AU2021102798A4 - Group target number discrimination method and system of the same - Google Patents
Group target number discrimination method and system of the same Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/66—Radar-tracking systems; Analogous systems
- G01S13/72—Radar-tracking systems; Analogous systems for two-dimensional tracking, e.g. combination of angle and range tracking, track-while-scan radar
- G01S13/723—Radar-tracking systems; Analogous systems for two-dimensional tracking, e.g. combination of angle and range tracking, track-while-scan radar by using numerical data
- G01S13/726—Multiple target tracking
-
- 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
- G01S13/04—Systems determining presence of a target
-
- 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
-
- 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
- G01S7/28—Details of pulse systems
- G01S7/285—Receivers
- G01S7/288—Coherent receivers
- G01S7/2883—Coherent receivers using FFT processing
-
- 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
- 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
- G01S7/418—Theoretical aspects
-
- 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
- G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
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- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The present disclosure relates to a group target number discrimination
method and a system of the same. The method comprises obtaining echo
signals of group targets; performing frequency mixing on the echo signals;
performing fractional order Fourier transform on the echo signals that are
processed by frequency mixing to form a data set; and according to the data
set, adopting a density clustering algorithm for clustering, and determining a
number of the group targets. The group target number discrimination method
and the system of the same provided in the present disclosure solves the
problems that the prior group target number discrimination method requires
an excessive signal duration and is interfered by cross items, and improves
the accuracy of target number discrimination.
ABSTRACT DRAWING FIG. 1
1/3
Obtain echo signals of group targets S101
Perform frequency mixing on the echo signals S102
Perform fractional order Fourier transform on the echo
signals upon frequency mixing to form a data set S103
According to the data set, adopt a density clustering
algorithm for clustering, and determining a number of S104
the group targets
FIG.1
Description
1/3
Obtain echo signals of group targets S101
Perform frequency mixing on the echo signals S102
Perform fractional order Fourier transform on the echo signals upon frequency mixing to form a data set S103
According to the data set, adopt a density clustering algorithm for clustering, and determining a number of S104 the group targets
FIG.1
[01] The present disclosure relates to the field of radar signal processing, and in particular to a group target number discrimination method and a system of the same.
[02] The electromagnetic environment in the modern warfare is deteriorating increasingly, and radar often faces complex multi-target environments in the battlefield. For example, attackers usually take the tight formation tactics as a major raid way, and aircrafts or ground radars decoy incoming missiles by means such as deception and interference all of which increase the difficulty for radars to accurately select and track targets. If the radar cannot distinguish multiple targets effectively or choose attack targets correctly, its target tracking performance will be greatly affected.
[03] Therefore, discrimination of the number of multiple targets is one of the key technologies that must be solved for radar signal processing, which is also an important part in the target tracking technology. Since echoes of multiple targets at a same speed among a formation of targets may be described by a group of linear frequency modulation (FM) signals with approximate FM, traditional methods often use methods such as the maximum entropy spectral estimation and the Winger-village distribution method to distinguish targets. However, these methods are often greatly affected by noise and cross-terms, and have the disadvantage of low resolution, which leads to fault distribution of the target number.
[04] The present disclosure aims at providing a group target number discrimination method and a system of the same, so as to solve the problems that the prior group target number discrimination method requires an excessive signal duration and is interfered by cross items, and to improve the accuracy of target number discrimination.
[05] In order to achieve the above purpose, the present disclosure provides the following scheme:
[06] A group target number discrimination method, including:
[07] Obtaining echo signals of group targets, wherein the echo signals are carrier signals;
[08] Performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals;
[09] Performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form a data set;
[10] According to the data set, adopting a density clustering algorithm for clustering, and determining a number of the group targets.
[11] Optionally, the step of obtaining the echo signals of the group targets specifically includes:
[12] Theformula x(t) Acos[2eft+2eft+wkt2 - 4efoRo+9 0 + ,] is utilized to determine the echo signals;
[13] Wherein A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, is a radial distance of a target relative to the
radar, fd is the Doppler frequency, k is a frequency modulation slope and 0r is a
phase shift due to the speed.
[14] Optionally, the step of performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form the data set specifically includes:
[15] Determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing; and
[16] Performing the fractional order Fourier transform on the mathematical model to form the data set.
[17] Optionally, the step of performing the fractional order Fourier transform on the mathematical model to form the data set specifically includes:
x(t)= x (t)= exp(j2fdft+jrckt')
[18] The formula "n=1 "n=1 is utilized to determine the mathematical model;
1- jcota(1) x(teeutcota-futscadt a# nc
X, x(t) a 2nc
[19] The formula -x(t) a (2n + 1)7c is utilized to perform the fractional order Fourier transform to form the data set;
[201 Wherein x(t) is an echo signal of a group target, M is a total number of
grouptargets, x"(t) isthe mth target among the group targets, fd is a Doppler
frequency of the m th target echo signal, k. is a modulation frequency of the
m th target echo signal, O ! t ! T , T is a signal duration of the target, i is an
imaginary part, a=pT/2 pe [0,4], and u is a transform domain.
