CN109100762A - Bistatic radar sea moving target detecting method based on big-dipper satellite radiation source - Google Patents
Bistatic radar sea moving target detecting method based on big-dipper satellite radiation source 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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
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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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
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Abstract
The invention discloses a kind of bistatic radar sea moving target detecting method based on big-dipper satellite radiation source, it carries out range migration correction using symmetrical second order Keystone transformation to the echo-signal under long observation time, and it goes tiltedly to handle to what the echo-signal under entire observation time was unified, then sub-frame processing is carried out, signal carries out coherent accumulation in frame, interframe signal carries out no-coherence cumulating, can efficiently solve the big-dipper satellite problem low as external sort algorithm target echo signal-to-noise ratio.Due to being converted using symmetrical second order Keystone, range walk and range curvature can be removed simultaneously in the case where unknown Doppler parameter, range migration correction is better achieved；And when due to energy accumulation processing, signal need to only carry out sum operation in frame, and interframe signal is not required to carry out Doppler frequency center compensating operation, substantially reduce operand.
Description
Technical field
The invention belongs to bistatic radar Detection for Moving Target fields, and in particular to one kind is radiated based on big-dipper satellite
The bistatic radar sea moving target detecting method in source.
Background technique
Emit signal different from conventional radar transmitter, and receive the form of target radar signal reflected with receiver, outside
It is the opportunity illuminating source signal of target reflection that radiation source radar is received.Since external illuminators-based radar itself does not emit signal, this
So that it is with good concealment；Since it does not have to transmitting signal, it can reduce volume, reduce cost；It will not be produced using it
Raw this advantage of electromagnetic pollution, makes it possible to applied to most of regions.In recent years, with opportunity illuminating source category and quantity
Increase, the research about external illuminators-based radar also increasingly increases.
Common external sort algorithm has FM signal, digital broadcasting-television signal, navigation satellite signal etc..Wherein, FM signal, number
Sea area cannot be completely covered due to that can only cover land area in the land signal source such as word broadcast television signal, be not suitable for
In the detection of sea moving target.And the one kind of Beidou satellite navigation system as Global Navigation Satellite System, with the covering of more stars
The whole world, the irradiation source that can be provided round-the-clock for dumb station, be available anywhere are conducive to large-scale to sea-surface target regional sustained
Observation.Meanwhile Beidou satellite navigation system transmitted signal bandwidth is larger, it is possible to provide more accurate distance resolution.And by
The spatial mixing constellation of high rail satellite composition in Beidou satellite navigation system use, anti-to block ability stronger.Therefore, it can incite somebody to action
Big Dipper satellite signal is as external sort algorithm, in the detection applied to sea moving target.
Since the transmission power of Beidou navigation satellite is lower, and it is extremely remote apart from earth surface distance, so that Beidou navigation is defended
Power density is very low when the signal of star transmitting reaches earth surface, to make the sea Moving Target Return signal noise received
Than very low, difficulty is brought for the detection of sea moving target.
In order to improve the signal-to-noise ratio of Moving Target Return signal, the prior art proposes a kind of mesh under long observation time
The method that echo-signal carries out energy accumulation is marked, this method, which is adjusted the distance, carries out single order Keystone reality to the compressed signal of pulse
Existing range migration correction, then carries out sub-frame processing for the signal after range migration correction, utilizes FrFT for each frame data
The spatio-temporal domain coherent accumulation to moving target energy is realized, finally in conjunction with the Doppler shift alignment and phase between multiframe data
Position compensation deals realize the incoherent fusion to multiframe data in Doppler frequency center-doppler frequency rate domain (DC-DFR).But it should
Method can only remove the range walk of single order using single order Keystone, and the range curvature of second order still has, without well
It realizes range migration correction, and carries out Doppler frequency center compensation and there is a problem of that process is complicated, computationally intensive.
Summary of the invention
Goal of the invention of the invention is: in order to solve problem above existing in the prior art, the invention proposes one kind
Bistatic radar sea moving target detecting method based on big-dipper satellite radiation source.
