) Interpolation is carried out to find the corresponding triData s ofr(ta,tri) And compensate for the phase generated by the antenna motion:
Figure BDA0002481921990000034
wherein t isr0Is the target center position (x)i0,yi0,zi0) To the antenna (x)a(ta),ya(ta),za(ta) Distance delay of);
finally, for all taSuperposition
Figure BDA0002481921990000035
Obtaining a three-dimensional image value I (x)i,yi,zi)：
Figure BDA0002481921990000036
To I (x)i,yi,zi) The maximum value is taken along the radar sight line direction as a two-dimensional display image.
The embodiment 2 of the invention provides a terahertz security inspection imaging method, which is realized based on the imaging system and comprises the following steps:
the rotating platform rotates at a constant speed in a horizontal plane at a rotating speed omega under the control of a motor and reciprocates up and down at a vertical speed v;
the transmitter generates a transmitting signal and transmits the transmitting signal out through the terahertz antenna, the receiver receives an echo signal reflected by a target, and the echo signal is sent to the data processing module;
and the data processing module processes the echo signal and outputs a two-dimensional display image.
As an improvement of the above method, the data processing module processes the echo signal and outputs a two-dimensional display image; the method specifically comprises the following steps:
the echo signal reflected by the target is subjected to pulse compression to obtain distance direction compression data sr(ta,tr)：
Figure BDA0002481921990000041
Wherein t isrFor the fast time of distance, ρ (x)P,yP,zP) To be located at (x)P,yP,zP) Scattering coefficient of target, B is transmission signal bandwidth, fcIs the carrier frequency, c is the speed of light, RP(ta) Distance of target from antenna:
Figure BDA0002481921990000042
(xa(ta),ya(ta),za(ta) Is t)aThree-dimensional coordinates of the antenna phase center at time:
Figure BDA0002481921990000043
wherein, omega is the horizontal rotating speed of the rotating platform; v is the vertical linear motion speed of the rotary platform; r is the radius of the antenna phase center from the center of the rotating platform circle
Dividing a target area into three-dimensional discrete pixel points (x)i,yi,zi) The target center position is (x)i0,yi0,zi0) For each pixel point, calculate (x)i,yi,zi) To the antenna (x)a(ta),ya(ta),za(ta) A distance delay t ofri：
Figure BDA0002481921990000044
Then to sr(ta,tr) Interpolation is carried out to find the corresponding triData s ofr(ta,tri) And compensate for the phase generated by the antenna motion:
Figure BDA0002481921990000045
wherein t isr0Is the target center position (x)i0,yi0,zi0) To the antenna (x)a(ta),ya(ta),za(ta) Distance delay of);
finally, for all taSuperposition
Figure BDA0002481921990000046
Obtaining a three-dimensional image value I (x)i,yi,zi)：
Figure BDA0002481921990000047
To I (x)i,yi,zi) The maximum value is taken along the radar sight line direction as a two-dimensional display image.
The invention has the advantages that:
1. the system of the invention obtains target information through two-dimensional scanning while reducing the number of channels, and then realizes high-resolution imaging of the target through an aperture synthesis technology;
2. the system accelerates the whole calculation process through GPU parallel calculation, and rapidly splices and fuses the images of a plurality of groups of receiving and transmitting channels to obtain the image of the whole target;
3. the antenna of the system of the invention realizes omnidirectional observation by rotating and scanning, images a target in a range of 360 degrees, and can simultaneously carry out security inspection on a plurality of people.
