CN107748357A - A kind of radar fine day G- Design method of FIR filter - Google Patents
A kind of radar fine day G- Design method of FIR filter Download PDFInfo
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- 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
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Abstract
The invention discloses the radar fine day G- Design method of FIR filter, including calculate radar parameter：According to the mode of operation and systematic parameter of radar.FIR processing：It is low-velocity scanning by tested rotating platform, processing is filtered to pulse echo, calculates land clutter estimation.Modulus is taken the logarithm：Data are converted to logarithm, and for carrying out, succeeding target is rejected and clutter energy is estimated.Target is rejected：Threshold processing was carried out to sector data, removes the narrow pulse signal that distance tieed up thresholding.Distance merges：The big processing of cell data of adjusting the distance choosing, obtains fine day map distance cell data.The amendment of fine day figure and renewal：The Communication Jamming rejected in fine day figure influences, and the method accumulated by clutter map updates fine day figure, obtains accurate fine day figure valuation.Present method solves static Clutter Background under bad weather can not accurate valuation problem, ensure that radar accurately identifies Radar Clutter Background under any weather condition and obtains radar fine day figure.
Description
Technical Field
The invention relates to a radar sunny-day pattern design method, in particular to a radar sunny-day pattern design method of an FIR filter.
Background
The radar echo not only comprises a large amount of target information, but also comprises ground clutter, sea clutter, weather clutter, interference and other information. In radar operation, clutter echo amplitudes in the surrounding environment are typically stored sequentially in a two-dimensional plane of range and azimuth to create a clutter map. And storing the background clutter power of each distance-orientation unit by using a clutter map, and respectively carrying out iterative average processing on the estimated values of different scanning periods to calculate clutter background estimated values.
The design of a radar clear-sky map is developed, a radar ground clutter map is established, and the significance of clutter estimation and clutter partition is great. The design of the sunny day map has the following functions:
(1) By carrying out partition and clutter characteristic analysis on the clutter map, clutter power estimation, clutter distribution judgment, interference type judgment and the like can be carried out.
(2) By carrying out clutter partition on clutter intensity distribution, a clutter-free area, a weak clutter area, a strong clutter area and an ultra-strong clutter area can be distinguished, weight coefficients of a coherent accumulation filter are determined in different clutter areas, and maximum accumulation gain can be obtained. In general, an equal weight filter is used in a clutter free region, and a weighted filter is used in a clutter region.
(3) The clutter partition determines the target detection method of different areas: different clutter types adopt different processing modes, a noise area adopts slow threshold detection, a ground clutter area adopts super-clutter detection, and an interference area and a cloud and rain clutter area adopt constant false alarm detection.
(4) Determining a target detection threshold: different clutter areas need to adopt a specific target detection method and a specific detection threshold setting. The clutter map is continuously updated along with the change of the clutter environment, and in this case, the clutter partition also needs to be updated and brings about the adjustment of the detection threshold. The threshold adjustment must satisfy a constant false alarm rate criterion, and the threshold change value is related to the actual clutter distribution.
The existing clear sky map adopts a radar zero-frequency channel partition method under a clear environment, and has the following defects:
(1) The method has strong dependence on the environment, is difficult to acquire radar echo data in clear weather in a short time and cannot acquire clear weather maps under the bad weather conditions.
(2) The existing clutter map partitions are updated based on signal amplitude fluctuation, and when a point target exists in the clutter, the accurate estimation of the clutter map is influenced.
(3) When the existing static ground clutter estimation is carried out, if communication interference, television interference and the like exist, the estimation of the clutter map is influenced, and the clutter map needs to be corrected.
Disclosure of Invention
The invention aims to design a radar sunny-day picture design method of an FIR filter, which has the advantages of simple algorithm, strong applicability, good effect and suitability for engineering realization.
