CN116125418A - Interference SAR motion ship wake area acquisition and wake velocity field measurement method - Google Patents

Interference SAR motion ship wake area acquisition and wake velocity field measurement method Download PDF

Info

Publication number
CN116125418A
CN116125418A CN202310037687.5A CN202310037687A CN116125418A CN 116125418 A CN116125418 A CN 116125418A CN 202310037687 A CN202310037687 A CN 202310037687A CN 116125418 A CN116125418 A CN 116125418A
Authority
CN
China
Prior art keywords
ship
wake
interference
sar
representing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310037687.5A
Other languages
Chinese (zh)
Inventor
田敏
李强
曾慧然
张学攀
廖桂生
罗丰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou Research Institute Of Xi'an University Of Electronic Science And Technology
Original Assignee
Hangzhou Research Institute Of Xi'an University Of Electronic Science And Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hangzhou Research Institute Of Xi'an University Of Electronic Science And Technology filed Critical Hangzhou Research Institute Of Xi'an University Of Electronic Science And Technology
Priority to CN202310037687.5A priority Critical patent/CN116125418A/en
Publication of CN116125418A publication Critical patent/CN116125418A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • 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
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/589—Velocity or trajectory determination systems; Sense-of-movement determination systems measuring the velocity vector
    • 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
    • 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
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9023—SAR image post-processing techniques combined with interferometric techniques
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/40—Extraction of image or video features
    • G06V10/42—Global feature extraction by analysis of the whole pattern, e.g. using frequency domain transformations or autocorrelation
    • G06V10/422—Global feature extraction by analysis of the whole pattern, e.g. using frequency domain transformations or autocorrelation for representing the structure of the pattern or shape of an object therefor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/70—Arrangements for image or video recognition or understanding using pattern recognition or machine learning
    • G06V10/74—Image or video pattern matching; Proximity measures in feature spaces
    • G06V10/761—Proximity, similarity or dissimilarity measures
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/70—Arrangements for image or video recognition or understanding using pattern recognition or machine learning
    • G06V10/762—Arrangements for image or video recognition or understanding using pattern recognition or machine learning using clustering, e.g. of similar faces in social networks
    • G06V10/763—Non-hierarchical techniques, e.g. based on statistics of modelling distributions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Landscapes

  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Multimedia (AREA)
  • Software Systems (AREA)
  • Artificial Intelligence (AREA)
  • Health & Medical Sciences (AREA)
  • Computing Systems (AREA)
  • Databases & Information Systems (AREA)
  • Evolutionary Computation (AREA)
  • General Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Electromagnetism (AREA)
  • Probability & Statistics with Applications (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention discloses a method for acquiring a wake area and measuring a wake velocity field of an interference SAR moving ship, which comprises the following steps: s1, calculating key parameters of SAR equipment interfered along a track according to ship wake characteristics and an electromagnetic wave propagation mechanism; s2, carrying out normalized SAR interference processing on the echo data of the observation scene; s3, detecting ship wake pixel points based on the normalized interference result obtained in the step S2; s4, clustering ship trail pixel points based on the information of the spatial Euclidean distance and the normalized interference result; s5, detecting ship wake; s6, inverting a radial velocity field of the ship wake by utilizing the interference phase information; s7, inverting the parameters of the moving ship by utilizing the Kelvin trail of the ship; s8, outputting the ship wake area, the radial speed field and corresponding ship navigational speed and navigational direction information. The method for acquiring the wake area and measuring the wake velocity field of the interference SAR moving ship is adopted to realize the acquisition of the wake radial velocity field of the interference SAR ship and the inversion of ship parameters.

