CN112710997B - Radar maneuvering target detection method and system in scanning mode - Google Patents
Radar maneuvering target detection method and system in scanning mode Download PDFInfo
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Abstract
The invention relates to a method and a system for detecting a radar maneuvering target in a scanning mode. The method comprises the following steps: obtaining a distance-azimuth pulse two-dimensional echo of a maneuvering target in the current azimuth obtained in a radar scanning mode; performing FRFT operation on the pulse echo of each distance unit under the condition of FRFT conversion parameters to obtain detection statistics corresponding to each distance unit, detecting a maneuvering target in each distance unit according to the detection statistics, and outputting a first color group; carrying out non-coherent accumulation on the pulse echoes to obtain an amplitude average value, detecting the maneuvering target of the distance unit according to the amplitude average value, and outputting a second color group; superposing the first color group and the second color group to obtain the color display of the maneuvering target detection result; and updating the scanning direction of the antenna, and detecting the echo of the next scanning direction. The invention can realize the detection of the radar maneuvering target in the scanning mode and can distinguish different motion states of the moving target.
Description
Technical Field
The invention relates to the field of radar signal processing, in particular to a method and a system for detecting a maneuvering target of a radar in a scanning mode.
Background
The radar is used as a main means of target detection and plays an important role in civil and military fields such as environmental monitoring, early warning detection and the like. However, under the influence of the complex motion characteristics and the complex background environment of the target, the target echo shows low observable characteristics to different degrees, and the difficulty of radar detection is increased. The radar operating modes are mostly divided into a scanning mode in which the radar antenna performs a search in a space in a mechanical scanning or point scanning manner, and a staring (dwell) observation mode in which the number of target dwell pulses is small, and the mode is generally used for warning or monitoring a radar; the latter beam points to a specific direction, can obtain a long dwell time, has more available pulse numbers, and is generally used for further confirmation of the target and identification of the target. For gaze (dwell) observations, the overall data volume is less because the radar does not scan, although there are more direction-specific pulses. Therefore, how to realize the effective detection of the maneuvering target in the scanning mode is a difficult problem for engineering application.
At present, FRFT is applied to staring observation radar in a plurality of ways and has mature conditions, but the application of scanning mode radar has a difficult problem, which is mainly embodied in the following two aspects: firstly, the algorithm has large computation amount, FRFT is two-dimensional parameter search transformation, the transformation angle of FRFT corresponds to the speed change (acceleration) of a target, the motion characteristic of the target can be matched more accurately, but the two-dimensional transformation domain parameter search is needed, and compared with the one-dimensional Doppler domain search of the traditional MTD, the engineering realization difficulty and the computation amount are increased; secondly, one transformation angle only corresponds to the acceleration of one numerical value, so that only the target of the acceleration is matched when one-dimensional transformation domain search is carried out under a certain transformation angle condition, and other maneuvering targets are easy to lose; in addition, since the coherent accumulation detects the radial velocity, a part of stationary (doppler is zero), slow-moving (doppler overlaps with sea clutter) or tangential-moving (doppler is zero) targets are easily lost, thereby resulting in missed detection.
Disclosure of Invention
The invention aims to provide a method and a system for detecting a maneuvering target of a radar in a scanning mode so as to improve the detection performance of the maneuvering target.
In order to achieve the purpose, the invention provides the following scheme:
a radar maneuvering target detection method in a scanning mode comprises the following steps:
obtaining a distance-azimuth pulse two-dimensional echo of a maneuvering target in a current azimuth obtained in a radar scanning mode;
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of FRFT conversion parameters to obtain detection statistics corresponding to each distance unit; the detection statistics corresponding to the ith distance unit is an amplitude result obtained by performing FRFT operation, each distance unit comprises a plurality of pulse echoes, and the number of the pulse echoes in each distance unit is the same as the number of channels in an FRFT domain;
detecting maneuvering targets in the distance units according to the detection statistics corresponding to each distance unit, and outputting a first color group; the first color group comprises a color corresponding to each distance unit;
carrying out non-coherent accumulation on the pulse echo of each distance unit in the current direction to obtain an amplitude average value;
detecting the maneuvering target of each distance unit according to the average value of the amplitude of each distance unit, and outputting a second color group; the second color group comprises a color corresponding to each distance unit; colors in the second color set do not overlap colors in the first color set;
superposing the first color group and the second color group to obtain the color display of the detection result of the maneuvering target in the current direction;
and updating the scanning azimuth of the antenna, returning to the step of obtaining the distance-azimuth pulse two-dimensional echo of the maneuvering target in the current azimuth obtained in the radar scanning mode, and detecting the echo in the next scanning azimuth.
