CN109061626A - A kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target - Google Patents
A kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target Download PDFInfo
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- CN109061626A CN109061626A CN201810795771.2A CN201810795771A CN109061626A CN 109061626 A CN109061626 A CN 109061626A CN 201810795771 A CN201810795771 A CN 201810795771A CN 109061626 A CN109061626 A CN 109061626A
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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
- G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S13/588—Velocity or trajectory determination systems; Sense-of-movement determination systems deriving the velocity value from the range measurement
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Abstract
The present invention relates to narrowband ground-based radars, and moving-target field is detected in clutter environment, and spy is related to a kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target.The present invention is by by homogenous frequency signal between radar emission arteries and veins, frequency stepping between arteries and veins group signal, first by each carrier frequency arteries and veins group signal in the AMTI for organizing the orders such as interior completion in received signal processing, the result of AMTI between each carrier frequency after time unifying is subjected to Step Frequency phase measurements after phase compensation, Step Frequency synthesized image is finally completed into correlative accumulation between slow clap, to complete moving-target with clutter is remaining separates, achieve the purpose that improve moving-target SCNR detected.
Description
Technical field
The present invention relates to narrowband ground-based radars, and moving-target field is detected in clutter environment, and spy is related to a kind of Step Frequency coherent
The method of the low signal to noise ratio moving-target of processing detection.
Background technique
The vital task that moving-target is radar is detected from strong clutter background, while being also a difficult point.Use biography
The AMTI or the optimal AMTD of point of system are when coping with ground (sea) clutter of varying environment, if not estimating clutter environment simultaneously in real time
It is remaining all inevitably to generate clutter for production filter coefficient, so that moving-target needs are remaining with these in the detection process
The competition of clutter progress energy.Clutter residue can be divided into two kinds of situations: first is that the spectrum shape of filter null and clutter
It mismatches, leading to the minor lobe region of moving-target filter, there are stronger clutter residues；Second is that the spectrum of clutter is for PRF
It is wider, so that moving-target will also compete in the filter passband of itself with clutter.Which kind of either above-mentioned situation, or
It is that the synthesis of the two situation can all increase the detection difficulty of moving-target.Therefore one, which must be found, can reduce clutter in Range resolution
The method of unit self-energy.
The core concept of moving-target detection is the SCNR of raising moving-target, therefore can be from distance list locating for reduction moving-target
The clutter energy of member improves the SCR of moving-target, and the SNR of moving-target is improved by correlative accumulation, so come integrate improve it is dynamic
The SCNR of target.Since the signal of radar emission is finite bandwidth, the echo samples point of the distance unit locating for clutter
Contain all clutters in signal resolution echo-signal energy and.For conventional narrow-band surface search radar, generally
In the case of radar resolution be greater than detection moving-target size.It follows that the transient echo signal is when detecting not
Only to be competed with the clutter of itself position, it will also be with the other positions in the radar resolution cell locating for transient echo
Clutter competition.If improving the resolution ratio of radar, the clutter power of distance unit locating for moving-target can be reduced, promotes SCR.Cause
This, Step Frequency technology can realize the increase resolution of radar under the premise of not increasing radar receiver bandwidth.But radar
The low SNR situation of the strong clutter environment and moving-target that face can not realize that merely the SCNR of moving-target is mentioned by Step Frequency
It is raised to detectable level, therefore also needs to combine by correlative accumulation means to realize the SCNR for promoting moving-target.
Existing Narrow-band Radar technical solution is all to filter out the vacation of complete or SCR pre-filtering to acceptable level in clutter
If premise goes down to realize the detection of moving-target, but can contain some strength in actual strong clutter area echo signal processing result
Clutter is remaining, therefore will lead to used signal processing model and actual ghosts data mismatch, shows as existing moving-target
Detection means uses under strong clutter environment to fail sometimes.This method is exactly to solve existing signal processing method in reality
What the problem of encountered in use, was proposed.
