CN105158745A - Shift-change double-base forward-looking synthetic aperture radar distance migration correction method - Google Patents

Abstract

The invention discloses a shift-change double-base forward-looking synthetic aperture radar distance migration correction method. Based on a shift-change double-base forward-looking synthetic aperture radar distance migration rule, variable substitution is introduced for realizing azimuth-variant distance migration correction; and combined with iteration assessment and comparison of the correction quality, the influences of motion errors are removed, the shift-change double-base forward-looking synthetic aperture radar distance migration correction is finally realized under the condition that the motion errors exist, and precise doppler fuzzy number estimation can be obtained. The method can be applied to other high-squint synthetic aperture radar modes and is wide in application value.

Description

Move and become double-basis forward sight synthetic-aperture radar range migration correction method

Technical field

The invention belongs to Radar Technology field, be specifically related to a kind of design moving change double-basis forward sight synthetic-aperture radar range migration correction method.

Background technology

It is strong that synthetic-aperture radar (SAR) has penetrability, and can round-the-clock, all weather operations, be widely used in that military surveillance, topographic mapping, vegetational analysis, ocean and hydrologic observation, environment and disaster monitor at present, the field such as resource exploration and the micro-change detection of the earth's crust.

Double-basis Forward-looking SAR is a kind of new tool of earth observation from space.Compared with traditional SAR, double-basis Forward-looking SAR can obtain the non-post of target to scattered information, in operating distance, disguise and anti-interference etc., have advantage.In addition, Bistatic SAR receiver because of not containing high power device, make it have low in energy consumption, volume is little, lightweight advantage, be convenient to different types of machines and carry.Double-basis Forward-looking SAR is scouted the fields such as strike, independent landing, cargo assault, the accurate terminal guidance of guided missile over the ground and is had unique advantage in opportunity of combat.Therefore, double-basis Forward-looking SAR has wide development space in civil and military field.

Move the transmitting-receiving dual station relative position becoming double-basis Forward-looking SAR to change along with the time, have the advantage of double-basis Forward-looking SAR, shift variant mode makes it have better dirigibility simultaneously.But because transmitting-receiving dual station relative position changes in time, make data processing more complicated.Especially, moving under change double-basis forward-looking mode, range migration (RCM) has orientation space-variant, namely orientation to identical double-basis oblique distance and target there is different range migration rules, make range migration correction (RCMC) problem more outstanding.Simultaneously due to the impact of transmitting-receiving dual station kinematic error, make to move the range migration correction becoming double-basis Forward-looking SAR and become more difficult.

At document " Processingofazimuth-invariantbistaticSARdatausingtherang eDoppleralgorithm " (GeoscienceandRemoteSensing, IEEETransactionson, vol.48, no.1, pp.:14-21,2008), in, by being multiplied by the correction of phase factor realization to RCM at distance frequency domain, but the method is not suitable for the situation that RCM has orientation space-variant; Document " Asubaperturerange-Dopplerprocessorforbistatic-fixed-rece iverSAR " (EUSAR06,2006) the orientation sub-aperture method in can overcome the problem of RCM orientation space-variant, but after how dividing sub-aperture and correction, how sub-aperture splices, and is still problem to be solved; Document " Keystonetransform-basedspace-variantrangemigrationcorrec tionforairborneforward-lookingscanningradar " (Electronicsletters, vol.48, no.2, pp.121 – 122,2012) RCM of Keystone transfer pair forward sight scanning radar is utilized to correct, but the method does not consider the impact of kinematic error, and the existence of kinematic error can make the calibration result of RCM decline, and then image quality is declined.

Summary of the invention

The object of the invention is cannot be used for moving the problem becoming double-basis forward sight synthetic-aperture radar to solve conventional range migration correction method in prior art, proposing one and moving change double-basis forward sight synthetic-aperture radar range migration correction method.

Technical scheme of the present invention is: one is moved and become double-basis forward sight synthetic-aperture radar range migration correction method, comprises the following steps:

S1, according to arbitrfary point target in imaging region, calculate the distance course of receiving station and cell site, produce TV-BFSAR system point target simulator echo matrix;

S2, distance is carried out to pulse compression to artificial echo matrix;

S3, calculating initial Doppler fuzzy number;

The doppler ambiguity of data after S4, removal Range compress;

S5, to the range migration correction removed the data after doppler ambiguity and carry out based on substitution of variable;

The entropy of the data after S6, calculating range migration correction;

S7, respectively organize the size of entropy, according to comparative result adjust the distance migration correct after data process.