Description

Interference SAR motion ship wake area acquisition and wake velocity field measurement method
Technical Field
The invention relates to the technical field of marine remote sensing monitoring, in particular to a method for acquiring a wake area and measuring a wake velocity field of an interference SAR motion ship.
Background
The radar has the advantages of all-day, all-weather work and wide area monitoring, and has important application in the field of marine remote sensing monitoring. The ship is used as the main information input of the human ocean activities, the tail part of the moving ship can be accompanied with the wake characteristics in open water, the duration of the ship wake wave is long, the space distribution range is large, and the space distribution range is closely related to the volume, the weight and the motion parameters of the ship. The radar measurement of the ship wake signals has important significance for indirectly realizing detection and parameter estimation of the low radar cross-sectional area moving ship targets.
In the prior art, a wake image of a moving ship target usually appears on an SAR ocean image, but the intensity contrast between the wake image and the ocean background is limited, and the wake image is easily influenced by wind driving water waves around the wake, so that the ship wake measurement is not stable. A method for acquiring ship speed and width using wake SAR images is disclosed in the "The speed andbeam ofa ship from its wake's SAR images" article by Zilman, A.Zapolski and M.Marom, journal 42, 10 th edition. The method is based on linear characteristics of wake on SAR images, kelvin wake and turbulence wake of a moving ship in SAR image domain are extracted by utilizing rapid discrete Radon transformation, and then model analysis is carried out on the Kelvin wake and the turbulence wake respectively, so that the navigational speed and the ship width information of the corresponding moving ship are inverted. However, as sea conditions rise, sea surface water wave motion is more intense, wake waves are continuously attenuated, and intensity on SAR images is reduced. Moreover, the increase of the resolution of the SAR image and the change of the radar observation visual angle can lead the wake not to present linear characteristics, but to present the characteristics close to the surface targets in the optical image, so that the wake detection method utilizing the linear characteristics fails, and further, the result of ship parameter inversion is greatly different from the actual situation.
Disclosure of Invention
The invention aims to provide an interference SAR motion ship wake area acquisition and wake speed field measurement method, which overcomes the defects of the prior art, combines multi-dimensional information of wake and improves the motion ship wake acquisition probability under complex sea conditions.
In order to achieve the purpose, the invention provides a method for acquiring a wake area and measuring a wake velocity field of an interference SAR motion ship, which comprises the following steps:
s1, calculating key parameters of SAR equipment interfered along a track according to ship wake characteristics and an electromagnetic wave propagation mechanism;
s2, carrying out normalized SAR interference processing on the echo data of the observation scene;
s3, detecting ship wake pixel points based on the normalized interference result obtained in the step S2;
s4, clustering ship trail pixel points based on the information of the spatial Euclidean distance and the normalized interference result;
s5, detecting ship wake;
s6, inverting a radial velocity field of the ship wake by utilizing the interference phase information;
s7, inverting the parameters of the moving ship by utilizing the Kelvin trail of the ship;
s8, respectively outputting the ship wake area, the ship wake radial velocity field and ship navigational speed and navigational direction information corresponding to the ship wake.
Preferably, the mode adopted by the interferometric SAR equipment in the step S1 is a full-aperture transmitting sub-aperture independent receiving mode, and the full-aperture transmitting sub-aperture independent receiving mode carries out SAR imaging on echo data received by each sub-array by adopting an R-D imaging method;
the key parameters comprise the product X of the average transmitting power of the radar and the receiving and transmitting aperture of the antenna, the area S of the transmitting antenna and the length D of the antenna along the course a Antenna vertical heading length D e The antenna unit, the adjacent receiving subarray distance d and the signal bandwidth B adopt the following calculation modes:
1) Product of radar average transmit power and antenna transmit-receive aperture:
Figure BDA0004045568070000031
wherein X represents the product of the radar average transmitting power and the antenna receiving and transmitting aperture, and is x=p av G t G r ，P av Representing the average transmit power, G, of a track-following interferometric SAR device t Representing the transmit antenna gain, G, of a track-following interferometric SAR device r Representing the gain, beta, of the receiving antenna of a track-following interferometric SAR apparatus 0 Represents the wake-to-noise power ratio, k is the Boltzmann constant, T 0 C for interfering system noise temperature of SAR equipment along track B Representing a noise bandwidth correction factor, F is a receiver noise coefficient of the along-track interference SAR equipment, L represents system loss of the along-track interference SAR equipment, R represents an inclined distance between the along-track interference SAR equipment and a ship trail to be measured, and T a The coherent accumulation time of the SAR equipment is shown along the track, lambda shows the wavelength of electromagnetic waves emitted by the SAR equipment along the track, and sigma shows the radar scattering sectional area of the ship trail;
2) Transmitting antenna area:
Figure BDA0004045568070000032
wherein N represents the number of subarrays divided by the antenna, a 1 Indicating antenna efficiency, a 2 Representing pulse duty cycle, P 0 Representing the radiated power of a single antenna;
3) The length of the antenna along the course:
Figure BDA0004045568070000033
wherein W represents the breadth of the observation scene and is larger than the maximum breadth of the ship wake area;
4) Antenna vertical heading length:
D e ≤D a
5) The antenna unit is a rectangular planar array with half-wavelength arrangement, and the following constraint is satisfied:
Figure BDA0004045568070000034
wherein b represents the total number of antenna units, b a Representing the number of antenna elements along the track, b b The number of antenna elements representing the vertical track direction,<·>representing a rounding operation;
6) Adjacent receive subarray spacing:
Figure BDA0004045568070000041
