CN106597443B - Low frequency diameter radar image compares cancellation radio frequency interference suppressing method - Google Patents
Low frequency diameter radar image compares cancellation radio frequency interference suppressing method Download PDFInfo
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- CN106597443B CN106597443B CN201611187960.9A CN201611187960A CN106597443B CN 106597443 B CN106597443 B CN 106597443B CN 201611187960 A CN201611187960 A CN 201611187960A CN 106597443 B CN106597443 B CN 106597443B
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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
- 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
- G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
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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
- G01S13/9004—SAR image acquisition techniques
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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
- G01S13/904—SAR modes
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- 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 present invention provides a kind of low frequency diameter radar images to compare cancellation radio frequency interference suppressing method, including three steps: (1) being imaged apart from spectral balancing and SAR based on radar time-frequency domain echo obtains image(2) RFI inhibits in the arteries and veins based on adaptive-filtering and SAR is imaged, and obtains image(3) by imageWithPixel range value carry out point-by-point comparison, eliminate remnants RFI, obtain image Io(tm,tf), which is the SAR image for using image comparison phase elimination to inhibit remaining RFI.The present invention feature steady to RFI rejection using spectral balancing method, combining adaptive NLMS filter method, realize the complementation on RFI rejection, and the image generated, without being registrated, error is not present in the position of target, directly can carry out point-by-point comparison in image area, eliminate remnants RFI, operand is small, and strong real-time is easy to Project Realization.
Description
Technical field
The invention belongs to signal processing technology field, in particular to a kind of low frequency diameter radar image comparison cancellation is penetrated
Frequency disturbance restraining method.
Background technique
Low frequency SAR (Synthetic Aperture Radar, synthetic aperture radar) refers to that radar operating frequency is located at VHF
The SAR of (Very High Frequency very high frequency(VHF))/UHF (Ultra High Frequency hyperfrequency) frequency range, due to the frequency
For section there are mass communication, broadcast, TV signal source, radar image will receive the RFI with narrow-band characteristic, time variation and space-variant
(Radio Frequency Interference, radio frequency interference) influences.Experiment shows that RFI can seriously affect the matter of SAR image
Amount and subsequent applications.
Currently, low frequency SAR application RFI suppressing method is primarily to improve SAR image quality, and with SAR image quality
Evaluate rejection.Its principal element in need of consideration is that the amplitude of the stronger RFI signal of single channel energy inhibits.Believed according to RFI
Whether number frequency is it is known that RFI suppressing method is segmented into two classes.First is that nonparametric method, typical method is spectral balancing method, based on more
The average amplitude spectrum of radar echo signal extracts the amplitude and frequency of stronger RFI in a pulse period, then constructs apart from frequency domain
Spectral balancing device remove interference, the image signal to noise ratio of such method is higher, it can be difficult to inhibit time-varying RFI, can stay on the image
The clutter of lower remnants；Second is that parametric method, is joined by the frequency, phase and amplitude of RFI signal in the estimation single pulse period
Number rebuilds narrowband RFI, and interference signal is then subtracted from radar echo signal, such method is able to suppress time-varying RFI, but by
In limitation of the signal-to-noise ratio to Parameter Estimation Precision, the imaging results after RFI inhibits can generate higher secondary lobe apart from time domain, cover
Weak signal target in lid image.Therefore at present in engineering, it not can be implemented simultaneously time-varying RFI still and inhibit and improve after imaging by target
Valve performance.
Summary of the invention
For above-mentioned shortcoming in the prior art, the technical problem to be solved in the present invention is to provide a kind of synthesis of low frequency
Aperture radar (SAR) image comparison cancellation radio frequency interference (RFI) suppressing method solves to inhibit time-varying RFI in low frequency SAR imaging
The problem of, improve the quality of image.
The present invention includes the following steps:
The first step, being imaged apart from spectral balancing and SAR based on radar time-frequency domain echo.