Further, step S2 is specially:

The artificial echo matrix obtained in obtaining step S1, utilizes ordinary matches filtering method to realize distance to pulse compression, obtains data S (t, f) after Range compress, wherein t be orientation to the time, f is that distance is to Doppler frequency.

Further, step S3 is specially:

According to the transmit-receive platform movement velocity obtained from Motion Measuring Equipment and angle of inclination information, formula (1) is utilized to calculate doppler centroid f _dc:

Wherein V _r, V _tbe respectively receiver, transmitter movement velocity, receiving station's downwards angle of visibility and angle of squint, cell site respectively;

The initial value N of doppler ambiguity number is obtained again by formula (2) _am:

N _am＝round(f _dc/PRF)(2)

Wherein, PRF is transmit signal pulse repetition frequency, and round () is nearest bracket function;

And then by the initial value N of doppler ambiguity number _amadd 1 and subtract 1 respectively, obtain N _am+and N _am-.

Further, step S4 is specially:

Doppler ambiguity phase factor is removed according to formula (3) structure:

$P=\exp (-j2\mathrm{\π}(\frac{N_m}{T_s})t)---\left(3\right)$

Wherein, N _mfor doppler ambiguity number, T _sfor transmit signal pulse recurrence interval, t is that orientation is to the time;

Make N _mequal N respectively _am, N _am+and N _am-, obtain three and remove doppler ambiguity phase factor P, P ₊and P _-;

Three are gone doppler ambiguity phase factor respectively with Range compress after data S (t, f) be multiplied, obtain three groups and remove data S ' (t, f), S ' (t, f) after doppler ambiguity ₊with S ' (t, f) _-.

Further, step S5 is specially:

Three groups that according to formula (4), step S4 are obtained remove doppler ambiguities after data carry out substitution of variable:

$t^{\′}=\frac{(f_c+f)}{f_c}t---\left(4\right)$

Wherein, f _cfor the centre frequency transmitted;

The t that three groups are removed in the data after doppler ambiguities is replaced with t ', obtain data S ' after three groups of substitution of variable (t ', f), S ' (t ', f) ₊with S ' (t ', f) _-;

Again to data after three groups of substitution of variable along distance to doing inverse Fourier transform, obtain the data S ' after three groups of range migration corrections (t ', τ), S ' (t ', τ) ₊with S ' (t ', τ) _-.

Further, step S6 is specially:

Data after the three groups of range migration corrections obtained by step S5, along orientation to projecting, obtain three groups of energy sequence x (m), x (m) ₊with x (m) _-, m=0,1 ..., M-1, wherein M is that distance is to sampling unit number;

The entropy of the data after range migration correction is calculated according to formula (5) and formula (6):

$p_m=\frac{\left|x\left(m\right)\right|}{\underset{m=0}{\overset{M-1}{\Σ}}\left|x\left(m\right)\right|}---\left(5\right)$

$H=-\underset{m=0}{\overset{M-1}{\Σ}}{p}_m{\mathrm{logp}}_m---\left(6\right)$

Three groups of energy sequence correspondences calculate three groups of entropy H, H ₊and H _-.

Further, step S7 specifically comprises step by step following:

S71, compare three groups of entropy H, H ₊and H _-size;

If H ₊for minimum value, then enter step S72;

If H _-for minimum value, then enter step S74;

If H is minimum value, then enter step S76;

S72, by H ₊assignment is to H, N _am+assignment is to N _am, and by N _amadd 1 and obtain N _am+, repeat step S4-S6, obtain the entropy H after range migration correction ₊;

S73, compare H ₊with the size of H, if H≤H ₊then enter step S76, otherwise return step S72;

S74, by H _-assignment is to H, N _am-assignment is to N _am, and by N _amsubtract 1 and obtain N _am-, repeat step S4-S6, obtain the entropy H after range migration correction _-;

S75, compare H _-with the size of H, if H≤H _-then enter step S76, otherwise return step S74;

S76, output N _amcarry out the result S ' after range migration correction (t ', τ).

