CN106597444A - Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR - Google Patents

Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR Download PDF

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CN106597444A
CN106597444A CN201611236517.6A CN201611236517A CN106597444A CN 106597444 A CN106597444 A CN 106597444A CN 201611236517 A CN201611236517 A CN 201611236517A CN 106597444 A CN106597444 A CN 106597444A
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pulse
target
recurrence interval
calculating
pulse recurrence
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CN106597444B (en
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孙兵
李景文
谭林
姜予名
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Beihang University
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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
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • 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
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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

Abstract

The invention discloses an azimuth ambiguity calculating method of a variable pulse recurrence interval airborne SAR. The method comprises the following steps of according to a pulse recurrence interval, determining a position of a radar at each pulse emission moment and a target position to be analyzed; determining an echo intensity of a target in a pulse-by-pulse mode and calculating and acquiring an energy sum of the target; and determining an echo intensity of a fuzzy region in the pulse-by-pulse mode, calculating and acquiring total fuzzy energy, and calculating a ratio of total fuzzy region energy and total target energy so as to acquire an azimuth ambiguity. In the invention, a theoretical basis and a realization method are provided for a variable pulse recurrence interval airborne SAR system. A traditional frequency domain analysis method can not be suitable for variable pulse recurrence interval airborne SAR system analysis. Because there is no requirement to antenna pointing at any moments, the method can be suitable for any non-fixed directional antenna SAR systems.

Description

A kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR
Technical field
The present invention relates to synthetic aperture radar (Synthetic Aperture Radar, SAR) technical field, specifically refers to A kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR.
Background technology
Azimuth ambiguity is that impulse sampling working system causes in orientation due to synthetic aperture radar.Synthetic aperture thunder The Doppler frequency spectrum of the echo-signal for reaching is weighted by antenna bearingt to transmitting-receiving round trip directional diagram, and by system pulse recurrence frequency To sample, it is folded in orientation process bandwidth higher than the Doppler frequency spectrum of pulse recurrence frequency, together with main signal aliasing, Therefore the signal spectrum of secondary lobe can produce impact to the signal in doppler bandwidth after sampling, and cause azimuth ambiguity, thus side It is by caused by the operation principle of SAR that position is fuzzy.Impact of the azimuth ambiguity to SAR image quality is mainly shown as two aspects： One side blurred signal focuses on generation false target after imaging；On the other hand the fuzzy energy for spreading causes the letter of image Make an uproar than deteriorating.So the azimuth ambiguity characteristic of further investigation carried SAR, significant to optimizing carried SAR system design.
Become pulse recurrence interval (PRT) carried SAR system and refer to that the interval time of radar transmitted pulse may differ, and It is the SAR system according to certain rule change, becomes pulse recurrence interval and the heavy multiple interval correlation's schematic diagram of fixed pulse is for example attached Shown in Fig. 2.Become pulse recurrence interval carried SAR because its pulse recurrence interval is variable, with fixed pulse recurrence interval SAR system phase Than, there is certain advantage in high-resolution high squint SAR imaging, but just because of orientation that its pulse recurrence interval is variable, traditional Fuzzy Calculation method is no longer suitable for.
The azimuth ambiguity computational methods of classical carried SAR be by positioned at different azimuth to the corresponding time noise of target To orientation frequency domain, frequency domain antenna directional diagram is folded according to fixed pulse recurrence frequency, it is corresponding for antenna main lobe Doppler spectral is considered as effective target energy, and to the antenna both sides secondary lobe energy that aliasing is entered by way of sampling fuzzy energy is considered as Amount, so as to calculate the ratio of the energy of blurred portions and the energy of target area, so as to obtain azimuth ambiguity degree.But become pulse weight Under multiple spaced apart condition, transmitting pulse and echo reception pulse there may be certain deviation, be that this is fuzzy in target area both sides Occur during the position in area dramatically different, it is impossible to complete simply simply by Doppler frequency and the equivalent mode of space angle Conversion.The present invention proposes a kind of azimuth ambiguity degree computational methods for becoming pulse recurrence interval carried SAR.