wherein V is a Representing the speed of the platform along the track, L K Representing the wavelength of the Kelvin wake of the ship as
Figure BDA0004045568070000042
g represents the gravity acceleration value of 9.8m/s 2 ，U s Representing the speed of the ship;
7) The signal bandwidth satisfies the following constraint:
Figure BDA0004045568070000043
wherein c represents the speed of light.
Preferably, the normalized SAR interferometry in the step S2 is set upSAR complex image data of adjacent subarrays are z respectively 1 (n) and z 2 (n) the calculation is as follows:
Figure BDA0004045568070000044
wherein n represents the index of the pixel point on the SAR image, Z (n) represents the normalized interference result of the nth pixel point, K represents the multiview number, K pixel points closest to the nth pixel point on the SAR image are taken, x represents the conjugation operation, E [. Cndot ] represents the mathematical expectation operation;
the result of the normalized SAR interference processing is the interference amplitude and interference phase of the observed scene, and the sum of xi (n) is used
Figure BDA0004045568070000047
The normalized interference amplitude and interference phase of n pixel points are respectively represented, specifically:
Figure BDA0004045568070000045
Figure BDA0004045568070000046
preferably, the normalized interference result is based on the interference amplitude and the interference phase information of the pixel point, and the specific steps of the detection in the step S3 are as follows:
s31, constructing ship trail pixel point detection quantity according to the following steps:
Figure BDA0004045568070000051
wherein T (n) represents the detection quantity, ζ (n) and
Figure BDA0004045568070000052
respectively represent the normalized interference amplitude and the interference amplitude of the nth pixel pointInvolving phase, ζ s And->
Figure BDA0004045568070000059
Mean and standard deviation of interference amplitude respectively representing sea clutter background>
Figure BDA0004045568070000053
And->
Figure BDA0004045568070000058
Respectively representing the mean value and standard deviation of the interference phases of the sea clutter background;
s32, taking the pixel point with T (n) being more than or equal to eta as a ship trail pixel point, and enabling eta to be represented as a trail pixel point detection threshold.
Preferably, the specific step of clustering in the step S4 is as follows:
s41, recording a ship trail pixel point group as a set G t The spatial Euclidean distance between pixel points m and n is denoted as P m , n The interference amplitude difference is denoted as A m,n = |ζ (m) - ζ (n) |, the interference phase difference is noted as
Figure BDA0004045568070000054
Constructing feature vector [ P ] of pixel points m and n m,n ,A m,n ,B m,n ]；/>
S42, in collection G t In the method, traversing and judging whether the feature vectors of the mth pixel point and the nth pixel point meet the following formula:
Figure BDA0004045568070000055
wherein m is 1 ,m 2 ,m 3 Respectively represent 3 adjustment coefficients, and m 1 ＞0,m 2 ＞0,m 3 ＞0，δ A Representing the interference amplitude difference threshold, delta A ≥0，δ P Representing the clustering space distance threshold value as
Figure BDA0004045568070000056
δ B Representing the interference phase difference threshold as
Figure BDA0004045568070000057
v 0 Representing the radial velocity variation scale of the wake pixel points;
if the pixel points are satisfied, the mth pixel point and the nth pixel point are gathered into one class, if the pixel points are not satisfied, the pixel points are not gathered into one class, and any two classes with common pixel points are combined into the same class;
s43, pair set G t And (3) clustering the middle pixel points in the step S42 to obtain H pixel classes.
Preferably, the step S5 of detecting the ship wake includes the following steps:
s51, carrying out area inspection on H pixels, calculating the minimum external graphic area of each pixel, comparing the minimum external graphic area with an area threshold, reserving pixels larger than the area threshold, removing pixels smaller than the area threshold, carrying out area inspection on H pixels, and marking as H 1 A pixel class;
s52, extracting H respectively 1 Minimum external graphics of each pixel class, for H 1 And carrying out pattern inspection on the pixels, wherein the pixels with the minimum external patterns close to the acute triangle are reserved, the pixels not close to the acute triangle are removed, and M pixels are obtained and used as M ship trails.
Preferably, in the step S6, the radial velocity field of the ship wake is inverted, and the calculation mode is as follows:
Figure BDA0004045568070000061
wherein v is w (n) represents the radial velocity of the wake area pixel point n.
Preferably, the specific step of inversion in the step S7 is as follows:
s71, for each ship trail, respectively extracting an acute angle edge in a graph as each Kelvin trail, and obtaining Kelvin trail spectrum distribution by FFT operation, wherein the maximum spectrum peak corresponds to the wave number k of the Kelvin trail wave d Estimating the shipWake corresponds to the speed of the ship
Figure BDA0004045568070000062
The calculation method is as follows:
Figure BDA0004045568070000063
s72, the angular bisector direction of the included angles of the two Kelvin tails of each ship is recorded as the corresponding ship route, wherein the included angles of the two Kelvin tails in the tail point to the corresponding ship navigation direction.
Therefore, the method for acquiring the wake area and measuring the wake speed field of the interference SAR moving ship is suitable for measuring parameters of the moving ship wake, the speed field of the moving ship wake area and inversion corresponding ship targets by microwaves. The technical effects are as follows:
1) According to the invention, by combining the distribution characteristics of the wake wave of the moving ship and the electromagnetic wave scattering mechanism, the interference SAR equipment parameters are designed, so that accurate interference measurement information and speed field information of the wake wave of the moving ship can be obtained.
2) The invention combines the interference amplitude and interference phase information of the motion ship trail, constructs the motion ship trail enhancement detection quantity, improves the contrast ratio of the motion ship trail and the sea clutter background, and improves the acquisition probability of the motion ship trail and the detection performance of the pixel point under complex sea conditions.
3) According to the invention, through image analysis of the wake of the moving ship, the motion parameters such as the radial velocity field of the wake area of the corresponding ship can be inverted.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a flow chart of a method for acquiring wake areas and measuring wake velocity fields of an interferometric SAR motion ship;