Summary of the invention
For the classical signal processing technique in the prior art limitation low for low SCR moving-target detection probability, originally
Invention proposes a kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target, by MTI between arteries and veins, arteries and veins group Step Frequency at
The method of coherent processing, realizes the detection of low SCNR moving-target between picture and picture.The present invention by by between radar emission arteries and veins with frequency
Each carrier frequency arteries and veins group signal first the orders such as is completed in received signal processing by signal, frequency stepping between arteries and veins group signal in group
AMTI, the result of AMTI between each carrier frequency after time unifying is subjected to Step Frequency phase measurements after phase compensation, finally will
Step Frequency synthesized image completes correlative accumulation between slow clap, thus complete moving-target with clutter is remaining separates, reach raising and move mesh
Mark the detected purpose of SCNR.
The technical scheme is that a kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target, sequence is wrapped
Include transmission signal parameters configuration step, echo AMTI step, arteries and veins group phase of echo compensation process, Step Frequency imaging and phase in arteries and veins group
Ginseng accumulation step, it is characterised in that:
The transmission signal parameters configuration step includes:
1.1 transmitting signal coherent points calculate sub-step；
According to the transmitting PRF of radar and wave beam residence time Tbeam, obtain the pulse total number N of unicast position；According to radar
Step frequency step delta f and overall system bandwidth B, obtain Step Frequency synthesize N frequency pointsΔf；
The full coherent maximum number of points of 1.2 single-frequency points calculates sub-step；
The unicast digit pulse total number N that step 1.1 is calculated synthesizes N frequency points divided by Step FrequencyΔf, obtain list
The full coherent maximum number of points N of frequency pointf-max；
1.3AMTI filter order calculates sub-step；
The full coherent maximum number of points N of the single-frequency point that step 1.2 is calculatedf-max, bring the calculating of AMTI filter order into
Constraint condition obtains AMTI filter order Nmti；
Correlative accumulation points calculate sub-step between 1.4 pictures；
The full coherent maximum number of points N of the single-frequency point that step 1.2 and step 1.3 are calculatedf-maxWith AMTI filter order
Nmti, the correlative accumulation points N as between is calculatedfft；
Echo AMTI step in the arteries and veins group completes the first of clutter using the corresponding equal orders AMTI filter of each carrier frequency
Walk filtering function, including following sub-steps:
2.1AMTI filter generates sub-step；
The AMTI filter order N that step 1.3 is obtainedmti, it brings AMTI filter into and generates in order constraint condition, root
According to clutter center Doppler frequency point f0With Doppler width σf, different carrier frequency fc are calculated(i)Under AMTI filter H
(τ)i_mti, and obtain its first phase
2.2AMTI sub-step of filtering；
The AMTI filter H (τ) that will be obtained in step 2.1i_mti, respectively to the echo-signal S of each carrier frequencyi(τ) is slow
It claps and carries out point-by-point sliding window filtering, the signal after obtaining preliminary filtering clutter
The arteries and veins group phase of echo compensation process, the AMTI result of each carrier frequency is aligned in time, and complete arteries and veins
Between and arteries and veins group phase compensation, including following sub-steps:
3.1 echoes clap time unifying sub-step slowly；
By the signal in step 2.2According to filter sequence in carrier frequency variation sequence and arteries and veins, it is defeated that arrangement forms Step Frequency
Enter matrix X (i, m)；
Phase compensation sub-step between 3.2 arteries and veins；
By slow time dimension of the data matrix X (i, m) in step 3.1 in arteries and veins, according in compensation speed v and step 2.1
Filter first phasePhase compensation is carried out, is obtained data matrix Y (i, m)；
3.3 arteries and veins group phase compensation sub-steps；
By big slow time dimension of the data matrix Y (i, m) in step 3.2 between arteries and veins group, phase is carried out according to compensation speed v
Compensation obtains data matrix Z (i, m)；
The Step Frequency imaging and correlative accumulation step, ranks two dimensions of the data matrix that compensation is completed in matrix
Degree carries out coherent calculating, including following sub-steps:
Sub-step is imaged in 4.1 Step Frequencies；
By the data matrix Z (i, m) in step 3.3, carry out IFFT operation in carrier frequency stepping dimension, obtain moving-target with it is miscellaneous
The high resolution picture of wave mixing, result are matrix U (i, m)；
Fine distance unit correlative accumulation sub-step between 4.2 pictures；
By the data matrix U (i, m) in step 4.1, according to the distribution of fine distance unit, one by one in same fine distance
The different of unit carry out FFT operation as between, and the points of FFT are N in step 1.4fft2 smallest positive integral power, to be moved
The high resolution picture that target is separated with clutter, result are matrix P (i, m)；
4.3 moving-targets detect sub-step；
Data matrix P (i, m) in step 4.2 is used into CFAR along fine distance unit dimension direction on Doppler domain,
Complete the moving-target detection for reaching focus detection level；
4.4 moving-targets focus sub-step；
By in step 4.2 P (i, m) calculate after, replace compensation speed v value, bring into step 3.2, repeat to
The operation of step 4.3 is completed all preset compensation speeds until traversal and is calculated.