Drawings
FIG. 1 is a schematic structural diagram of a terahertz security inspection imaging system of the present invention;
FIG. 2 is an imaging geometry map for point target simulation according to the present invention;
FIG. 3 is a simulation result of imaging a point target according to the present invention;
FIG. 4 is an optical image of an object viewed directly in front of the present invention;
FIG. 5 is a radar image of an observed target directly in front of the present invention;
FIG. 6 is a radar image of an observed target directly behind the present invention.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
The invention discloses a terahertz security inspection imaging system and method; the imaging system comprises N groups (N is more than or equal to 1) of terahertz transceiving channels; each group of terahertz transceiving channels comprises a transmitting channel and M (M is more than or equal to 2) receiving channels; the N groups of terahertz transceiving channels transmit electromagnetic waves to a target and receive echo signals reflected by the target; the N groups of terahertz receiving and transmitting channels are subjected to circumferential mechanical scanning in the horizontal direction and linear mechanical scanning in the vertical direction, namely spiral scanning is integrally formed, so that complete information acquisition is carried out on a target; the imaging method comprises the steps that a circular rotation mode is adopted in a horizontal plane, a linear motion mode is adopted in a vertical direction, spiral scanning is integrally formed, and the resolution ratio superior to the centimeter level is obtained through synthetic aperture imaging; and the target three-dimensional imaging is realized by combining large-bandwidth ranging. The system of the invention has low number of array elements and controllable system cost; through the rotation type to emitting signal all around, can realize the formation of image to many people simultaneously to the application range is big, can be used to human safety inspection closely, also can be used to formation of image monitoring on a large scale.
Example 1
As shown in fig. 1, the present invention provides a terahertz security inspection imaging system, which adopts a synthetic aperture imaging mode in two dimensions, combines circumferential scanning and vertical motion, that is, forms helical scanning, forms a synthetic aperture by using the motion of an antenna, and the antenna is covered by a wide beam, so that the volume and weight of the antenna are reduced, and meanwhile, the wide beam can obtain a large doppler bandwidth, and a high azimuth resolution is obtained after the synthetic aperture processing.
The imaging system includes: the terahertz wave transmission and receiving device comprises a rotating platform capable of vertically moving up and down, a motor, a terahertz wave transmission and receiving channel and a data processing module arranged on an upper computer; the terahertz transceiving channel is arranged at the edge part of the rotary platform, and can realize spiral scanning in the movement of the rotary platform.
The terahertz transceiving channel is arranged on the rotating platform, and the radius of the antenna phase center from the circle center is r; the motor comprises a rotation control motor and a vertical motion control motor; the rotation control motor is used for controlling the rotating platform to rotate at a constant speed at a rotating speed omega; the vertical motion control motor is used for controlling the rotary platform to do periodic up-and-down reciprocating motion at the vertical speed v.
The terahertz receiving and dispatching channel comprises: the system comprises a terahertz antenna, a transmitter and M receivers (M is more than or equal to 2); the terahertz antenna is positioned at the edge of the rotating platform, and other components are positioned at the center of the rotating platform; the terahertz transceiving channel performs circumferential mechanical scanning in the horizontal direction and linear mechanical scanning in the vertical direction, namely integrally forms spiral scanning to acquire complete information of a target;
the Taihe Z transceiving channels can be a group, and also can be vertically provided with a plurality of groups for covering a larger height range, and the plurality of groups of Taihe Z transceiving channels are fixed into a whole from top to bottom and then are arranged on the edge part of the rotary platform.
A transmitter for generating a transmission signal of a terahertz frequency band;
the terahertz antenna is used for transmitting the transmitted electromagnetic waves; receiving echo signals reflected by the target;
the receiver is used for collecting echo signals reflected by the target and received by the terahertz antenna and then sending the echo signals to the data processing module;
the data processing module is configured to perform imaging processing on a target signal sent by the receiver, and specifically includes:
the antenna adopts a spiral scanning mode, the horizontal plane rotating speed is omega, and the vertical speed is v. At taAt the moment, the coordinate of the phase center of the antenna in the horizontal plane is xa(ta),ya(ta) Expressed in a vertical coordinate of za(ta)，
Figure BDA0002481921990000061
The distance compression is carried out on the echo signal reflected by the target to obtain sr(ta,tr)：
Figure BDA0002481921990000062
Wherein t isrFor the fast time of distance, ρ (x)P,yP,zP) To be located at (x)P,yP,zP) Scattering coefficient of target, B is transmission signal bandwidth, fcIs the carrier frequency, c is the speed of light, RP(ta) Distance of target from antenna:
Figure BDA0002481921990000071
the imaging algorithm adopts a Background (BP) algorithm, and comprises the following specific steps:
(1) firstly, a target area is divided into three-dimensional discrete pixel points (x)i,yi,zi) The target center position is (x)i0,yi0,zi0) For each pixel point, calculate (x)i,yi,zi) To the antenna (x)a(ta),ya(ta),za(ta) A distance delay t ofri：
Figure BDA0002481921990000072
(2) Then to sr(ta,tr) Interpolation is carried out to find the corresponding triData s ofr(ta,tri) And compensate for the phase generated by the antenna motion:
Figure BDA0002481921990000073
wherein t isr0Is the target center position (x)i0,yi0,zi0) To the antenna (x)a(ta),ya(ta),za(ta) Distance delay of);
(3) finally, for all taSuperposition
Figure BDA0002481921990000074
Obtain the image value I (x)i,yi,zi)，
Figure BDA0002481921990000075
In the aspect of BP algorithm implementation, GPU + CUDA parallel processing is adopted to improve the imaging speed, and finally a three-dimensional image I (x) is obtainedi,yi,zi). To I (x)i,yi,zi) The maximum value is taken along the radar sight line direction as a two-dimensional display image.