The content of the invention
The purpose of the present invention is to solve the azimuth ambiguity degree design problem of change pulse recurrence interval carried SAR, it is proposed that A kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR.This method is prolonged using the echo of adjacent several pulses Late relation, determines the fuzzy zone position of each pulse time, and Pulse by Pulse calculates confusion region echo strength and target-echo intensity, the two Compare and try to achieve the azimuth ambiguity degree for becoming pulse recurrence interval carried SAR.
For achieving the above object, the present invention provides a kind of azimuth ambiguity degree calculating side of change pulse recurrence interval carried SAR Method, including：
Step 1, the position that each impulse ejection moment radar is determined according to pulse recurrence interval and target to be analyzed Position；
Step 2, Pulse by Pulse determine the echo strength of target, and the antenna weighting of each moment target and each moment are calculated respectively Oblique distance, using the corresponding target energy sum of whole pulses as total target energy；
Step 3, Pulse by Pulse determine the echo strength of confusion region, and the equivalent pulse recurrence interval of each x time is calculated respectively And the Doppler frequency of target, further according to equivalent pulse recurrence interval and target Doppler frequency calculate obtain each obscure The orientation off-axis angle in area, and then the oblique distance of each confusion region is obtained, and using the energy accumulation of whole fuzzy objects as current arteries and veins The confusion region energy of punching, finally using the corresponding confusion region energy sum of whole pulses as total confusion region energy；
The total confusion region energy of step 4, calculating and the ratio of total target energy, obtain azimuth ambiguity degree.
As a further improvement on the present invention, in step 1, echo central instant beam center is chosen in the target location Irradiation position.
As a further improvement on the present invention, the step 1 includes：
Step 11, input radar system parameters and radar orbit parameter, the radar system parameters include that radar is effectively fast Degree V, radar operation wavelength λ, orientation antenna length La, antenna downwards angle of visibility γ and reference pulse repetition rate prf, Yi Jibian Pulse recurrence interval sequence tp, the radar orbit parameter include radar altitude H；
Step 12, antenna bearingt is calculated to beam angle βa；Calculated target positionsAnd most short oblique distance Tr, profit With antenna bearingt to beam angle βaMost short oblique distance TrObtain synthetic aperture time ts；
Tr=H/cos γ (3)
Step 13, the sampling number N being calculated in the synthetic aperture time；
Wherein, prf is reference pulse repetition rate；
Step 14, it is calculated radar site
As a further improvement on the present invention, the step 2 includes：
Step 21, the antenna weighting G (θ for calculating each moment targeta(i))；
In formula, θa(i) be orientation off-axis angle, βaFor Azimuth beam width, sin () expression SIN functions；
Step 22, oblique distance r (i) for calculating the correspondence moment；
Wherein, | | represent modulo operation；
Step 23, calculating target energy sum St；
As a further improvement on the present invention, the step 3 includes：
Step 31, the equivalent pulse recurrence interval PRT for calculating each momenti；
Step 32, Doppler frequency f for calculating each moment targetdi；
If radar speed vector is：
Then Doppler frequency f of targetdiFor：
Step 33, the orientation off-axis angle θ for calculating each confusion region at momentak(i)；
Wherein, k represents confusion region Position Number, and M represents the number of maximum confusion region, and Z represents set of integers, arccos () table Show inverse cosine function；
Step 34, oblique distance r for calculating each confusion region at momentk(i)；
Step 35, echo strength sum S for calculating each confusion regiona(i)；
The total fuzzy energy S of step 36, calculatinga；
As a further improvement on the present invention, in the step 4, computer azimuth fuzziness AASRt：
Compared with prior art, beneficial effects of the present invention are：
1st, a kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR are proposed, is to become between pulse repetition Theoretical foundation and implementation method are provided every the system design of carried SAR, traditional frequency domain analysis method cannot be applied to and become pulse Recurrence interval SAR system analysis；
2nd, this method for each moment antenna due to pointing to no requirement (NR), therefore goes for any on-fixed directional antenna SAR system.
