CN111580057A - Moving target echo range migration correction method - Google Patents

Moving target echo range migration correction method Download PDF

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Publication number
CN111580057A
CN111580057A CN201910121191.XA CN201910121191A CN111580057A CN 111580057 A CN111580057 A CN 111580057A CN 201910121191 A CN201910121191 A CN 201910121191A CN 111580057 A CN111580057 A CN 111580057A
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frequency domain
domain signal
multiplying
signal
correction method
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任鹏冲
陈燕丽
李艳龙
艾岚
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Beijing Huahang Radio Measurement Research Institute
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Beijing Huahang Radio Measurement Research Institute
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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
    • 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

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention relates to a distance correction method under the condition of range migration of radar echo during detection of a moving target, which comprises the steps of multiplying the detected target echo by a coefficient according to system characteristics to construct an input signal g (n), carrying out time-frequency domain conversion on g (n) to obtain a frequency domain result G (k), constructing a unit sampling response h (n) according to the system characteristics, carrying out time-frequency domain conversion on h (n) to obtain a frequency domain result H (k), multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k), converting V (k) to a time domain to obtain a time domain signal v (n), constructing a coefficient sequence α (n), and multiplying the coefficient sequence v (n) to obtain a final range migration corrected signal x (z)n). The method has the advantages of small calculation amount, high precision and convenient engineering realization, and can improve the signal-to-noise ratio of the motion target echo after accumulation.