The invention discloses a radar sunny day picture design method of an FIR filter, which comprises the following steps:
step 1, calculating radar parameters: calculating radar distance sampling units n and a sector number j of a clear-sky image contained in a radar clear-sky image according to the total number Rmax of the distance units of the radar and the total number I of pulses in a single sector;
step 2, FIR treatment: adjusting an antenna to be low-speed scanning, filtering pulse echoes, and calculating ground clutter estimation;
step 3, modulus and logarithm obtaining: converting the data into logarithms;
step 4, target elimination: carrying out threshold processing on sector data, and removing narrow pulse signals with the distance exceeding a threshold;
step 5, distance combination: selecting large distance unit data to obtain distance unit data of a fine weather map;
step 6, fine weather picture correction and update: and eliminating communication interference influence in the clear sky map, updating the clear sky map by a clutter map accumulation method, and acquiring an accurate clear sky map estimation value.
In step (2), the pulse echo data with the pulse sequence number i in the j-th sunny-day picture sector is processed according to the following formula:
x ji (n), J =0, · J-1; i = 0.. 1, I-1, where I is the total number of pulses in a single sector, I is the pulse number in the sector, J is the total number of sectors in a clear sky map, J represents the sector number in the clear sky map, and k is the distance number; for n =0 max Performing FIR processing on the first M sweep data in the step-1, wherein M is less than or equal to I, and Rmax is the total number of distance units of a single sweep, so as to obtain a filtering output signal y1 of the jth fine sky figure sector corresponding to the radar distance sampling unit number n j (n)：
Wherein, w i Is a filter coefficient, w for ground clutter i And =1, when the number of pulses exceeds M, the data stops accumulating.
In step (3) of the present invention, FIR output data y1 are processed j (n) performing modulo logarithm processing to obtain the jth sector data y2 j (n)：
y2 j (n)＝A*log[abs(y1 j (n))],j＝0,1,…,J-1；n＝0,1,…,Rmax-1
Wherein A is a scaling factor.
In step (4) of the invention, for the j (th) sunny day map sector data y2 j (n) carrying out threshold-crossing processing, removing the narrow pulse signal of the distance dimension threshold, and obtaining the data y3 after the target is removed j (n) comprising:
step 41, for the j-th sunny day map sector y2 j (n) processing the constant false alarm to obtain a detection result y2 j '(n)；
Step 42, labeling the detection result y2 j ' (n), narrow pulse data, narrow pulse discrimination method: counting the detection result y2 j ' (n) is the pulse width of the target signal, which is less than a given threshold V 3T Judging the pulse to be a narrow pulse;
step 43, according to the narrow pulse mark, the j-th sunny day map sector y2 j (n) the corresponding position data is set to zero to obtain sector correction data y3 j (n)。
The distance in the step (5) of the invention is selected as follows:
for data y3 j (n) carrying out selection processing in the kth clear-sky-map distance unit, wherein K =0,1, K-1, and K is the total number of clear-sky-map distance resolution units, and obtaining temporary clear-sky-map data CDM of the current frame of the jth clear-sky-map unit (j, K) now (j,k)，
CDM now (j,k)＝max(y3 j (2k),y3 j (2k-1))
Wherein J =0,1, \8230, J-1; k =0,1,.., rmax/2-1.
In step (6), the fine day map correction and update comprises:
and step 61, correcting: the clear sky picture contains fixed sector interference, and the interference information in the clear sky picture is removed to obtain accurate ground clutter and noise partitions;
2) Updating:
the updating of the clear sky map is realized by the iterative accumulation of the Fr frame data, so as to obtain the final clear sky map data CDM (j, k), the Fr frame clear sky map data CDM fr The update formula of (j, k) is:
and (3) final clear sky picture, namely the updated clear sky picture of the last frame: CDM (j, k) = CDM Fr (j, k) in the formula, CDM fr-1 And (j, k) represents the Fr-1 frame of clear day map data, the range of Fr is 1-Fr, alpha =1/8 is a clutter map updating coefficient, and Fr is the total data frame number required by clear day map updating.
The step (61) of the present invention comprises:
interference exists in a sector of a current sunny day image, and interference energy IM (j) is counted:
the value range of i satisfies the condition: i is 0. Ltoreq. M, and x ji (n) > 3. Set of all i of NoiseVal; wherein NoiseVal is a radar noise power estimate, and M represents M sweep data;
the following formula is used for correction:
CDM′ now (j,k)＝CDM now (j,k)-IM(j)。
CDM now representing temporary sunny-day map data before correction, CDM now ' denotes the corrected temporary sunny day map data.