Detailed description of the invention
Fig. 1 is that transmission signal parameters of the invention configure block diagram；
Fig. 2 is reception signal processing block diagram of the invention；
Fig. 3 is signal data Structural assignments schematic diagram of the invention；
Fig. 4 is the Step Frequency synthesized image of AMTI result of the invention；
Fig. 5 is Step Frequency of the invention as the result figure after correlative accumulation；
Fig. 6 is CFAR moving-target testing result figure of the invention；
Fig. 7 is the full coherent classical signal processing result figure of pulse SCR=-40dB；
Fig. 8 is the full coherent classical signal processing result figure of pulse SCR=-80dB.
Specific embodiment
Explanation of nouns:
AMTI: adaptive moving-target instruction (Adapted Moving Targets Indication).
AMTD: adaptive moving-target detection (Adapted Moving Targets Detection).
SNR: signal-to-noise ratio (Signal Noise Ratio).
SCR: signal to noise ratio (Signal Clutter Ratio).
SCNR: letter miscellaneous noise ratio (Signal Clutter Noise Ratio).
PRF: pulse recurrence frequency.
PRI: the pulse repetition period is the inverse of PRF.
FIR filter: there is limit for length's unit impulse response filter (Finite Impulse Response).
Snap: the sampling time in the same PRI counts.
It is slow to clap: the time counting between different PRI pulses.
CFAR: CFAR detection (Constant False Alarm Rate).
MTD: moving-target detects (Moving Targets Detection).
LFM: linear FM signal (Linear Frequency Modulation), chirp rate are fixed constant.
DB: decibel, a kind of intensity rate unit, Y (dB)=20log10(X), X is amplitude ratio.
Fd: frequency domain Doppler (Frequency Doppler).
Below in conjunction with attached drawing, the present invention is described further.
The present invention provides a kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target, realizes narrowband ground thunder
Up to the purpose that moving-target detectability is promoted in strong clutter environment.
As shown in Figure 1, transmission signal parameters configuration section sequence of the invention includes that transmitting signal coherent points calculate son
Step, the full coherent maximum number of points of single-frequency point calculate sub-step, and AMTI filter order calculates sub-step, as a correlative accumulation points
Calculate sub-step.
As shown in Fig. 2, reception signal processing sequence of the invention includes that AMTI filter generates sub-step, AMTI filter
Marble step, echo clap time unifying sub-step slowly, phase compensation sub-step between arteries and veins, arteries and veins group phase compensation sub-step, Step Frequency
Sub-step is imaged, as a fine distance unit correlative accumulation sub-step, moving-target detects sub-step, and moving-target focuses sub-step.
Below in conjunction with the drawings and specific embodiments, the present invention is further described.