Description of the drawings
Fig. 1 is the disclosed azimuth ambiguity degree computational methods for becoming pulse recurrence interval carried SAR of an embodiment of the present invention Flow chart；
Fig. 2 is the contrast schematic diagram for becoming pulse recurrence interval and fixed pulse recurrence interval in the present invention；
Fig. 3 is the off-axis angle situation of change of second each confusion region of pulse time in the embodiment of the present invention；
Fig. 4 is the oblique distance situation of change of second each confusion region of pulse time in the embodiment of the present invention.
Specific embodiment
To make purpose, technical scheme and the advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present invention In accompanying drawing, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is A part of embodiment of the present invention, rather than the embodiment of whole.Based on the embodiment in the present invention, ordinary skill people The every other embodiment that member is obtained on the premise of creative work is not made, belongs to the scope of protection of the invention.
The present invention is described in further detail below in conjunction with the accompanying drawings：
As shown in figure 1, the present invention provides a kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR, bag Include following step：
Step 1, the position that each impulse ejection moment radar is determined according to pulse recurrence interval and target to be analyzed Generally choose echo central instant beam center irradiation position in position, target location.Specially：
Step 11, input radar system parameters and radar orbit parameter, radar system parameters include radar effective speed V, Radar operation wavelength λ, orientation antenna length La, antenna downwards angle of visibility γ and reference pulse repetition rate prf, radar track ginseng Number includes radar altitude H；
Step 12, antenna bearingt is calculated to beam angle β according to formula (1)a；Mesh is calculated according to formula (2) and (3) Cursor positionIts coordinate is Tx, Ty, Tz, and most short oblique distance Tr；
Tr=H/cos γ (3)
Formula (4) is recycled to obtain synthetic aperture time ts；
Step 13, the sampling number N being calculated using formula (5) in the synthetic aperture time；
Wherein, prf is reference pulse repetition rate；
Step 14, it is calculated radar site using formula (6)
Step 2, Pulse by Pulse determine the echo strength of target, and the antenna weighting of each moment target and each moment are calculated respectively Oblique distance, using the corresponding target energy sum of whole pulses as total target energy；Specially：
Step 21, the antenna weighting G (θ for calculating each moment targeta(i))；
In formula, θa(i) be orientation off-axis angle, βaFor Azimuth beam width；
Step 22, oblique distance r (i) for calculating the correspondence moment；
Wherein, | | represent modulo operation；
Step 23, calculating target energy sum St；
Step 3, Pulse by Pulse determine the echo strength of confusion region, and the equivalent pulse recurrence interval of each x time is calculated respectively And the Doppler frequency of target, further according to equivalent pulse recurrence interval and target Doppler frequency calculate obtain each obscure The orientation off-axis angle in area, and then the oblique distance of each confusion region is obtained, and using the energy accumulation of whole fuzzy objects as current arteries and veins The confusion region energy of punching, finally using the corresponding confusion region energy sum of whole pulses as total confusion region energy；Specially：
Step 31, the equivalent pulse recurrence interval PRT for calculating each momenti；
Step 32, Doppler frequency f for calculating each moment targetdi；
If radar speed vector is：
Then Doppler frequency f of targetdiFor：
Step 33, the orientation off-axis angle θ for calculating each confusion region at momentak(i)；
Wherein, k represents confusion region Position Number, and M represents the number of maximum confusion region, and Z represents set of integers, arccos () table Show inverse cosine function；
Step 34, oblique distance r for calculating each confusion region at momentk(i)；
Step 35, echo strength sum S for calculating each confusion regiona(i)；
The total fuzzy energy S of step 36, calculatinga；
The total confusion region energy of step 4, calculating and the ratio of total target energy, obtain azimuth ambiguity degree；Computer azimuth mould Paste degree AASRt：
So far, it is calculated the azimuth ambiguity degree for becoming pulse recurrence interval carried SAR.