The technical scheme is that a kind of bistatic radar sea moving object detection based on big-dipper satellite radiation source
Method, comprising the following steps:
A, system parameter is initialized；The system parameter includes orientation sample frequency fa, distance is to sample frequency fs, mesh
Mark observation time Ta；
B, direct wave and target echo are enrolled and is demodulated respectively using two antennas, obtain corresponding base band direct wave
Signal sd(τ, η) and base band target echo signal secho(τ, η), wherein τ, η respectively indicate distance to time, orientation time；
C, the base band target echo signal s that step B is obtainedecho(τ, η) and base band are gone directly reference signal wave sd(τ, η) into
Row relevant treatment obtains distance to the compressed signal s of pulsepc(τ,η)；
D, the distance obtained to step C is to the compressed signal s of pulsepc(τ, η) carries out symmetrical second order Keystone transformation,
Signal s after obtaining range migration correctionSSOKT(τ,η)；
E, the signal s after the range migration correction obtained to step DSSOKT(τ, η) takes same distance to obtain signal to the time
sτ(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp(fdr,η)；
F, the 2D signal s that step E is obtaineddechirp(fdr, η) and sub-frame processing is carried out, and coherent accumulation in frame is carried out, it obtains
To the corresponding signal zero-frequency value S of the i-th framefra-i(fdr)；
G, each frame signal zero-frequency value S for obtaining step Ffra-i(fdr) no-coherence cumulating is carried out, obtain corresponding signal zero
Frequency value S (fdr)；
H, from the signal s after the range migration correction that step D is obtainedSSOKTLetter of the different distance to the time is taken out in (τ, η)
Number obtain corresponding signal sτ(η), and return step E.
Further, the distance that the step D obtains step C is to the compressed signal s of pulsepc(τ, η) carries out symmetrical
Second order Keystone transformation, the signal s after obtaining range migration correctionSSOKT(τ, η), specifically include it is following step by step:
D1, the distance obtained to step C are to the compressed signal s of pulsepc(τ, η) carries out distance and becomes to fast Fourier
It changes, obtains apart from frequency domain-orientation time-domain signal Spc(fτ, η), it is expressed as
Spc(fτ, η) and=FFTrg{spc(τ,η)}
Wherein, FFTrgIndicate distance to fast Fourier transformation operation, fτIndicate distance to after Fast Fourier Transform (FFT)
Frequency of distance；
D2, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out positive second order Keystone change
It changesObtain SSSOKT-P(fτ,ηm), wherein fcFor carrier frequency, ηmFor the orientation time new after transformation；Use η
Instead of ηm, by SSSOKT-P(fτ,ηm) it is expressed as SSSOKT-P(fτ,η)；
D3, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out negative second order Keystone change
It changesObtain SSSOKT-N(fτ,ηm), η is replaced with ηm, by SSSOKT-N(fτ,ηm) it is expressed as SSSOKT-N(fτ,η)；
D4, the S for obtaining step D2SSOKT-P(fτ, η) and the obtained S of step D3SSOKT-N(fτ, η) and it is multiplied, obtain SSSOKT
(fτ,η)；
D5, the S for obtaining step D4SSOKT(fτ, η) and distance is carried out to inverse fast Fourier transform, obtain range migration school
Signal s after justSSOKT(τ, η), is expressed as
sSSOKT(τ, η)=IFFT { SSSOKT(fτ,η)}
Wherein, IFFT indicates distance to inverse fast Fourier transform.
