CN108919250B - Low and small slow moving target processing method based on multispectral accurate interpolation - Google Patents

Low and small slow moving target processing method based on multispectral accurate interpolation Download PDF

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CN108919250B
CN108919250B CN201810763418.6A CN201810763418A CN108919250B CN 108919250 B CN108919250 B CN 108919250B CN 201810763418 A CN201810763418 A CN 201810763418A CN 108919250 B CN108919250 B CN 108919250B
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frequency
distance unit
frequency spectrum
value
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CN108919250A (en
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周骏
王锰
丁友峰
张恒
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724th Research Institute of CSIC
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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
    • G01S13/02—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
    • G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
    • 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
    • G01S13/522—Discriminating between fixed and moving objects or between objects moving at different speeds using transmissions of interrupted pulse modulated waves
    • 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
    • G01S7/414—Discriminating targets with respect to background clutter
    • 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
    • G01S7/415—Identification of targets based on measurements of movement associated with the 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
    • 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

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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 discloses a low and small slow moving target processing method based on multispectral accurate interpolation, wherein a storage module (101) stores pulse compression IQ data of N radar related pulses and outputs N IQ data of the same distance unit according to the distance unit. The weighting module (102) weights the storage module (101), and the FFT module (103) performs FFT on the weighted data to acquire N spectral line data. The Doppler interpolation estimation module (104) calculates the main frequency spectrum component of the current distance unit by using the N frequency spectrum line data, and performs frequency spectrum leakage compensation on the N frequency spectrum line data by using the main frequency spectrum component information to further calculate the secondary frequency spectrum component of the current distance unit. The Doppler information judging module (105) utilizes the main frequency spectrum component and the secondary frequency spectrum component information output by the Doppler interpolation estimation module (104) to determine whether the current distance unit has a moving target or not, and if so, the current distance unit is output.