Compared with the prior art, the invention has the following remarkable advantages:
(1) The method overcomes the influence of weather, can accurately identify the radar clutter environment under any weather condition, and obtains the radar sunny-sky picture. (2) When the point target and the communication interference exist, the method can accurately eliminate the point target according to the amplitude and the azimuth distribution characteristics of the point target, eliminate the interference according to the spatial distribution of the communication interference, and obtain an accurate clear sky map estimation value. (3) The radar sunny day picture design method of the FIR filter is simple in principle, convenient to design, good in real-time performance and suitable for engineering implementation.
Drawings
Fig. 1 is a process flow diagram.
Fig. 2 is a schematic illustration of a sunny day map sector.
Fig. 3 is a schematic diagram of constant false alarm detection.
Figure 4 is radar echo data.
Fig. 5 is clear sky plot data without interference rejection.
Fig. 6 is sunny day map data.
Detailed Description
The invention relates to a method for designing a radar clear sky map, in particular to a method for designing a radar clear sky map of an FIR filter. The method overcomes the problem that the static ground clutter background can not be estimated accurately in severe weather, and adopts an FIR filter method to ensure that the radar can accurately identify the radar clutter environment and acquire a radar clear sky map under any weather conditions. The method solves the problem that the existing radar can obtain accurate clutter estimation value in clear weather, eliminates the influence of point targets and communication interference, and provides guarantee for radar clutter partition and adaptive target detection. The radar clear sky pattern design method based on the FIR filter is simple in principle, convenient to design, good in instantaneity and suitable for engineering implementation.
The invention discloses a radar sunny day picture design method of an FIR filter, which comprises the following steps:
step 1, calculating radar parameters: calculating radar distance sampling units n and a sector number j of a clear sky map contained in the radar clear sky map according to the total number Rmax of the distance units of the radar and the total number I of pulses in a single sector;
step 2, FIR treatment: adjusting an antenna to be low-speed scanning, filtering pulse echoes, and calculating ground clutter estimation;
step 3, modulus and logarithm obtaining: converting the data into logarithms;
step 4, target elimination: carrying out threshold processing on sector data, and removing narrow pulse signals with the distance exceeding a threshold;
step 5, distance combination: selecting large distance unit data to obtain distance unit data of a fine weather map;
step 6, fine day picture correction and updating: and eliminating communication interference influence in the clear sky map, updating the clear sky map by a clutter map accumulation method, and acquiring an accurate clear sky map estimation value.
In step (2), the pulse echo data with the pulse sequence number i in the j-th sunny-day picture sector is processed according to the following formula:
x ji (n), J =0, · J-1; i = 0.. 1, I-1, where I is the total number of pulses in a single sector, I is the pulse number in the sector, J is the total number of sectors in a clear sky map, J represents the sector number in the clear sky map, and k is the distance number; for n =0, R max Performing FIR processing on the first M sweep data in the step-1, wherein M is less than or equal to I, and Rmax is the total number of distance units of a single sweep, so as to obtain a filtering output signal y1 of the jth fine sky image sector corresponding to the radar distance sampling unit number n j (n)：
Wherein, w i Is a filter coefficient, w for ground clutter i And =1, when the number of pulses exceeds M, the data stops accumulating.
In step (3) of the present invention, FIR output data y1 are processed j (n) performing modulo logarithm processing to obtain the jth sector data y2 j (n)：
y2 j (n)＝A*log[abs(y1 j (n))],j＝0,1,…,J-1；n＝0,1,…,Rmax-1
Wherein A is a scaling factor.