A specific embodiment of the invention:
Transmission signal parameters configuration step described in one,
1.1 transmitting signal coherent points calculate sub-step；
According to the transmitting PRF of radar and wave beam residence time Tbeam, obtain the pulse total number N of unicast position；According to radar
Step frequency step delta f and overall system bandwidth B, obtain stepping carry N frequency pointsΔf。
The present embodiment uses and detects single moving target model in clutter, moving-target speed 8m/s, SNR before pulse pulse pressure
It is 1KHz, wave beam residence time 0.32s, single-frequency for 0dB, transmitted signal bandwidth 2MHz, the LFM of time width 300us, repetition PRF
It is 5 that point arteries and veins group pulse number, which is 20, MTI order, and frequency hopping frequency point number is 16, and basic carrier frequency is 5GHZ, average pulse echo SCR
For -80dB, clutter is uniformly distributed in thick distance unit, speed Gaussian distributed (mean value 0, standard deviation 0.32m/s),
Each basis distance unit possesses the small scattering unit clutter point and 10 stronger strong scattering units of 200 Rayleigh distributeds
Clutter point.Pulse total number in wave beam residence time are as follows:
N=Tbeam·PRF
Stepping carries frequency points are as follows:
NΔf=B/ Δ f
The full coherent maximum number of points of 1.2 single-frequency points calculates sub-step；
The unicast digit pulse total number N that step 1.1 is calculated synthesizes N frequency points divided by Step FrequencyΔf, obtain list
The full coherent maximum number of points N of frequency pointf-maxAre as follows:
Nf-max=N/NΔf
1.3AMTI filter order calculates sub-step；
The full coherent maximum number of points N of the single-frequency point that step 1.2 is calculatedf-max, bring the calculating of AMTI filter order into
Constraint condition obtains AMTI filter order Nmti.Constraint condition are as follows:
Nmti< Nf-max-8
Correlative accumulation points calculate sub-step between 1.4 pictures；
The full coherent maximum number of points N of the single-frequency point that step 1.2 and step 1.3 are calculatedf-maxWith AMTI filter order
Nmti, the correlative accumulation points N as between is calculatedfft:
Nfft=Nf-max-Nmti+1
Echo AMTI step in arteries and veins group described in two, completes clutter using the corresponding equal orders AMTI filter of each carrier frequency
Preliminary filtering function, including following sub-steps:
2.1AMTI filter generates sub-step；
The AMTI filter order N that step 1.3 is obtainedmti, it brings AMTI filter into and generates in order constraint condition, root
According to clutter center Doppler frequency point f0With Doppler width σf, different carrier frequency fc are calculated(i)Under AMTI filter H
(τ)i_mti, and obtain its first phase
h(τ)mti=A-1·(-w0U)
Wherein: ()-1Expression is inverted, and j is(·)TIndicate transposition, RcIndicate clutter autocorrelation matrix, f0For clutter
Center Doppler frequency point, σfFor the Doppler width that the different carrier frequency of correspondence are calculated,τmnIt indicates slow to clap the time, U=(1,
0,…,0)T, w0For non-zero constant, A f0The Taylor series m rank that place's FIR filter defines leads matrix, Tα, α=1,2,3 ...,
M indicates the integration time clapped slowly.AMTI filter H (τ)i_mtiFirst phaseIt can be measured by filter amplitude-frequency response
It obtains, first phase is AMTI filter inherent characteristic, and when filter coefficient determines, first phase is fixed.
2.2AMTI sub-step of filtering；
The AMTI filter H (τ) that will be obtained in step 2.1i_mti, respectively to the echo-signal S of each carrier frequencyi(τ) is slow
It claps and carries out point-by-point sliding window filtering, the signal after obtaining preliminary filtering clutter
Wherein,Indicate convolution.
The AMTI result of each carrier frequency is aligned in time, and completes by arteries and veins group phase of echo compensation process described in three,
Between arteries and veins and the phase compensation of arteries and veins group, including following sub-steps:
3.1 echoes clap time unifying sub-step slowly；
By the signal in step 2.2According to filter sequence in carrier frequency variation sequence and arteries and veins, it is defeated that arrangement forms Step Frequency
Enter matrix X (i, m):
Wherein, m=1,2,3 ..., Nfft, the maximum value of i is NΔf。
It is as shown in Figure 3 that unicast position receives signal data Structural assignments.It can be seen that the echo-signal arteries and veins group that each carrier frequency receives
The structure of interior (between arteries and veins) sliding window AMTI, arteries and veins group AMTI result carry out the arrangement of Step Frequency synthesis.