By received orientation time domain apart from time domain echo R (tm,tf) Fourier transform is carried out, obtain orientation time domain distance frequency
Domain echo R (tm,fr), wherein tmIndicate orientation slow time, tfIndicate distance to fast time, frIndicate frequency of distance.In order to chat
Orientation time domain is referred to as time domain apart from time domain hereinafter by the simplicity stated, and orientation time domain is referred to as time-frequency domain apart from frequency domain, will be square
Position frequency domain is referred to as frequency domain apart from frequency domain.If each step operates plural echo data without specified otherwise.Specific packet
It includes:
Step 1.1: calculating average amplitude spectrum
Take continuous N time domain echo Ri(tm,tf), wherein i=1,2 ... N, to every time domain echo along apart from time domain into
Row Fourier transform obtains N time-frequency domain echo Ri(tm,fr), acquire average amplitude spectrum
Step 1.2: spectral balancing RFI inhibits
With every time-frequency domain echo Ri(tm,fr) composed multiplied by average amplitude in signal bandwidth it is reciprocal to being higher than signal strength
Interference carry out RFI inhibition, the time-frequency domain echo R after obtaining spectral balancingi'(tm,fr):
Step 1.3: echo is rebuild
To the time-frequency domain echo R after spectral balancingi'(tm,fr) in the signal of time-frequency domain add hamming window, then to carry out Fourier inverse
Transformation obtains the time-domain signal R after RFI inhibitsi'(tm,tf)；
Step 1.4: low frequency SAR imaging
Time-domain signal R after inhibiting to RFIi'(tm,tf) low frequency SAR imaging algorithm is used, after obtaining spectral balancing RFI inhibition
Time-domain image I1(tm,tf)；
Low frequency SAR imaging algorithm can be using a variety of low frequency SAR imaging algorithms in the prior art, such as in the step 1.4
NCS (Nonlinear Chirp Scaling, Non-linear chirp scaling) algorithm, BP (Back projection, rear orientation projection)
Algorithm, omega-K algorithm etc. can use as long as the algorithm of low-frequency ultra-wideband SAR imaging may be implemented.
Step 1.5: picture amplitude normalization
Find image I1(tm,tf) in pixel Amplitude maxima point max (| I1(tm,tf) |), amplitude is carried out to image
Normalization, obtains the time-domain image of amplitude normalization
Second step, RFI inhibits and SAR imaging in the arteries and veins based on adaptive-filtering.
Step 2.1: sef-adapting filter estimates RFI signal in pulse
Adaptive N LMS (Nonlinear Least Mean Square, non-linear least mean squares) filter can be used,
Or adaptive RLS (Recursive Least Square, recursive least-squares) filter carries out RFI estimation, as long as can
The sef-adapting filter of time-varying RFI signal may be used to the present invention in estimation pulse.Below with adaptive N LMS filter
For be illustrated.
By received time domain echo Ri(tm,tf) input adaptive NLMS (Nonlinear Least Mean Square, it is non-
Linear least mean-square) filter progress RFI estimation, obtain Radio Frequency Interfere Si(tm,tf)；
The structure that adaptive RF I inhibits consists of three parts: delay, sef-adapting filter estimation and error output.It will be away from
The time domain echo-signal R for being L from time-domain sampling pointsi(tm,tf) input signal sequence X=[x (0), x as adaptive-filtering
(1) ..., x (L-1)], if sef-adapting filter length is M, then the continuous N in input signal sequence is taken to adopt when n-th is estimated
Sampling point vector constructs Xn:
Xn=[x (n-M+1), x (n-M+2) ..., x (n)] n ∈ [0 ..., L-1]
As n < M-1, the leading portion X to signal vector is needednM-n-1 zero is mended, then by XnIt is delayed a sampling period
Reference signal vector as sef-adapting filter:
dn(k)=Xn-1=[x (n-M), x (n-M+1) ..., x (n-1)] n ∈ [0 ..., L-1]
Wn(k), k ∈ [0 ..., M-1] is the coefficient vector of sef-adapting filter in n-th of circulation, and H indicates conjugate transposition.
The interference estimate of n-th of circulation are as follows:
Y (n)=Wn H(k)dn(k)
The evaluated error of sef-adapting filter output are as follows:
E (n)=x (n)-y (n)
The coefficient of sef-adapting filter is updated using NLMS algorithm iteration, definition:
In above formula, in order to avoid denominator is zero, the constant δ > 0 an of very little is introduced, | | | | indicate European norm, *
Indicating complex conjugate, μ indicates step-length, it can use:
Wherein λmaxFor reference signal vector dn(k) maximum eigenvalue of autocorrelation matrix.
The y (n) of sef-adapting filter Sequential output, n ∈ [0 ..., L-1] constitute the RFI estimation signal S of time domaini(tm,
tf)。
Step 2.2: echo time domain offsets
Use Ri(tm,tf) subtract Si(tm,tf), obtain Ri”(tm,tf) be RFI inhibit after time-domain signal.
Step 2.3: low frequency SAR imaging
Time-domain signal R after inhibiting to RFIi”(tm,tf) low frequency SAR imaging algorithm identical with the first step is used, it obtains
Time-domain image I after adaptive RF I inhibition2(tm,tf)。
Step 2.4: picture amplitude normalization
The Amplitude maxima point for finding pixel in image obtains amplitude normalization after carrying out amplitude normalization to image
Time-domain image
Third step, image comparison cancellation.