FIG. 2 is a scene interference amplitude diagram obtained by an interference SAR motion ship wake area acquisition and wake velocity field measurement method;
FIG. 3 is a scene interference phase diagram obtained by an interference SAR motion ship wake area acquisition and wake velocity field measurement method;
FIG. 4 is a wake area extracted by the method for acquiring wake velocity fields and measuring wake areas of an interferometric SAR motion ship;
FIG. 5 is a Kelvin wake spectrum distribution in a wake area extracted by an interferometric SAR motion ship wake area acquisition and wake velocity field measurement method;
FIG. 6 is a radial velocity inversion result of a wake area obtained by the method for obtaining the wake area and measuring the wake velocity field of the interference SAR motion ship.
Detailed Description
The technical scheme of the invention is further described below through the attached drawings and the embodiments.
As shown in fig. 1, a method for acquiring wake areas and measuring wake velocity fields of an interferometric SAR moving ship combines a flow chart, and specifically comprises the following implementation steps:
s1, calculating the aperture of an antenna of the SAR equipment, the arrangement distance of receiving subarrays and the bandwidth of a transmitted signal along the track interference according to the wake wave height distribution, the speed field distribution and the electromagnetic wave propagation mechanism of the moving ship. The interference SAR equipment adopts a full-aperture transmitting sub-aperture independent receiving mode, and carries out SAR imaging on echo data received by each sub-array by adopting an R-D imaging method.
1) The product X of the radar average transmit power and the antenna transmit-receive aperture is determined according to the following equation:
Figure BDA0004045568070000081
wherein X represents the product of the radar average transmitting power and the antenna receiving and transmitting aperture, and is x=p av G t G r ，P av Representing the average transmit power, G, of a track-following interferometric SAR device t Representing the transmit antenna gain, G, of a track-following interferometric SAR device r Representing the gain, beta, of the receiving antenna of a track-following interferometric SAR apparatus 0 Representation ofThe wake to noise power ratio, k is the Boltzmann constant, T 0 C for interfering system noise temperature of SAR equipment along track B Representing a noise bandwidth correction factor, F is a receiver noise coefficient of the along-track interference SAR equipment, L represents system loss of the along-track interference SAR equipment, R represents an inclined distance between the along-track interference SAR equipment and a ship trail to be measured, and T a The coherent accumulation time of the SAR equipment is shown along the track, lambda shows the wavelength of electromagnetic waves emitted by the SAR equipment along the track, and sigma shows the radar scattering sectional area of the ship wake.
2) According to the product X of the average transmitting power of the radar and the receiving and transmitting aperture of the antenna, the transmitting antenna area S of the interference SAR equipment along the track is calculated according to the following formula:
Figure BDA0004045568070000082
wherein N represents the number of subarrays divided by the antenna, a 1 Indicating antenna efficiency, a 2 Representing pulse duty cycle, P 0 Representing the radiated power of a single antenna.
3) Antenna along course length D of along-track interference SAR equipment a Satisfies the following formula:
Figure BDA0004045568070000083
wherein W represents the breadth of the observed scene and is larger than the maximum width of the ship wake area.
4) Antenna vertical heading length D of SAR device along track interference e Satisfies the following formula:
D e ≤D a
5) The antenna units of the SAR equipment are rectangular planar arrays distributed along half wavelength, and the following constraint is satisfied:
Figure BDA0004045568070000091
wherein b representsTotal number of antenna elements, b a Representing the number of antenna elements along the track, b b The number of antenna elements representing the vertical track direction,<·>representing a rounding operation.
6) The adjacent receiving subarray spacing d of the along-track interferometric SAR device needs to satisfy the following equation:
Figure BDA0004045568070000092
wherein V is a Representing the speed of the platform along the track, L K Representing the wavelength of the Kelvin wake of the ship as
Figure BDA0004045568070000093
g represents the gravity acceleration value of 9.8m/s 2 ，U s Indicating the speed of the ship.
7) The constraint condition of the signal bandwidth B of the track interference SAR equipment is as follows:
Figure BDA0004045568070000094
wherein c represents the speed of light.
S2, carrying out normalized SAR interference processing on the echo data of the observation scene, namely acquiring the interference amplitude and the interference phase of the observation scene by using an interference SAR device. Recording SAR complex image domain data of a group of adjacent subarrays as z 1 (n) and z 2 (n). Normalized interference processing is carried out on SAR images of the two subarrays according to the following steps:
Figure BDA0004045568070000095
wherein n represents the index of the pixel point on the SAR image, Z (n) represents the normalized interference result of the nth pixel point, K represents the multiview number, K pixel points closest to the nth pixel point on the SAR image are obtained, x represents the conjugation operation, E [. Cndot ] represents the mathematical expectation operation.
By xi (n) sum
Figure BDA0004045568070000101
The normalized interference amplitude and interference phase of the nth pixel point are respectively represented, specifically:
Figure BDA0004045568070000102
Figure BDA0004045568070000103
s3, detecting ship wake pixel points by using the normalized interference result obtained in the step S2, namely based on the interference amplitude and the interference phase information of the pixel points, wherein the specific steps are as follows:
s31, constructing ship trail pixel point detection quantity:
Figure BDA0004045568070000104
wherein T (n) represents the detection amount, ζ, of the nth pixel s And
Figure BDA0004045568070000108
mean and standard deviation of interference amplitude respectively representing sea clutter background>
Figure BDA0004045568070000105
And->
Figure BDA0004045568070000107
The mean and standard deviation of the interference phase of the sea clutter background are respectively shown.
S32, taking the pixel point with T (n) being more than or equal to eta as a ship trail pixel point, wherein eta represents a trail pixel point detection threshold.