Optionally, the acquiring a range-azimuth pulse two-dimensional echo of a current azimuth obtained in a radar scanning mode further includes:
acquiring a maneuvering target detection mode; the maneuvering target detection mode includes a manual detection mode and an automatic detection mode.
Optionally, in the manual detection mode, performing an FRFT operation on the pulse echo of each range unit in the current direction under an FRFT transformation parameter condition to obtain a detection statistic corresponding to each range unit, specifically including:
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of current FRFT transformation parameters to obtain detection statistics corresponding to each distance unit; the detection statistic corresponding to each distance unit is a matrix of 1 multiplied by N; n is the number of pulse echoes of one range unit and is also the number of FRFT domain channels.
Optionally, in the manual detection mode, the maneuvering target in the distance unit is detected according to the detection statistic corresponding to each distance unit, and the first color group is output, which specifically includes:
judging whether a maneuvering target exists in each distance unit based on a two-dimensional constant false alarm detection method according to the detection statistics corresponding to all the distance units;
if the maneuvering target exists in the kth distance unit, outputting a first color at the position corresponding to the kth distance unit;
if no maneuvering target exists in the kth distance unit, not outputting the first color at the position corresponding to the kth distance unit;
and sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group.
Optionally, in the automatic detection mode, the performing FRFT operation on the pulse echo of each range unit in the current position under the condition of FRFT transformation parameters to obtain a detection statistic corresponding to each range unit specifically includes:
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of a plurality of FRFT conversion parameters to obtain detection statistics corresponding to each distance unit; the detection statistic corresponding to each distance unit is N p A matrix of x N; n is the number of pulse echoes of one FRFT operation of a range unit, N p Is FRFTThe number of transformation parameters, different FRFT transformation parameters correspond to different motion states; the motion states comprise a uniform motion state, a maneuvering motion state and a high maneuvering motion state.
Optionally, in the automatic detection mode, the method detects a maneuvering target in the distance unit according to the detection statistic corresponding to each distance unit, and outputs the first color group, which specifically includes:
for a kth distance unit, extracting the maximum value of the amplitude of each column in a detection statistic matrix corresponding to the kth distance unit to obtain the detection statistic after dimension reduction of the kth distance unit; the detection statistic of the kth distance unit after dimensionality reduction is a matrix of 1 multiplied by N, and the ith element in the detection statistic matrix after dimensionality reduction is the maximum value of the amplitude in the ith column in the detection statistic matrix before dimensionality reduction;
sequentially obtaining the detection statistic of each distance unit after dimension reduction;
judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method according to the detection statistics of all distance units after dimension reduction;
if the motor target exists in the kth distance unit, outputting a color corresponding to the motion state at the position corresponding to the kth distance unit according to the motion state of the motor target; the colors corresponding to different motion states are different;
if no maneuvering target exists in the kth distance unit, not outputting the color at the corresponding position of the kth distance unit;
and sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group.
Optionally, in the manual detection mode, the superimposing the first color group and the second color group to obtain a color display of the maneuvering target detection result, and then further including:
adjusting FRFT conversion parameters, returning to the step of performing FRFT operation on the pulse echo of each distance unit under the condition of the FRFT conversion parameters to obtain detection statistics corresponding to each distance unit, and detecting targets with different mobility performances; different FRFT transformation parameters correspond to target detection with different mobility, and the first color group output by the target detection with different mobility has different depth degrees.
Optionally, the detecting a maneuvering target in a distance unit according to the detection statistic corresponding to each distance unit, and outputting a first color group, and then further includes:
and estimating the initial speed and the acceleration of the maneuvering target according to the output first color set and by combining the FRFT parameters and the pulse echo parameters.