Phase compensation sub-step between 3.2 arteries and veins；
By slow time dimension of the data matrix X (i, m) in step 3.1 in arteries and veins, according in compensation speed v and step 2.1
Filter first phasePhase compensation is carried out, is obtained data matrix Y (i, m):
Wherein, C is the light velocity, fc(i)It is the carrier frequency of stepping, subscript i is stepping label.
3.3 arteries and veins group phase compensation sub-steps；
By big slow time dimension of the data matrix Y (i, m) in step 3.2 between arteries and veins group, phase is carried out according to compensation speed v
Compensation obtains data matrix Z (i, m):
Wherein, C is the light velocity, fc(i)It is the carrier frequency of stepping, subscript i is stepping label.
The imaging of Step Frequency described in four, and correlative accumulation step, ranks two of the data matrix that compensation is completed in matrix
A dimension carries out coherent calculating, including following sub-steps:
Sub-step is imaged in 4.1 Step Frequencies；
By the data matrix Z (i, m) in step 3.3, carry out IFFT operation in carrier frequency stepping dimension, obtain moving-target with it is miscellaneous
The high resolution picture of wave mixing, result are matrix U (i, m):
U (i, m)=ifft (Z (i, m))col
Wherein, ifft [] indicates inverse fast Fourier transform, ()colIt indicates to be transported in the column dimension of data matrix
It calculates.
The single AMTI result that Step Frequency is imaged between each frequency point is as shown in Figure 4.As we can see from the figure it is original it is thick away from
From unit, 16 fine distance unit are uniformly separated into, clutter residue is evenly distributed in No. 1401 thick distance unit
In corresponding all fine distance unit, moving-target is covered by clutter.
Fine distance unit correlative accumulation sub-step between 4.2 pictures；
By the data matrix U (i, m) in step 4.1, according to the distribution of fine distance unit, one by one in same fine distance
The different of unit carry out FFT operation as between, and the points of FFT are N in step 1.4fft2 smallest positive integral power, to be moved
The high resolution picture that target is separated with clutter, result are matrix P (i, m):
Wherein, fft [] indicates inverse fast Fourier transform,Indicate Nfft2 smallest positive integral power fortune
It calculates, ()rowIt indicates to carry out operation in the row dimension of data matrix.
16 fine distance unit in No. 1401 thick distance unit are after the correlative accumulation for carrying out 16 AMTI results
Result it is as shown in Figure 5.When velocity compensated value is matched with the true velocity value of moving-target, it can be seen that moving-target energy is poly-
Coke, and separated with the Doppler dimension of clutter residue after normalization, to ensure that being detected property of moving-target.
4.3 moving-targets detect sub-step；
Data matrix P (i, m) in step 4.2 is used into CFAR along fine distance unit dimension direction on Doppler domain,
Complete the moving-target detection for reaching focus detection level.
Moving-target CFAR testing result in No. 1401 thick distance unit is as shown in Figure 6.It can be seen that clutter remains in
It is suppressed in detection process, false-alarm point is not detected；Moving-target is normally detected.
4.4 moving-targets focus sub-step；
By in step 4.2 P (i, m) calculate after, replace compensation speed v value, bring into step 3.2, repeat to
The operation of step 4.3 is completed all preset compensation speeds until traversal and is calculated.
In step of the present invention, alternative scheme is: in step 1.1, if the baseband signal first phase emitted in arteries and veins group is not
Together, then signal and the precompensation of filter convolution should be clapped slowly in step 2.2.In step 1.1, if the baseband signal emitted in arteries and veins group
First phase is identical, and the baseband signal between different carrier frequency is different, then should compensate together with filter first phase in step 3.2.