The time-domain image that the first step and second step are obtainedWithPixel range value carry out by
Point compares, and takes out the relatively small pixel point value of range value, and is stored in the same position of new images, then by new images
The range value equal proportion of middle pixel is amplified, and obtains 256 grades of grayscale images, and be converted to bmp (Bitmap, bitmap) image Io(tm,
tf), which is the SAR image for using image comparison phase elimination to inhibit remaining RFI.
In conclusion the feature that the present invention is steady to RFI rejection using spectral balancing method, combining adaptive NLMS filtering
Method inhibits the untamed time-varying RFI signal of spectral balancing method, realizes the complementation on RFI rejection, and two kinds of algorithms all have knot
Structure is simple, strong robustness, strong real-time and the advantages of be easily achieved, and the image of generation is without being registrated, and the position of target is not
There are errors, directly can carry out point-by-point comparison in image area, eliminate remnants RFI, algorithm operation quantity is small, and strong real-time is easy to
Project Realization.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention without any creative labor, may be used also for those of ordinary skill in the art
To obtain other drawings based on these drawings.
Fig. 1 is the principle of the present invention flow diagram；
Fig. 2 is data flow diagram of the invention；
Fig. 3 is the structural block diagram that adaptive RF I inhibits in embodiment；
Fig. 4 is the SAR imaging effect figure that emulation data use after spectral balancing RFI inhibition in embodiment one；
Fig. 5 is the SAR imaging effect figure that emulation data use after adaptive RF I inhibition in embodiment one；
Fig. 6 is the SAR imaging effect figure that emulation data use after RFI of the present invention inhibition in embodiment one；
Fig. 7 is that the point target distance after data RFI inhibits is emulated in embodiment one to sectional view；
Fig. 8 is the SAR imaging effect figure that measured data uses after spectral balancing RFI inhibition in embodiment two；
Fig. 9 is the SAR imaging effect figure that measured data uses after adaptive RF I inhibition in embodiment two；
Figure 10 is the SAR imaging effect figure that measured data uses after RFI of the present invention inhibition in embodiment two.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Fig. 1 is a kind of principle stream of the present invention " low frequency diameter radar image comparison cancellation radio frequency interference suppressing method "
Journey schematic diagram.The present invention is conducive to improve low frequency SAR imaging to the inhibitory effect and imaging performance of RFI.Below by two realities
Example is applied to be illustrated.
Embodiment one, the emulation data set A formed to the time domain echo that time-varying and non-time-varying RFI is added are handled.
The first step, being imaged apart from spectral balancing and SAR based on radar time-frequency domain echo.It specifically includes:
Step 1.1: calculating average amplitude spectrum
Take continuous N time domain echo Ri(tm,tf), wherein i=1,2 ... N, to every time domain echo along apart from time domain into
Row Fourier transform obtains N time-frequency domain echo Ri(tm,fr), acquire average amplitude spectrum
Step 1.2: spectral balancing RFI inhibits
With every time-frequency domain echo Ri(tm,fr) composed multiplied by average amplitude in signal bandwidth it is reciprocal to being higher than signal strength
Interference carry out RFI inhibition, the time-frequency domain echo R after obtaining spectral balancingi'(tm,fr):
The specific calculation process of RFI method is inhibited to can be found in the paper delivered on " electronics and information journal " apart from spectral balancing
" RFI suppressing method of the VHF/UHF UWB SAR based on channel-equalization ".
Step 1.3: echo is rebuild
To the time-frequency domain echo R after spectral balancingi'(tm,fr) in the signal of time-frequency domain add hamming window, then to carry out Fourier inverse
Transformation obtains the time-domain signal R after RFI inhibitsi'(tm,tf)；
Step 1.4: low frequency SAR imaging
Time-domain signal R after inhibiting to RFIi'(tm,tf) low frequency SAR imaging algorithm is used, after obtaining spectral balancing RFI inhibition
Time-domain image I1(tm,tf)。
Low frequency SAR imaging algorithm can be found in delivered on " National University of Defense technology's journal " " at Airborne UWB SAR live signal
Manage algorithm research ".
Step 1.5: picture amplitude normalization
The Amplitude maxima point for finding pixel in image carries out amplitude normalization to image, obtains amplitude normalization
Time-domain image
After emulation data set A has carried out first step step process, obtained spectral balancing RFI inhibits time-domain imageIt is showed to obtain Fig. 4 with contour map.Fig. 4 be emulate data using spectral balancing RFI inhibit after SAR at
As effect picture.Number 1~5 in figure represents the label of 5 observed objects.It can be seen from figure 4 that when spectral balancing RFI inhibits
Since the inhibitory effect to time-varying RFI is poor, point target is along range direction distal end remnants interference.