Optionally, the detecting the maneuvering target of the distance unit according to the average value of the amplitude of each distance unit and outputting the second color group specifically include:
judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method according to the average value of the amplitude values of all the distance units;
when a maneuvering target exists in the kth distance unit, outputting a second color at the corresponding position of the kth distance unit;
when no maneuvering target exists in the kth distance unit, not outputting a second color at the corresponding position of the kth distance unit;
and sequentially obtaining second color output results corresponding to all the distance units to obtain a second color group.
The invention also provides a radar maneuvering target detection system in the scanning mode, which comprises:
the echo acquisition module is used for acquiring a distance-azimuth pulse two-dimensional echo of the maneuvering target in the current azimuth, which is obtained in a radar scanning mode;
the FRFT operation module is used for carrying out FRFT operation on the pulse echo of each distance unit in the current direction under the condition of FRFT conversion parameters to obtain detection statistics corresponding to each distance unit; the detection statistics corresponding to the ith distance unit is an amplitude result obtained by performing FRFT operation, each distance unit comprises a plurality of pulse echoes, and the number of the pulse echoes in each distance unit is the same as the number of channels in an FRFT domain;
the first color group output module is used for detecting maneuvering targets in the distance units according to the detection statistics corresponding to each distance unit and outputting a first color group; the first color group comprises a color corresponding to each distance unit;
the non-coherent accumulation module is used for performing non-coherent accumulation on the pulse echo of each distance unit in the current direction to obtain an amplitude average value;
the second color output module is used for detecting the maneuvering targets of the distance units according to the average value of the amplitude of each distance unit and outputting a second color group; the second color group comprises a color corresponding to each distance unit; colors in the second color set do not overlap with colors in the first color set;
the maneuvering target detection result color display module is used for superposing the first color group and the second color group to obtain the color display of the maneuvering target detection result of the current position;
and the updating module is used for updating the scanning direction of the antenna, returning to the echo acquisition module and detecting the echo of the next scanning direction.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the method has the advantages that the FRFT can be used for effectively accumulating the maneuvering target, and the detection performance of the radar maneuvering target is effectively improved; and the search detection is only carried out at a certain or a plurality of conversion angles, thereby greatly reducing the computation amount and being suitable for the moving target detection of the scanning mode short pulse sequence. Meanwhile, FRFT coherent accumulation and the traditional inter-pulse non-coherent accumulation processing result are fused and output, static, slow, tangential movement and maneuvering targets can be detected simultaneously, and the probability of missed detection is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a method for detecting a maneuvering target of a radar in a scanning mode according to the present invention;
FIG. 2 is a schematic structural diagram of a radar maneuvering target detection system in a scanning mode according to the invention;
FIG. 3 is a schematic flow chart of embodiment 1 of the present invention;
fig. 4 is a schematic flow chart of embodiment 2 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a method for detecting a maneuvering target of a radar in a scanning mode according to the present invention. As shown in fig. 1, the method for detecting a radar maneuvering target in a scanning mode of the invention comprises the following steps:
step 100: and acquiring a distance-azimuth pulse two-dimensional echo of the maneuvering target in the current azimuth obtained in a radar scanning mode. The radar works in a scanning mode, the antenna points to one azimuth every time, then a series of distance units in the azimuth obtain a target detection result of the current azimuth, and then the next azimuth is scanned and sequentially performed. Therefore, for the current direction, the radar echo data of the distance direction is subjected to pulse compression processing to obtain radar echo data s after the distance pulse pressure PC (t,t m )：
Wherein t is the intra-pulse fast time t m For slow time between pulses, R s (t m ) Is the line-of-sight distance of the radar from the target, A r Is the echo amplitude, 2R s (t m ) C is time delay, B is transmission signal bandwidth, c 0 Representing the speed of light and λ the signal wavelength. Assuming that the target moves towards the radar and only the radial velocity component is considered, the range walk of the target is a polynomial function of time, and because the radar works in a scanning mode, the dwell time of a target beam is limited, and the range walk of the moving target can be represented by only a quadratic term.
In the formula, R s (t m ) Denotes the radial distance, r 0 Representing an initial distance; v. of 0 、a s Respectively representing the initial speed and the acceleration of the target as vectors, and storing a distance-orientation pulse two-dimensional data matrix S M×N ＝{s PC (i, j) | i =1,2, ·, M; j =1,2,.. N }, where M is the number of range cells and N is the number of pulse echoes in one range cell.