In step (4) of the invention, for jth sunny day picture sector data y2 j (n) carrying out threshold-crossing processing, removing the narrow pulse signal of the distance dimension threshold, and obtaining the data y3 after the target is removed j (n) comprising:
step 41, for the j-th sunny day map sector y2 j (n) processing the constant false alarm to obtain a detection result y2 j '(n)；
In a step 42, the process is carried out,marker detection result y2 j ' (n), narrow pulse data, narrow pulse discrimination method: counting the detection result y2 j ' (n) is the pulse width of the target signal, which is less than a given threshold V 3T Judging the pulse to be a narrow pulse;
step 43, according to the narrow pulse mark, the j-th sunny day map sector y2 j (n) the corresponding position data is set to zero to obtain sector correction data y3 j (n)。
The distance in the step (5) of the invention is selected as follows:
for data y3 j (n) carrying out selection processing in the kth clear-sky-map distance unit, wherein K =0,1, K-1, and K is the total number of clear-sky-map distance resolution units, and obtaining temporary clear-sky-map data CDM of the current frame of the jth clear-sky-map unit (j, K) now (j,k)，
CDM now (j,k)＝max(y3 j (2k),y3 j (2k-1))
Wherein J =0,1, \8230, J-1; k =0,1,.., rmax/2-1.
In step (6), the fine day map correction and update comprises:
and step 61, correcting: the clear sky picture contains fixed sector interference, and the interference information in the clear sky picture is removed to obtain accurate ground clutter and noise partitions;
2) Updating:
updating the clear sky graph by iterative accumulation of Fr frame data to obtain final clear sky graph data CDM (j, k), wherein the Fr frame clear sky graph data CDM fr The update formula of (j, k) is:
and (3) final clear sky picture, namely the updated clear sky picture of the last frame: CDM (j, k) = CDM Fr (j, k) in the formula, CDM fr-1 And (j, k) represents the Fr-1 frame of clear day map data, the range of Fr is 1-Fr, alpha =1/8 is a clutter map updating coefficient, and Fr is the total data frame number required by clear day map updating.
The step (61) of the present invention comprises:
and (3) interference exists in the sector of the current fine sky image, and the statistical interference energy IM (j):
the value range of i satisfies the condition: i is 0. Ltoreq. M, and x ji (n) > 3. Set of all i of NoiseVal; wherein, noiseVal is the radar noise power estimate, M represents M sweep data;
the following formula is used for correction:
CDM′ now (j,k)＝CDM now (j,k)-IM(j)。
CDM now representing temporary sunny day map data before correction, CDM now ' denotes the corrected temporary sunny day map data.
Example 1
The invention will be described in further detail below with reference to the accompanying drawings.
Fig. 1 is an overall process flow diagram. With reference to fig. 1, the method of the present invention comprises the following steps:
1. calculating radar parameters: and calculating the distance n = Rmax/2 of the radar clear sky plot, the direction resolution unit j = I/128 and the radar noise power estimation NoiseVal according to the total number Rmax of the distance units of the radar and the total number I of pulses in a single sector. A schematic diagram of sectors is shown in fig. 2.
2, FIR treatment: the antenna is adjusted to scan at a low speed, and pulse echo data x in the jth sector is processed ji (n),j＝0,...,J-1；i＝0,...,I-1,n＝0,...,R max Front M (M) in-1&= I) sweep data are FIR processed (generally M =2/3 × I), where I is the total number of pulses in a single sector, J is the total number of sectors in a clear sky picture, and Rmax is the total number of range cells of a single sweep. Thereby obtaining a filtered output signal y1 for that sector j (n)
Wherein M is an integer less than I, I is a pulse number in a sector, j is a sector number, n is a distance number, and M is an accumulated pulse number; w is a i Is a filter coefficient, w for ground clutter i =1. When the number of pulses exceeds M, the data is not accumulated.
3. Modulus and logarithm obtaining: for FIR output data y1 j (n) performing modulo logarithm processing to obtain the jth sector data y2 j (n)：
y2 j (n)＝A*log[abs(y1 j (n))],j＝0,1,…,J-1；n＝0,1,…,Rmax-1
Wherein A is a scaling factor.
The selection of the proportion coefficient A needs to consider the problem of gain normalization of a sunny day map.
4. Target elimination: for jth sector data y2 j (n) performing threshold-passing processing to remove narrow pulse signals with less distance and 3 resolution units to obtain data y3 after target elimination j (n) of (a). A clear sky plot without interference rejection is shown in fig. 5.