Further, the signal s after the range migration correction that the step E obtains step DSSOKT(τ, η) take it is same away from
The descriscent time obtains signal sτ(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp(fdr, η), specifically include with
Under step by step:
E1, the range [f that doppler frequency rate is setdr-min,fdr-max] and interval delta fdr, wherein fdr-minAnd fdr-maxRespectively
Indicate the minimum value and maximum value of doppler frequency rate value；
E2, the value f for taking out a doppler frequency ratedr, one centre frequency of composition is 0, linear frequency modulation rate is fdrLinear tune
Frequency signal, i.e. sLFM(η)=exp (- j π fdrη2), by linear FM signal sLFM(η) and sτ(η) is multiplied, and obtains sfdr(η)；
E3, the value of whole doppler frequency rates is handled by step E2, obtains 2D signal sdechirp(fdr,η)。
Further, the 2D signal s that the step F obtains step Edechirp(fdr, η) and sub-frame processing is carried out, it goes forward side by side
Coherent accumulation in row frame obtains the corresponding signal zero-frequency value S of the i-th framefra-i(fdr), specifically include it is following step by step:
F1, selection time span TfraFor a frame time length, the 2D signal for being obtained step E according to the orientation time
sdechirp(fdr, η) and it is divided into N frame,I-th frame signal is expressed as sfra-i(fdr, η), i=1,2 ..., N；
F2, corresponding value of every frame signal each orientation time is added, is obtained in different doppler frequency rate conditions
The lower corresponding signal zero-frequency value of i-th frame, i.e.,
The beneficial effects of the present invention are: the present invention is by using symmetrical second order to the echo-signal under long observation time
Keystone transformation carries out range migration correction, and goes tiltedly to handle to what the echo-signal under entire observation time was unified,
Then sub-frame processing is carried out, signal carries out coherent accumulation in frame, and interframe signal carries out no-coherence cumulating, can efficiently solve north
Struggle against the satellite problem low as external sort algorithm target echo signal-to-noise ratio.Due to being converted using symmetrical second order Keystone, Ke Yi
Range walk and range curvature are removed simultaneously in the case where unknown Doppler parameter, range migration correction is better achieved；And
When due to energy accumulation processing, signal need to only carry out sum operation in frame, and interframe signal is not required to carry out Doppler frequency center compensation behaviour
Make, substantially reduces operand.
Detailed description of the invention
Fig. 1 is the process of the bistatic radar sea moving target detecting method of the invention based on big-dipper satellite radiation source
Schematic diagram；
Fig. 2 is the bistatic radar geometric configuration schematic diagram based on big-dipper satellite radiation source in the embodiment of the present invention；
Fig. 3 is two-dimensional time-domain schematic diagram after midpoint of embodiment of the present invention moving target simulation echo-signal pulse compression；
Fig. 4 is to carry out Second-order Symmetric Keystone transformation in the embodiment of the present invention to realize the signal of range migration correction result
Figure；
Fig. 5 is echo-signal energy accumulation result schematic diagram in the embodiment of the present invention.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that described herein, specific examples are only used to explain the present invention, not
For limiting the present invention.
As shown in Figure 1, being the bistatic radar sea moving object detection side of the invention based on big-dipper satellite radiation source
The flow diagram of method.A kind of bistatic radar sea moving target detecting method based on big-dipper satellite radiation source, including with
Lower step:
A, system parameter is initialized；The system parameter includes orientation sample frequency fa, distance is to sample frequency fs, mesh
Mark observation time Ta；
B, direct wave and target echo are enrolled and is demodulated respectively using two antennas, obtain corresponding base band direct wave
Signal sd(τ, η) and base band target echo signal secho(τ, η), wherein τ, η respectively indicate distance to time, orientation time；
C, the base band target echo signal s that step B is obtainedecho(τ, η) and base band are gone directly reference signal wave sd(τ, η) into
Row relevant treatment obtains distance to the compressed signal s of pulsepc(τ,η)；
D, the distance obtained to step C is to the compressed signal s of pulsepc(τ, η) carries out symmetrical second order Keystone transformation,
Signal s after obtaining range migration correctionSSOKT(τ,η)；
E, the signal s after the range migration correction obtained to step DSSOKT(τ, η) takes same distance to obtain signal to the time
sτ(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp(fdr,η)；
F, the 2D signal s that step E is obtaineddechirp(fdr, η) and sub-frame processing is carried out, and coherent accumulation in frame is carried out, it obtains
To the corresponding signal zero-frequency value S of the i-th framefra-i(fdr)；
G, each frame signal zero-frequency value S for obtaining step Ffra-i(fdr) no-coherence cumulating is carried out, obtain corresponding signal zero
Frequency value S (fdr)；
H, from the signal s after the range migration correction that step D is obtainedSSOKTLetter of the different distance to the time is taken out in (τ, η)
Number obtain corresponding signal sτ(η), and return step E.