Step 200: and performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of FRFT conversion parameters to obtain the detection statistic corresponding to each distance unit. The invention comprises two maneuvering target detection modes, namely a manual detection mode and an automatic detection mode. In the manual detection mode, performing FRFT operation on pulse echoes of all distance units under the condition of one FRFT conversion parameter to obtain detection statistic corresponding to each distance unit, wherein the detection statistic corresponding to each distance unit is a matrix of 1 multiplied by N, the detection statistic of all distance units is a matrix of M multiplied by N, and D is used M×N Represents:
D M×N the middle row represents the detection statistic for each distance unit, and the columns represent different distancesAnd detecting the position of the same pulse echo of the unit. N is the number of pulse echoes of a distance unit and is also the number of FRFT domain channels; m is the number of distance units.
In the automatic detection mode, the pulse echo of each distance unit in the current direction is subjected to FRFT operation under the condition of a plurality of FRFT conversion parameters, and the detection statistic corresponding to each distance unit is obtained. The detection statistic corresponding to each distance unit is N p X N matrix, N being the number of pulse echoes of a range bin, N p The number of the FRFT conversion parameters is the number, different FRFT conversion parameters correspond to different motion states, and the motion states comprise a uniform motion state, a maneuvering motion state and a high maneuvering motion state. For the ith distance cell, the corresponding detection statistic is used
Represents:
Step 300: and detecting the maneuvering target in the distance unit according to the detection statistic corresponding to each distance unit, and outputting a first color group. And under the manual detection mode, judging whether a maneuvering target exists in each distance unit based on a two-dimensional constant false alarm detection method directly according to the detection statistics corresponding to all the distance units. If the maneuvering target exists in the kth distance unit, outputting a first color at the position corresponding to the kth distance unit; if no maneuvering target exists in the kth distance unit, not outputting the first color at the position corresponding to the kth distance unit; and sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group. Wherein, the two-dimensional constant false alarm detection method is the existing mature technology.
In the automatic detection mode, first, the dimension reduction of the detection statistic for each distance unit is required to obtain a 1 × N matrix. For the kth distance unit, extracting a detection statistic matrix corresponding to the kth distance unit
Obtaining the detection statistic after dimensionality reduction of the kth distance unit according to the maximum amplitude value of each column:
in the formula (I), the compound is shown in the specification,
represents the distance r k Of
And (4) the transformation parameter corresponding to the maximum value of the amplitude in the jth column vector. The detection statistic of the kth distance unit after dimensionality reduction is a matrix of 1 multiplied by N, and the jth element in the detection statistic matrix after dimensionality reduction is the maximum value of the amplitude in the jth column in the detection statistic matrix before dimensionality reduction.
Sequentially obtaining the detection statistic after dimension reduction of each distance unit, and obtaining the detection statistic C after dimension reduction of all distance units M×N ：
Then, the dimension reduced detection statistic C is obtained according to all distance units M×N And judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method. If the motor target exists in the kth distance unit, outputting the color corresponding to the motion state at the position corresponding to the kth distance unit according to the motion state of the motor target, wherein the color is differentThe corresponding colors of the motion states are different; and if no maneuvering target exists in the kth distance unit, not outputting the color at the corresponding position of the kth distance unit. And sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group.
After the first color set is output, the initial velocity and the acceleration of the maneuvering target can be estimated according to the output first color set in combination with the FRFT transformation parameter and the pulse echo parameter in both the manual detection mode and the automatic detection mode.
Step 400: and performing non-coherent accumulation on the pulse echoes of each distance unit in the current direction to obtain an amplitude average value. When non-coherent accumulation is performed, amplitude value average may be performed on the pulse echoes of each distance unit in sequence to obtain an amplitude average value, and the amplitude average value at this time is a value average value. Or carrying out amplitude weighted average on the pulse echoes of each distance unit in sequence to obtain an amplitude average value, wherein the amplitude average value corresponding to each unit is the weighted average value.
Step 500: and detecting the maneuvering target of the distance unit according to the average value of the amplitude of each distance unit, and outputting a second color group. The specific process is as follows:
judging whether the average value of the amplitude values corresponding to each distance unit is greater than a second threshold or not;
when the average value of the amplitude values corresponding to the kth distance unit is larger than a second threshold, determining that a maneuvering target exists in the kth distance unit, and outputting a second color at the position corresponding to the kth distance unit;
when the amplitude average value corresponding to the kth distance unit is not larger than a second threshold, determining that no maneuvering target exists in the kth distance unit, and not outputting a second color at the corresponding position of the kth distance unit;
and sequentially obtaining output results of the second colors corresponding to all the distance units to obtain a second color group.