1) Distance data y2 j (n) obtaining a detection result y2 by constant false alarm processing j ' (n). A schematic block diagram of constant false alarm detection is shown in fig. 3.
2) Marking narrow pulse data in the detection result, and judging the narrow pulse: statistics of y2 j ' (n) is the pulse width of the target signal, the width being less than a given threshold V 3T Then the pulse is considered to be a narrow pulse; generally the target will not exceed 3 range units, V 3T ＝3；
3) Sector data y2 according to the narrow pulse mark j (n) the corresponding position data is set to zero to obtain y3 j (n)；
5. And (3) selecting the distance to be large: for data y3 j (n) performing a selection process in the K (K =0, 1.., K-1) th distance unit to obtain the current frame temporary clear sky map data CDM of the clear sky map unit (j, K) now (j,k)，
CDM now (j,k)＝max(y3 j (2k),y3 j (2k-1))
Wherein J =0,1, \8230, J-1; k =0,1, 1.., rmax/2-1.
6. And eliminating the interference according to the spatial distribution of the communication interference to obtain an accurate clear sky map estimation value. And accumulating and updating data of the multi-frame radar clear sky map to form a final clear sky map and obtain a real ground clutter profile. And (3) fine sky picture correction and updating:
1) And (3) interference sector calculation: fixed sector interference is included in the clear sky plot. And the interference information in the clear sky picture is removed to obtain accurate clutter information. If x ji If (n) > 3 NoiseVal, considering that the interference exists in the sector of the current fine day map, and counting the interference energy IM (j):
where j denotes the clear sky plot sector number, noiseVal is the radar noise power estimate, x ji (n) is the pulse-echo data in the j-th sector, and n is the number of radar range resolution elements.
2) And (3) correction: CDM now Representing temporary sunny day map data before correction, CDM now ' denotes the corrected temporary sunny day map data. Then:
CDM′ now (j,k)＝CDM now (j,k)-IM(j)
3) Updating:
the clear sky map is updated through iterative accumulation of Fr frame data, so that final clear sky map data CDM (j, k) is obtained, and an updating formula is as follows:
and accumulating the data of the multiple frames of fine sky pictures in an iterative mode, removing the random jitter of the signals and acquiring accurate clutter characteristic information. And (3) final clear sky map, namely the updated clear sky map of the last frame:
CDM(j,k)＝CDM Fr (j,k)
where α =1/8 is a clutter map update coefficient, fr represents a data frame, and Fr is a total number of data frames required for fine map update. The sunny day picture is shown in fig. 6.
The present invention is described in further detail below with reference to examples:
example 2
1. Analyzing the XX radar measured data, wherein the radar works in an MTD system, the distance resolution unit is 30m, the distance unit is 4000 (120 km in total), the antenna scans for 6 r/min, the pulse repetition frequency is 300Hz, the word length of the acquired data is 8 bits (0-255), the radar scanning area of 360 degrees is divided into 4096 azimuth units, the distance resolution of a fine sky map is 60m, the number of the distance units is 2000, the azimuth resolution of the fine sky map is 360 degrees/128, and the estimation value of the radar noise power is 20. The radar input echo data is shown in figure 4.
FIR treatment: the antenna is adjusted to scan at a low speed, and pulse echo data x in the jth sector is processed ji (n), j =0, ·,127; i =0,.. 7, 45, n =0,.. 1999, the first 30 sweep data are FIR processed to obtain the filtered output signal y1 of the sector j (n)
Wherein i is a pulse number in a sector, j is a sector number, n is a distance number, and M =45 is an accumulated pulse number; for ground clutter, w i =1. When the number of pulses exceeds M, the data is not accumulated. The antenna scan was adjusted to 3 revolutions per minute.
3. Modulus and logarithm obtaining: for FIR output data y1 j (n) performing modulo logarithm processing to obtain jth sector data y2 j (n)：
y2 j (n)＝A*log[abs(y1 j (n))],j＝0,1,…,127；n＝0,1,…,1999
Wherein A is a scaling factor. The selection of the proportion coefficient A needs to consider the problem of gain normalization of a sunny day map. In the actual processing, a =20.