S4, clustering the motion ship trail pixel points detected in the step S3 based on the consistency of the spatial Euclidean distance, the interference amplitude and the interference phase, wherein the specific steps are as follows:
s41, recording the detected motion ship trail pixel point group as a set G t The spatial Euclidean distance between pixel points m and n is denoted as P m,n The interference amplitude difference is denoted as A m,n = |ζ (m) - ζ (n) |, the interference phase difference is noted as
Figure BDA0004045568070000106
Constructing feature vector [ P ] of pixel points m and n m,n ,A m,n ,B m,n ]。
S42, in collection G t In the method, traversing and judging whether the feature vectors of the mth pixel point and the nth pixel point meet the following formula:
Figure BDA0004045568070000111
wherein m is 1 ,m 2 ,m 3 Respectively represent 3 adjustment coefficients, and m 1 ＞0,m 2 ＞0,m 3 ＞0，δ A Representing the interference amplitude difference threshold, delta A ≥0，δ P Representing the clustering space distance threshold value as
Figure BDA0004045568070000112
δ B Representing the interference phase difference threshold as
Figure BDA0004045568070000113
v 0 Representing the radial velocity variation scale of the wake pixel points.
If the pixel points are satisfied, the mth pixel point and the nth pixel point are gathered into one type; if not, the polymers are not classified into one type. Any two classes have a combination of common pixels.
S43, pair set G t And (3) clustering the middle pixel points in the step S42 to finally obtain H pixel classes.
S5, carrying out area inspection and graphic inspection on the H pixel classes in the step S4 to obtain M pixel classes as detected M ship trails, wherein the specific steps are as follows:
s51, carrying out area inspection on H pixel classes, and calculating each pixel classThe minimum external graphic area of one pixel class is compared with an area threshold value, the pixel class larger than the area threshold value is reserved, the pixel class smaller than the area threshold value is removed, and the area of H pixel classes is checked to be H 1 A pixel class.
S52, extracting H respectively 1 Minimum external graphics of each pixel class, for H 1 And carrying out pattern inspection on the pixels, wherein the minimum external pattern is close to the reservation of the acute triangle, and is not removed, and finally M pixels are obtained and used as M ship trails.
S6, inverting radial velocity fields of the wake respectively by utilizing the interference phase information, wherein the calculation mode is as follows:
taking one ship trail from the M ship trails, inverting the radial speed of the ship trails according to the interference phase of the pixel points in the trail area and the following steps:
Figure BDA0004045568070000114
wherein v is w (n) represents the radial velocity of the wake area pixel point n.
S7, inverting the motion ship parameters by utilizing the Kelvin wake of the ship wake, wherein the method comprises the following specific steps of:
s71, for each ship trail, respectively extracting an acute angle edge in a graph as each Kelvin trail, and obtaining Kelvin trail spectrum distribution by FFT operation, wherein the maximum spectrum peak corresponds to the wave number k of the Kelvin trail wave d Estimating the speed of the ship corresponding to the ship trail according to the following formula
Figure BDA0004045568070000121
Figure BDA0004045568070000122
S72, the angular bisector direction of the included angles of the two Kelvin tails of each ship is recorded as the corresponding ship route, wherein the included angles of the two Kelvin tails in the tail point to the corresponding ship navigation direction.
S8, outputting M wake areas and radial velocity fields thereof and corresponding ship navigation speed and course information respectively.
Experimental test:
the experimental environment of the invention is: MATLAB R2010a, specialty version of Intel (R) Core (TM) 2Duo CPU3.4GHz,Window XP.
The experiment of the invention is based on a double-channel airborne interference SAR system, and adopts a full-aperture sub-aperture receiving mode. The interference SAR equipment is placed on an airplane along the track, the platform speed is 50m/s, the height is 5000m, the interference SAR working frequency band is 3GHz, the antenna receiving and transmitting aperture is 2.5 multiplied by 0.1m (along the track direction multiplied by the vertical track direction), the number of receiving subarrays is 2, the receiving subarrays are distributed at equal intervals, the centroid distance is 1.25m, and the transmitted signal bandwidth is 67MHz. The linear frequency modulation signal is adopted, the pulse repetition frequency is 500Hz, the pulse duty ratio is 15%, and the coherent accumulation time is 1s.
In the experiment, the simulated ship target is 160m long, 20m wide, 5m draft and 20m/s in navigational speed. And according to the designed equipment parameters, carrying out simulation, SAR imaging and normalized interference processing on the echo of the sea surface and the wake area.
Fig. 2 is a view of the scene interference amplitude obtained by the present invention, and fig. 3 is a view of the scene interference amplitude obtained by the present invention. It can be seen that the interference amplitude and interference phase of the wake area of the moving ship are different from those of the surrounding sea area, and the wake characteristics of the ship can be clearly seen.
Fig. 4 is an extracted wake region of the present invention, and fig. 5 is a kelvin wake spectral distribution in the extracted wake region of the present invention. The wave number of Kelvin wave can be obtained from Kelvin spectrum peak value by using the formula
Figure BDA0004045568070000131
The estimated speed of the ship is 19.7m/s, which is very close to the real speed of the simulated ship target by 20m/s.
Fig. 6 is a radial velocity inversion result of a wake area obtained by the invention, and radial velocity information corresponding to each pixel point of the wake area can be read out through gray scale values on the right side of an image, so that motion parameter inversion of a corresponding ship is realized. The validity of the invention is verified by the experimental test.
Therefore, by adopting the method for acquiring the wake velocity field of the moving ship wake by the interference SAR, the interference amplitude and the interference phase information of the moving ship wake can be obtained, the measurement dimension of the moving ship wake is enlarged, the influence of other wave systems on the detection of the moving ship wake wave is relieved, more accurate measuring results of the moving ship wake area and the velocity field are obtained, and further, the reliability of the ship parameter indirect inversion method based on the ship wake is improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.