Step 600: and superposing the first color group and the second color group to obtain the color display of the detection result of the maneuvering target in the current direction.
In the manual detection mode, after a detection result corresponding to the current FRFT conversion parameter is obtained, the step 200-the step 600 are executed again by adjusting the FRFT conversion parameter, so that target detection results with different mobility can be further obtained, and the depth degrees of first color groups output by target detection with different mobility are different. The larger the FRFT transformation parameters, the darker the color of the first color set, and the stronger the corresponding target mobility.
Step 700: the scanning orientation of the antenna is updated. And returning to the step 100, detecting the echo of the next scanning azimuth until all azimuths are scanned, and obtaining target detection results of all azimuths.
Based on the above method, the present invention further provides a system for detecting a radar maneuvering target in a scanning mode, and fig. 2 is a schematic structural diagram of the system for detecting a radar maneuvering target in a scanning mode according to the present invention. As shown in fig. 2, the system for detecting a maneuvering target of a radar in a scanning mode of the invention includes:
and the echo acquisition module 201 is configured to acquire a two-dimensional echo of a distance-azimuth pulse of the maneuvering target in the current azimuth, which is obtained in the radar scanning mode.
The FRFT operation module 202 is configured to perform FRFT operation on the pulse echo of each range unit in the current azimuth under the condition of an FRFT transformation parameter, so as to obtain detection statistics corresponding to each range unit; the detection statistics corresponding to the ith distance unit is an amplitude result obtained by performing FRFT operation, each distance unit comprises a plurality of pulse echoes, and the number of the pulse echoes in each distance unit is the same as the number of channels in an FRFT domain.
A first color group output module 203, configured to detect a maneuvering target in a distance unit according to the detection statistic corresponding to each distance unit, and output a first color group; the first color set includes a color corresponding to each distance cell.
And the non-coherent accumulation module 204 is configured to perform non-coherent accumulation on the pulse echo of each range unit in the current position to obtain an amplitude average value.
A second color output module 205, configured to detect a maneuvering target of a distance unit according to the average value of the amplitude of each distance unit, and output a second color group; the second color group comprises a color corresponding to each distance unit; the colors in the second color set do not overlap with the colors in the first color set.
A maneuvering target detection result color display module 206, configured to superimpose the first color group and the second color group to obtain a color display of a maneuvering target detection result in the current position;
and the updating module 207 is used for updating the scanning direction of the antenna, returning to the echo acquiring module and detecting the echo of the next scanning direction.
The above-described aspects of the present invention are further illustrated by the following examples.
Detailed description of the preferred embodiment 1
In this embodiment, a manual detection mode is adopted, and fig. 3 is a schematic flow chart of embodiment 1 of the present invention. As shown in fig. 3, the detection process includes two branches:
the first branch is an FRFT coherent accumulation branch, FRFT conversion parameters and an accumulated pulse number are set, according to the motion characteristics of the target to be detected, FRFT operation under the condition of specific conversion parameters is sequentially carried out on pulses in different distance units, the result is compared with a first threshold, the operation is repeated until the radar scanning is finished, and the detection result of the maneuvering target is output.