The invention has the beneficial effects as follows: the present invention utilizes the rule of moving and becoming double-basis Forward-looking SAR range migration, a range migration correction method based on substitution of variable and minimum entropy theory are combined, by the iteration to doppler ambiguity number, complete the range migration correction moving and become double-basis Forward-looking SAR, obtain the accurate estimation of doppler ambiguity number simultaneously.Advantage of the present invention to overcome the problem of moving and becoming double-basis Forward-looking SAR range migration orientation space-variant and kinematic error, obtains doppler ambiguity number accurately simultaneously.And the method is with a wide range of applications under also can be applicable to other large slanting view angle machine synthetic-aperture radar pattern.

Accompanying drawing explanation

Fig. 1 is that one provided by the invention moves change double-basis forward sight synthetic-aperture radar range migration correction method flow diagram.

Fig. 2 is step S7 of the present invention process flow diagram step by step.

Fig. 3 is embodiment of the present invention simulation objectives scene schematic diagram.

Fig. 4 is schematic diagram data after embodiment of the present invention Range compress.

Fig. 5 is schematic diagram data after embodiment of the present invention range migration correction.

Fig. 6 is embodiment of the present invention point target imaging results schematic diagram.

Embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are further described.

Content of the present invention for convenience of description, first makes an explanation to following term:

Term 1: double-basis Forward-looking SAR (BistaticForward-lookingSAR).

Double-basis Forward-looking SAR refers to the SAR system that systems radiate station and receiving station are placed in different platform, wherein has at least a platform to be motion platform, and under receiving station is operated in forward sight receiving mode, conceptually belongs to bistatic radar.

Term 2: move and become double-basis Forward-looking SAR (TV-BFSAR).

Move and become the one that double-basis Forward-looking SAR is double-basis Forward-looking SAR, and its transmitting-receiving dual station relative position changed along with the time.

Term 3: doppler ambiguity number.

When pulse repetition rate is lower than Echo Doppler Frequency, the Doppler frequency be sampled paired pulses repetition frequency can produce " winding ", and this quantity be wound around is exactly doppler ambiguity number.

Solution of the present invention is being moved under change double-basis Forward-looking SAR pattern, consider the impact of kinematic error, Binding distance migration (RCM) feature and minimum entropy theory, iteration is carried out to doppler ambiguity number, when obtaining minimum entropy, range migration correction effect reaches best, obtains the accurate estimation of doppler ambiguity number simultaneously.

The invention provides one and move change double-basis forward sight synthetic-aperture radar range migration correction method, as shown in Figure 1, comprise the following steps:

S1, according to arbitrfary point target in imaging region, calculate the distance course of receiving station and cell site, produce TV-BFSAR system point target simulator echo matrix.

S2, distance is carried out to pulse compression to artificial echo matrix.

The artificial echo matrix obtained in obtaining step S1, utilizes ordinary matches filtering method to realize distance to pulse compression, obtains data S (t, f) after Range compress, wherein t be orientation to the time, f is that distance is to Doppler frequency.

S3, calculating initial Doppler fuzzy number.

According to the transmit-receive platform movement velocity obtained from Motion Measuring Equipment (as GPS/INS etc.) and angle of inclination information, formula (1) is utilized to calculate doppler centroid f _dc:

Wherein V _r, V _tbe respectively receiver, transmitter movement velocity, receiving station's downwards angle of visibility and angle of squint, cell site respectively.

The initial value N of doppler ambiguity number is obtained again by formula (2) _am:

N _am＝round(f _dc/PRF)(2)

Wherein, PRF is transmit signal pulse repetition frequency, and round () is nearest bracket function.

And then by the initial value N of doppler ambiguity number _amadd 1 and subtract 1 respectively, obtain N _am+and N _am-.

The doppler ambiguity of data after S4, removal Range compress.

Doppler ambiguity phase factor is removed according to formula (3) structure:

$P=\exp (-j2\mathrm{\π}(\frac{N_m}{T_s})t)---\left(3\right)$

Wherein, N _mfor doppler ambiguity number, T _sfor transmit signal pulse recurrence interval, t is that orientation is to the time.

Make N _mequal N respectively _am, N _am+and N _am-, obtain three and remove doppler ambiguity phase factor P, P ₊and P _-.

Three are gone doppler ambiguity phase factor respectively with Range compress after data S (t, f) be multiplied, obtain three groups and remove data S ' (t, f), S ' (t, f) after doppler ambiguity ₊with S ' (t, f) _-.

S5, to the range migration correction removed the data after doppler ambiguity and carry out based on substitution of variable.