Embodiment 1：
For a typical carried SAR, the orientation fuzziness of the system is analyzed, specific computational methods are by following Step is realized：
Step one, input radar system parameters and radar orbit parameter, and initialization process is carried out to parameter.
(a) input radar system parameters (it is 250m/s including radar effective speed V, radar operation wavelength λ is 0.032m, Orientation antenna length LaFor 1m, antenna downwards angle of visibility γ is 45 degree, doppler bandwidth 443Hz, and reference pulse repetition rate prf is 600Hz and change pulse recurrence interval sequence tp) and orbit parameter (being 10km including radar altitude H)；
B () is calculated antenna bearingt to beam angle β according to formula (18)a, calculated according to formula (19) to (20) and counted Calculate target locationIts coordinate is Tx, Ty, TzAnd most short oblique distance Tr；
Tr=H/cos γ (20)
Formula (21) is recycled to obtain synthetic aperture time ts。
C () is calculated the sampling number N in the synthetic aperture time using formula (22).
D () is calculated radar site according to formula (23)The corresponding radar site of second pulse time is as follows (following individual pulse is analyzed by taking second pulse as an example).
Step 2, Pulse by Pulse determine the echo strength of target.
A () calculates the antenna weighting G (θ of each moment targeta(i))。
B () calculates oblique distance r at correspondence momenti。
C () calculates target energy sum St。
Step 3, Pulse by Pulse determine the echo strength of confusion region.
A () calculates the equivalent PRT at each momenti。
B () calculates Doppler frequency f of each moment targetdi；
If radar speed vector is：
Then the Doppler frequency of target is：
C () calculates the orientation off-axis angle θ of each confusion region at momentak(i)；
The off-axis angle of 1 second each confusion region of pulse time of table
Table 1 gives the off-axis angle numerical value of second each confusion region of pulse time in the present embodiment.Accompanying drawing 3 gives The off-axis angle situation of change of two each confusion regions of pulse time, from figure 3, it can be seen that the off-axis angle of confusion region is with fuzzy Zone position numbers linear change.
D () calculates oblique distance r of each confusion region at momentik；
Wherein, TrFor most short oblique distance.
The oblique distance of 2 second each confusion regions of pulse time of table
Table 2 gives the oblique distance numerical value of second each confusion region of pulse time in the present embodiment.Accompanying drawing 4 gives second The oblique distance situation of change of individual each confusion region of pulse time, figure 4, it is seen that the confusion region oblique distance of the right and left is with respect to mesh Punctuate almost symmetry.
D () calculates echo strength sum S of each confusion regiona(i)；
E () calculates total fuzzy energy Sa；
Step 4, azimuth ambiguity degree index are calculated.
Azimuth ambiguity degree AASR is calculated using equation belowt；
Shown in simulation result table 3 and table 4：
The fixed pulse recurrence interval SAR system azimuth ambiguity degree of table 3
PRT(s) The method of the invention (dB) Traditional frequency domain analysis method (dB)
1/200 -3.3776 -3.3170
1/400 -15.3924 -15.2788
1/600 -22.0333 -21.9439
Table 4 becomes pulse recurrence interval SAR system azimuth ambiguity degree
PRT averages (s) The method of the invention (dB)
1/200 -3.3740
1/400 -13.7146
1/600 -18.8192
So far the azimuth ambiguity degree ANALYSIS OF CALCULATING for becoming pulse recurrence interval carried SAR system is completed, calculated Fixed pulse recurrence interval azimuth ambiguity degree is as shown in table 3, by can be seen that for solid with the contrast of traditional frequency domain analysis method Determine pulse recurrence interval carried SAR system, this method is basically identical with traditional frequency domain analysis method, illustrate the side that this method is calculated Position fuzziness is effective；Become pulse recurrence interval azimuth ambiguity degree as shown in table 4, by using change pulse recurrence interval Carried SAR, can use this method computer azimuth fuzziness, and traditional frequency domain method cannot be calculated.