For scanning mode radar, the target residence time is short, and the maneuvering target echo of a certain range unit
With a distance r i I =1,2, M, using Linear Frequency Modulated (LFM) as an approximation
In the formula (I), the compound is shown in the specification,
denotes a distance r i Amplitude of echo at, by a distance r i Initial velocity of signal at
Initial frequency of generation
By a distance r i Signal acceleration of
Frequency modulation rate generated
The FRFT of the echo signal is expressed as
Wherein p is a transformation parameter, and belongs to (-2,2)]，F p For FRFT operator, T n For coherent integration time, T for scanning radar n I.e. dwell time of one beam, K p (t m And u) represents a FRFT kernel function,
in the formula, A p Is a coefficient, n is an integer,
is the angle of rotation;
performing p on N pulse echoes in a certain range unit i FRFT operation under the condition that N represents the total number of azimuth pulses in a beam range and the time length of the azimuth pulses is not more than T n According to the motion characteristics of the target to be detected, specific transformation parameters p are sequentially carried out on the pulses in different distance units i FRFT operation under the conditions p i Given by the following relationship:
transformation parameter p and frequency modulation
In a relationship of
In the formula (I), the compound is shown in the specification,
is the frequency modulation rate after dimension normalization,
fs is the sampling frequency; due to the fact that
The value range of (0, pi) is obtained, so the value range of p after dimension normalization is (0,2), and the value range of p is [1,2) due to the symmetry of p, so the value range of p is [1,p ] 1 ,p 2 ,...,p i ,., 2), the larger the value of p, the higher the corresponding frequency modulation rate, the stronger the target maneuverability is represented, and the value of the FRFT conversion parameter can be adjusted according to the requirement in the manual mode;
sequentially carrying out specific transformation parameters p on pulses in different distance units i Performing FRFT operation under the condition, and forming the amplitude value into detection statistic D M×N ：
In the formula (I), the compound is shown in the specification,
represents the distance r i Where (i.e. distance unit r) i ) Echo transformation parameter p i FRFT domain of D, D M×N And comparing each element with a threshold, if the amplitude is lower than the detection threshold, judging that the distance unit has no maneuvering target, and if the amplitude is higher than the detection threshold, judging that the distance unit has maneuvering target.
And the second branch is a non-coherent accumulation branch, the number of accumulated pulses in the second branch is the same as that of the accumulated pulses in the first branch, the pulse amplitude values in each distance unit are sequentially averaged, the average value of the amplitude values is compared with a second threshold, the steps are repeated until the radar scanning is finished, and a target detection result is output and displayed by a color B.
And superposing and displaying the results of the first branch and the second branch to obtain a final detection result.
Manually adjusting transformation parameter p i And expressing the detection results under different conversion parameter conditions by using a color A, wherein the color depth corresponds to the size of the conversion parameter, and the darker the color is, the larger the conversion parameter is, and the stronger the target mobility is. And finally, target detection results under different maneuvering performances can be obtained.
Finally, the motion parameters of the target may be estimated. The transformation parameter corresponding to the peak value of the over-detection threshold and the peak value coordinate of the optimal transformation domain are
Then the initial velocity estimate of the target
And an acceleration estimate
Comprises the following steps:
specific example 2
In this embodiment, an automatic detection mode is adopted, and fig. 4 is a schematic flow chart of embodiment 2 of the present invention. As shown in fig. 4, in the automatic detection mode, the first branch is an FRFT coherent accumulation branch, a certain number of FRFT conversion parameters are set, which correspond to the motion states of uniform motion, maneuver, high maneuver, and the like, the FRFT operations under the condition of multiple conversion parameters are sequentially performed on the pulses in different distance units, the result is compared with a threshold, the operations are repeated until the radar scanning is finished, the maneuvering target detection result is output, and the result is displayed in a color C \ D \ E …, where the number is the same as the number of the conversion parameters; the second branch has the same process as the second branch in the manual detection mode and is displayed in color B; and the results of the first branch and the second branch are displayed in an overlapping manner.
In this embodiment, the FRFT conversion parameter setting method includes: p is a radical of 1 =1, corresponding to a uniform motion target; p is a radical of 2 =1+ Δ p', corresponding to a maneuvering target; p is a radical of formula 3 =1+2 Δ p', corresponding to a high maneuver target; p is a radical of i =1+ (i-1) Δ p', transformation parameter p i Number is N p ，N p And the interval Δ p' is adjusted according to the resources of the radar system, typically not more than 5 for scanning the radar.
The FRFT operation method under the condition of a plurality of transformation parameters comprises the following steps: first, N is performed for each range bin p FRFT operation under the condition of individual transformation parameters to obtain the distance r i Matrix of (2)
Reducing the dimension of the operation result of each distance unit, taking the maximum value of the column vector amplitude value to obtain the FRFT amplitude value of the optimal transformation parameter of different FRFT domain channels
In the formula (I), the compound is shown in the specification,
represents the distance r i Of
The transformation parameter corresponding to the maximum value of the amplitude of the jth column vector;
sequentially carrying out FRFT operation on the pulses in different distance units under the condition of a plurality of transformation parameters to form detection statistic C M×N ，
C is to be M×N Comparing the distance unit with a threshold, if the amplitude is lower than the detection threshold, judging that the distance unit has no maneuvering target, and if the amplitude is higher than the detection threshold, judging that the distance unit has maneuvering target; and repeating the steps until the radar scanning is finished, outputting a maneuvering target detection result, and displaying by using the color C \ D \ E …, wherein the number is the same as the number of the conversion parameters, and different colors represent different motion states.