[21] A system of group target number discrimination, including:
[22] An echo signal acquisition module, which is used for obtaining echo signals of group targets, wherein the echo signals are carrier signals;
[23] A frequency mixing module, which is used for performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals;
[24] A data set determination module, which is used for performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form the data set;
[251 A group target number determination module, which is used for, according to the data set, adopting a density clustering algorithm for clustering, and determining a number of the group targets.
[26] Optionally, the echo signal acquisition module specifically includes:
[27] An echo signal determination unit, which is used for utilizing the formula x(t)= Acos(2xfot+2xft+wkt2 -4fwR +90+ ,] to determine the echo signals;
[28] Wherein A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, is a radial distance of a target relative to the
radar, fd is the Doppler frequency, k is a frequency modulation slope and 0r is a
phase shift due to the speed.
[29] Optionally, the data set determination module specifically includes:
[30] A mathematical model determination unit, which is used for determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing; and
[31] A data set determination unit, which is used for performing the fractional order Fourier transform on the mathematical model to form the data set.
[32] Optionally, the data set determination unit specifically includes:
[33] A mathematical model determination sub-unit, which is used for utilizing the
x(t)= x,,(t)= exp(j2rcfft+jrckt) formula "n=1 rn=1 to determine the mathematical model;
[34] A data set determination sub-unit, which is used for utilizing the formula
1- j cot af( x(te)cotafuiscadt 2 a # nc
X,-(U) x(t) a =2n+c -x(t) a =(2n + 1); to perform the fractional order Fourier transform to form the data set;
[351 Wherein x(t) is an echo signal of a group target, M is a total number of
grouptargets, x"(t) isthe mth target among the group targets,f dn is a Doppler
frequency of the m th target echo signal, k. is a modulation frequency of the
m th target echo signal, O0 t: T , T is a signal duration of the target, i is an
imaginary part, a=pT/2 pe [0,4], and u is a transform domain.
[36] According to embodiments provided in the present disclosure, the present disclosure discloses the following technical effects:
[37] The group target number discrimination method and the system of the same provided by the present disclosure perform the fractional order Fourier transform according to obtained echo signals of group targets, and then adopt a density clustering algorithm, so as to solve the problems that the prior group target number discrimination method requires an excessive signal duration and is interfered by cross items. By virtue of the FFT fast algorithm, the method and system also have the advantages of reducing the computation load and simplifying the implementation process; and at the same time the method and system may cluster targets in the fractional Fourier domain according to the energy density of fractional Fourier transform, thus greatly reducing the influence caused by noises and improving the accuracy of the target number discrimination.
[38] In order to illustrate the embodiments of the present disclosure or technical schemes in the prior art more clearly, the accompanying drawings required in the embodiments will be briefly introduced below. Apparently, the drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skills in the art may obtain other drawings according to these drawings without creative work.
[39] Fig. 1 is a flow chart of a group target number discrimination method provided in the present disclosure;
[40] Fig. 2 is a schematic diagram of the determination of the group target number;
[41] Fig. 3 is a structure schematic diagram of a group target number discrimination system provided in the present disclosure.
[42] Technical schemes in the embodiments of the present disclosure will be described clearly and completely with reference to the accompanying drawings thereof. Apparently, the embodiments described herein are only part of, not all of, embodiments in the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skills in the art without creative work belong to the scope claimed by the present disclosure.
[43] The present disclosure aims at providing a group target number discrimination method and a system of the same, so as to solve the problems that the prior group target number discrimination method requires an excessive signal duration and is interfered by cross items, and to improve the accuracy of target number discrimination.
[44] So that the above mentioned purposes, features and advantages of the present disclosure can be more apparently understood, the present disclosure will be further described with reference to figures and embodiments below.
[45] Fig. 1 is a flow chart of a group target number discrimination method provided in the present disclosure. As shown in Fig. 1,the present disclosure provides a group target number discrimination method, including:
[46] In Step 101, obtaining echo signals of group targets, wherein the echo signals are carrier signals. The determination of echo signals is done in the premise that the radar transmits linear FM signals and the group targets move at a constant speed within a short time, without considering the attenuation of propagation process, low frequency modulation and noises.
[47] Step 101 specifically includes:
[48] Theformula x(t) Acos[2eft+2eft+wkt2 - 4efoRO+9 0 + ,] is utilized to determine the echo signals.
[49] Wherein A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, k is a radial distance of a target relative to the
radar, fd is the Doppler frequency, k is a frequency modulation slope and 0r is a
phase shift due to the speed.