The present invention is applied to the carried SAR with following constraints：
1st, impulse ejection and reception are adopted and stop walking modes, and do not consider particular location of the target in different pulse echo windows Difference, but consider when receiving confusion region energy；
2nd, Practical Calculation azimuth ambiguity area be ± 20, outside confusion region energy ignore；
3rd, the backward energy difference that the corresponding incident angular difference in confusion region brings is ignored.
The purpose of the present invention is to solve the azimuth ambiguity degree design problem of change pulse recurrence interval carried SAR, it is proposed that Become the computational methods of pulse recurrence interval carried SAR azimuth ambiguity degree in one.Using the echo delay relation of adjacent several pulses, Determine the fuzzy zone position at each moment, and then the corresponding confusion region of current PRF is obtained by oblique distance and antenna radiation pattern weighting Echo strength and target-echo intensity, finally using in the full illumination time pulse energy summation obtain total vague intensity with it is total Target strength, asks the two than being worth to azimuth ambiguity degree, so as to realize becoming the azimuth ambiguity degree point of pulse recurrence interval carried SAR Analysis, and by instance analysis, the implementation process of this method has been described in further detail.
The present invention proposes a kind of azimuth ambiguity degree computational methods of change pulse recurrence interval carried SAR, is to become pulse weight The system design for being spaced carried SAR again provides theoretical foundation and implementation method, and traditional frequency domain analysis method cannot be applied to and become Pulse recurrence interval SAR system analysis；This method goes for arbitrarily due to pointing to no requirement (NR) for each moment antenna The SAR system of on-fixed directional antenna.
The preferred embodiments of the present invention are these are only, the present invention is not limited to, for those skilled in the art For member, the present invention can have various modifications and variations.All any modifications within the spirit and principles in the present invention, made, Equivalent, improvement etc., should be included within the scope of the present invention.

Claims (6)

1. azimuth ambiguity degree computational methods of a kind of change pulse recurrence interval carried SAR, it is characterised in that include：
Step 1, position and target location to be analyzed that each impulse ejection moment radar is determined according to pulse recurrence interval；
Step 2, Pulse by Pulse determine the echo strength of target, and antenna weighting and each moment that each moment target is calculated respectively is oblique Away from using the corresponding target energy sum of whole pulses as total target energy；
Step 3, Pulse by Pulse determine the echo strength of confusion region, calculate respectively each x time equivalent pulse recurrence interval and The Doppler frequency of target, the Doppler frequency calculating further according to equivalent pulse recurrence interval and target obtains each confusion region Orientation off-axis angle, and then the oblique distance of each confusion region is obtained, and using the energy accumulation of whole fuzzy objects as current PRF Confusion region energy, finally using the corresponding confusion region energy sum of whole pulses as total confusion region energy；
The total confusion region energy of step 4, calculating and the ratio of total target energy, obtain azimuth ambiguity degree.
2. the azimuth ambiguity degree computational methods of pulse recurrence interval carried SAR are become as claimed in claim 1, it is characterised in that In step 1, echo central instant beam center irradiation position is chosen in the target location.
3. the azimuth ambiguity degree computational methods of pulse recurrence interval carried SAR are become as claimed in claim 1, it is characterised in that The step 1 includes：
Step 11, input radar system parameters and radar orbit parameter, the radar system parameters include radar effective speed V, Radar operation wavelength λ, orientation antenna length La, antenna downwards angle of visibility γ and reference pulse repetition rate prf, and become pulse Recurrence interval sequence tp, the radar orbit parameter include radar altitude H；
Step 12, antenna bearingt is calculated to beam angle βa；Calculated target positionsAnd most short oblique distance Tr, using antenna Azimuth beam width betaaMost short oblique distance TrObtain synthetic aperture time ts；
β a = λ L a - - - ( 1 )
T → x y z = T x T y T z = H · t a n γ 0 0 - - - ( 2 )
Tr=H/cos γ (3)
t s = T r · β a V - - - ( 4 )
Step 13, the sampling number N being calculated in the synthetic aperture time；
Wherein, prf is reference pulse repetition rate；
Step 14, it is calculated radar site
P → x y z = P x P y P z = 0 V · t p H - - - ( 6 ) .