4. Target elimination: for jth sector data y2 j (n) carrying out threshold-crossing processing, removing the narrow pulse signal of the distance dimension threshold, and obtaining the data y3 after the target is removed j (n) of (a). A clear sky plot without interference rejection is shown in fig. 5.
1) Distance data y2 j (n) obtaining a detection result y2 by constant false alarm processing j ' (n). A schematic block diagram of constant false alarm detection is shown in fig. 3.
2) Marking narrow pulse data in the detection result, and judging the narrow pulse: statistics of y2 j ' (n) is the pulse width of the target signal, and a width of less than 3 range bins is considered a narrow pulse.
3) Sector data y2 according to the narrow pulse mark j (n) the corresponding position data is set to zero to obtain sector correction data y3 j (n)；
5. The distance is selected to be large: for data y3 j (n) performing a selective enlargement process in the kth (K =0, 1.., K) distance unit to obtain the current frame temporary clear sky map data CDM of the clear sky map unit (j, K) now (j,k)，
CDM now (j,k)＝max(y3 j (2k),y3 j (2k-1))
Wherein j =0,1, \8230;, 127; k =0,1. K =1999.
6. And (3) fine sky picture correction and update:
1) And (3) interference sector calculation: fixed sector interference is included in the clear sky plot. And the interference information in the clear sky picture is removed to obtain accurate clutter information. If x ji If (n) > 3. NoiseVal, considering that the interference exists in the sector of the current fine sky image, and counting the interference energy IM (j):
where j denotes the clear sky plot sector number, noiseVal is the radar noise power estimate, x ji (n) is the pulse-echo data in the j-th sector, and n is the number of radar range resolution elements.
2) And (3) correction: CDM now Indication repairCurrent temporary sunny day map data, CDM now ' denotes the corrected temporary sunny day map data. Then:
CDM′ now (j,k)＝CDM now (j,k)-IM(j)
3) Updating: the clear sky map is updated through iterative accumulation of 6 frames of data, so that final clear sky map data CDM (j, k) is obtained, and an updating formula is as follows:
and (3) final clear sky picture, namely the updated clear sky picture of the last frame: CDM (j, k) = CDM Fr (j,k)
Where α =1/8 is a clutter map update coefficient, fr represents a data frame, fr is a total number of data frames required for a clear-sky map update, fr =6, and the clear-sky map is shown in fig. 6.
The method for designing the radar clear sky map based on the FIR filter can be seen to ensure that the radar accurately identifies the radar clutter environment and acquires the radar clear sky map under any weather conditions. The method solves the problem that the existing radar can obtain accurate clutter estimation value in clear weather, eliminates the influence of point targets and communication interference, and provides guarantee for radar clutter partition and adaptive target detection.
The present invention provides a method and a method for designing a radar sunny day map of an FIR filter, and a plurality of methods and ways for implementing the technical scheme are provided, the above description is only a preferred embodiment of the present invention, it should be noted that, for those skilled in the art, a plurality of improvements and embellishments can be made without departing from the principle of the present invention, and these improvements and embellishments should also be regarded as the protection scope of the present invention. All the components not specified in this embodiment can be implemented by the prior art.
Claims (7)
1. A radar sunny day picture design method of an FIR filter is characterized by comprising the following steps:
step 1, calculating radar parameters: calculating radar distance sampling units n and a sector number j of a clear-sky image contained in a radar clear-sky image according to the total number Rmax of the distance units of the radar and the total number I of pulses in a single sector;
step 2, FIR treatment: adjusting an antenna to be low-speed scanning, filtering pulse echoes, and calculating ground clutter estimation;
step 3, modulus and logarithm obtaining: converting the data into logarithms;
step 4, target elimination: carrying out threshold processing on sector data, and removing narrow pulse signals with the distance exceeding a threshold;
step 5, distance combination: selecting large distance unit data to obtain distance unit data of a fine weather map;
step 6, fine day picture correction and updating: and eliminating communication interference influence in the clear sky map, updating the clear sky map by a clutter map accumulation method, and acquiring an accurate clear sky map estimation value.