[50] In Step 102, performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals. In other words, the carrier signals are converted into intermediate frequency signals.
[51] After frequency mixing, the echo signal frequency is moved from fo to a
place close to fd, and the echo signals upon frequency mixing are expressed as:
[52] x(t)= Acos[2Jft +1kt2]
[53] In Step 103, performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form a data set.
[54] Step 103 specifically includes:
[55] Determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing, which means for facilitating researches and analysis, a real signal is transformed into an analytical signal, and a mathematical model of echo signals of a target can be expressed as x(t)= Aexp(j2fit+jkt) wherein 0 t T, with T being a signal duration of a target.
[56] Performing the fractional order Fourier transform on the mathematical model to form the data set.
[57] The step of performing the fractional order Fourier transform on the mathematical model to form the data set specifically includes:
x(t)= Ix (t)= exp(j2cfdft+jrck.t)
[58] The formula "n=1 "n=1 is utilized to determine the mathematical model.
X, (U) !1- jcota () x(t) x(t )ect°°f-u""°c°dt a# nic
a 2nr
[59] The formula -x(t) a=(2n-+1)x is utilized to perform the fractional order Fourier transform to form the data set.
[60] In the formula, x(t) is an echo signal of a group target, M is a total number
of group targets, (t) is the m th target among the group targets, dA is a
Doppler frequency of the m th target echo signal, k' is a modulation frequency of
the m th target echo signal, o t T , T is a signal duration of the target, i is an
imaginary part, a=pT/2 pe [0,4], and u is a transform domain.
[61] In other words, the data set formed by performing the fractional order Fourier transform enables the signals to show the energy aggregation in a specific fractional order Fourier domain, and presents an obvious peak in amplitude; while the white noise remains the same after the fractional Fourier transform and has the energy evenly distributed on an axis of the transform domain u, without any energy aggregation in any fractional order Fourier domain. By virtue of this characteristic, multi-target signals may be aggregated into multiple energy clusters.
[62] In Step 104, according to the data set, adopting a density clustering algorithm for clustering, and determining a number of the group targets.
[63] Step 104 specifically includes:
[64] Assuming that X(u) is a data set containing 500x3600 objects, c=20 is a
search radius, and Minpts is a neighborhood density threshold, which is set to
2 Minpts = 2 X,(u), 3 herein.
[65] (1) Objects in all XU) are labeled as unpassed.
[66] (2) An object P is selected from an object XU) at random, and P is labeled as passed.
[67] (3) If at least one of 6 neighbors of P has more than or equal to Minpts
objects, a new cluster C is created and P is added to C.
[68] (4) Assuming that N is an object set in the 6 neighbor of P , as for each
point P in N, if P is unpassed, it is labeled as passed; if at least one of the8
neighbors of P has more than or equal to Minpts objects, these objects are
added to N, and if P does not pertain to any cluster, P is added to C.
[69] (5) C is output until there is no unpassed object left.
[70] The output result is as shown in Fig. 2, wherein C is the number of group
targets.
[71] Fig. 3 is a structure schematic diagram of a group target number discrimination system provided in the present disclosure. As shown in Fig. 3, the present disclosure provides a group target number discrimination system, including: an echo signal acquisition module 301, a frequency mixing module 302, a data set determination module 303, and a group target number determination module 304.
[72] The echo signal acquisition module 301 is used for obtaining echo signals of group targets, wherein the echo signals are carrier signals.
[73] The frequency mixing module 302 is used for performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals.
[74] The data set determination module 303 is used for performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form a data set.
[75] The group target number determination module 304 is used for, according to the data set, adopting a density clustering algorithm for clustering, and for determining a number of the group targets.
[76] The echo signal acquisition module 301 specifically includes:
[77] An echo signal determination unit, which is used for utilizing the formula x(t)= Acos(2xfot+2xft+Zkt2 -4fORO+90+ ,] to determine the echo signals.
[78] In the formula, A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, is a radial distance of a target relative to the
radar, fd is the Doppler frequency, k is a frequency modulation slope and 0r is a
phase shift due to the speed.
[79] The data set determination module 303 specifically includes: a mathematical model determination unit and a data set determination unit.
[80] The mathematical model determination unit is used for determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing.
[81] The data set determination unit is used for performing the fractional order Fourier transform on the mathematical model to form the data set.
[82] The data set determination unit specifically includes: a mathematical model determination sub-unit and a data set determination sub-unit.
[83] The mathematical model determination sub-unit is used to utilize the formula
x(t)= x,,(t)= exp(j2fdft+jrck.t) M=1 M=1 to determine the mathematical model,
sub-unit is used to utilize the formula
!1-
[84] The data set determination
jcota () x(tje jucota-utscadt a # nc
X, (U) x(t) a (2n+c -x(t) a = (2n + 1)c for performing the fractional order Fourier transform to form the data set.