Second step, RFI inhibits and SAR imaging in the arteries and veins based on adaptive-filtering
Step 2.1: sef-adapting filter estimates RFI signal in pulse
By received time domain echo Ri(tm,tf) input adaptive NLMS (Nonlinear Least Mean Square, it is non-
Linear least mean-square) filter progress RFI estimation, obtain Radio Frequency Interfere Si(tm,tf)。
RFI estimation method is wherein carried out based on adaptive N LMS filter, reference can be made to " IEEE Geoscience and
Remote Sensing Letters " on paper " the RFI Suppression in ultrawideband SAR that delivers
using an adaptive line enhancer》。
Fig. 3 gives the structural block diagram of adaptive RF I inhibition, by input signal sequence XnDelay a cycle obtains dn
(k), it then is entered into sef-adapting filter and obtains RFI estimated value y (n), subtract y (n) with x (n) and obtain evaluated error e (n)
Then sef-adapting filter parameter is adjusted.
Step 2.2: echo time domain offsets
The y (n) of sef-adapting filter Sequential output, n ∈ [0 ..., L-1] constitute the RFI estimation signal S of time domaini(tm,
tf), use Ri(tm,tf) subtract Si(tm,tf), obtain Ri”(tm,tf) be RFI inhibit after time-domain signal.
Step 2.3: low frequency SAR imaging
Using low frequency SAR imaging algorithm identical with the first step, the time-domain image I after adaptive RFI inhibits is obtained2(tm,
tf)。
Step 2.4: picture amplitude normalization
The Amplitude maxima point for finding pixel in image obtains amplitude normalization after carrying out amplitude normalization to image
Time-domain image
After emulation data set A has carried out second step step process, the time-domain image of obtained adaptive N LMS filteringIt is showed to obtain Fig. 5 with contour map.Fig. 5 is emulation data using adaptive N LMS filtering progress RFI
SAR imaging effect figure after inhibition.From fig. 5, it is seen that adaptive N LMS filtering is more preferable to time-varying RFI inhibitory effect, do not have
There is the residual interference of distal end, but nearby there is higher secondary lobe in target's center.
Third step, image comparison cancellation
The time-domain image that the first step and second step are obtainedWithPixel range value carry out by
Point compares, and takes out the relatively small pixel point value of range value, and is stored in the same position of new images, then by new images
The range value equal proportion of middle pixel is amplified, and obtains 256 grades of grayscale images, and be converted to bmp image Io(tm,tf), which is
The SAR image of remaining RFI is inhibited using image comparison phase elimination.
After emulation data set A has carried out third step step process, the time-domain image I exported after comparison cancellation is obtainedo(tm,
tf), it is showed to obtain Fig. 6 with contour map.Fig. 6 is to compare the SAR imaging effect figure obtained after cancellation in image area.
From fig. 6 it can be seen that not only eliminating the remaining RFI interference of distal end after being handled using the method for the invention, also improving
The focusing quality of proximal end point target.
Fig. 4 will be located at, the point target 5 among Fig. 5, Fig. 6 along distance to making sectional view, as shown in fig. 7, observe its apart from when
Main lobe and secondary lobe in domain, wherein solid line is that spectral balancing RFI inhibits as a result, dotted line is that adaptive N LMS filtering RFI inhibits
As a result, chain-dotted line is the result compared after cancellation, it can be seen that the main lobe of target is narrower than the result of spectral balancing after comparison cancellation, closely
Secondary lobe is held obviously to filter than adaptive N LMS low.
Embodiment two handles measured data
Detailed process is similar to embodiment one, and details are not described herein again, is only illustrated to processing result.
Fig. 8 gives the result for inhibiting method to handle measured data using spectral balancing RFI.Exist in the measured data
Time-varying RFI interference.Upper right side arrow pointed location has clutter caused by apparent remnants RFI in Fig. 8, has in the circle of lower left
The last one target.
Fig. 9 gives the result for inhibiting method to handle measured data using adaptive N LMS filtering RFI.It is right in Fig. 9
At upper arrow instruction substantially without remnants RFI interference, but the same strong target in the circle of lower left with respect to Fig. 8 along distance to
There is higher secondary lobe.
Figure 10 gives the result handled using the method for the invention measured data.As shown in Figure 10, upper right
The remaining RFI of side, which is interfered, to disappear, and the distance of the same strong target in lower left is also offseted to secondary lobe.