Description

Moving target echo range migration correction method
Technical Field
The invention belongs to the field of radar signal processing, and particularly relates to a distance correction method under the condition of range migration of radar echoes during detection of a moving target.
Background
In pulse system radar, a radar system generally adopts a basic operation of pulse accumulation on pulse echo samples to improve a signal-to-noise ratio, so that the detection performance of the radar system is improved. The ideal target signal-to-noise ratio after the accumulation of the N coherent pulses is N times of the target signal-to-noise ratio of the monopulse echo, but when the detected target is a moving target, the radar echo can generate a range migration phenomenon in the range direction, so that the signal-to-noise ratio of the accumulated target echo signal is reduced, and the radar detection performance is influenced. The invention aims at the actual situation, performs range correction on the pulse echo, and improves the signal-to-noise ratio after accumulation, thereby improving the radar detection performance.
Disclosure of Invention
The invention provides a solution based on Keystone transformation aiming at the range migration condition of radar echo during moving target detection. In the Keystone transform, the signal is transformed from the slow time dimension tm to the virtual slow time dimension τ m, there is a difference in scale, and the spacing of the sample points on the unit circle is frequency dependent and no longer uniformly distributed, and therefore cannot be directly implemented by FFT. The method of the invention is a rapid algorithm for obtaining the sampling values of the various points with unequal intervals, and the basic principle is to adopt spiral sampling to obtain the z transformation of each sampling point, so as to be used as the DFT value of each point, thereby correcting the radar echo distance migration caused by the target motion.
A moving target echo range migration correction method comprises the following steps:
s1, multiplying a detection target echo by a coefficient according to system characteristics to construct an input signal g (n), and performing FFT on the input signal g (n) to obtain a frequency domain result G (k);
s2, constructing unit sampling response h (n), and performing FFT on the unit sampling response h (n) to obtain a frequency domain result H (k);
s3, multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k), and carrying out IFFT on the composite frequency domain signal V (k) to obtain a time domain signal of the composite frequency domain signal;
s4, constructing a coefficient sequence α (n), and multiplying the time domain signal v (n) with the coefficient sequence α (n) to obtain a final distance migration corrected time domain signal x (z)n)。
Has the advantages that: the invention provides a distance correction method under the condition that a radar echo undergoes range migration during moving target detection. And according to the characteristics of the echo signals and the system characteristics, obtaining the z transformation of each sampling point by adopting spiral sampling on the echo signals, and taking the z transformation as the DFT value of each point. The method greatly reduces the operation amount of correction and is convenient for engineering realization.
Drawings
Fig. 1 is a flow chart of range migration correction in an embodiment of the present invention;
FIG. 2 is a simulation moving target echo pulse accumulation top view and a fuzzy function three-dimensional graph;
FIG. 3 is a top view and a three-dimensional image of a fuzzy function of the echo pulse accumulation of a moving target processed by a range migration correction method.
Detailed Description
The technical solution of the present invention will be explained and explained in further detail with reference to the accompanying drawings and the detailed description.
A moving target echo range migration correction method comprises the following steps:
s1, multiplying a detection target echo by a coefficient according to system characteristics to construct an input signal g (n), and performing FFT on the input signal g (n) to obtain a frequency domain result G (k);
the concrete implementation steps are as follows:
s1.1 constructs an input pulse sequence x (n).
Figure BDA0001971915990000021
Wherein the content of the first and second substances,
Figure BDA0001971915990000022
represents intra-pulse time, m-0, 1.., t-1; n-0, 1,2 …, M-1, indicating the serial number of the pulse; m is the number of coherent accumulated pulses, TrFor the pulse repetition period, fcIs the carrier frequency, RnC is the distance between the radar and the target when the nth pulse is transmitted, and c is the speed of light.
S1.2 inputting pulse sequence x (n) and
Figure BDA0001971915990000023
the multiplication results in an input signal g (n).
Calculating x (n) and
Figure BDA0001971915990000024
multiplying to obtain an input signal g (n):
Figure BDA0001971915990000025
wherein:
Figure BDA0001971915990000026
s1.3, performing FFT on an input signal g (n) to obtain a frequency domain signal G (k):
G(k)＝FFT(g(n)) (3)
s2, constructing unit sampling response h (n), and performing FFT to obtain frequency domain result H (k).
The concrete implementation steps are as follows:
s2.1 construction of Unit sample response h (n):
Figure BDA0001971915990000031
wherein the content of the first and second substances,
Figure BDA0001971915990000032
s2.2, FFT is carried out on h (n), and a frequency domain result H (k) is obtained:
H(k)＝FFT(h(n)) (6)
s3, multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k), and carrying out IFFT on the composite frequency domain signal V (k) to obtain a time domain signal of the composite frequency domain signal;
the method specifically comprises the following steps:
s3.1, multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k):
V(k)＝G(k)H(k) (7)
s3.2, IFFT is carried out on the frequency domain signal V (k) to obtain a time domain signal v (n).
The method specifically comprises the following steps:
V(k)＝IFFT(v(n)) (8)
s4, constructing a coefficient sequence α (n), and multiplying the time domain signal v (n) with the coefficient sequence α (n) to obtain a final distance migration corrected time domain signal x (z)n)；
The method comprises the following specific steps:
s4.1, constructing a coefficient sequence alpha (n), specifically:
Figure BDA0001971915990000033
wherein:
Figure BDA0001971915990000034
s4.2, multiplying the time domain signal v (n) by the coefficient sequence α (n) to obtain the final time domain signal x (z) after the distance migration correctionn)：
x(zn)＝v(n)α(n) (10)
Wherein z isnThe sampled points are sampled using a spiral.
In summary, the invention provides a distance correction method under the condition of range migration of radar echo when a moving target is detected. The method is a simple and convenient realization method of a Keystone distance migration compensation algorithm, and the basic principle is that the z transformation of each sampling point is obtained by adopting spiral sampling and is used as the DFT value of each sampling point. The method is used for detecting a moving target by a pulse system radar, and can improve the signal-to-noise ratio after coherent accumulation of radar echoes, thereby improving the detection performance of the system.
The above-mentioned embodiments are only used for explaining and explaining the technical solution of the present invention, but should not be construed as limiting the scope of the claims. It should be clear to those skilled in the art that any simple modification or replacement based on the present invention will still fall within the scope of the present invention.