Example 2
Based on the above system, embodiment 2 of the present invention provides a terahertz security inspection imaging method, including:
adopt the circular rotation mode in the horizontal plane, vertical to adopting linear motion, the whole spiral scanning that forms, outwards launch the signal through transmitter and terahertz antenna, obtain echo signal through the receiver after the target reflection, through synthetic aperture imaging processing for horizontal and vertical resolution ratio is superior to centimetre level.
4 point targets are set in a three-dimensional space for simulation verification, imaging geometric relations are shown in figure 2, and a simulation result of the 4 point targets is obtained by using the imaging method of the invention, as shown in figure 3. Through analysis, the target horizontal and vertical 3dB widths of the point at the center are 2.2mm multiplied by 3.4mm, and the target horizontal and vertical 3dB widths of the point at the edge are 3.4mm multiplied by 3.6 mm.
The terahertz security inspection imaging system provided by the invention is constructed by taking N as 1 and M as 2 as a specific embodiment, namely 1 group of terahertz transceiving channels, and 2 receiving channels with 1 transmitting channel in each group, and the imaging method provided by the invention is verified through tests. By utilizing the system and the imaging method provided by the invention, imaging tests are carried out on the metal letters and the scalpel; fig. 4 is an optical image of the target, and fig. 5 and 6 are radar images in two directions, and it can be seen by comparison that the system and the method can clearly image the target and verify the effectiveness of the method.
The system can image the surrounding targets at the same time, the metal letters and the scalpel are positioned right in front of the system in an experiment, and the metal control support is arranged right behind the system. The back metal support can be imaged while the letters and the scalpel are imaged, and fig. 6 is a radar image of the metal support, so that the system and the method can simultaneously image targets in multiple directions.
Under the condition of adopting different M and N, namely different receiving and transmitting groups and receiving channels of each group, the effectiveness of the method can be proved through a plurality of experiments, the different time is different when the system sampling is not carried out, and the effectiveness of the system and the method is consistent.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (2)

1. A terahertz security inspection imaging system, characterized in that the system comprises: the terahertz transmitter-receiver comprises a rotating platform capable of vertically moving up and down, a motor, a terahertz transceiver channel and a data processing module arranged on an upper computer;
the motor controls the horizontal rotation and the vertical movement of the rotary platform; the terahertz transceiving channel is arranged at the edge part of the rotary platform and can realize spiral scanning in the movement of the rotary platform;
the terahertz transceiving channel is used for transmitting signals outwards, acquiring echo signals reflected by a target and sending the echo signals to the data processing module;
the data processing module is used for processing the echo signal and outputting a two-dimensional display image;
the terahertz transceiving channel is arranged on the rotary platform; the motor comprises a rotary control motor and a vertical motion control motor; the rotation control motor is used for controlling the rotating platform to rotate at a constant speed at a rotating speed omega; the vertical motion control motor is used for controlling the rotating platform to move up and down at a vertical speed v;
the terahertz receiving and transmitting channels are one or more groups; a plurality of groups of terahertz transceiving channels are fixed into a whole from top to bottom;
a set of terahertz transceiving channels includes: the terahertz antenna comprises a terahertz antenna, a transmitter and a plurality of receivers; the terahertz antenna is positioned at the edge of the rotating platform;
a transmitter for generating a transmission signal of a terahertz frequency band;
the terahertz antenna is used for transmitting the transmitted electromagnetic waves; receiving echo signals reflected by the target;