Finally, the motion parameters of the target may be estimated. The transformation parameter corresponding to the peak value of the over-detection threshold and the peak value coordinate of the optimal transformation domain are
Then the initial velocity estimate of the target
And an acceleration estimate
Comprises the following steps:
the embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A method for detecting a radar maneuvering target in a scanning mode is characterized by comprising the following steps:
obtaining a distance-azimuth pulse two-dimensional echo of a maneuvering target in a current azimuth obtained in a radar scanning mode;
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of FRFT transformation parameters to obtain detection statistics corresponding to each distance unit; the detection statistics corresponding to the ith distance unit is an amplitude result obtained by performing FRFT operation, each distance unit comprises a plurality of pulse echoes, and the number of the pulse echoes in each distance unit is the same as the number of channels in an FRFT domain;
detecting maneuvering targets in the distance units according to the detection statistics corresponding to each distance unit, and outputting a first color group; the first color group comprises a color corresponding to each distance unit;
carrying out non-coherent accumulation on the pulse echo of each distance unit in the current direction to obtain an amplitude average value;
detecting the maneuvering target of each distance unit according to the average value of the amplitude of each distance unit, and outputting a second color group; the second color group comprises a color corresponding to each distance unit; colors in the second color set do not overlap with colors in the first color set;
the detecting the maneuvering target of the distance unit according to the average value of the amplitude of each distance unit and outputting a second color group specifically comprises:
judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method according to the average value of the amplitude values of all the distance units;
when a maneuvering target exists in the kth distance unit, outputting a second color at the corresponding position of the kth distance unit;
when no maneuvering target exists in the kth distance unit, outputting no second color in the corresponding position of the kth distance unit;
sequentially obtaining second color output results corresponding to all the distance units to obtain a second color group;
superposing the first color group and the second color group to obtain the color display of the detection result of the maneuvering target in the current direction;
and updating the scanning azimuth of the antenna, returning to the step of obtaining the distance-azimuth pulse two-dimensional echo of the maneuvering target in the current azimuth obtained in the radar scanning mode, and detecting the echo in the next scanning azimuth.
2. The method for detecting a radar maneuvering target in scanning mode according to claim 1, characterized in that the obtaining a range-azimuth pulse two-dimensional echo of the current azimuth obtained in radar scanning mode further comprises:
acquiring a maneuvering target detection mode; the maneuvering target detection mode includes a manual detection mode and an automatic detection mode.
3. The method according to claim 2, wherein in the manual detection mode, the FRFT operation is performed on the pulse echo of each range bin in the current orientation under the condition of FRFT transformation parameters to obtain a detection statistic corresponding to each range bin, and specifically includes:
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of current FRFT conversion parameters to obtain detection statistics corresponding to each distance unit; the detection statistic corresponding to each distance unit is a matrix of 1 multiplied by N; n is the number of pulse echoes of one range bin.
4. The method according to claim 3, wherein in the manual detection mode, detecting the maneuvering target in the range bin according to the detection statistic corresponding to each range bin, and outputting the first color set, specifically comprises:
judging whether a maneuvering target exists in each distance unit based on a two-dimensional constant false alarm detection method according to the detection statistics corresponding to all distance units;
if the maneuvering target exists in the kth distance unit, outputting a first color at the position corresponding to the kth distance unit;
if no maneuvering target exists in the kth distance unit, not outputting the first color at the corresponding position of the kth distance unit;
and sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group.
5. The method according to claim 2, wherein in the automatic detection mode, the FRFT operation is performed on the pulse echo of each range bin in the current orientation under the condition of FRFT transformation parameters to obtain a detection statistic corresponding to each range bin, and specifically includes:
performing FRFT operation on the pulse echo of each distance unit in the current direction under the condition of a plurality of FRFT transformation parameters to obtain detection statistics corresponding to each distance unit; the detection statistic corresponding to each distance unit is N p A matrix of x N; n is the number of pulse echoes of a range unit, N p The number of the FRFT transformation parameters is the same, and different FRFT transformation parameters correspond to different motion states; the motion states comprise a uniform motion state, a maneuvering motion state and a high maneuvering motion state.