As shown in Fig. 2, for the bistatic radar geometric configuration signal in the embodiment of the present invention based on big-dipper satellite radiation source
Figure.Receiving station is fixed, and sea moving target considers that acceleration, the big-dipper satellite as radiation source are selected as middle round Earth's orbit
(MEO) satellite, the B3I signal for selecting big-dipper satellite to broadcast is as external sort algorithm signal, carrier frequency fcFor
1268.520MHz signal bandwidth 20.46MHz.
In an alternate embodiment of the present invention where, above-mentioned steps A initializes system parameter, specifically includes orientation sampling
Frequency fa: 1000Hz, distance is to sample frequency fs: 50MHz, target observation time Ta: 60s.
In an alternate embodiment of the present invention where, above-mentioned steps B enrolls direct wave, and it is through that demodulation obtains base band
Wave signal sd(τ,η)；Target echo is enrolled, demodulation obtains base band target echo signal secho(τ,η)；Wherein, τ be away from
The descriscent time, η is the orientation time, in the range of [- 30,30] s.
In an alternate embodiment of the present invention where, the base band target echo signal s that above-mentioned steps C obtains step Becho
(τ, η) and base band are gone directly reference signal wave sd(τ, η) carries out relevant treatment, obtains distance to the compressed signal s of pulsepc(τ,
η), it is expressed as
Wherein, σηFor the complex scattering coefficients of target, for value with time change, c is the light velocity, and λ is carrier wavelength,
fcFor carrier frequency, ρ () is the cross-correlation function of echo-signal and through reference signal wave, and ρ () here is triangular wave,
R (η) is that difference is biradical apart from history, is expressed as
R (η)=RT(η)+RR(η)-Rb(η)
Wherein, RT(η) and RR(η) respectively indicates big-dipper satellite and receiving station's range-to-go, Rb(η) indicates that Beidou is defended
The distance between star and receiving station；R (η) can be expressed as with three rank Taylor expansions
Wherein, R0Indicate the value of R (η) at η=0, A, B, C respectively indicate R (η) and lead about the single order of η, second order, three ranks
Value of the number at η=0.As shown in figure 3, for two dimension after midpoint of embodiment of the present invention moving target simulation echo-signal pulse compression
Time domain schematic diagram.
In an alternate embodiment of the present invention where, the distance that above-mentioned steps D obtains step C is to the compressed letter of pulse
Number spc(τ, η) carries out symmetrical second order Keystone transformation, the signal s after obtaining range migration correctionSSOKT(τ, η), specifically includes
Below step by step:
D1, the distance obtained to step C are to the compressed signal s of pulsepc(τ, η) carries out distance and becomes to fast Fourier
It changes, obtains apart from frequency domain-orientation time-domain signal Spc(fτ, η), it is expressed as
Wherein, FFTrgIndicate distance to fast Fourier transformation operation, fτIndicate distance to after Fast Fourier Transform (FFT)
Frequency of distance, P () are the Fourier transformation of ρ (), and have
Wherein, fτCoupling with η causes range walk, fτWith η2Coupling cause secondary range bending, fτWith η3's
Coupling causes range curvature three times；
D2, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out positive second order Keystone change
It changesObtain SSSOKT-P(fτ,ηm), wherein ηmFor the orientation time new after transformation；Simultaneously for transformed
As a result η is replaced with ηm, by SSSOKT-P(fτ,ηm) it is expressed as SSSOKT-P(fτ, η), it is expressed as
Wherein,
F is eliminated by positive second order Keystone transformationτWith η2Coupling, that is, eliminate secondary range bending；
D3, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out negative second order Keystone change
It changesObtain SSSOKT-N(fτ,ηm), η is replaced with η simultaneously for transformed resultm, by SSSOKT-N(fτ,ηm)
It is expressed as SSSOKT-N(fτ, η), it is expressed as
Wherein,
Secondary range bending is had also been removed by negative second order Keystone transformation；
D4, the S for obtaining step D2SSOKT-P(fτ, η) and the obtained S of step D3SSOKT-N(fτ, η) and it is multiplied, obtain SSSOKT
(fτ, η), it is expressed as
Wherein,
It is dependent phase；
Realized by symmetrical second order Keystone transformation adjust the distance walk about, secondary range bending and range curvature three times
It removes simultaneously；
D5, the S for obtaining step D4SSOKT(fτ, η) and distance is carried out to inverse fast Fourier transform, obtain range migration school
Signal s after justSSOKT(τ, η), is expressed as
sSSOKT(τ, η)=IFFT { SSSOKT(fτ,η)}
Wherein, IFFT indicates distance to inverse fast Fourier transform.