Three groups that according to formula (4), step S4 are obtained remove doppler ambiguities after data carry out substitution of variable:

$t^{\′}=\frac{(f_c+f)}{f_c}t---\left(4\right)$

Wherein, f _cfor the centre frequency transmitted;

This process is about to three groups of t removed in the data after doppler ambiguities and replaces with t ', obtain data S ' after three groups of substitution of variable (t ', f), S ' (t ', f) ₊with S ' (t ', f) _-, then to data after three groups of substitution of variable along distance to doing inverse Fourier transform, obtain the data S ' after three groups of range migration corrections (t ', τ), S ' (t ', τ) ₊with S ' (t ', τ) _-.

The entropy of the data after S6, calculating range migration correction.

Data after the three groups of range migration corrections obtained by step S5, along orientation to projecting, obtain three groups of energy sequence x (m), x (m) ₊with x (m) _-, m=0,1 ..., M-1, wherein M is that distance is to sampling unit number.

The entropy of the data after range migration correction is calculated according to formula (5) and formula (6):

$p_m=\frac{\left|x\left(m\right)\right|}{\underset{m=0}{\overset{M-1}{\Σ}}\left|x\left(m\right)\right|}---\left(5\right)$

$H=-\underset{m=0}{\overset{M-1}{\Σ}}{p}_m{\mathrm{logp}}_m---\left(6\right)$

Three groups of energy sequence correspondences calculate three groups of entropy H, H ₊and H _-.

S7, respectively organize the size of entropy, according to comparative result adjust the distance migration correct after data process.

As shown in Figure 2, this step specifically comprises step by step following:

S71, compare three groups of entropy H, H ₊and H _-size.

If H ₊for minimum value, then enter step S72.

If H _-for minimum value, then enter step S74.

If H is minimum value, then enter step S76.

S72, by H ₊assignment is to H, N _am+assignment is to N _am, and by N _amadd 1 and obtain N _am+, repeat step S4-S6, namely utilize formula (3) (4) (5) (6) to the N newly obtained _am+carry out doppler ambiguity phase factor structure, remove doppler ambiguity, based on substitution of variable range migration correction and calculate the process such as entropy, finally obtain the entropy H after range migration correction ₊.

S73, compare H ₊with the size of H, if H≤H ₊then enter step S76, otherwise return step S72.

S74, by H _-assignment is to H, N _am-assignment is to N _am, and by N _amsubtract 1 and obtain N _am-, repeat step S4-S6, namely utilize formula (3) (4) (5) (6) to the N newly obtained _am-carry out doppler ambiguity phase factor structure, remove doppler ambiguity, based on substitution of variable range migration correction and calculate the process such as entropy, finally obtain the entropy H after range migration correction _-.

S75, compare H _-with the size of H, if H≤H _-then enter step S76, otherwise return step S74.

S76, output N _amcarry out the result S ' after range migration correction (t ', τ).

Here, when the value of H is minimum, the N that the last assignment obtains is proved _ambe the fine estimation of doppler ambiguity number, now output N _amcarry out the result S ' after range migration correction (t ', τ), finishing iteration process.

Move change double-basis forward sight synthetic-aperture radar range migration correction method with a specific embodiment to one provided by the invention to be below described further:

Matlab2010 moves one provided by the invention to become double-basis forward sight synthetic-aperture radar range migration correction method validation process as follows:

S1, according to arbitrfary point target in imaging region, calculate the distance course of receiving station and cell site, produce TV-BFSAR system point target simulator echo matrix.As shown in Figure 3, the black round dot in figure is for being arranged in ground 3 point targets, and these 3 points (cut flight path) in the x-direction 50 meters, interval, in the y-direction 50 meters, (along flight path) interval, transmit-receive platform moves along y-axis for simulation objectives scene.Emulate parameter used as shown in the table:

Parameter	Symbol	Numerical value
			Carrier frequency	f 0	9.6GHz
Transmitted signal bandwidth	B r	40MHz
			Wide when transmitting	T r	1μs
Transmit signal pulse repetition frequency	PRF	400Hz
			Position, cell site	x T,y T,h T	0km,-1km,8km
Receiving station zero moment position	x R,y R,h R	1km,-5km,8km
			Transmitter movement velocity	V T	120m/s
Receiver movement velocity	V R	100m/s
			Motion platform kinematic error	v e	0.2m/s

S2, distance is carried out to pulse compression to artificial echo matrix.