From the application of emulation data set A and measured data the results showed that spectral balancing RFI inhibit after method adding window to target away from
Descriscent Sidelobe Suppression effect is preferable, but will cause the main lobe broadening of target, and adaptive N LMS filter method carries out mesh after RFI inhibition
Gauge length descriscent main lobe width is constant, but can generate asymmetric high secondary lobe, can using the comparison cancellation method in the present invention
The point target congregational rate that main lobe is narrow while secondary lobe is low is obtained, improves imaging performance, illustrates effectiveness of the invention.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, corresponding RFI restrainable algorithms
It is also not limited to spectral balancing mentioned above and adaptive N LMS filter method, as long as RFI rejection has complementary side
Method can improve the performance of final map of magnitudes using this method, therefore these improvements and modifications also should be regarded as guarantor of the invention
Protect range.
Claims (3)
1. a kind of low frequency diameter radar image compares cancellation radio frequency interference suppressing method, include the following steps:
The first step, being imaged apart from spectral balancing and SAR based on radar time-frequency domain echo, specifically include:
Step 1.1 takes continuous N time domain echo Ri(tm,tf), wherein i=1,2 ... N, to every time domain echo along apart from time domain
Fourier transform is carried out, N time-frequency domain echo R is obtainedi(tm,fr), acquire average amplitude spectrumi
=1,2 ..., N；Wherein tmIndicate orientation slow time, tfIndicate distance to fast time, frIndicate frequency of distance；
Step 1.2, with every time-frequency domain echo Ri(tm,fr) composed multiplied by average amplitude in signal bandwidthInverse to height
RFI inhibition is carried out in the interference of signal strength, the time-frequency domain echo after obtaining spectral balancingI=1,
2,...,N；
Step 1.3, to the time-frequency domain echo R after spectral balancingi'(tm,fr) in the signal of time-frequency domain add hamming window, then carry out Fourier
Leaf inverse transformation obtains the time-domain signal R after RFI inhibitsi'(tm,tf)；
Step 1.4, to RFI inhibit after time-domain signal Ri'(tm,tf) low frequency SAR imaging algorithm is used, obtain spectral balancing RFI suppression
Time-domain image I after system1(tm,tf)；
Step 1.5 finds image I1(tm,tf) in pixel Amplitude maxima point max (| I1(tm,tf) |), image is carried out
Amplitude normalization obtains the time-domain image of amplitude normalization
RFI inhibits in second step, the arteries and veins based on adaptive-filtering and SAR is imaged, and specifically includes:
Step 2.1, by received time domain echo Ri(tm,tf) the progress RFI estimation of input adaptive NLMS filter, obtain radio frequency
Interference signal Si(tm,tf)；
Step 2.2 uses Ri(tm,tf) subtract Si(tm,tf), obtain the time-domain signal R after RFI inhibitsi”(tm,tf)；
Step 2.3, to RFI inhibit after time-domain signal Ri”(tm,tf) low frequency SAR imaging algorithm identical with the first step is used,
Obtain the time-domain image I after adaptive RFI inhibits2(tm,tf)；
Step 2.4 finds image I2(tm,tf) in pixel Amplitude maxima point max (| I2(tm,tf) |), image is carried out
After amplitude normalization, the time-domain image of amplitude normalization is obtained
Third step, the time-domain image that the first step and second step are obtainedWithPixel range value into
Row point-by-point comparison takes out the relatively small pixel point value of range value, and is stored in the same position of new images, then will be new
The range value equal proportion amplification of pixel, obtains 256 grades of grayscale images, and be converted to bmp image I in imageo(tm,tf), the figure
As Io(tm,tf) it is the SAR image that remaining RFI is inhibited using image comparison phase elimination.
2. the method as described in claim 1, which is characterized in that carried out in the step 2.1 using adaptive RLS filter
RFI estimation.
3. the method as described in claim 1, which is characterized in that low frequency SAR imaging algorithm can use in the step 1.4
NCS algorithm perhaps BP algorithm or omega-K algorithm.
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| CN111913162B (en) * | 2020-09-04 | 2023-02-24 | 内蒙古工业大学 | Radio frequency interference detection method and device and radio frequency interference suppression method and device |
| CN113298802A (en) * | 2021-06-15 | 2021-08-24 | 中国人民解放军国防科技大学 | Method for detecting SAR image quality problem caused by external radiation source |
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| US20220065983A1 (en) * | 2020-09-03 | 2022-03-03 | Vaisala, Inc. | Rfi mitigation in weather radar data |
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