In an alternate embodiment of the present invention where, the signal after the range migration correction that above-mentioned steps E obtains step D
sSSOKT(τ, η) takes same distance to obtain signal s to the timeτ(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp
(fdr, η), specifically include it is following step by step:
E1, the range [f that doppler frequency rate is setdr-min,fdr-max] and interval delta fdr, wherein fdr-minAnd fdr-maxRespectively
Indicate the minimum value and maximum value of doppler frequency rate value；
From the signal s after range migration correctionSSOKTSame distance is taken out in (τ, η) to the signal of time, is denoted as sτ(η),
Assuming that it is distance where target to the time, due to sτ(η) only considers doppler frequency rate f 'dr, and its Doppler frequency center is
Zero, f ' in treatment processdrValue be unknown, therefore be arranged doppler frequency rate range, which should include f 'dr, Doppler
Range [the f of frequency modulation ratedr-min,fdr-max] it is [- 2.5,2.5] Hz/s, interval delta fdrFor 0.01Hz/s；
E2, the range [f from doppler frequency ratedr-min,fdr-max] in take out a doppler frequency rate value fdr, constitute one
Centre frequency is 0, linear frequency modulation rate is fdrLinear FM signal, i.e. sLFM(η)=exp (- j π fdrη2), by the linear frequency modulation
Signal sLFM(η) and sτ(η) is multiplied, and obtains sfdr(η)=sLFM(η)×sτ(η)；
E3, the range [f to doppler frequency ratedr-min,fdr-max] in the values of whole doppler frequency rates press step E2
It is handled, obtains 2D signal sdechirp(fdr,η)。
In an alternate embodiment of the present invention where, the 2D signal s that above-mentioned steps F obtains step Edechirp(fdr,η)
Sub-frame processing is carried out, and carries out coherent accumulation in frame, obtains the corresponding signal zero-frequency value S of the i-th framefra-i(fdr), specifically include with
Under step by step:
F1, selection time span TfraFor a frame time length, the 2D signal for being obtained step E according to the orientation time
sdechirp(fdr, η) and it is divided into N frame,I-th frame signal is expressed as sfra-i(fdr, η), i=1,2 ..., N；
Select time span Tfra=2s is a frame time length, according to the orientation time by 2D signal sdechirp(fdr,
η) it is divided into 30 frames；For the i-th frame signal sfra-i(fdr, η), corresponding η range is [- 32+2i, -30+2i] s, due to signal in frame
Complex scattering coefficients σ can be ignoredηBring influences, if not considering amplitude and constant phase, the i-th frame signal is indicated are as follows:
Wherein, f 'drFor sτActual doppler frequency rate value, f in (η)drFor selected doppler frequency rate value；
F2, by every frame signal sfra-i(fdr, η) and in different doppler frequency rate value fdrUnder each orientation time corresponding value
It is added, obtains the corresponding signal zero-frequency value of the i-th frame, i.e.,
As selected fdrWith actual doppler frequency rate f 'drIt is equal, i.e., when going oblique completely, only consider the value in η
In range, every frame signal is expressed as
sfra-i(f′dr, η)=1
By Fourier transformation by the energy accumulation of the signal at zero-frequency, here directly by the value of different η time-ofday signals
Zero-frequency value required for addition obtains accumulates result to get to signal energy in frame.
In an alternate embodiment of the present invention where, the zero-frequency value S that above-mentioned steps G obtains step Ffra-i(fdr) carry out
Interframe no-coherence cumulating is obtained in different doppler frequency rate value fdrCorresponding signal zero-frequency value down, i.e.,
Since when going oblique completely, each frame signal has run up to energy at zero-frequency, therefore do not need to carry out Doppler
Mass center compensating operation directly carries out the energy accumulation result that the zero-frequency value that interframe signal no-coherence cumulating obtains is 60s signal.