The beneficial effects of the present invention are:
The parameter for emitting signal in step 1.1 can be with flexible configuration, so that baseband signal possesses stronger low intercepting and capturing generally
Rate, but can achieve the effect of broadband signal detection.The rule of carrier frequency jump and arteries and veins group signal composition is different from typical step
Into frequency signal process flow, so that jammer is difficult to.
It has been used in step 2.1 a little most preferably with the most flat AMTI filter combined of null, so that the zero of filter
It falls into position and width is controllable, compared to conventional mti filter, further reduce since null shape and clutter spectrum mismatch
Caused clutter leakage.Using AMTI rather than AMTD, then allowing for moving-target may appear under different carrier frequency
In different filter passbands, to eliminate the huge calculation amount that different filter passbands are mutually paired.
Moving-target is considered in step 3.2 and exports the slow situation of change for clapping phase in AMTI filter, to cause
The picture of the fine distance unit of moving-target slow clap the result that is subjected to displacement and can not focus different.Therefore each AMTI is filtered
The result of wave device carries out phase compensation, not only ensure that tentatively filtering out for clutter, but also secure moving-target in fine distance unit
Position as in.
The invention method has been allowed for different from the frequency agile of typical Step Frequency to arteries and veins group phase compensation in step 3.3
Design, it is therefore desirable to calculate phase change of the moving-target between arteries and veins group, and then Step Frequency optics coherence tomography essence can be completed after compensating
The step of thin picture.
As shown in figure 5, Step Frequency synthesis is finely as rear moving-target is still with clutter in thick distance unit in step 4.2
It is overlapped, but the clutter energy of fine distance unit reduces where moving-target, so that moving-target is in the remaining Doppler's minor lobe of clutter
Area is no longer blanked, so as to effectively be detected.
The present invention is as shown in Figure 7 and Figure 8 compared to the benefit of traditional full Coherent signal processing.In Fig. 7, when overall pulse product
When tired points are identical with value set by the present invention, when the simulated conditions of SCR are relaxed to -40dB, classical signal handles to obtain
Moving-target intensity about 10dB by force than clutter minor lobe, just reached the detectable thresholding of CFAR.In fig. 8, if by the emulation of SCR
When intensity keeps consistent with set by the present invention (SCR=-80dB), moving-target will be submerged in completely under classical signal process flow
Clutter minor lobe hereinafter, can not be detected completely.It is found that moving-target is in SCR=-80dB, full coherent is long-pending by comparison diagram 7 and Fig. 8
SCR after tired is about that -30dB, the detection threshold (detection threshold SCR=15dB) much smaller than CFAR, therefore moving-target can not be by
It detects.And effect of the invention, as described in the preceding paragraph, moving-target can be detected.
Claims (3)
1. a kind of method that Step Frequency coherent processing detects low signal to noise ratio moving-target sequentially includes transmission signal parameters configuration step
Suddenly, echo AMTI step, arteries and veins group phase of echo compensation process, Step Frequency imaging and correlative accumulation step, feature exist in arteries and veins group
In:
The transmission signal parameters configuration step includes:
1.1 transmitting signal coherent points calculate sub-step；
According to the transmitting PRF of radar and wave beam residence time Tbeam, obtain the pulse total number N of unicast position；According to the stepping of radar
Frequency step Δ f and overall system bandwidth B obtains Step Frequency and synthesizes N frequency pointsΔf；
The full coherent maximum number of points of 1.2 single-frequency points calculates sub-step；
The unicast digit pulse total number N that step 1.1 is calculated synthesizes N frequency points divided by Step FrequencyΔf, obtain single-frequency point
Full coherent maximum number of points Nf-max；
1.3AMTI filter order calculates sub-step；
The full coherent maximum number of points N of the single-frequency point that step 1.2 is calculatedf-max, bring the constraint of AMTI filter order calculating into
Condition obtains AMTI filter order Nmti；