6. The method according to claim 5, wherein in the automatic detection mode, detecting the maneuvering target in the range bin according to the detection statistic corresponding to each range bin, and outputting the first color set, specifically comprises:
for a kth distance unit, extracting the maximum value of the amplitude of each column in a detection statistic matrix corresponding to the kth distance unit to obtain the detection statistic after dimension reduction of the kth distance unit; the detection statistic of the kth distance unit after dimensionality reduction is a matrix of 1 multiplied by N, and the ith element in the detection statistic matrix after dimensionality reduction is the maximum value of the amplitude in the ith column in the detection statistic matrix before dimensionality reduction;
sequentially obtaining the detection statistics of each distance unit after dimension reduction;
judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method according to the detection statistics of all distance units after dimension reduction;
if the motor target exists in the kth distance unit, outputting a color corresponding to the motion state at the position corresponding to the kth distance unit according to the motion state of the motor target; the colors corresponding to different motion states are different;
if no maneuvering target exists in the kth distance unit, not outputting the color at the corresponding position of the kth distance unit;
and sequentially obtaining the color result output by the corresponding position of each distance unit to obtain the first color group.
7. The method according to claim 3, wherein in the manual detection mode, the overlaying the first color set and the second color set results in a color display of a maneuvering target detection result, and then further comprises:
adjusting FRFT conversion parameters, returning to the step of performing FRFT operation on the pulse echo of each distance unit under the condition of the FRFT conversion parameters to obtain detection statistics corresponding to each distance unit, and detecting targets with different mobility performances; different FRFT transformation parameters correspond to target detection with different mobility, and the first color group output by the target detection with different mobility has different depth degrees.
8. The method of claim 1, wherein the detecting maneuvering targets in range cells according to the detection statistics corresponding to each range cell, outputting a first color set, and then further comprising:
and estimating the initial speed and the acceleration of the maneuvering target according to the output first color group by combining the FRFT parameters and the pulse echo parameters.
9. A radar maneuvering target detection system in a scanning mode, comprising:
the echo acquisition module is used for acquiring a distance-azimuth pulse two-dimensional echo of the maneuvering target in the current azimuth, which is obtained in a radar scanning mode;
the FRFT operation module is used for carrying out FRFT operation on the pulse echo of each distance unit in the current direction under the condition of FRFT conversion parameters to obtain detection statistics corresponding to each distance unit; the detection statistics corresponding to the ith distance unit is an amplitude result obtained by performing FRFT operation, each distance unit comprises a plurality of pulse echoes, and the number of the pulse echoes in each distance unit is the same as the number of channels in an FRFT domain;
the first color group output module is used for detecting the maneuvering target in the distance unit according to the detection statistic corresponding to each distance unit and outputting a first color group; the first color group comprises a color corresponding to each distance unit;
the non-coherent accumulation module is used for performing non-coherent accumulation on the pulse echo of each distance unit in the current position to obtain an amplitude average value;
the second color output module is used for detecting the maneuvering targets of the distance units according to the average value of the amplitude of each distance unit and outputting a second color group; the second color group comprises a color corresponding to each distance unit; colors in the second color set do not overlap with colors in the first color set;
the detecting the maneuvering target of the distance unit according to the average value of the amplitude of each distance unit and outputting a second color group specifically comprises:
judging whether a maneuvering target exists in the first distance unit or not based on a two-dimensional constant false alarm detection method according to the average value of the amplitude values of all the distance units;
when a maneuvering target exists in the kth distance unit, outputting a second color at the corresponding position of the kth distance unit;
when no maneuvering target exists in the kth distance unit, outputting no second color in the corresponding position of the kth distance unit;
sequentially obtaining second color output results corresponding to all the distance units to obtain a second color group;
the maneuvering target detection result color display module is used for overlapping the first color group and the second color group to obtain the color display of the maneuvering target detection result in the current direction;
and the updating module is used for updating the scanning direction of the antenna, returning to the echo acquisition module and detecting the echo of the next scanning direction.
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