2. The radar clear sky pattern design method of the FIR filter according to claim 1, characterized in that in step (2), the pulse echo data with pulse number i in the jth clear sky pattern sector is processed according to the following formula:
x ji (n), J =0, · J-1; i = 0., I-1, where I is the total number of pulses in a single sector, I is the pulse number in the sector, J is the total number of sectors in a clear day picture, J represents the sector number of the clear day picture, and k is the distance number; for n =0, R max Performing FIR processing on the first M sweep data in the step-1, wherein M is less than or equal to I, and Rmax is the total number of distance units of a single sweep, so as to obtain a filtering output signal y1 of the jth fine sky figure sector corresponding to the radar distance sampling unit number n j (n)：
Wherein w i Is a filter coefficient, w for ground clutter i And =1, when the number of pulses exceeds M, the data stops accumulating.
3. The method as claimed in claim 2, wherein in step (3), the FIR filter is used to output FIR data y1 j (n) performing modulo logarithm processing to obtain the jth sector data y2 j (n)：
y2 j (n)＝A*log[abs(y1 j (n))],j＝0,1,…,J-1；n＝0,1,…,Rmax-1
Wherein A is a scaling factor.
4. The method of claim 3, wherein in the step (4), the j-th clear sky pattern sector data y2 is processed j (n) carrying out threshold-crossing processing, removing the narrow pulse signal of the distance dimension threshold, and obtaining the data y3 after the target is removed j (n) comprising:
step 41, for the j-th sunny day map sector y2 j (n) processing the constant false alarm to obtain a detection result y2 j '(n)；
Step 42, labeling the detection result y2 j ' (n), narrow pulse data, narrow pulse discrimination method: counting the detection result y2 j ' (n) is the pulse width of the target signal, which is less than a given threshold V 3T Judging the pulse to be a narrow pulse;
step 43, according to the narrow pulse mark, the jth fine sky figure sector y2 j (n) the corresponding position data is set to zero to obtain sector correction data y3 j (n)。
5. The method of claim 4, wherein the distance in step (5) is selected from the group consisting of:
for data y3 j (n) carrying out large selection processing in the kth clear sky picture distance unit, wherein K =0,1, and K-1, K is the total number of clear sky picture distance resolution units, and obtaining temporary clear sky picture data CDM of the current frame of the jth clear sky picture unit (j, K) now (j,k)，
CDM now (j,k)＝max(y3 j (2k),y3 j (2k-1))
Wherein J =0,1, \8230, J-1; k =0,1, 1.., rmax/2-1.
6. The method of claim 5, wherein the step (6) of modifying and updating the clear sky pattern comprises:
and step 61, correcting: the clear sky picture contains fixed sector interference, and the interference information in the clear sky picture is removed to obtain accurate ground clutter and noise partitions;
2) Updating:
the updating of the clear sky map is realized by the iterative accumulation of the Fr frame data, so as to obtain the final clear sky map data CDM (j, k), the Fr frame clear sky map data CDM fr The update formula of (j, k) is:
and (3) final clear sky map, namely the updated clear sky map of the last frame: CDM (j, k) = CDM Fr (j, k) in the formula, CDM fr-1 And (j, k) represents the Fr-1 frame of clear day map data, the range of Fr is 1-Fr, alpha =1/8 is a clutter map updating coefficient, and Fr is the total data frame number required by clear day map updating.
7. The method of claim 6, wherein the step (61) comprises:
interference exists in a sector of a current sunny day image, and interference energy IM (j) is counted:
the value range of i satisfies the condition: i is 0. Ltoreq. M, and x ji (n) > 3. Set of all i of NoiseVal; wherein, noiseVal is the radar noise power estimate, M represents M sweep data;
the following formula is used for correction:
CDM′ now (j,k)＝CDM now (j,k)-IM(j)。
CDM now representing temporary sunny day map data before correction, CDM now ' denotes the corrected temporary sunny day map data.
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