In an alternate embodiment of the present invention where, unknown to the time since there are the distances of target, above-mentioned steps H is from step
Signal s after the range migration correction that rapid D is obtainedSSOKTDifferent distance is taken out in (τ, η) to be believed accordingly to the signal of time
Number sτ(η), and return step E repeat step E-H, until completing to all distances to the signal processing of time.
The present invention is extremely low using big-dipper satellite as the bistatic radar target echo signal signal-to-noise ratio of radiation source in order to solve
Problem increases the observation time of target；In the case where long observation time and consideration moving target acceleration, target echo letter
Number range walk and range curvature cannot ignore, need to consider simultaneously, the present invention using symmetrical second order Keystone convert,
In the case where unknown Doppler parameter, range walk and range curvature can be removed simultaneously, realize range migration correction；Meanwhile by
Different in the scattering properties of the target under long observation time, target echo signal is noncoherent in observation time, the present invention
Using the method that target echo signal is carried out sub-frame processing, it is believed that signal is relevant in frame, is concerned with to signal in frame
Accumulation, interframe signal carry out no-coherence cumulating；The present invention is to the signal after symmetrical second order Keystone conversion process using unified
Go tiltedly handle, for removing oblique signal completely, its energy is all run up at Doppler frequency center by Fourier transformation, and
Symmetrical second order Keystone is converted so that the Doppler frequency center of signal becomes zero, therefore, can will not Tongfang for signal in frame
The signal at position moment, which is directly added, realizes that energy is all run up at zero-frequency；Simultaneously as using unification between different frame
It goes tiltedly to handle, Doppler frequency center does not change, and when interframe signal no-coherence cumulating does not need to carry out Doppler frequency center compensation.This hair
It is bright that there are the outstanding advantages that target echo signal energy accumulation effect is good, calculation amount is small.
As shown in figure 4, realizing range migration correction knot to carry out symmetrical second order Keystone transformation in the embodiment of the present invention
Fruit schematic diagram, the present invention are gone while realizing under long observation time range walk and range curvature in echo-signal well
It removes.As shown in figure 5, for echo-signal energy accumulation result schematic diagram in the embodiment of the present invention, the present invention realizes well
To the accumulation of target echo signal energy under long observation time；Therefore, the present invention can be effectively realized with big-dipper satellite as radiation
The detection of the bistatic sea moving target in source；In addition, the present invention for every frame signal due to being only added to obtain zero
Frequency is worth, and interframe signal does not need to carry out Doppler frequency center compensation, greatly reduces the burden of calculation process.
Those of ordinary skill in the art will understand that the embodiments described herein, which is to help reader, understands this hair
Bright principle, it should be understood that protection scope of the present invention is not limited to such specific embodiments and embodiments.This field
Those of ordinary skill disclosed the technical disclosures can make according to the present invention and various not depart from the other each of essence of the invention
The specific variations and combinations of kind, these variations and combinations are still within the scope of the present invention.
Claims (4)
1. a kind of bistatic radar sea moving target detecting method based on big-dipper satellite radiation source, which is characterized in that including
Following steps:
A, system parameter is initialized；The system parameter includes orientation sample frequency fa, distance is to sample frequency fs, target sight
Survey time Ta；
B, direct wave and target echo are enrolled and is demodulated respectively using two antennas, obtain corresponding base band direct-path signal
sd(τ, η) and base band target echo signal secho(τ, η), wherein τ, η respectively indicate distance to time, orientation time；
C, the base band target echo signal s that step B is obtainedecho(τ, η) and base band are gone directly reference signal wave sd(τ, η) carries out phase
Pass processing, obtains distance to the compressed signal s of pulsepc(τ,η)；
D, the distance obtained to step C is to the compressed signal s of pulsepc(τ, η) carries out symmetrical second order Keystone transformation, obtains
Signal s after range migration correctionSSOKT(τ,η)；
E, the signal s after the range migration correction obtained to step DSSOKT(τ, η) takes same distance to obtain signal s to the timeτ
(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp(fdr,η)；
F, the 2D signal s that step E is obtaineddechirp(fdr, η) and sub-frame processing is carried out, and coherent accumulation in frame is carried out, obtains the
The corresponding signal zero-frequency value S of i framefra-i(fdr)；
G, each frame signal zero-frequency value S for obtaining step Ffra-i(fdr) no-coherence cumulating is carried out, obtain corresponding signal zero-frequency value S
(fdr)；
H, from the signal s after the range migration correction that step D is obtainedSSOKTDifferent distance is taken out in (τ, η) to obtain to the signal of time
To corresponding signal sτ(η), and return step E.