Correlative accumulation points calculate sub-step between 1.4 pictures；
The full coherent maximum number of points N of the single-frequency point that step 1.2 and step 1.3 are calculatedf-maxWith AMTI filter order Nmti,
The correlative accumulation points N as between is calculatedfft；
Echo AMTI step in the arteries and veins group completes the preliminary filter of clutter using the corresponding equal orders AMTI filter of each carrier frequency
Except function, including following sub-steps:
2.1AMTI filter generates sub-step；
The AMTI filter order N that step 1.3 is obtainedmti, bring AMTI filter into and generate in order constraint condition, according to miscellaneous
Wave center Doppler frequency point f0With Doppler width σf, different carrier frequency fc are calculated(i)Under AMTI filter H (τ)i_mti, and
Obtain its first phase
2.2AMTI sub-step of filtering；
The AMTI filter H (τ) that will be obtained in step 2.1i_mti, respectively to the echo-signal S of each carrier frequencyi(τ) slowly clap into
The point-by-point sliding window filtering of row, the signal after obtaining preliminary filtering clutter
The arteries and veins group phase of echo compensation process, the AMTI result of each carrier frequency is aligned in time, and complete between arteries and veins and
The phase compensation of arteries and veins group, including following sub-steps:
3.1 echoes clap time unifying sub-step slowly；
By the signal in step 2.2According to filter sequence in carrier frequency variation sequence and arteries and veins, arrangement forms Step Frequency input square
Battle array X (i, m)；
Phase compensation sub-step between 3.2 arteries and veins；
By slow time dimension of the data matrix X (i, m) in step 3.1 in arteries and veins, according to the filter in compensation speed v and step 2.1
Wave device first phasePhase compensation is carried out, is obtained data matrix Y (i, m)；
3.3 arteries and veins group phase compensation sub-steps；
By big slow time dimension of the data matrix Y (i, m) in step 3.2 between arteries and veins group, phase benefit is carried out according to compensation speed v
It repays, obtains data matrix Z (i, m)；
The described Step Frequency imaging and correlative accumulation step, the data matrix that compensation is completed matrix two dimensions of ranks into
Row coherent calculates, including following sub-steps:
Sub-step is imaged in 4.1 Step Frequencies；
By the data matrix Z (i, m) in step 3.3, IFFT operation is carried out in carrier frequency stepping dimension, moving-target is obtained and clutter is mixed
The high resolution picture of conjunction, result are matrix U (i, m)；
Fine distance unit correlative accumulation sub-step between 4.2 pictures；
By the data matrix U (i, m) in step 4.1, according to the distribution of fine distance unit, one by one in same fine distance unit
It is different FFT operations are carried out as between, the points of FFT are N in step 1.4fft2 smallest positive integral power, to obtain moving-target
The high resolution picture separated with clutter, result are matrix P (i, m)；
4.3 moving-targets detect sub-step；
Data matrix P (i, m) in step 4.2 is used into CFAR along fine distance unit dimension direction on Doppler domain, is completed
Reach the moving-target detection of focus detection level；
4.4 moving-targets focus sub-step；
After P (i, m) in step 4.2 is calculated, the value of compensation speed v is replaced, brings into step 3.2, repeats to step
4.3 operation is completed all preset compensation speeds until traversal and is calculated.
2. the method that a kind of Step Frequency coherent processing according to claim 1 detects low signal to noise ratio moving-target, feature exist
In: AMTI filter H (τ) in step 2.1i_mtiCalculation formula are as follows:
h(τ)mti=A-1·(-w0U)
Wherein: ()-1Expression is inverted, and j is(·)TIndicate that transposition, Rc indicate clutter autocorrelation matrix, f0For clutter center
Doppler's frequency point, σfFor the Doppler width that the different carrier frequency of correspondence are calculated,τmnIt indicates slow and claps time, U=(1,0 ..., 0)T,
w0For non-zero constant, A f0The Taylor series m rank that place's FIR filter defines leads matrix, Tα, α=1,2,3 ..., m indicate slow and clap
Integration time.
3. the method that a kind of Step Frequency coherent processing according to claim 1 detects low signal to noise ratio moving-target, feature exist
In: the calculation formula of Step Frequency input matrix X (i, m) in step 3.1 are as follows:
Wherein, m=1,2,3 ..., Nfft, the maximum value of i is NΔf。
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