According to simulation parameter structure distance to pulse compression reference function, by artificial echo along distance to doing Fourier transform, and being multiplied to reference function with distance, completing the distance of artificial echo to pulse compression, data after note Range compress are S (t, f).Data after Range compress as shown in Figure 4.

S3, calculating initial Doppler fuzzy number.

The receiving station provided by upper table and reflecting station position, movable information, target scenario parameters and impulse sampling frequency PRF, calculate the doppler centroid theoretical value f of artificial echo _dcfor 2168.7Hz, get f _dcthe nearest integer 5 of/PRF=5.42 ratio is as doppler ambiguity number N _amthe initial value estimated.

The doppler ambiguity of data after S4, removal Range compress.

Make N _m=N _am=5, remove doppler ambiguity phase factor P according to formula (3) structure:

$P=\exp (-j2\mathrm{\π}(\frac{N_m}{T_s})t)---\left(3\right)$

Wherein, N _mfor doppler ambiguity number, T _sfor transmit signal pulse recurrence interval, t is that orientation is to the time.

Data S (t, f) after this phase factor P and Range compress is multiplied and obtains S ' (t, f), namely complete and utilize doppler ambiguity number N _amremove the impact of doppler ambiguity.

S5, to the range migration correction removed the data after doppler ambiguity and carry out based on substitution of variable.

According to formula (4), S ' (t, f) is obtained to step S4 and carries out substitution of variable:

$t^{\′}=\frac{(f_c+f)}{f_c}t---\left(4\right)$

Wherein, f _cfor the centre frequency transmitted.

Replace with t ' by the t in S ' (t, f), obtain data S ' after substitution of variable (t ', f), then to it along distance to doing inverse Fourier transform, obtain the data S ' after range migration correction (t ', τ).Data after range migration correction as shown in Figure 5.

The entropy of the data after S6, calculating range migration correction.

By S ' (t ', τ) along orientation to projecting, namely at each distance samples unit (the often row of matrix), the data of all azimuth sample cells (often going of matrix) are carried out absolute value addition, obtain energy sequence x (m), m=0,1 ... M-1, wherein M is that distance is to sampling unit number.

Then the entropy of the data after range migration correction is calculated according to formula (5) and formula (6):

$p_m=\frac{\left|x\left(m\right)\right|}{\underset{m=0}{\overset{M-1}{\Σ}}\left|x\left(m\right)\right|}---\left(5\right)$

$H=-\underset{m=0}{\overset{M-1}{\Σ}}{p}_m{\mathrm{logp}}_m---\left(6\right)$

Utilize doppler ambiguity number N _am=5 entropy H=7.53 calculating the data after range migration correction.

Afterwards by doppler ambiguity number N _amadd 1 and subtract 1 and obtain N respectively _am+=6, N _am-=4, repeat step S4-S6, obtain the entropy H after range migration correction ₊=7.30, H _-=7.56.

S7, compare H, H ₊and H _-value known, use doppler ambiguity number N _am+=6 range migration correction effects removed after doppler ambiguity are best, therefore should carry out doppler ambiguity number estimation to the direction increased.By 6 assignment in doppler ambiguity number N _am, then N _am+=7, repeat step S4-S6, obtaining entropy is H ₊=7.60, then obtain minimum entropy when known doppler ambiguity number is 6, now calibration result is best.Data after output calibration, and the estimated value obtaining doppler ambiguity number is 6, completes to move to become the process of double-basis forward sight synthetic-aperture radar range migration correction.Sink node target simulator result as shown in Figure 6.

As can be seen from the specific embodiment of the invention, when the present invention can realize there is kinematic error, to moving the correction becoming double-basis Forward-looking SAR range migration, obtain the accurate estimation of doppler ambiguity number simultaneously.

Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to so special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combination of not departing from essence of the present invention according to these technology enlightenment disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.

Claims (7)

1. move and become a double-basis forward sight synthetic-aperture radar range migration correction method, it is characterized in that, comprise the following steps:

S1, according to arbitrfary point target in imaging region, calculate the distance course of receiving station and cell site, produce TV-BFSAR system point target simulator echo matrix;

S2, distance is carried out to pulse compression to artificial echo matrix;

S3, calculating initial Doppler fuzzy number;

The doppler ambiguity of data after S4, removal Range compress;

S5, to the range migration correction removed the data after doppler ambiguity and carry out based on substitution of variable;

The entropy of the data after S6, calculating range migration correction;

S7, respectively organize the size of entropy, according to comparative result adjust the distance migration correct after data process.

