CN106291502A - Background extracting and the maximum of probability time-domain processing method of counteracting in target rcs measurement - Google Patents

Abstract

The invention discloses background extracting and the maximum of probability time-domain processing method of counteracting during a kind of target radar scattering cross-section (RCS) is measured, the sliding window average treatment that the method is extracted based on Maximum Probability Principle and fixed background zero Doppler's clutter (ZDC), utilize a class subsidiary body or the original RCS width phase measurement data of measured target itself such as low scattering end cap, through the conversion of data field to time domain and maximum of probability threshold processing, it is thus achieved that " maximum of probability " time domain ZDC is estimated；The most again through the conversion of time domain to data field, thus obtain " maximum of probability " possibility predication of data field ZDC, eliminate the subsidiary body signal residual components adverse effect to ZDC estimated value in traditional method.By time domain maximum of probability statistic threshold processing, eliminate the residual components of subsidiary volume scattering signal in ZDC estimated value, thus improve ZDC estimated accuracy and the effectiveness of subsequent background counteracting process.

Description

Background extracting and the maximum of probability time-domain processing method of counteracting in target rcs measurement

Technical field

The present invention relates to communication and Radar Technology field, in measuring particularly to a kind of target radar scattering cross-section (RCS), Use the measurement data of subsidiary body or directly use target self measurement data, derive background data and support for background The signal procesing in time domain method disappeared.

Background technology

Scale model or the microwave dark room of full-scale target and outfield static measurement are that the low scattering of low detectable target sets Meter, the important tests means verified and improve.In microwave dark room and outfield RCS static measurement, the low scattering support of general employing Supporting measured target, distance instrumentation radar at a distance maintains static, and the target being placed on support makees orientation rotation, and instrumentation radar is recorded After taking rolling target scatter echo under different azimuth corner and carrying out background counteracting and calibration process, obtain measured target Comprehensive rcs measurement data.Typical outfield measure geometry relation is as shown in Figure 1.

For the ease of discussing target broadband radar signal (RCS) amplitude and the measurement of phase place and calibration, define target The multiple scattering function in broadband (namely multiple RCS of target alleged in some documents)For:

$\sqrt{\mathrm{\σ}\left(f\right)}=\underset{R\→\mathrm{\∞}}{\lim }\sqrt{4\mathrm{\π}}R\·\frac{E_s\left(f\right)}{E_i\left(f\right)}---\left(1\right)$

In formula, E_i(f) and E_sF () represents radar in-field (at target) and target scattering field (at radar antenna) respectively；It With the relation between RCS it is

By Fig. 1, calibration body and target to be measured be received back to wave power be satisfied by radar equation (see document E.F.Knott, Radar Cross Section, New York:Van Nostrand Reinhold, 1993.):

$P_r=\frac{P_t{G}^2{\mathrm{\λ}}^2}{{\left(4\mathrm{\π}\right)}^3{R}^{4}L}\·\mathrm{\σ}---\left(2\right)$

In formula, P_r,P_tIt is respectively radar receive and launch power；G is antenna gain；λ is radar wavelength；R be radar away from From；L is round trip transmission attenuation；σ is target RCS.

Calibration in target rcs measurement can use relative calibration method, it may be assumed that measure known to its theoretical RCS simultaneously Standard calibration body and the target to be measured of RCS the unknown, according to radar equation (2), have:

$V_{Cr}\left(f\right)={\left(\frac{P_t{G}^2{(c/f)}^2}{{\left(4\mathrm{\π}\right)}^3{R}^{4}L}\right)}^{1/2}\·\sqrt{{\mathrm{\σ}}_C\left(f\right)}---\left(3\right)$

$V_{Tr}\left(f\right)={\left(\frac{P_t{G}^2{(c/f)}^2}{{\left(4\mathrm{\π}\right)}^3{R}^{4}L}\right)}^{1/2}\·\sqrt{{\mathrm{\σ}}_T\left(f\right)}---\left(4\right)$

In formula (3)-(4), V_Cr(f),V_TrF () represents the calibration body echo that receiver receives in WB-RCS is measured respectively Voltage and measured target echo voltage；Represent the multiple scattering function of theory and the measured target of calibration body respectively The multiple scattering function in broadband；F is radar frequency；C is spread speed.

By formula (3) and (4), the calibration formula of the multiple scattering function of target is represented by:

$\sqrt{{\mathrm{\σ}}_T\left(f\right)}=\frac{V_{Tr}\left(f\right)}{V_{Cr}\left(f\right)}\·\sqrt{{\mathrm{\σ}}_C\left(f\right)}---\left(5\right)$

In formula,Multiple scattering function for measured target；Theory for determined standard type scatters letter again Number, can be calculated by exact numerical；V_Cr(f),V_TrF () represents the calibration body echo electricity that radar receiver receives respectively Pressure and measured target echo voltage.

The echo-signal that in actual rcs measurement, radar receives is complex signal, and by checkout area background and various noise Impact.The echo-signal that when assuming survey target and measure standard type, radar receives is represented by:

S_T(f)=T (f)+B_T(f)+N_T (6)

With

S_C(f)=C (f)+B_C(f)+N_C (7)

In formula, S_T(f) and S_CThe echo-signal that when () represents survey target respectively and measure standard type f, radar receives；T (f) table Show the true echo of target；C (f) represents the true echo of calibration body；B_T(f) and B_CF () represents when surveying target and measure standard type respectively Background return；N_TAnd N_CRepresent influence of noise, and its average is E{N_T}=E{N_C}=0.Above-mentioned echo-signal is plural number phase Amount.

In actual target rcs measurement, typically by improving radar emission acc power, using floor field, reception Machine uses the technology such as correlative accumulation to improve measurement signal to noise ratio so that the impact measured can be ignored by noise, thus has following Formula approximation is set up:

S_T(f)=T (f)+B_T(f) (8)

With

S_C(f)=C (f)+B_C(f) (9)

Visible, backscatter is the principal element affecting rcs measurement precision.For improving rcs measurement precision, typically in calibration Middle employing background phasor subtraction technique processes, and the calibration equation of target scattering function is:

$\begin{array}{c}\sqrt{{\mathrm{\σ}}_T\left(f\right)}=\frac{T\left(f\right)}{C\left(f\right)}\·\sqrt{{\mathrm{\σ}}_C\left(f\right)}\\ =\frac{S_T\left(f\right)-B_T\left(f\right)}{S_C\left(f\right)-B_C\left(f\right)}\·\sqrt{{\mathrm{\σ}}_C\left(f\right)}\end{array}---\left(10\right)$

In formula (10), S_T(f) and S_CF () represents echo when surveying target and measure standard type respectively, comprise clutter background；B_T (f) and B_CF () represents echo when not placing measured target or calibration body respectively, namely by Metal pylon and checkout area other The clutter background that angle echo is constituted；For target scattering function (namely multiple RCS, be to need to measure and the amount of calibration)；For the scattering function of calibration body, it is to pass through the calculated known quantity of accurate Theory.

Therefore, the target rcs measurement calibration equation that the counteracting of band background processes is:

${\mathrm{\σ}}_T\left(f\right)=|\frac{S_T\left(f\right)-B_T\left(f\right)}{S_C\left(f\right)-B_C\left(f\right)}{|}^2\·{\mathrm{\σ}}_C\left(f\right)---\left(11\right)$

In most indoor RCS checkout areas, it is to use to be placed on the same of same distance when measuring standard type and survey target Complete on support, now survey background return B during target_TBackground return B when (f) and mensuration standard type_CF () is identical, B_T (f)=B_C(f)=B (f), therefore have:

${\mathrm{\σ}}_T\left(f\right)=|\frac{S_T\left(f\right)-B\left(f\right)}{S_C\left(f\right)-B\left(f\right)}{|}^2\·{\mathrm{\σ}}_C\left(f\right)---\left(12\right)$

Therefore, according to formula (12), offsetting and RCS calibration process to complete background, the basic step of rcs measurement is as follows:

Step-1:t₁In the moment, measure target area background return B (f) comprising the Metal pylon for support target；

Step-2:t₂In the moment, calibration body is installed, measures calibration body echo S_C(f)；

Step-3:t₃Moment, installation targets, measure target echo S_T(f)；

Step-4: carry out background phasor according to formula (12) and subtract each other and target RCS calibration process.

For using the RCS checkout area of metal rack, the top of general objectives support is provided with and makes measured object physical ability complete The turntable of 360 ° of orientation rotations, surveying target or it is hidden in the intraperitoneal of testee during calibration body, therefore survey target or The echo turning top during calibration body will not produce substantial effect by echo total to radar.On the other hand, if to record and not install mesh When mark or calibration body, the background return of support itself, needs to remove stage makeup and costume target or calibration body from support, now originally hides Turn top then to reveal.Therefore, how background return B (f) of measurement bracket is to realize the pass that target RCS precise calibration is measured Key.

The background clutter being widely used in the world at present reduces and background subsidiary includes with extractive technique:

(1) by careful low scattering design so that in measurement frequency range interested, the scatter echo of support is much smaller than mesh Mark scattering (general low more than 20dB).The RCS level of modern Stealthy Target can as little as below-30dBsm, it means that require institute Its RCS level of the Metal pylon manufactured and designed to be less than-55dBsm, and at microwave frequency low side, this is unpractical.

(2) the low scattering end cap of a subsidiary is designed, when cradle top being turned top as surveying target when surveying background Equally " hide " by it with low scattering end cap, and think that the echo now recorded is mainly fixed background clutter.But, by It is usually less than-35dBsm in metal target support RCS level own, to accurately measure the fixed background echo of Metal pylon, Typically requiring low more than the 20dB of RCS level of low scattering end cap, namely reach below-55dBsm, this is the most unpractical.Cause This, more in the case of the Main Function of low scattering end cap be to install additional on support after low scattering end cap " low scattering end cap+mesh Mark support " under the conditions of carry out background measurement, with checking and guarantee the thresholding that the RCS level of Metal pylon is given less than technical specification Value.Obviously, it is accurate not that this employing low scattering end cap directly measures " the background measurement " obtained, and is only used for generally assessing Ambient level, typically cannot be directly used to background counteracting and processes.

(3) using background aided measurement device, the low scattering carrier that such as can translate, eccentric cylinder etc., by auxiliary Measure and signal processing completes background extracting and follow-up background counteracting processes.

(a) prior art-1: use the object translated on support as background subsidiary body

This technology installs one in cantilever tip self can be with the subsidiary carrier of anterior-posterior translation motion, as shown in Figure 2. Test (sees D.P.Morgan, " RCS Target Support Background Determination Using a Translating Test Body, " Proc.AMTA 1996, pp.15-17.), move by controlling this carrier anterior-posterior translation, And record radar return amplitude and phase place, for subsequent treatment to extract background return.

The shortcoming of prior art-1: use the major defect of this auxiliary device to have two, one is that this auxiliary device can not Take into account and calibrate for RCS；Two is to need to design special arrangement to drive subsidiary carrier to carry out anterior-posterior translation, for large-scale target RCS checkout area, owing to target turns top size very greatly, and needs in measuring to hide turn top in carrier, therefore it is required that designed Subsidiary carrier dimensions inevitable the biggest.Additionally, the distance of carrier translation is proportional to thunder required by background extracting subsidiary Reach wavelength.Frequency is the lowest, and wavelength is the longest, and distance range to be translated is the biggest.Thus, the actual application of this technology is limited System.

(b) prior art-2: use eccentric cylinder as calibration body and background subsidiary body

Document (L.A.Muth, C.M.Wang, and T.Conn, " Robust Separation of Background and Target Signals in Radar Cross Section Measurements,”IEEE Trans.Instrum.Meas., Vol.54, No.6,2005, pp.2462-2468.) for the shortcoming existing for technology-1, carry Go out a kind of substitute technology, i.e. use the cylinder of bias to carry out subsidiary and background extracting, as shown in Figure 3.In test, logical Cross and turn heading tape and move eccentric cylinder and make azimuth rotational motion.Owing to looking over from radar line of sight, under any corner outside the projection of cylinder Shape is constant, and its scattering amplitude is constant, but pushes up because cylinder is eccentrically mounted at turning of support, and this is equivalent to see at radar Come, there is the translational motion of a kind of equivalence, therefore it is the same to the extraction process method of background return compared with technology-1.

The shortcoming of prior art-2: the technology using eccentric cylinder to carry out subsidiary and background extracting avoids and makes load The requirement of body translation, but this technology there is also following distinct disadvantage:

At high frequency region, the RCS level of upright metal cylinder self meets below equation:

σ (f)=kah² (13)

In formula,For wave number, c is spread speed, and f is radar frequency；A is cylindrical radius；H is circle The height of cylinder.

When large-scale target is carried out rcs measurement, usually require that low Scattering Targets support and target turn weight average of bearing responsibility very big, It is the biggest that this causes target to turn the size on top.Owing to must be buried in wherein by turning top for the eccentric cylinder of background subsidiary, The support background condition under real goal measuring condition could be simulated and measure, now required eccentric cylinder size To be the biggest.And cylindrical theoretical RCS value and cylinder radius, square being directly proportional of cylinder height, be unfavorable for background measurement and Extract.Such as, when target turn top size reach diameter 1m, high 0.5m time, if having required the minimum radar of accurate rcs measurement frequently Rate 1GHz, then required eccentric cylinder diameter is up to more than 1.2m, according to (13) formula, the now RCS of eccentric cylinder self Level is at 0dBsm (1m²) magnitude, and the RCS level of Metal pylon background is typically at-30dBsm (0.001m²) below, both it Between differ 3 orders of magnitude.Now, according to the ambient level of eccentric cylinder assisted extraction support, being equivalent to will be from measuring echo In accurately extract a small-signal of 1000 times less than main echo, its background extracting precision is difficult to ensure that.

Visible, according to (13) formula, the theoretical RCS value of this calibration body raises with frequency and increases, is unfavorable for background extracting Subsidiary and process.

(c) prior art-3: use CAM calibration body as calibration body and background subsidiary body

Document (W.D.Wood, P.J.Collins, T.Conn, " The CAM RCS Dual-Cal Standard, " Proc.of the 25th Antenna Measurement Techniques Association Symposium,Irvine, CA, 2003.) proposing a kind of CAM calibration body, it is the perpendicular cylinder different and tangent by two radiuses and with two cylinders The closed geometry structure that the tangent plane of the arc surface of body collectively forms, its detailed geometry is as shown in Figure 4.Owing to CAM is fixed The special geometric profile of standard type, when CAM calibration body being made orientation to rotation, single calibration body equivalence can be used as small column (SC), 3 kinds of standard calibration bodies such as big cylinder (LC) and flat board (FP), therefore can be used for multiple calibration in rcs measurement and measure and process. Additionally, as eccentric cylinder, if reasonable in design, its large and small two cylinder scattering object in certain bearing range, also Can be used for background extracting subsidiary.

Formula (10) is still used to calculate in high frequency region, the big cylinder of CAM calibration body and the theoretical RCS value of small column, flat board RCS then to square being directly proportional of frequency.

The major defect of prior art-3: CAM calibration body can be equivalent to small column, big cylinder peace plate totally 3 standards and dissipate Beam, thus can be used for multiple calibration and measure and process.In addition, it is structure based on cylinder and flat board because of its geometric shape Build, therefore there is the every other shortcoming that same cylinder is the same.

(d) prior art-4: use SCAM calibration body as calibration body and background subsidiary body

The present inventor and partner thereof are recently proposed a kind of new standard calibration body configuration design, and this configuration design is to set up On the basis of CAM calibration body configuration design, (Xu little Jian, Liu Yongze " are used for can to regard the improvement to CAM profile as In target rcs measurement, the device of multiple calibration and background extracting designs and signal processing method, " number of patent application CN201610237378.2,2016).Specifically, on the basis of CAM profile, along the small column of CAM profile, big cylinder peace Plate face, comprehensive at 360 ° on increase semicircle cambered surface, wherein the diameter of semicircle cambered surface is equal to the height of CAM calibration body.We claim this One new profile is designed as sphere CAM (Spheroid CAM, be abbreviated as SCAM), and its geometric shape is as shown in Figure 5.

At high frequency region, the RCS electricity of the large and small goalpost (orientation corresponding to the large and small cylinder of CAM calibration body) of SCAM calibration body Divide equally and do not meet below equation:

${\mathrm{\σ}}_L\left(f\right)=\frac{\mathrm{\π}}{4}h(h+2a)---\left(14\right)$

${\mathrm{\σ}}_S\left(f\right)=\frac{\mathrm{\π}}{4}h(h+2b)---\left(15\right)$

In formula, σ_L(f) and σ_SF () is respectively big goalpost and the RCS of little goalpost；A is big cylindrical radius；B is small column The radius of body；H is the height of SCAM calibration body, is also the diameter of SCAM external arc curved surface simultaneously.

Compared with CAM, the advantage of SCAM calibration body is: at high frequency region, 3 equivalence margin bodies of CAM calibration body are respectively Cylinder and flat board, its RCS all raises with frequency and quickly raises；And the RCS of the large and small goalpost of SCAM calibration body is not with radar frequency Rate changes；The cylindrical RCS that maximum RCS and radius are h/2 of SCAM calibration body both sides (CAM flat board direction) cylinder just becomes Ratio.This RCS level of SCAM is not conducive to improving rcs measurement calibration precision with the characteristic of frequency change；Although generally The geometric shape size of the SCAM size than CAM is big, but on three equivalence margin body directions, the RCS value of SCAM is respectively less than CAM RCS value.It is true that SCAM calibration body its average RCS level on comprehensive is below the RCS level of CAM calibration body.

This low RCS level nature of SCAM is advantageously used as background subsidiary body.But, for full-scale target RCS checkout area, owing to its Metal pylon and turn top size are big, it is desirable to the size of SCAM is also big, still can cause subsidiary body RCS level exceeds the situation of tens of dB than ambient level, and background extracting precision now is difficult to ensure that.

(e) prior art-5: use low scattering end cap as background subsidiary body

The present inventor is it is proposed that the low scattering end cap of a kind of directly employing is as background subsidiary body, and then passes through at signal Reason obtains background estimating value and completes method (list of references: Xu X.J., " the A background and that background counteracting processes target signal separation technique for exact RCS measurement,"Int.Conf.on Electromagnetics in Advanced Applications(ICEAA),pp.891-894,Sep.2012.).It is basic Principle is as follows:

No matter for calibration body or target measurement, echo-signal can be collectively expressed as:

V (f, θ)=S (f, θ)+B (f) (16)

In formula, S (f, θ) is the scatter echo signal of target or calibration body, and B (f) represents fixed background signal.

Assume that target scattering function is that (x y), or is expressed as f (r, φ), the rotation that instrumentation radar receives under polar coordinate to f Turn target echo signal to be represented by:

In formulaFor radar wavelength；L is the full-size of target；R₀For between radar to target center of rotation away from From；R represent radar to target any one scattering pointBetween distance, have:

For far-field measurement, have:

Formula (17) is combined with (19), has:

In formulaFor imaginary number；

With

Homophase (I) and quadrature phase (Q) component for target scattering echo-signal.

It is apparent from, for given radar frequency f or wavelength X, if surveyed target is the target of electrically large sizes, i.e. L ＞ ＞ λ, BecauseHave:

$\begin{array}{c}\underset{\mathrm{\θ}\∈\[0,2\mathrm{\π})}{E}\[S(f,\mathrm{\θ})\]=\underset{\mathrm{\θ}\∈\[0,2\mathrm{\π})}{E}\[S_I(f,\mathrm{\θ})\]-j\underset{\mathrm{\θ}\∈\[0,2\mathrm{\π})}{E}\[S_Q(f,\mathrm{\θ})\]\\ =f(0,0)\end{array}---\left(23\right)$

In formulaRepresent azimuthal θ ∈ [0,2 π) mathematic expectaion.

Therefore,

$\begin{array}{c}\underset{\mathrm{\θ}\∈\[0,2\mathrm{\π})}{E}\[V(f,\mathrm{\θ})\]=\underset{\mathrm{\θ}\∈\[0,2\mathrm{\π})}{E}\[S(f,\mathrm{\θ})\]+B\left(f\right)\\ =f(0,0)+B\left(f\right)\end{array}---\left(24\right)$

Above formula teaches that: as long as measured target does not exist important scattering center at turntable center, i.e. f (0,0)= 0, then by the I of echo-signal, Q component are sought azimuth averaging, fixed background component of signal can be directly obtained.And low scattering end cap This condition of design general satisfaction, therefore can be used as background extracting subsidiary body.

The major defect of prior art-5 is: owing to background extracting is to obtain along orientation low scattering end cap to being averaging , the background signal extracted exists the impact of the scatter echo of subsidiary body own.Especially, for low scattering end cap this Class scattering object, its lateral RCS level is higher, can exceed more than background noise level 50dB, now can have a strong impact on background and survey Amount and the precision extracted, and then affect the effectiveness that background counteracting processes.

Summary of the invention

Present invention seek to address that techniques below problem: in low detectable target rcs measurement, use low scattering end cap etc. Type objects, the most directly use measured target itself as background subsidiary body time, how to eliminate subsidiary body self The adverse effect of the scatter echo background clutter for being extracted, improves background extracting precision.

The technical solution used in the present invention is as follows:

Traditional subsidiary body such as metal eccentric cylinder, CAM, SCAM that utilizes carries out substantially setting out of background clutter measurement Point is to measure the subsidiary body making orientation rotation, and design makes subsidiary volume scattering echo width in rotary course Degree does not changes with corner, and only phase place changes with orientation rotation.So, scattering amplitude and phase can be extracted by signal processing Position is not the most with the fixed background clutter of Orientation differences, also referred to as zero Doppler's clutter (ZDC).

The present invention based on a kind of diverse technical thought, i.e. utilize subsidiary volume scattering echo amplitude and phase place with Azimuth Rapid Variable Design thus in certain azimuth coverage, make average treatment, its mathematical expectation is zero, and fixed background is miscellaneous Ripple because of have not with subsidiary body make orientation rotation measure and change, its mathematical expectation is the characteristic of constant, propose one It is fixed the time-domain processing method that background clutter extracts based on Maximum Probability Principle.

Being used as the low scattering end cap of subsidiary body, be typically designed as the low scattering profile being similar to shown in Fig. 6, it dissipates Penetrating feature is: when radar wave along its nose cone to or Caudad irradiate time, the scatter echo of low scattering end cap mostly come from two ends point The scattering on top, this scattering has the scattering level of the lowest scattering level, generally below Metal pylon background or at least same One magnitude；When radar wave laterally irradiates, its scatter echo then mostlys come from the direct reflection of side, and scattering now can Can be far above support ambient level.

Therefore, in time domain (namely radial distance-orientation angular domain), the high resolution range profile of this type of low scattering end cap is with side The characteristic of parallactic angle change has the variation characteristic shown in Fig. 7.For the low scattering end cap as background extracting subsidiary body Above-mentioned time domain scattering properties, can be designed that and utilize this type of subsidiary body to carry out orientation rotation measurement, and from measurement data Extract the time-domain processing method of fixed background signal, namely background based on Maximum Probability Principle is measured and extracts Time Domain Processing Method.

Background based on maximum of probability is measured and be make use of low scattering end cap one class subsidiary with extraction time-domain processing method The frequency of its scatter echo of body-orientation angular domain variation characteristic and one-dimensional High Range Resolution (HRRP) thereof are special with the change in orientation Property.

Formula (21) and (22) are rewritten as follows:

With

In formula:

Owing to, under the most of azimuths in addition to lateral scattering, the echo level of low scattering end cap is than fixed support background Scattering level is low or magnitude suitable, and the length of low scattering end cap is generally up to several meters of even more than 10m, and its scattering is main Come from the scattering on pinnacle, two ends, therefore, formula (27) be apparent from, for microwave frequency band (wavelength be centimetre～decimeter level), return Wave phase is violent with the change in orientation, according to formula (25)～(27), even if using little orientation window that data are carried out sliding window Statistical average processes, and its mathematic expectaion the most easily meets following formula:

$\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[S(f,\mathrm{\θ})\]=\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[S_I(f,\mathrm{\θ})\]-j\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[S_Q(f,\mathrm{\θ})\]=0---\left(28\right)$

In formulaRepresent that azimuth window is θ_k-Δ≤θ≤θ_kThe mathematic expectaion of all measurement data in+Δ, θ_k Representing kth azimuth position, 2 Δs represent with θ_kCentered by, scatter echo data are done the orientation sliding window width of average treatment.

Therefore, have:

$\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[V(f,\mathrm{\θ})\]=\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[S(f,\mathrm{\θ})\]+B\left(f\right)=B\left(f\right)---\left(29\right)$

Formula (29) shows, does the scatterometry data making the low scattering end cap one class subsidiary body that orientation rotation is measured Orientation sliding window average treatment, the estimated value of zero Doppler's clutter (ZDC) that available fixed background produces.

The major defect using above-mentioned orientation slide window processing to obtain ZDC estimated value is: when the scattering level of subsidiary body More much better than than fixed background noise level, or strong scattering source deviation center of rotation (example when remote not of subsidiary body As when low scattering end cap is laterally irradiated by instrumentation radar), obtained ZDC estimated value self can be scattered by subsidiary body Remaining the having a strong impact on of echo, have impact on ZDC estimated accuracy.

According to formula (29), the subsidiary volume scattering data making orientation rotation measurement are done orientation sliding window average treatment After, obtain is that the ZDC estimated value of fixed background is with frequency and the variable quantity in orientation.And in theory, being scattered back of fixed background Ripple is not with azimuthal variation.Therefore, ZDC estimated value is mainly caused by following two component of signal with the variable quantity in orientation: (1) residual components of subsidiary volume scattering signal after sliding window average treatment；(2) with orientation between subsidiary body-Metal pylon The coupling scattering component of change.

In order to eliminate the impact that the true ZDC of both component of signals estimates, the present invention proposes a kind of based on maximum of probability Background is measured and extracts time-domain processing method, and its ultimate principle is discussed below:

Formula (29) two ends are made Inverse Fast Fourier Transforms (IFFT), and according to the linear transformation characteristic of IFFT, have:

$\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[IFFT\left(V\right(f,\mathrm{\θ}\left)\right)\]=\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[IFFT\left(S\right(f,\mathrm{\θ}\left)\right)\]+IFFT\left(B\right(f\left)\right)=IFFT\left(B\right(f\left)\right)---\left(30\right)$

Namely:

$\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[v(f,\mathrm{\θ}))\]=\underset{\mathrm{\θ}\∈{\mathrm{\θ}}_k\±\mathrm{\Δ}}{E}\[s(t,\mathrm{\θ}))\]+b\left(t\right)=b\left(t\right)---\left(31\right)$

In formula, v (t, θ)=IFFT (V (f, θ)), s (t, θ)=IFFT (S (f, θ)), b (t)=IFFT (B (f)), respectively Represent " subsidiary body+support " HRRP and the HRRP of subsidiary body with Orientation differences and not consolidating with Orientation differences Determine the HRRP of background clutter.

Notice for any azimuth, if exist subsidiary volume scattering signal residual components and/or subsidiary body- The impact of coupling scattering component between Metal pylon, i.e.Then in time domain for given distance list Unit (is represented by t in time domain_iUnder), have:

$\hat{b}(t_i,\mathrm{\θ})=\mathrm{\Δ}s(t_i,\mathrm{\θ})+b\left(t_i\right)---\left(32\right)$

Δ s (t in formula_i, θ) and represent coupling between subsidiary volume scattering residual components and/or subsidiary body-Metal pylon The impact of scattering component.

When Fig. 8 shows the typical low scattering end cap of employing as subsidiary body, the ZDC obtained by sliding window average treatment Estimating and HRRP is with the characteristic of Orientation differences, wherein Fig. 8 (a) is data field (ZDC is with frequency-orientation) variation characteristic, Fig. 8 B () is time domain (ZDC is with radial distance-orientation) variation characteristic.Notice that no matter fixed background ZDC is in data field or time Territory is all not with Orientation differences.But, it is evident from figure 8 that under some azimuth, subsidiary volume scattering is remaining ZDC is estimated to cause to have a strong impact on by component and coupling scattering component, this from Fig. 8 (b) ZDC-HRRP with the change in orientation Can be clearly seen in characteristic.In order to eliminate the impact of this error, it is based on maximum of probability that the present invention proposes to use shown in Fig. 9 Time Domain Processing flow process, its fundamental measurement is as follows with the step of background clutter extraction process:

Step-1: the comprehensive RCS width phase data of subsidiary body obtains

When the subsidiary bodies such as low scattering end cap be installed on Metal pylon turn on top, to low scattering end cap etc. Class subsidiary body is made 360 ° of all-directional rotations and is measured, it is thus achieved that arrowband under different orientations or Wide band scattering echo amplitude and phase Bit data, thus obtain the mixing echo wide-band width measurement sample of " subsidiary body+Metal pylon ", it is referred to as " comprehensive rcs measurement Original width phase data ".

Step-2: data field ZDC estimates

For each measurement frequency in " comprehensive rcs measurement original width phase data ", select the orientation window of one fixed width Do orientation sliding window average treatment, obtain the ZDC under each orientation and estimate, including amplitude Estimation and phase estimation value.

The HRRP that step-3:ZDC estimates calculates

ZDC width phase data under each orientation obtain orientation sliding window average treatment makees fast adverse Fourier transform (IFFT), obtain the HRRP that under each azimuth, ZDC estimates, namely time domain ZDC is estimated, is abbreviated as ZDC-HRRP, including amplitude And phase place.

Step-4: maximum of probability amplitude and maximum of probability phase calculation

By probability statistics histogram treatment, ask for amplitude and the full side of phase estimation under ZDC-HRRP each distance unit Position statistic: maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_i), i=1,2 ..., N_t, wherein N_tRepresent The distance unit number of ZDC-HRRP.

Step-5: time domain threshold processing based on maximum of probability statistic

The amplitude threshold factor and the Phase Threshold factor is set, for often according to above-mentioned maximum of probability amplitude and phase place statistic Individual distance unit and the ZDC-HRRP amplitude in each orientation and phase estimation, complete threshold processing, it may be assumed that if active cell ZDC-HRRP amplitude or phase estimation and maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_iDifference between) Exceed threshold value, then the ZDC-HRRP at this estimates to use maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_i) value Replace.So, the final ZDC-HRRP estimated value under each distance unit and orientation, namely the high score of fixed background clutter are obtained Resolution Range Profile estimated value.

Step-6: time domain background subtracting processes

The HRRP of raw measurement data is subtracted each other with the catch cropping phasor of the ZDC-HRRP time domain estimation of background clutter, is carried on the back Target echo time domain data after scape counteracting.

Step-7: time domain to data field converts

Time domain data after offsetting background makees one-dimensional FFT, obtains the data field data of target echo after background is offset, also I.e. target RCS amplitude-phase is with frequency and the data of Orientation differences, can be used for follow-up various process.

The processing sequence of above-mentioned steps-6 and step-7 also can be carried out in turn, the most first by ZDC-HRRP data through one-dimensional FFT is to data field ZDC, more directly at data field, raw measurement data is made background subtracting process.

The important technical advantage of the present invention is:

(1) proposed by the invention based on Maximum Probability Principle, survey from the RCS of class subsidiary bodies such as low scattering end cap Amount is extracted the time domain processing method of background signal, it is possible to obtain " maximum of probability " possibility predication of background signal, eliminate and pass The subsidiary volume scattering signal residual components impact on background signal valuation in system ZDC estimation, improves ZDC estimated accuracy.

(2) proposed by the invention based on Maximum Probability Principle, survey from the RCS of class subsidiary bodies such as low scattering end cap Amount is extracted the time domain processing method of background signal, remaining owing to eliminating subsidiary volume scattering signal at ZDC in estimating Component, obtained ZDC estimates, when background counteracting processes, can preferably avoid because background counteracting processes real goal The impact of signal.

(3) proposed by the invention based on Maximum Probability Principle, survey from the RCS of class subsidiary bodies such as low scattering end cap Extracting the data field processing method of background signal in amount, its threshold processing realizes for ZDC-HRRP in time domain, therefore Threshold processing criterion can be not limited to use " maximum of probability " criterion.Such as, for not only there is fixed clutter but also there is subsidiary Body and the distance unit of coupling scattering impact, use " maximum of probability " to process；For special with the change in orientation by ZDC-HRRP Property may determine that, some specific range unit does not exist fixed background clutter and only comprises subsidiary body residue signal and divide During amount, can use software range gate technology to ZDC-HRRP process so that the residue signals in these distance unit Thoroughly eliminated.

(4) proposed by the invention based on Maximum Probability Principle, survey from the RCS of class subsidiary bodies such as low scattering end cap Amount is extracted the time domain processing method of background signal, be not limited to only to low scattering end cap as the rcs measurement of subsidiary body Data carry out background extracting and counteracting processes.In principle, as long as its scattering properties of any measured target meets do not deposit in Zhuan Ding district At notable scattering source, then it is used equally to background extracting with the measurement data of orientation rotation and counteracting processes.Therefore, the present invention is real The side that the maximum of probability background extracting of a kind of general " being derived background estimating by target measurement " processes is proposed with counteracting in matter Method.

Accompanying drawing explanation

Fig. 1 is target rcs measurement geometrical relationship schematic diagram；

Fig. 2 is the translatable carrier schematic diagram for background extracting subsidiary；

Fig. 3 is the eccentric cylinder schematic diagram for background extracting subsidiary；Wherein, Fig. 3 (a) is that low Scattering Targets props up Frame pushes up with turning；Fig. 3 (b) is supporting eccentric cylinder；

Fig. 4 is the geometry schematic diagram of CAM calibration body；Wherein, Fig. 4 (a) is the 3D moulding of CAM calibration body；Fig. 4 (b) Transverse cross-sectional view for CAM calibration body；

Fig. 5 is the geometry schematic diagram of SCAM calibration body；Wherein, Fig. 5 (a) is the 3D moulding of SCAM calibration body；Fig. 5 B () is the transverse cross-sectional view of SCAM calibration body；

Fig. 6 is typical low scattering end cap class subsidiary body appearance schematic diagram；

Fig. 7 is the high resolution range profile characteristic schematic diagram with azimuthal variation of " subsidiary body+Metal pylon "；

Fig. 8 is to use the ZDC that obtains of sliding window average treatment to estimate schematic diagram, wherein Fig. 8 (a) be ZDC estimate with frequency and Orientation differences characteristic, Fig. 8 (b) is the HRRP variation characteristic schematic diagram with orientation of the ZDC obtained through inverse Fourier transform；

Fig. 9 is that background based on maximum of probability is measured and extracts Time Domain Processing flow chart；

Figure 10 is to use background extracting Time Domain Processing based on maximum of probability to obtain ZDC to estimate, wherein Figure 10 (a) is ZDC HRRP with the variation characteristic in orientation, Figure 10 (b) is that the fast fourier transformed ZDC obtained estimates with frequency and Orientation differences Characteristic schematic diagram；

Figure 11 is that the target RCS amplitude using traditional Z DC to obtain after estimating to carry out background subtracting becomes with frequency and azimuth Change characteristic schematic diagram；

Figure 12 is to use to process, based on maximum of probability data territory, the target RCS width obtained after ZDC estimates to carry out background subtracting Degree is with frequency and azimuthal variation characteristic schematic diagram；

Figure 13 is the target high-resolution Range Profile characteristic schematic diagram with Orientation differences, wherein: Figure 13 (a) is that background is offset Front result；Figure 13 (b) is result after using traditional Z DC estimation background to offset；Figure 13 (c) estimates for using maximum of probability to process ZDC Result after meter background counteracting.

Detailed description of the invention

Below in conjunction with the accompanying drawings and detailed description of the invention further illustrates the present invention.

Class subsidiary bodies such as low scattering end cap are used to complete background subsidiary, background extracting the most general with counteracting Rate time-domain processing method to be embodied as step as follows:

Step-1: the comprehensive rcs measurement original width phase data of subsidiary body obtains

When the subsidiary bodies such as low scattering end cap be installed on Metal pylon turn on top, auxiliary to low scattering end cap etc. Help measurement body to make 360 ° of all-directional rotations to measure, it is thus achieved that the arrowband under different orientations or Wide band scattering echo data, thus To the mixing echo wide-band width measurement sample of " subsidiary body+Metal pylon ", it is referred to as " the comprehensive rcs measurement original width number of phases According to ".

Note " comprehensive rcs measurement original width phase data " is V (f_i,θ_k), i=1,2 ..., N_f；K=1,2 ..., N_a, its Middle V (f_i,θ_k) represent i-th frequency, the width phase data in kth orientation, N_f,N_aRepresent that frequency and azimuth sample are counted respectively.

The RCS amplitude of " subsidiary body+Metal pylon " is with frequency and Orientation differences characteristic as shown in Figure 7.

Step-2:ZDC estimates

For each measurement frequency of wide-band width measurement, the orientation window of one fixed width is selected to do orientation sliding window average treatment, Obtain the ZDC under each orientation to estimate.

Remember that the ZDC estimated value under each frequency and orientation isI=1,2 ..., N_f；K=1,2 ..., N_a, its InRepresent the i-th frequency, the kth orientation that obtain after slide window processing, comprise subsidiary volume scattering residual echo The ZDC estimated value of impact,

$\begin{array}{c}\hat{B}(f_i,{\mathrm{\θ}}_k)=\mathrm{\Δ}s(f_i,{\mathrm{\θ}}_k)+B\left(f_i\right)\\ =\hat{A}(f_i,{\mathrm{\θ}}_k)e^{j\widehat{\mathrm{\φ}}(f_i,{\mathrm{\θ}}_k)}\end{array}---\left(33\right)$

Wherein Δ s (f_i,θ_k) it is residual echo,Represent ZDC amplitude and phase estimation value respectively.

The typical ZDC using tradition orientation slide window processing method to obtain estimates as shown in Figure 8, and wherein Fig. 8 (a) is data field Result (ZDC estimates with frequency and the variation characteristic in orientation), Fig. 8 (b) is that (ZDC-HRRP is with radial distance and side for time domain result The variation characteristic of position).

As can be seen from Fig. 8, no matter in data field or time domain, lateral at the low scattering end cap as subsidiary body (-90 ° and 90 ° of orientation near zone), the residual scatter echo measuring body is very serious on the impact of ZDC, but at comprehensive model In enclosing, residue signal affects serious region and only accounts for 360 ° of omnibearing sub-fractions, so that by " maximum of probability " door Limit processes and eliminates Δ s (f_i,θ_k) impact be possibly realized.

The HRRP that step-3:ZDC estimates calculates

ZDC width phase data under each orientation obtain orientation sliding window average treatment makees fast adverse Fourier transform (IFFT), the HRRP that under each azimuth, ZDC estimates is obtained, including HRRP amplitude and phase place.

Inverse Fast Fourier Transforms (IFFT) is made along frequency dimension in formula (33) two ends, and the linear transformation according to IFFT is special Property, have:

$\hat{b}(t_i,{\mathrm{\θ}}_k)=\mathrm{\Δ}s(t_i,{\mathrm{\θ}}_k)+b\left(t_i\right)---\left(34\right)$

In formula,Δ s (t, θ)=IFFT (Δ S (f, θ)), b (t)=IFFT (B (f)), point Do not represent " subsidiary body+support " HRRP and the HRRP of subsidiary body with Orientation differences and not with Orientation differences The HRRP of fixed background clutter；I=1,2 ..., N_t,N_tCounting for IFFT, namely radial distance unit number；K=1, 2,...,N_a, N_aCount for azimuth sample.

For to set a distance unit t_iWith given azimuth angle theta_k, have:

$\hat{b}(t_i,{\mathrm{\θ}}_k)=\mathrm{\Δ}s(t_i,{\mathrm{\θ}}_k)+b\left(t_i\right)={\hat{A}}_t(t_i,{\mathrm{\θ}}_k)e^{j{\widehat{\mathrm{\φ}}}_t(t_i,{\mathrm{\θ}}_k)}---\left(35\right)$

Δ s (t in formula_i, θ) and represent coupling between subsidiary volume scattering residual components and/or subsidiary body-Metal pylon The impact of scattering component,Represent that time domain ZDC-HRRP is to set a distance unit t_iAnd azimuth angle theta_kUnder width Degree and phase place.

Step-4: maximum of probability amplitude and maximum of probability phase calculation

By probability statistics histogram treatment, ask for amplitude and the full side of phase estimation under ZDC-HRRP each distance unit Position statistic: maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_i), i=1,2 ..., N_t, wherein N_tRepresent The distance unit number of HRRP.

Step-5: threshold processing based on maximum of probability statistic

Amplitude threshold factor-alpha is set according to above-mentioned maximum of probability statistic_A1, α_A2With Phase Threshold factor-alpha_φ1, α_φ2。

For each distance unit and the ZDC-HRRP amplitude in each orientation and phase estimation, complete following threshold processing:

If that is: the ZDC-HRRP amplitude of active cell or phase estimation and maximum of probability amplitude A_pmax(t_i) and the most general Rate phase_pmax(t_iDifference between) exceedes threshold value, then the ZDC-HRRP at this estimates to use maximum of probability amplitude A_pmax(t_i) With maximum of probability phase_pmax(t_i) value replacement.So, the final ZDC-HRRP obtained under each distance unit and orientation estimates Value, namely the high resolution range profile estimated value of fixed background clutter.So, the final ZDC under each frequency and orientation is obtained Estimated value, namely the estimated value of fixed background clutter:

$b(t_i,{\mathrm{\θ}}_k)=A_t(t_i,{\mathrm{\θ}}_k)e^{{\mathrm{j\φ}}_t(t_i,{\mathrm{\θ}}_k)}---\left(38\right)$

The ZDC using background extracting Time Domain Processing based on maximum of probability to obtain estimates as shown in Figure 10.Due to beyond institute Its amplitude of data point and the phase value that set thresholding are replaced by maximum of probability amplitude-phase statistic, therefore residue signal Δ s (t_i,θ_k) impact of ZDC estimator is eliminated.

Figure 10 (a) shows that the ZDC-HRRP obtained through maximum of probability time domain threshold processing estimates.Visible, subsidiary body Residue signal impact significantly suppressed.

Step-6: ZDC data field based on maximum of probability is estimated

Fast fourier transform (FFT) is made for ZDC-HRRP after maximum of probability threshold processing under each orientation, The data field amplitude of ZDC and phase estimation under each azimuth.

$B(f_i,{\mathrm{\θ}}_k)=FFT\left(b\right(t_i,{\mathrm{\θ}}_k\left)\right)=A(f_i,{\mathrm{\θ}}_k)e^{j\mathrm{\φ}(f_i,{\mathrm{\θ}}_k)}---\left(39\right)$

After Figure 10 (b) shows by the ZDC-HRRP obtained through maximum of probability time domain threshold processing is made Fourier transform ZDC data field is estimated.Visible, at data field, the residue signal impact of subsidiary body is suppressed the most significantly.

Step-7: background subtracting processes

Raw measurement data V (f_i,θ_k) estimate data B (f with fixed background clutter_i,θ_k) catch cropping phasor subtract each other, obtain Target echo data after background counteracting:

S(f_i,θ_k)=V (f_i,θ_k)-B(f_i,θ_k) (40)

Obtained result is the target echo data after background is offset, and can be used for follow-up various signal processing.

Figure 11 is that the target RCS amplitude using traditional Z DC to obtain after estimating to carry out background subtracting becomes with frequency and azimuth Change characteristic schematic diagram.Figure 12 is to use to process, based on maximum of probability time domain, the target obtained after ZDC estimates to carry out background subtracting RCS amplitude is with frequency and azimuthal variation characteristic schematic diagram.

Figure 13 is the target high-resolution Range Profile that obtains through the Inverse Fast Fourier Transforms characteristic with Orientation differences, wherein Figure 13 (a) is result before background is offset, and Figure 13 (b) is result after using traditional Z DC estimation background to offset, and Figure 13 (c) is for using Maximum of probability processes ZDC and estimates result after background counteracting.

From Figure 13 it is apparent that use traditional Z DC to estimate, the high resolution range profile that background obtains after offsetting makes Partial target scattering component distortion, such as indicate the elliptic region of 1～6, all have distortion compared with Figure 13 (a) in Figure 13 (b).And Use data field maximum of probability to process the ZDC obtained and estimate after background is offset, owing to all frequencies of data field are all carried out Maximum of probability threshold processing, eliminates target residual component in ZDC estimates, therefore remains target scattering signal, example well As indicated the elliptic region of 1～6 in Figure 13 (c), compared with Figure 13 (a), target scattering component is all retained.

Claims (5)

1. background extracting and the maximum of probability time-domain processing method of counteracting in a target rcs measurement, it is characterised in that: the method Comprise the steps:

Step-1: the comprehensive RCS width phase data of subsidiary body obtains

When subsidiary body be installed on Metal pylon turn on top, subsidiary body is made 360 ° of all-directional rotations and surveys Amount, it is thus achieved that arrowband under different orientations or Wide band scattering echo amplitude and phase data, thus obtain " subsidiary body+mesh Mark support " mixing echo wide-band width measurement sample, be referred to as " comprehensive rcs measurement original width phase data "；

Step-2: data field ZDC estimates

For each measurement frequency in " comprehensive rcs measurement original width phase data ", select the window side of doing, orientation of one fixed width Position sliding window average treatment, obtains the ZDC under each orientation and estimates, including amplitude Estimation and phase estimation value；

The HRRP that step-3:ZDC estimates calculates

ZDC width phase data under each orientation obtain orientation sliding window average treatment makees fast adverse Fourier transform (IFFT), Obtain the HRRP that under each azimuth, ZDC estimates, namely time domain ZDC is estimated, is abbreviated as ZDC-HRRP, including amplitude and phase place；

Step-4: maximum of probability amplitude and maximum of probability phase calculation

By probability statistics histogram treatment, ask for amplitude and the comprehensive system of phase estimation under ZDC-HRRP each distance unit Metering: maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_i), i=1,2 ..., N_t, wherein N_tRepresent ZDC- The distance unit number of HRRP；

Step-5: time domain threshold processing based on maximum of probability statistic

Set the amplitude threshold factor and the Phase Threshold factor according to above-mentioned maximum of probability amplitude and phase place statistic, for each away from From ZDC-HRRP amplitude and the phase estimation in unit and each orientation, complete threshold processing, it may be assumed that if the ZDC-of active cell HRRP amplitude or phase estimation and maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_iDifference between) exceedes Threshold value, then the ZDC-HRRP at this estimates to use maximum of probability amplitude A_pmax(t_i) and maximum of probability phase_pmax(t_i) value replaces Change, so, obtain the final ZDC-HRRP estimated value under each distance unit and orientation, namely the high-resolution of fixed background clutter Rate Range Profile estimated value；

Step-6: time domain background subtracting processes

The HRRP of raw measurement data is subtracted each other with the catch cropping phasor of the ZDC-HRRP time domain estimation of background clutter, obtains background and support Target echo time domain data after disappearing；

Step-7: time domain to data field converts

Time domain data after offsetting background makees one-dimensional FFT, obtains the data field data of target echo after background is offset, namely mesh Mark RCS amplitude-phase, with frequency and the data of Orientation differences, can be used for follow-up various process.

Background extracting and the maximum of probability Time Domain Processing side of counteracting in a kind of target rcs measurement the most according to claim 1 Method, it is characterised in that: the processing sequence of above-mentioned steps-6 and step-7 also can be carried out in turn, the most first by ZDC-HRRP data warp One-dimensional FFT is to data field ZDC, more directly at data field, raw measurement data is made background subtracting process.

Background extracting and the maximum of probability Time Domain Processing side of counteracting in a kind of target rcs measurement the most according to claim 1 Method, it is characterised in that: subsidiary body be specially low scattering end cap, eccentric cylinder, eccentric spherical cylinder, CAM calibration body, SCAM calibration body or measured target itself.

Background extracting and the maximum of probability Time Domain Processing side of counteracting in a kind of target rcs measurement the most according to claim 1 Method, it is characterised in that: in step-1, the comprehensive RCS width phase data of subsidiary body obtains also can be comprehensive with non-360-degree Wheel measuring replaces, in the case, then at the rectangular histogram that can again take statistics the obtained ZDC estimation data with Orientation differences Reason, asks for " maximum of probability " amplitude and phase place statistic, as not with final ZDC amplitude and the phase estimation amount of Orientation differences.

Background extracting and the maximum of probability Time Domain Processing side of counteracting in a kind of target rcs measurement the most according to claim 1 Method, it is characterised in that: when being measured as the measurement of non-360-degree all-directional rotation for subsidiary body, in step-6 background subtracting In process, use final ZDC amplitude and phase estimation amount described in claim 4, process for background counteracting.