Claims (5)

1. A moving target echo range migration correction method comprises the following steps:
s1, multiplying a detection target echo by a coefficient according to system characteristics to construct an input signal g (n), and performing FFT on the input signal g (n) to obtain a frequency domain result G (k);
s2, constructing unit sampling response h (n), and performing FFT on the unit sampling response h (n) to obtain a frequency domain result H (k);
s3, multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k), and carrying out IFFT on the composite frequency domain signal V (k) to obtain a time domain signal of the composite frequency domain signal;
s4, constructing a coefficient sequence α (n), and multiplying the time domain signal v (n) with the coefficient sequence α (n) to obtain a final distance migration corrected time domain signal x (z)n)。
2. The echo range migration correction method of claim 1, wherein the step S1 includes the steps of:
s1.1, constructing an input pulse sequence x (n);
Figure RE-FDA0002062680590000011
wherein the content of the first and second substances,
Figure RE-FDA0002062680590000012
represents intra-pulse time, m-0, 1.., t-1; n-0, 1,2 …, M-1, indicating the serial number of the pulse; m is the number of coherent accumulated pulses, TrFor the pulse repetition period, fcIs the carrier frequency, RnC is the distance between the radar and the target when the nth pulse is transmitted, and c is the speed of light;
s1.2 inputting pulse sequence x (n) and
Figure RE-FDA0002062680590000013
multiplying to obtain an input signal g (n);
calculating x (n) and
Figure RE-FDA0002062680590000014
multiplying to obtain an input signal g (n):
Figure RE-FDA0002062680590000015
wherein:
Figure RE-FDA0002062680590000016
s1.3, performing FFT on an input signal g (n) to obtain a frequency domain signal G (k):
G(k)＝FFT(g(n)) (3)。
3. the echo range migration correction method of claim 1, wherein the step S2 includes the steps of:
s2.1 construction of Unit sample response h (n):
Figure RE-FDA0002062680590000021
wherein the content of the first and second substances,
Figure RE-FDA0002062680590000022
s2.2 h (n) FFT, obtaining the frequency domain result H (k):
H(k)＝FFT(h(n)) (6)。
4. the echo range migration correction method of claim 1, wherein the step S3 includes the steps of:
s3.1, multiplying G (k) by H (k) to obtain a composite frequency domain signal V (k):
V(k)＝G(k)H(k) (7)
s3.2, performing IFFT on the frequency domain signal V (k) to obtain a time domain signal v (n);
the method specifically comprises the following steps:
V(k)＝IFFT(v(n)) (8)。
5. the echo range migration correction method of claim 1, wherein the step S4 includes the steps of:
s4.1, constructing a coefficient sequence alpha (n), specifically:
Figure RE-FDA0002062680590000023
wherein：
Figure RE-FDA0002062680590000024
S4.2, multiplying the time domain signal v (n) by the coefficient sequence α (n) to obtain the final time domain signal x (z) after the distance migration correctionn)：
x(zn)＝v(n)α(n) (10)
Wherein z isnThe sampled points are sampled using a spiral.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104062640A (en) * 2014-06-30 2014-09-24 北京理工大学 Quick implementation method for passive radar range migration compensation
CN204009063U (en) * 2014-06-12 2014-12-10 北京华航无线电测量研究所 Phased-array radar beam control device
CN106886177A (en) * 2016-12-16 2017-06-23 北京华航无线电测量研究所 A kind of Radar Signal Processing System
CN108279403A (en) * 2018-01-04 2018-07-13 电子科技大学 Parallel Implementation method is converted based on the Keystone apart from framing

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN204009063U (en) * 2014-06-12 2014-12-10 北京华航无线电测量研究所 Phased-array radar beam control device
CN104062640A (en) * 2014-06-30 2014-09-24 北京理工大学 Quick implementation method for passive radar range migration compensation
CN106886177A (en) * 2016-12-16 2017-06-23 北京华航无线电测量研究所 A kind of Radar Signal Processing System
CN108279403A (en) * 2018-01-04 2018-07-13 电子科技大学 Parallel Implementation method is converted based on the Keystone apart from framing

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
王娟 等: "Keystone变换实现方法研究", 《火控雷达技术》 *

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