2. according to claim 1 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S2 is specially:

The artificial echo matrix obtained in obtaining step S1, utilizes ordinary matches filtering method to realize distance to pulse compression, obtains data S (t, f) after Range compress, wherein t be orientation to the time, f is that distance is to Doppler frequency.

3. according to claim 2 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S3 is specially:

According to the transmit-receive platform movement velocity obtained from Motion Measuring Equipment and angle of inclination information, formula (1) is utilized to calculate doppler centroid f _dc:

Wherein V _r, V _tbe respectively receiver, transmitter movement velocity, receiving station's downwards angle of visibility and angle of squint, cell site respectively;

The initial value N of doppler ambiguity number is obtained again by formula (2) _am:

N _am＝round(f _dc/PRF)(2)

Wherein, PRF is transmit signal pulse repetition frequency, and round () is nearest bracket function;

And then by the initial value N of doppler ambiguity number _amadd 1 and subtract 1 respectively, obtain N _am+and N _am-.

4. according to claim 3 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S4 is specially:

Doppler ambiguity phase factor is removed according to formula (3) structure:

$P=\exp (-j2\mathrm{\π}(\frac{N_m}{T_s})t)---\left(3\right)$

Wherein, N _mfor doppler ambiguity number, T _sfor transmit signal pulse recurrence interval, t is that orientation is to the time;

Make N _mequal N respectively _am, N _am+and N _am-, obtain three and remove doppler ambiguity phase factor P, P ₊and P _-;

Three are gone doppler ambiguity phase factor respectively with Range compress after data S (t, f) be multiplied, obtain three groups and remove data S ' (t, f), S ' (t, f) after doppler ambiguity ₊with S ' (t, f) _-.

5. according to claim 4 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S5 is specially:

Three groups that according to formula (4), step S4 are obtained remove doppler ambiguities after data carry out substitution of variable:

$t^{\′}=\frac{(f_c+f)}{f_c}t---\left(4\right)$

Wherein, f _cfor the centre frequency transmitted;

The t that three groups are removed in the data after doppler ambiguities is replaced with t ', obtain data S ' after three groups of substitution of variable (t ', f), S ' (t ', f) ₊with S ' (t ', f) _-;

Again to data after three groups of substitution of variable along distance to doing inverse Fourier transform, obtain the data S ' after three groups of range migration corrections (t ', τ), S ' (t ', τ) ₊with S ' (t ', τ) _-.

6. according to claim 5 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S6 is specially:

Data after the three groups of range migration corrections obtained by step S5, along orientation to projecting, obtain three groups of energy sequence x (m), x (m) ₊with x (m) _-, m=0,1 ..., M-1, wherein M is that distance is to sampling unit number;

The entropy of the data after range migration correction is calculated according to formula (5) and formula (6):

$p_m=\frac{\left|x\left(m\right)\right|}{\underset{m=0}{\overset{M-1}{\Σ}}\left|x\left(m\right)\right|}---\left(5\right)$

$H=-\underset{m=0}{\overset{M-1}{\Σ}}{p}_m{\mathrm{logp}}_m---\left(6\right)$

Three groups of energy sequence correspondences calculate three groups of entropy H, H ₊and H _-.

7. according to claim 6 moving becomes double-basis forward sight synthetic-aperture radar range migration correction method, and it is characterized in that, described step S7 specifically comprises step by step following:

S71, compare three groups of entropy H, H ₊and H _-size;

If H ₊for minimum value, then enter step S72;

If H _-for minimum value, then enter step S74;

If H is minimum value, then enter step S76;

S72, by H ₊assignment is to H, N _am+assignment is to N _am, and by N _amadd 1 and obtain N _am+, repeat step S4-S6, obtain the entropy H after range migration correction ₊;

S73, compare H ₊with the size of H, if H≤H ₊then enter step S76, otherwise return step S72;

S74, by H _-assignment is to H, N _am-assignment is to N _am, and by N _amsubtract 1 and obtain N _am-, repeat step S4-S6, obtain the entropy H after range migration correction _-;

S75, compare H _-with the size of H, if H≤H _-then enter step S76, otherwise return step S74;

S76, output N _amcarry out the result S ' after range migration correction (t ', τ).