Description

Low and small slow moving target processing method based on multispectral accurate interpolation
Technical Field
The invention relates to the technical field of radar signal processing, in particular to a design method for low-small-slow moving target processing.
Background
With the opening of low altitudes below 3000 m in China and the explosive growth of various private small and medium-sized low-altitude aircrafts, higher technical requirements are provided for the control of the peripheral low-altitude flight of military aviation, civil aviation and navigation airports. In recent years, in many civil airports at home and abroad, the situation that flight stops due to black flight of small unmanned aerial vehicles occurs, most airports currently rely on large air traffic control radars, ADS-B, radio stations and the like to monitor and manage aerial flight targets, and small low-altitude aircrafts cannot be detected, monitored and controlled, so that great threat is brought to safety guarantee of the airports.
The traditional moving target processing algorithm uses two-pulse cancellation, three-pulse cancellation, an optimized IIR filter, a clutter map and the like. The two-pulse cancellation and the three-pulse cancellation use FIR filters which have the characteristics of linear phase, short transient response time and simple realization and are widely applied. However, the two-pulse cancellation and three-pulse cancellation methods have great inhibition on slow-speed moving targets. Due to the fact that the number of relevant pulses of the radar is limited, the traditional linear phase FIR filter is too large in transition band, low-speed targets are severely restrained, the nonlinear phase FIR filter is used, the notch of the filter is too narrow to effectively restrain ground objects, and the optimized IIR filter is used, so that the radar anti-jamming capability is weak. The traditional clutter map method cannot process weak and small slow targets.
Disclosure of Invention
The invention aims to design a moving target processing method based on Doppler estimation applied to radar signal processing, which is used for solving the problem that the existing radar moving target algorithm has large loss to low and small slow target processing and even can not process the low and small slow target processing at all.
The technical solution for realizing the purpose of the invention is as follows:
1) let x be ═ x1 x2 ... xn]The time series vector of the relevant pulse of the same range unit of the radar is shown, wherein n is the number of coherent pulses, n is more than or equal to 8, and n is the power of 2. Windowing the X, performing n-point FFT on the windowed data to obtain n-point FFT results X '(K), and taking an absolute value of the X' (K) to obtain X (K);
2) finding the maximum X (l) of X (K), and taking two adjacent spectral lines X (l-1) and X (l + 1); calculating the frequency value Fk of the main component of the frequency spectrum of the distance unit through X (l-1), X (l +1)0Intensity value Ak0And phase Pk0；
3) According to the frequency value Fk0Intensity value Ak0And phase Pk0The value of (a) is combined with a frequency spectrum compensation table to obtain a leakage value Fi (K) of the main component of the distance unit in other components, wherein K is 1,2,. n, and the result X' (K) of FFT is compensated; setting the compensated data as X _ new (k), and calculating an absolute value X _ nabs (k), wherein k is 1,2,. n;
4) in X _ nabs (k), 3 spectral lines l-1, l, l +1 obtained in step 2 are excluded to obtain X _ nabs ' (k), the maximum value X _ nabs ' (m) of X _ nabs ' (k) is further searched, two spectral lines X _ nabs ' (m-1) and X _ nabs ' (m +1) adjacent to the maximum value X _ nabs ' (k) are taken, and the frequency value Fk of the minor component of the spectrum of the distance unit is calculated through X _ nabs ' (m-1), X _ nabs ' (m) and X _ nabs ' (m +1)1Intensity value Ak1。
5) Through Fk0，Ak0，Fk1，Ak1And jointly judging whether the distance unit contains moving target information, if so, outputting, and if not, inhibiting.
By implementing the method for processing the moving target by the multispectral interpolation accurate Doppler estimation, the method has the following technical effects: the method can accurately estimate the frequency spectrum of the main energy of each distance unit through an interpolation algorithm, and calculate the frequency spectrum of the secondary energy through a compensation algorithm. And further, the moving target of each distance unit is refined, which cannot be realized by the traditional method, so that the low, small and slow target is detected.
Drawings
FIG. 1 is a computational flow diagram;
FIG. 2 is a schematic diagram of the calculation principle;
FIG. 3 is a schematic diagram before spectral compensation;
FIG. 4 is a schematic diagram after spectral compensation;
FIG. 5 is a moving object pre-processing simulation diagram;
FIG. 6 is a moving target processed simulation;
FIG. 7 is an echo diagram of a ground object in an actual test field;
FIG. 8 is an echo diagram of a ground object in an actual test field.
Detailed Description
The invention is further illustrated by the following examples and figures.
1) Let x be ═ x1 x2 ... xn]The time series vector of the relevant pulse of the same range unit of the radar is shown, wherein n is the number of coherent pulses, n is more than or equal to 8, and n is the power of 2. And windowing the X, performing n-point FFT on the windowed data to obtain n-point FFT results X '(K), and taking the absolute value of the X' (K) to obtain X (K). The partial diagram of X (K) is shown in FIG. 2, where FT represents the output of a single bin inclusion signal DTFT, where ω is0Is the true spectrum of the signal. X (l-1), X (l +1) are the output of FFT. X (l) is the maximum value of X (K), X (l-1) and X (l +1) are the outputs of X (l) adjacent FFT. Can be obtained by X (l-1), X (l), and X (l +1)And d, yielding delta:
Figure GDA0003511995280000021
Figure GDA0003511995280000022
wherein ═ sign (X (l +1) -X (l-1)).
2) Calculating frequency value Fk0Intensity value Ak0And phase Pk0Where Δ f is frequency resolution, Fs/N, Fs is radar repetition frequency:
Fk0＝(l+ε)×Δf
Figure GDA0003511995280000031
Pk0＝arg(X(l))-πδ
3) through Fk0，Ak0Using Fk in combination with a spectral compensation table0Obtaining the compensation coefficient of the frequency spectrum compensation table according to the coefficient and Ak0And obtaining leakage values Fi (k) of the main component of the distance unit in other components, wherein the spectrum compensation table is a complex envelope of the selected window function frequency, and the spectrum compensation is completed:
X_new(k)＝X(k)-Fi(k)
the compensated components are represented by X _ new (k), and the absolute value of X _ new (k) is obtained to obtain X _ nabs (k), as shown in fig. 3 and 4, the results of the spectrum components before and after compensation.
4) Firstly, setting the l-1, l, l +1 component in X _ nabs (k) as 0 to obtain X _ nabs '(k), and calculating the maximum value X _ nabs' (m) of X _ nabs '(k), wherein X _ nabs' (m-1) and X _ nabs '(m +1) are outputs of adjacent FFTs of X _ nabs' (m). δ 'can be obtained from X _ nabs' (m-1), X _ nabs '(m), and X _ nabs' (m + 1).
Figure GDA0003511995280000032
Figure GDA0003511995280000033
Where ∈ ═ sign (X _ nabs '(m +1) -X _ nabs' (m-1)).
5) Calculating frequency value Fk1Intensity value Ak1
Fk1＝(m+ε’)×Δf
Figure GDA0003511995280000034
6) Obtaining Fk of each distance unit0，Ak0，Fk1，Ak1The frequency, amplitude of the primary spectral component, and the frequency amplitude of the secondary spectral component of the range bin are then obtained. Further, a speed threshold can be set for each distance unit, if the frequency of the primary spectrum component is greater than the Doppler speed corresponding to the speed threshold, the primary spectrum component is output, otherwise, the secondary spectrum component is judged, if the frequency of the primary spectrum component is greater than the Doppler speed corresponding to the speed threshold, the secondary spectrum component is output, and if the frequency of the primary spectrum component is greater than the speed threshold, the noise level is output at the point, otherwise, the noise level is output. FIG. 5 is an effect diagram before processing of a simulated moving target, FIG. 6 is an effect diagram after processing of the simulated moving target, and a simulation result shows that strong ground objects can be restrained and weak targets can be extracted. FIG. 7 is a low-small slow target experiment site ground object echo diagram. Figure 8 is an echo diagram after doppler processing.