Claims (8)

1. A method for acquiring a wake area and measuring a wake speed field of an interference SAR motion ship is characterized by comprising the following steps of: the method comprises the following steps:
s1, calculating key parameters of SAR equipment interfered along a track according to ship wake characteristics and an electromagnetic wave propagation mechanism;
s2, carrying out normalized SAR interference processing on the echo data of the observation scene;
s3, detecting ship wake pixel points based on the normalized interference result obtained in the step S2;
s4, clustering ship trail pixel points based on the information of the spatial Euclidean distance and the normalized interference result;
s5, detecting ship wake;
s6, inverting a radial velocity field of the ship wake by utilizing the interference phase information;
s7, inverting the parameters of the moving ship by utilizing the Kelvin trail of the ship;
s8, respectively outputting the ship wake area, the ship wake radial velocity field and ship navigational speed and navigational direction information corresponding to the ship wake.
2. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: the mode adopted by the interference SAR equipment in the step S1 is a full-aperture transmitting sub-aperture independent receiving mode, and the full-aperture transmitting sub-aperture independent receiving mode carries out SAR imaging on echo data received by each sub-array by adopting an R-D imaging method;
the key parameters comprise the product X of the average transmitting power of the radar and the receiving and transmitting aperture of the antenna, the area S of the transmitting antenna and the length D of the antenna along the course a Antenna vertical heading length D e The antenna unit, the adjacent receiving subarray distance d and the signal bandwidth B adopt the following calculation modes:
1) Product of radar average transmit power and antenna transmit-receive aperture:
Figure FDA0004045568060000011
wherein X represents the product of the radar average transmitting power and the antenna receiving and transmitting aperture, and is x=p av G t G r ，P av Representing the average transmit power, G, of a track-following interferometric SAR device t Representing the transmit antenna gain, G, of a track-following interferometric SAR device r Representing the gain, beta, of the receiving antenna of a track-following interferometric SAR apparatus 0 Represents the wake-to-noise power ratio, k is the Boltzmann constant, T 0 C for interfering system noise temperature of SAR equipment along track B Representing a noise bandwidth correction factor, F is a receiver noise coefficient of the along-track interference SAR equipment, L represents system loss of the along-track interference SAR equipment, R represents an inclined distance between the along-track interference SAR equipment and a ship trail to be measured, and T a The coherent accumulation time of the SAR equipment is shown along the track, lambda shows the wavelength of electromagnetic waves emitted by the SAR equipment along the track, and sigma shows the radar scattering sectional area of the ship trail;
2) Transmitting antenna area:
Figure FDA0004045568060000021
wherein N represents the number of subarrays divided by the antenna, a 1 Indicating antenna efficiency, a 2 Representing pulse duty cycle, P 0 Representing the radiated power of a single antenna;
3) The length of the antenna along the course:
Figure FDA0004045568060000022
wherein W represents the breadth of the observation scene and is larger than the maximum breadth of the ship wake area;
4) Antenna vertical heading length:
D e ≤D a
5) The antenna unit is a rectangular planar array with half-wavelength arrangement, and the following constraint is satisfied:
Figure FDA0004045568060000023
wherein b represents the total number of antenna units, b a Representing the number of antenna elements along the track, b b The number of antenna elements representing the vertical track direction,<·>representing a rounding operation;
6) Adjacent receive subarray spacing:
Figure FDA0004045568060000031
wherein V is a Representing the speed of the platform along the track, L K Representing the wavelength of the Kelvin wake of the ship as
Figure FDA0004045568060000032
g represents gravity accelerationDegree value of 9.8m/s 2 ，U s Representing the speed of the ship;
7) The signal bandwidth satisfies the following constraint:
Figure FDA0004045568060000033
wherein c represents the speed of light.
3. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: the normalized SAR interference processing in the step S2 is to record SAR complex image data of a group of adjacent subarrays, which are z respectively 1 (n) and z 2 (n) the calculation is as follows:
Figure FDA0004045568060000034
wherein n represents the index of the pixel point on the SAR image, Z (n) represents the normalized interference result of the nth pixel point, K represents the multiview number, K pixel points closest to the nth pixel point on the SAR image are taken, x represents the conjugation operation, E [. Cndot ] represents the mathematical expectation operation;
the result of the normalized SAR interference processing is the interference amplitude and interference phase of the observed scene, and the sum of xi (n) is used
Figure FDA0004045568060000037
The normalized interference amplitude and interference phase of n pixel points are respectively represented, specifically:
Figure FDA0004045568060000035
Figure FDA0004045568060000036
4. the method for acquiring and measuring the wake velocity field of the wake area of the interferometric SAR moving ship according to claim 3, wherein the method comprises the following steps of: the normalized interference result is interference amplitude and interference phase information based on pixel points, and the specific steps of detection in the step S3 are as follows:
s31, constructing ship trail pixel point detection quantity according to the following steps:
Figure FDA0004045568060000041
wherein T (n) represents the detection quantity, ζ (n) and
Figure FDA0004045568060000042
respectively representing normalized interference amplitude and interference phase of nth pixel point s And h ξs Mean and standard deviation of interference amplitude respectively representing sea clutter background>
Figure FDA0004045568060000043
And->
Figure FDA0004045568060000048
Respectively representing the mean value and standard deviation of the interference phases of the sea clutter background;
s32, taking the pixel point with T (n) being more than or equal to eta as a ship trail pixel point, and enabling eta to be represented as a trail pixel point detection threshold.
5. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: the specific steps of clustering in the step S4 are as follows:
s41, recording a ship trail pixel point group as a set G t The spatial Euclidean distance between pixel points m and n is denoted as P m,n The interference amplitude difference is denoted as A m,n = |ζ (m) - ζ (n) |, the interference phase difference is noted as
Figure FDA0004045568060000044
Constructing feature vector [ P ] of pixel points m and n m,n ,A m,n ,B m,n ]；
S42, in collection G t In the method, traversing and judging whether the feature vectors of the mth pixel point and the nth pixel point meet the following formula:
Figure FDA0004045568060000045
wherein m is 1 ,m 2 ,m 3 Respectively represent 3 adjustment coefficients, and m 1 ＞0,m 2 ＞0,m 3 ＞0，δ A Representing the interference amplitude difference threshold, delta A ≥0，δ P Representing the clustering space distance threshold value as
Figure FDA0004045568060000046
δ B Representing the interference phase difference threshold as
Figure FDA0004045568060000047
v 0 Representing the radial speed variation scale of the trail pixel points, if the radial speed variation scale is satisfied, gathering the mth pixel point and the nth pixel point into one class, if the radial speed variation scale is not satisfied, not gathering the mth pixel point and the nth pixel point into one class, and merging any two classes with common pixel points into the same class;
s43, pair set G t And (3) clustering the middle pixel points in the step S42 to obtain H pixel classes.
6. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: the detection steps of the ship trail in the step S5 are as follows:
s51, carrying out area inspection on H pixel classes, calculating the minimum external graphic area of each pixel class, comparing the minimum external graphic area with an area threshold value, reserving the pixel class larger than the area threshold value and reserving the pixel class smaller than the area threshold valueRemoving pixels, and marking H pixels as H after carrying out area inspection 1 A pixel class;
s52, extracting H respectively 1 Minimum external graphics of each pixel class, for H 1 And carrying out pattern inspection on the pixels, wherein the pixels with the minimum external patterns close to the acute triangle are reserved, the pixels not close to the acute triangle are removed, and M pixels are obtained and used as M ship trails.
7. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: in the step S6, the radial velocity field of the ship wake is inverted, and the calculation mode is as follows:
Figure FDA0004045568060000051
wherein v is w (n) represents the radial velocity of the wake area pixel point n.
8. The method for acquiring and measuring the wake velocity field of the interference SAR motion ship wake area according to claim 1, wherein the method comprises the following steps of: the specific steps of inversion in the step S7 are as follows:
s71, for each ship trail, respectively extracting an acute angle edge in a graph as each Kelvin trail, and obtaining Kelvin trail spectrum distribution by FFT operation, wherein the maximum spectrum peak corresponds to the wave number k of the Kelvin trail wave d Estimating the speed of the ship corresponding to the ship wake
Figure FDA0004045568060000052
The calculation method is as follows:
Figure FDA0004045568060000053
s72, the angular bisector direction of the included angles of the two Kelvin tails of each ship is recorded as the corresponding ship route, wherein the included angles of the two Kelvin tails in the tail point to the corresponding ship navigation direction.
CN202310037687.5A 2023-01-09 2023-01-09 Interference SAR motion ship wake area acquisition and wake velocity field measurement method Pending CN116125418A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310037687.5A CN116125418A (en) 2023-01-09 2023-01-09 Interference SAR motion ship wake area acquisition and wake velocity field measurement method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310037687.5A CN116125418A (en) 2023-01-09 2023-01-09 Interference SAR motion ship wake area acquisition and wake velocity field measurement method