the receiver is used for collecting echo signals reflected by the target and received by the terahertz antenna and then sending the echo signals to the data processing module;
the specific implementation process of the data processing module is as follows:
the echo signal reflected by the target is subjected to pulse compression to obtain distance direction compression data sr(ta,tr)：
Figure FDA0002782347280000011
Wherein t isrFor fast time within a single radar pulse, taSlow time formed for transmitting multiple radar pulses, p (x)P,yP,zP) To be located at (x)P,yP,zP) Scattering coefficient of target, B is transmission signal bandwidth, fcIs the carrier frequency, c is the speed of light, RP(ta) Distance of target from antenna:
Figure FDA0002782347280000012
(xa(ta),ya(ta),za(ta) Is t)aThree-dimensional coordinates of the antenna phase center at time:
Figure FDA0002782347280000021
wherein, omega is the horizontal rotating speed of the rotating platform; r is the radius of the antenna phase center from the center of the circle of the rotary platform; v is the vertical linear motion speed of the rotary platform;
dividing a target area into three-dimensional discrete pixel points (x)i,yi,zi) The target center position is (x)i0,yi0,zi0) For each pixel point, calculate (x)i,yi,zi) To the antenna (x)a(ta),ya(ta),za(ta) A distance delay t ofri：
Figure FDA0002782347280000022
Then to sr(ta,tr) Interpolation is carried out to find the corresponding triData s ofr(ta,tri) And compensate for the phase generated by the antenna motion:
Figure FDA0002782347280000023
wherein t isr0Is the target center position (x)i0,yi0,zi0) To the antenna (x)a(ta),ya(ta),za(ta) Distance delay of);
finally, for all taSuperposition
Figure FDA0002782347280000024
Obtaining a three-dimensional image value I (x)i,yi,zi)：
Figure FDA0002782347280000025
To I (x)i,yi,zi) The maximum value is taken along the radar sight line direction as a two-dimensional display image.
2. A terahertz security inspection imaging method is realized based on the terahertz security inspection imaging system of claim 1, and the method comprises the following steps:
the rotating platform rotates at a constant speed in a horizontal plane at a rotating speed omega under the control of a motor and reciprocates up and down at a vertical speed v;
the transmitter generates a transmitting signal and transmits the transmitting signal out through the terahertz antenna, the receiver receives an echo signal reflected by a target, and the echo signal is sent to the data processing module;
the data processing module processes the echo signal and outputs a two-dimensional display image;
the data processing module processes the echo signal and outputs a two-dimensional display image; the method specifically comprises the following steps:
the echo signal reflected by the target is subjected to pulse compression to obtain distance direction compression data sr(ta,tr)：
Figure FDA0002782347280000031
Wherein t isrFor the fast time of distance, ρ (x)P,yP,zP) To be located at (x)P,yP,zP) Scattering coefficient of target, B is transmission signal bandwidth, fcIs the carrier frequency, c is the speed of light, RP(ta) Distance of target from antenna:
Figure FDA0002782347280000032
(xa(ta),ya(ta),za(ta) Is t)aThree-dimensional coordinates of the antenna phase center at time:
Figure FDA0002782347280000033
wherein, omega is the horizontal rotating speed of the rotating platform; v is the vertical linear motion speed of the rotary platform; r is the radius of the antenna phase center from the center of the rotating platform circle
Dividing a target area into three-dimensional discrete pixel points (x)i,yi,zi) The target center position is (x)i0,yi0,zi0) For each pixel point, calculate (x)i,yi,zi) To the antenna (x)a(ta),ya(ta),za(ta) A distance delay t ofri：
Figure FDA0002782347280000034
Then to sr(ta,tr) Interpolation is carried out to find the corresponding triData s ofr(ta,tri) And compensate for the phase generated by the antenna motion:
Figure FDA0002782347280000035
wherein t isr0Is the target center position (x)i0,yi0,zi0) To the antenna (x)a(ta),ya(ta),za(ta) Distance delay of);
finally, for alltaSuperposition
Figure FDA0002782347280000036
Obtaining a three-dimensional image value I (x)i,yi,zi)：
Figure FDA0002782347280000037
To I (x)i,yi,zi) The maximum value is taken along the radar sight line direction as a two-dimensional display image.
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