Claims (3)

1. A low and small slow moving target processing method based on multispectral accurate interpolation is characterized by comprising the following steps:
(1) let x be ═ x1 x2 ... xn]The time sequence vector of the relevant pulse of the same distance unit of the radar is shown, wherein n is the number of coherent pulses, n is more than or equal to 8, and n is the power of 2; windowing the X, performing n-point FFT on the windowed data to obtain n-point FFT results X '(K), and taking an absolute value of the X' (K) to obtain X (K);
(2) finding the maximum X (l) of X (K), and taking two adjacent spectral lines X (l-1) and X (l + 1); calculating the frequency value F of the main component of the frequency spectrum of the distance unit through X (l-1), X (l +1)k0Intensity value Ak0And phase Pk0；
(3) According to the frequency value Fk0Intensity value Ak0And phase Pk0The value of (a) is combined with a frequency spectrum compensation table to obtain a leakage value Fi (K) of the main component of the distance unit in other components, wherein K is 1,2,. n, and the result X' (K) of FFT is compensated; setting the compensated data as X _ new (k), and calculating an absolute value X _ nabs (k), wherein k is 1,2,. n;
(4) in X _ nabs (k), 3 spectral lines l-1, l, l +1 obtained in the step (2) are excluded, the maximum value X _ nabs ' (m) of X _ nabs (k) is further searched, and two spectral lines X _ nabs ' (m-1), X _ nabs ' (m +1) adjacent to the maximum value X _ nabs (k) are taken; calculating the frequency value Fk of the secondary component of the frequency spectrum of the distance unit through X _ nabs '(m-1), X _ nabs' (m +1)1Intensity value Ak1；
(5) Obtaining Fk of each distance unit0，Ak0，Fk1，Ak1Then, the frequency and the amplitude of the primary frequency spectrum component and the frequency and the amplitude of the secondary frequency spectrum component of the distance unit are obtained; further, a speed threshold can be set for each distance unit, if the frequency of the primary spectrum component is greater than the Doppler speed corresponding to the speed threshold, the primary spectrum component is output, otherwise, the secondary spectrum component is judged, if the frequency of the primary spectrum component is greater than the Doppler speed corresponding to the speed threshold, the secondary spectrum component is output, and if the frequency of the primary spectrum component is greater than the speed threshold, the noise level is output at the point, otherwise, the noise level is output.
2. The method for processing the low and small slow moving target based on the multispectral precise interpolation as claimed in claim 1, wherein: the spectral compensation table is a complex envelope of the selected window function frequencies.
3. The method for processing the low and small slow moving target based on the multispectral precise interpolation as claimed in claim 1 or 2, wherein: the secondary spectral components may also be calculated after X _ nabs (k) excludes 5 spectral lines l-2, l-1, l, l +1, l + 2.
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