[85] In the formula, x(t) is an echo signal of a group target, M is a total number
of group targets, (t) is the m th target among the group targets,dm is a
Doppler frequency of the m th target echo signal, k. is a modulation frequency of
the m th target echo signal, 0 t s T , T is a signal duration of the target, i is an
imaginary part, a=prT/2, pe [0,4], and u is a transform domain.
[86] In this specification, various embodiments are described in a progressive manner, with each embodiment focusing on its differences from other embodiments, while cross reference would be enough for those same or similar parts between the embodiments. As the system disclosed in the embodiment corresponds to the method disclosed in the embodiment, the description is relatively simple, and the correlated parts can be found in the method description.
[87] Principles and implementation of this present disclosure are described by specific examples, and the explanation of the above embodiments is only used to help understand the method and its core idea of the present disclosure. Also, those of ordinary skills in the art may take some modifications in the specific implementation and application scope according to the idea of the present disclosure. To sum up, the content of this specification should not be construed as limiting the present disclosure.
Claims (5)
1. A group target number discrimination method, comprising: Obtaining echo signals of group targets, wherein the echo signals are carrier signals; Performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals; Performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form a data set; and According to the data set, adopting a density clustering algorithm for clustering, and determining a number of the group targets.
2. The group target number discrimination method according to claim 1, wherein obtaining the echo signals of the group targets specifically comprises:
The formula x(t)= Acos[2cfot+2cft+Zkt2 -4cf0R +0 p9 + , is utilized to determine the echo signals;
Wherein A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, is a radial distance of a target relative
to the radar, d is the Doppler frequency, k is a frequency modulation slope
and 0r is a phase shift due to the speed.
3. The group target number discrimination method according to claim 1, wherein performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form the data set specifically comprises: Determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing; and Performing the fractional order Fourier transform on the mathematical model to form the data set; wherein performing the fractional order Fourier transform on the mathematical model to form the data set specifically comprises: x(t)= x.(t)= exp(j2rcf,.t+jrck.t The formula "n=1 "n=1 is utilized to determine the mathematical model;
1- jcota 0x(t)e z('u)cota - 2 zutscadt a #nc
X,(U) x() a 2nc
a (2n + 1)7c -x(t) The formula is utilized to perform the fractional order Fourier transform to form the data set;
Wherein, x(t) is an echo signal of a group target, M is a total number of
group targets, x",(t) is the m th target among the group targets,fd is a
Doppler frequency of the m th target echo signal, k - is a modulation
frequency of the m th target echo signal, 0 ts T , T is a signal duration of
the target, i is an imaginary part, a=pr/2, pe [0,4], and u is a transform
domain.
4. A group target number discrimination system, comprising: An echo signal acquisition module, which is used for obtaining echo signals of group targets, wherein the echo signals are carrier signals; A frequency mixing module, which is used for performing frequency mixing on the echo signals, wherein the echo signals upon frequency mixing are intermediate frequency signals; A data set determination module, which is used for performing the fractional order Fourier transform on the echo signals that are processed by frequency mixing to form the data set; A group target number determination module, which is used for, according to the data set, adopting a density clustering algorithm for clustering, and determining a number of the group targets.
5. The group target number discrimination system according to claim 4, wherein the echo signal acquisition module specifically comprises: An echo signal determination unit, which is used for utilizing the formula
x(t)= Acos(2xfot+2xft+kt2-4xfORO+ p%+ 9,] to determine the echo signals;
Wherein A is an amplitude factor, fo is a frequency emitted by a
transmitter, 0 is an initial phase, RO is a radial distance of a target relative
to the radar, Id is the Doppler frequency, k is a frequency modulation slope
and 0r is a phase shift due to the speed;
wherein the data set determination module specifically comprises: A mathematical model determination unit, which is used for determining a mathematical model of echo signals of the group targets according to the echo signals processed by frequency mixing; and A data set determination unit, which is used for performing the fractional order Fourier transform on the mathematical model to form the data set; wherein the data set determination unit specifically comprises: A mathematical model determination sub-unit, which is used for utilizing
x(t)= x,,(t)= exp(j2rcfft+jrckt) the formula 'n=1 'n=1 to determine the mathematical model; A data set determination sub-unit, which is used for utilizing the formula
1- jcota () x(tje jucota-utscad a # nc
X,-(U) x(t) a (2n+c -x(t) a = (2n + 1); to perform the
fractional order Fourier transform to form the data set;
Wherein, x(t) is an echo signal of a group target, M is a total number of
group targets, x(t) is the m th target among the group targets,f d is a
Doppler frequency of the m th target echo signal, k- is a modulation
frequency of the m th target echo signal, 0 ts T , T is a signal duration of
the target, i is an imaginary part, a=prc/2, pe [0,4], and u is a transform
domain.
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