4. the azimuth ambiguity degree computational methods of pulse recurrence interval carried SAR are become as claimed in claim 3, it is characterised in that The step 2 includes：
Step 21, the antenna weighting G (θ for calculating each moment targeta(i))；
G ( θ a ( i ) ) = { s i n [ πsinθ a ( i ) β a ] πsinθ a ( i ) β a } 2 - - - ( 7 )
In formula, θa(i) be orientation off-axis angle, βaFor Azimuth beam width, sin () expression SIN functions；
Step 22, oblique distance r (i) for calculating the correspondence moment；
r ( i ) = | P → x y z - T → x y z | - - - ( 8 )
Wherein, | | represent modulo operation；
Step 23, calculating target energy sum St；
S t = Σ i = 1 N G 2 ( θ a ( i ) ) r ( i ) 4 - - - ( 9 ) .
5. the azimuth ambiguity degree computational methods of pulse recurrence interval carried SAR are become as claimed in claim 4, it is characterised in that The step 3 includes：
Step 31, the equivalent pulse recurrence interval PRT for calculating each momenti；
PRT i = t p ( i + 1 ) - t p ( i - 1 ) 2 - - - ( 10 )
Step 32, Doppler frequency f for calculating each moment targetdi；
If radar speed vector is：
V → = [ 0 , V , 0 ] - - - ( 11 )
Then Doppler frequency f of targetdiFor：
f d i = - 2 λ V → ( T → x y z - P → x y z ) T | ( T → x y z - P → x y z ) | - - - ( 12 )
Step 33, the orientation off-axis angle θ for calculating each confusion region at momentak(i)；
θ a k ( i ) = π 2 - a r c c o s ( - λ 2 V ( f d + k · PRF i ) ) , k ∈ { k | - M ≤ k ≤ M , k ∈ Z , k ≠ 0 } - - - ( 13 )
Wherein, k represents confusion region Position Number, and M represents the number of maximum confusion region, and Z represents set of integers, and arccos () represents anti- Cosine function；
Step 34, oblique distance r for calculating each confusion region at momentk(i)；
r k ( i ) = T r cosθ a k ( i ) - - - ( 14 )
Step 35, echo strength sum S for calculating each confusion regiona(i)；
S a ( i ) = Σ k = - M k ≠ 0 M G 2 ( θ a k ( i ) ) r k ( i ) 4 - - - ( 15 )
The total fuzzy energy S of step 36, calculatinga；
S a = Σ i = - N / 2 N / 2 S a ( i ) - - - ( 16 ) .
6. the azimuth ambiguity degree computational methods of pulse recurrence interval carried SAR are become as claimed in claim 5, it is characterised in that In the step 4, computer azimuth fuzziness AASRt：
AASR t = S a S t - - - ( 17 ) .
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CN108008378B (en) * 2017-05-26 2018-12-14 北京航空航天大学 A kind of SAR false target energy ratio determines method and device
CN107271999A (en) * 2017-07-14 2017-10-20 北京航空航天大学 A kind of geographical stripmap SAR changing distance pulse train design method
CN107271999B (en) * 2017-07-14 2021-06-29 北京航空航天大学 Design method of variable-interval pulse sequence of geographic stripe SAR
CN107976674A (en) * 2017-10-31 2018-05-01 西安空间无线电技术研究所 The PRF systems of selection of dualbeam SAR obscured based on top optimization direction a kind of and system
CN109765540A (en) * 2019-02-26 2019-05-17 南京莱斯电子设备有限公司 A kind of frequency stepping system metre wave radar target extraction method
CN109765540B (en) * 2019-02-26 2021-03-19 南京莱斯电子设备有限公司 Frequency stepping system meter wave radar target extraction method

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