2. the bistatic radar sea moving target detecting method based on big-dipper satellite radiation source as described in claim 1,
It is characterized in that, the distance that the step D obtains step C is to the compressed signal s of pulsepc(τ, η) carries out symmetrical second order
Keystone transformation, the signal s after obtaining range migration correctionSSOKT(τ, η), specifically include it is following step by step:
D1, the distance obtained to step C are to the compressed signal s of pulsepc(τ, η) carries out distance to Fast Fourier Transform (FFT), obtains
To apart from frequency domain-orientation time-domain signal Spc(fτ, η), it is expressed as
Spc(fτ, η) and=FFTrg{spc(τ,η)}
Wherein, FFTrgIndicate distance to fast Fourier transformation operation, fτIndicate distance to the distance after Fast Fourier Transform (FFT)
Frequency；
D2, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out positive second order Keystone transformationObtain SSSOKT-P(fτ,ηm), wherein fcFor carrier frequency, ηmFor the orientation time new after transformation；With η generation
For ηm, by SSSOKT-P(fτ,ηm) it is expressed as SSSOKT-P(fτ,η)；
D3, to step D1 obtain apart from frequency domain-orientation time-domain signal Spc(fτ, η) and carry out negative second order Keystone transformationObtain SSSOKT-N(fτ,ηm), η is replaced with ηm, by SSSOKT-N(fτ,ηm) it is expressed as SSSOKT-N(fτ,η)；
D4, the S for obtaining step D2SSOKT-P(fτ, η) and the obtained S of step D3SSOKT-N(fτ, η) and it is multiplied, obtain SSSOKT(fτ,η)；
D5, the S for obtaining step D4SSOKT(fτ, η) and distance is carried out to inverse fast Fourier transform, after obtaining range migration correction
Signal sSSOKT(τ, η), is expressed as
sSSOKT(τ, η)=IFFT { SSSOKT(fτ,η)}
Wherein, IFFT indicates distance to inverse fast Fourier transform.
3. the bistatic radar sea moving target detecting method based on big-dipper satellite radiation source as claimed in claim 2,
It is characterized in that, the signal s after the range migration correction that the step E obtains step DSSOKT(τ, η) takes same distance to the time
Obtain signal sτ(η), that is unified goes tiltedly to handle, and obtains 2D signal sdechirp(fdr, η), specifically include it is following step by step:
E1, the range [f that doppler frequency rate is setdr-min,fdr-max] and interval delta fdr, wherein fdr-minAnd fdr-maxIt respectively indicates
The minimum value and maximum value of doppler frequency rate value；
E2, the value f for taking out a doppler frequency ratedr, one centre frequency of composition is 0, linear frequency modulation rate is fdrLinear frequency modulation letter
Number, i.e. sLFM(η)=exp (- j π fdrη2), by linear FM signal sLFM(η) and sτ(η) is multiplied, and obtains sfdr(η)；
E3, the value of whole doppler frequency rates is handled by step E2, obtains 2D signal sdechirp(fdr,η)。
4. the bistatic radar sea moving target detecting method based on big-dipper satellite radiation source as claimed in claim 3,
It is characterized in that, the 2D signal s that the step F obtains step Edechirp(fdr, η) and sub-frame processing is carried out, and carry out phase in frame
Dry accumulation, obtains the corresponding signal zero-frequency value S of the i-th framefra-i(fdr), specifically include it is following step by step:
F1, selection time span TfraFor a frame time length, the 2D signal s for being obtained step E according to the orientation timedechirp
(fdr, η) and it is divided into N frame,I-th frame signal is expressed as sfra-i(fdr, η), i=1,2 ..., N；
F2, corresponding value of every frame signal each orientation time is added, is obtained i-th under the conditions of different doppler frequency rates
The corresponding signal zero-frequency value of frame, i.e.,
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