Publications (1)

Publication Number Publication Date
CN116125418A true CN116125418A (en) 2023-05-16

Family

ID=86307600

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310037687.5A Pending CN116125418A (en) 2023-01-09 2023-01-09 Interference SAR motion ship wake area acquisition and wake velocity field measurement method

Country Status (1)

Country Link
CN (1) CN116125418A (en)

Similar Documents

Publication Publication Date Title
US11506776B2 (en) Method and device with improved radar resolution
KR100795497B1 (en) Wave measure method and system using radar
CN100365429C (en) Motive target imaging method of synthetic aperture radar
CN109633598B (en) Array radar target detection method based on characteristic analysis
JPH07505222A (en) Methods and devices for the detection and measurement of air phenomena and transmitters and receivers for use in such devices
CN102914773B (en) Multi-pass circumference SAR three-dimensional imaging method
CN112083417A (en) Distributed radar imaging topology design method based on wavenumber domain splicing
CN115166714B (en) Single-channel SAR moving ship two-dimensional speed estimation and repositioning method and device
US5164730A (en) Method and apparatus for determining a cross-range scale factor in inverse synthetic aperture radar systems
CN109343052A (en) Millimetre-wave radar tramcar anticollision method for early warning and system based on MIMO
Yang et al. A 3-D electromagnetic-model-based algorithm for absolute attitude measurement using wideband radar
CN113589275B (en) Combined observation method for sea surface wind field, sea wave and ocean current
CN113009473B (en) Multi-beam staring radar low elevation target height measurement method, device and medium
CN113419238A (en) Mountain landslide monitoring method based on millimeter wave radar, electronic device and storage medium
Hosseiny et al. Structural displacement monitoring using ground-based synthetic aperture radar
CN114355306A (en) Method for inverting wave height by using small-aperture high-frequency radar ocean echo
CN108776341A (en) Airborne synthetic aperture radar Doppler center offset calculation method
EP2562558B1 (en) Process for the localization of targets drifting in the sea
CN115546526B (en) Three-dimensional point cloud clustering method, device and storage medium
CN110308445B (en) Imaging method based on vehicle-mounted digital array frequency modulation continuous wave radar
CN116125418A (en) Interference SAR motion ship wake area acquisition and wake velocity field measurement method
Kupryashkin et al. Algorithm of signal processing in the radar system with continuous frequency modulated radiation for detection of small-sized aerial objects, estimation of their range and velocity
CN113093174B (en) PHD filter radar fluctuation weak multi-target-based pre-detection tracking method
CN116184343A (en) Three-dimensional space swarm target detection and information estimation method based on phased array radar
CN114942419A (en) Method for extracting three-degree-of-freedom micro-motion characteristics of scattering points of ship under long accumulation time

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination