CN109085549A - Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar - Google Patents
Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar Download PDFInfo
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- CN109085549A CN109085549A CN201810847812.8A CN201810847812A CN109085549A CN 109085549 A CN109085549 A CN 109085549A CN 201810847812 A CN201810847812 A CN 201810847812A CN 109085549 A CN109085549 A CN 109085549A
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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
- G01S7/36—Means for anti-jamming, e.g. ECCM, i.e. electronic counter-counter measures
Abstract
The invention discloses Doppler in a kind of external illuminators-based radar to tie up fuzzy side peaks suppression method.Mismatch filter is solved the problems, such as to fuzzy side peaks suppression.It realizes that step has: obtaining measured data, generate ambiguity function to be processed；Construct cost function；Cost function J is solved, optimal mismatch filter factor W is solved by the first order necessary condition theorem that unconstrained optimization convexity optimizes；Snr loss SNRL and peak sidelobe ratio PSLR is defined, exports the relational expression of the two factors Yu weight d respectively, for adjusting the performance that Doppler in external illuminators-based radar ties up fuzzy side peaks suppression method.The present invention is by construction cost function without obtaining signal prior information, submaximum near main lobe in Doppler's dimension of signal ambiguity function is effectively inhibited, false-alarm or false dismissed rate are reduced, complexity is low, the side peaks suppression tieed up for field of radar ambiguity function in Doppler.
Description
Technical field
It invents and belongs to Radar Technology field more particularly to external illuminators-based radar, it is more in specifically a kind of external illuminators-based radar
Pu Lewei obscures side peaks suppression method.For external illuminators-based radar target acquisition.
Background technique
The not outside electromagnetic radiation signal of external illuminators-based radar itself, but utilize already existing emitter Signals in space
As irradiation source, aerial target is detected, positioned and tracked.On the one hand, due to its not outside electromagnetic radiation signal, therefore
It is difficult to be found by enemy radar, anti-interference and survival ability is all stronger than conventional radar.On the other hand, because it possesses passive spy
The advantages such as survey, of simple structure and low cost, so by more extensive concern.
Because external illuminators-based radar is using the commercialization of already existing non-cooperating or civil signal as the chance of radar
Irradiation source, such as frequency modulation broadcasting, TV signal and satellite navigation signals etc..For opportunity illuminating source signal, ambiguity function is
One important indicator of external illuminators-based radar detection performance is the distance of measurement system and the factor of velocity resolution.It is ideal outer
Radiation source radar illuminators of opportunity signal ambiguity function shape is similar to drawing pin shape, but since opportunity illuminating source signal is not for radar
Detection and design, comprising the information such as pilot tone and cyclic prefix in signal, so that some emitter Signals are in distance or Doppler
There is fuzzy submaximum in dimension.Under normal conditions, target detection is to be detected in doppler cells, and Doppler ties up fuzzy submaximum
Presence can make big target minor lobe cover Small object main lobe cause the false dismissal of system so that Small object can not be detected
Rate increases.Meanwhile because same Doppler tie up occur it is multiple by same target caused by peak value so that the false alarm rate of system increases.
In original art, when inhibiting to the fuzzy submaximum of Doppler's dimension, it is often necessary to obtain external sort algorithm signal
Prior information first carries out frame synchronization to the prior information of acquisition, then carries out coded modulation to channel information, by these pretreatments
Afterwards, then by the pilot tone of signal live part and cyclic prefix information 0 is set.In the signal of actual measurement, to the pilot tones of all signals and
Cyclic prefix information is pre-processed, so that the inhibition of fuzzy submaximum is increasingly complex.It is a kind of more simple it is therefore desirable to propose
Fuzzy side peaks suppression method.
Summary of the invention
The purpose of the present invention is being directed to problem of the prior art and defect, a kind of more simple and effective external sort algorithm is proposed
Doppler ties up fuzzy side peaks suppression method in radar.
The present invention is that Doppler ties up fuzzy side peaks suppression method in a kind of external illuminators-based radar, which is characterized in that external radiation
Source radar includes two paths, and the first via is echo channel, and the second tunnel is reference channel, and Doppler ties up side peaks suppression method and includes
Following steps:
S1: generate ambiguity function figure to be processed: CDMA (CDMA) external sort algorithm signal based on the actual measurement obtains
The data for taking echo signal data and reference channel are made the processing of distance-Doppler two-dimensional correlation to the signal in two channels, are generated
Ambiguity function figure to be processed；In ambiguity function, the matching attribute of echo signal itself is W0；
S2: construction cost function J: the sum of submaximum energy is tieed up by minimizing mismatch filter snr loss and Doppler,
Construct echo-signal cost function J, cost function J is to consist of two parts, first part be the mismatch filter factor with
Difference with the factor, second part be Doppler's submaximum energy and；
S3: it solves the optimal mismatch filter factor W of cost function J: the solution of cost function J being converted into optimal value and is asked
Solution solves optimal mismatch filter factor W by the first order necessary condition theorem that unconstrained optimization convexity optimizes；It is complete with mismatch filter
Fuzzy side peaks suppression is tieed up at Doppler；
S4: defining snr loss SNRL and peak sidelobe ratio PSLR, exports by snr loss SNRL and peak value respectively
The relational expression of valve ratio PSLR and weight d tie up fuzzy side peaks suppression method to adjust Doppler in external illuminators-based radar
Performance.
The present invention can externally emitter Signals be effectively inhibited in the fuzzy submaximum phenomenon that Doppler ties up generation, energy
Significantly reduce the false-alarm occurred during target detection or false dismissal phenomenon.
Compared with prior art, technical advantage of the invention:
1, achieve the purpose that inhibit submaximum and solving the mismatch filter factor to mismatched filter, make side peaks suppression problem
Simplerization.In external illuminators-based radar, Doppler tie up submaximum be due in signal pilot tone and cyclic prefix generates, show
In some technologies, to achieve the purpose that inhibit submaximum, it is necessary to first by the prior information of signal by pilot tone and cyclic prefix zero setting, and
The present invention does not need to obtain the prior information of signal, that is, requires no knowledge about the specific structure of signal, it is only necessary to be directed to mismatch filter
The cost function of device solves the mismatch filter factor and achievees the purpose that inhibit submaximum, therefore false-alarm or false dismissal can be effectively reduced
Probability keeps side peaks suppression problem simpler.
2, optimal mismatch filter factor W is solved by using the first order necessary condition theorem of unconstrained optimization convexity optimization,
Operand can be reduced.In the prior art, be direct solution to the solution of filtering factor, not according to cost function the characteristics of
It solves, the present invention is by solving Hai Sai (Hessian) the matrix E of cost function, it was demonstrated that the function is convex function, can be to avoid making
Optimal value is solved with direct solving method, this can simplify the solution procedure of optimal value.
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 for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is schematic diagram of a scenario applied by external illuminators-based radar；
Fig. 2 is flow diagram of the invention；
Fig. 3 is the testing result figure of the 1. partial simulation content in the real emulation experiment of the present invention；
Fig. 4 is the testing result figure of the 2. partial simulation content in the real emulation experiment of the present invention；
Fig. 5 is the testing result figure of the 3. partial simulation content in the real emulation experiment of the present invention.
Specific embodiment
Below in conjunction with drawings and examples to the detailed description of the invention,
Embodiment 1
It, can be with successful probe and positioning target, but in external sort algorithm using matched filtering method in conventional active radar
In, since opportunity illuminating source signal is designed for radar detection, comprising information such as pilot tone and cyclic prefix in signal, make
Some emitter Signals are tieed up in distance or Doppler and there is fuzzy submaximum, this leads to the false-alarm and false dismissal of system, and existing skill
Side peaks suppression method in art needs to obtain the prior information of signal, and under external sort algorithm mode, signal ambiguity function is more
Situation Pu Lewei more complex there are submaximum and the prior art, in order to avoid obtain signal prior information problem and
Doppler ties up the case where there are submaximums, and the invention proposes a kind of more simple and effective suppressing methods.
The present invention is that Doppler ties up fuzzy side peaks suppression method in a kind of external illuminators-based radar, referring to Fig. 1, external sort algorithm thunder
Up to comprising two paths, the first via is echo channel, and the second tunnel is reference channel.
The first via is echo channel, is mainly used to receive the reflection echo signal from target, second tunnel is
Reference channel is mainly used to receive the direct-path signal from radiation source；Under normal conditions, target detection be tieed up from Doppler into
Capable, due to there is Doppler to tie up the presence of submaximum under outer emitter Signals, cause in the detection process, same Doppler ties up out
Existing multiple peak values as caused by the same target, so that the false alarm rate of system increases；Simultaneously as the minor lobe of big target can be covered
The main lobe of Small object, so that Small object can not be detected, so that the false dismissed rate of system increases；External illuminators-based radar of the invention
Middle Doppler ties up fuzzy side peaks suppression method, includes following steps:
S1: generate ambiguity function figure to be processed: CDMA (CDMA) external sort algorithm signal based on actual measurement obtains back
The data in wave channel and reference channel.Because it is too small to obtain target echo energy, need to utilize distance-Doppler processing pair
Energy carries out long time integration, improves target echo energy with this, by the signal to two channels makees distance-Doppler two
Relevant treatment is tieed up, while generating ambiguity function figure to be processed；In ambiguity function, the matching attribute of echo signal itself is
W0, have a series of fuzzy submaximums on ambiguity function figure.
S2: construction cost function J: to carry out mismatch filter to echo-signal, need to construct the cost function of echo-signal
J, the construction to cost function J are to tie up the sum of submaximum energy by minimizing mismatch filter snr loss and Doppler and carry out
, cost function J can be expressed as two parts, and first part is the difference of the mismatch filter factor and matching attribute, second part
For Doppler's submaximum energy and.W0For signal itself.
S3: it solves the optimal mismatch filter factor W of cost function J: the solution of cost function J being converted into optimal value and is asked
Solution solves optimal mismatch filter factor W by the first order necessary condition theorem that unconstrained optimization convexity optimizes；It is complete with mismatch filter
Fuzzy side peaks suppression is tieed up at Doppler；Optimal mismatch filter is acquired because period of the day from 11 p.m. to 1 a.m echo signal is by mismatch filter, that is, has reached pair
The purpose that peak inhibits.
S4: defining snr loss SNRL and peak sidelobe ratio PSLR, exports by snr loss SNRL and peak value respectively
The relational expression of valve ratio PSLR and weight d tie up fuzzy side peaks suppression method to adjust Doppler in external illuminators-based radar
Performance should adjust d in practical applications according to external radiation source radar system needs, further reach and tie up submaximum to Doppler
The purpose of inhibition.
The present invention can effectively inhibit ambiguity function to deposit in Doppler's dimension using the ionic size mismatch problem for solving cost function
The submaximum the problem of, the false-alarm or false dismissed rate in detection object procedure can be effectively reduced, realize effective detection to target.It is existing
It is mostly the prior information using signal by pilot tone and cyclic prefix zero setting, to achieve the purpose that inhibit submaximum in some technologies.
And the present invention does not need to obtain the prior information of signal, that is, requires no knowledge about the specific structure of signal, it is only necessary to be filtered for mismatch
The cost function of wave device solves the mismatch filter factor and achievees the purpose that inhibit submaximum, therefore false-alarm or leakage can be effectively reduced
Alarm probability keeps side peaks suppression problem simpler.
Embodiment 2
The fuzzy side peaks suppression method of Doppler's dimension is with embodiment 1 in external illuminators-based radar, construction generation described in step S2
Valence function J is to construct cost function for the ambiguity function figure that there is fuzzy submaximum:
In formula, W indicates the mismatch filter factor for needing to solve, W0It indicates match filter, is signal itself, d is indicated
Weight, [g]HConjugate transposition operation is asked in expression,Indicate that Doppler ties up frequency displacement, the model of m value in formula
It encloses for-Dfr,(-D+1),L,fr,fr,L,Dfr, the number for Doppler's dimension submaximum that D expression needs to inhibit.
The cost function that the present invention constructs, formula can be divided into two parts, first part indicate the mismatch filter factor with
The difference of match filter, the smaller expression mismatch filter snr loss of difference between the two is smaller, and vice versa；Second
Point indicate Doppler tie up submaximum energy and, it is better to illustrate that Doppler ties up side peaks suppression performance for submaximum energy and smaller；Submaximum suppression
Performance processed is better, then the snr loss of mismatch filter is bigger, intuitively can be seen that from above formula, weight d weight is bigger, submaximum
Rejection is better, but the loss of signal-to-noise ratio also will increase simultaneously.In technical solution of the present invention can by adjusting weight because
Sub- d can make to weigh between side peaks suppression performance and snr loss.
Embodiment 3
The fuzzy side peaks suppression method of Doppler's dimension is with embodiment 1-2 in external illuminators-based radar, solution described in step S3
When cost function J, first prove that cost function is convex function, seeks conjugate gradient to cost function J, enabling conjugate gradient is 0, acquires mistake
With filtering factor W.Complete the building of cost function.
3.1, when solving cost function J, Hai Sai (Hessian) matrix E is first asked to the cost function；
The Hai Sai (Hessian) of cost function J is represented by
In formula, INFor the unit matrix of N-dimensional.
3.2, it proves that cost function is convex function, first proves that Hai Sai (Hessian) matrix E is a positive semidefinite matrix, i.e.,
Prove that the cost function is convex function.
Cost function is convex function as evidence, and card E first is a positive semidefinite matrix, i.e., to make for any one 1 × N
Complex vector located x, inequality xExH>=0 all sets up.So having
Above-mentioned inequality is clearly to set up, therefore E is a positive semidefinite matrix, i.e. cost function J is a convex function.
The present invention by seeking Hai Sai (Hessian) battle array E to the cost function, can demonstrate,prove E is positive semidefinite matrix, i.e. cost function is
Convex function, the conjugate gradient of cost function J are equal to 0 when, that is, cost function and reach minimum value.
3.3, conjugate gradient first is asked to cost function J, enabling conjugate gradient is 0, acquires mismatch filter factor W: according to convex letter
Several optimal solutions be cost function conjugate gradient be 0 when value, acquire optimal mismatch filter factor W；
For convex function, as functional minimum value when conjugate gradient is equal to 0, that is, cost function J's are optimal
Solution.
Acquiring the conjugate gradient of cost function and enabling it is 0, i.e.,
Solution above formula obtains the optimal mismatch filter factor are as follows:
By the present invention in that with the first order necessary condition theorem that unconstrained optimization convexity optimizes solve optimal mismatch filter because
Sub- W can reduce operand, simplify the solution procedure of optimal mismatch filter factor W.
3.4, when echo signal have the filtering factor mismatched filter when, Doppler dimension fuzzy submaximum can by compared with
It offsets well, i.e., fuzzy submaximum is inhibited, and has achieved the purpose that side peaks suppression at this time.
Achieve the purpose that inhibit submaximum and solving the mismatch filter factor to mismatched filter, makes side peaks suppression problem more
Add simplification.In the prior art, it is direct solution to the solution of filtering factor, is asked not over according to the characteristics of cost function
Solution, the present invention is by solving Hai Sai (Hessian) the matrix E of cost function, it was demonstrated that the function is convex function, can be to avoid using
Direct solving method solves optimal value, can reduce operand.
Embodiment 4
Doppler ties up fuzzy side peaks suppression method with embodiment 1-3 in external illuminators-based radar, and verifying described in step S4 is outer
Doppler ties up the performance of fuzzy side peaks suppression method in radiation source radar, specifically includes, has the following steps:
4.1, snr loss is defined
Define peak sidelobe ratio
In formula, AmatIndicate matched filtering as a result, AmisIndicate the result of mismatch filter.
4.2, snr loss SNRL increases with the increase of weight d, and the value of SNRL is bigger, i.e., snr loss gets over
Greatly, side peaks suppression performance is poorer, and correspondingly false dismissed rate and false alarm rate will not reduce, and causes to be accurately located and detect mesh
Mark；Conversely, snr loss SNRL also reduces, i.e., snr loss is smaller, side peaks suppression when the reduction of weight d
Can be better, the case where false dismissal or false-alarm, which occurs, in corresponding earth signal also to be reduced, so as to be accurately positioned and detect target.
4.3, peak sidelobe ratio PSLR increases with the increase of weight d, and PSLR value is bigger, and side peaks suppression performance is got over
Good, side peaks suppression performance is better, and correspondingly false dismissed rate and false alarm rate can reduce, so as to be accurately located and detect target；Instead
It, when the reduction of weight d, peak sidelobe ratio PSLR also reduces, i.e., peak sidelobe ratio is smaller, and side peaks suppression performance is got over
Difference, there is false dismissal in corresponding earth signal or the probability of false-alarm increases, and can not accurately target be positioned and be visited so as to cause radar
It surveys.
4.4, weight d in practical applications, as needed, is adjusted, the performance of side peaks suppression is changed.In the application,
It cannot increase or reduce simply weight d, because along with snr loss's while side peaks suppression performance improves
Increase, weighs so needing to adjust weight d and being done between side peaks suppression performance and snr loss.
Weight d is a variable, by adjusting weight d, obtains peak sidelobe ratio PSLR and snr loss
SNRL adjusts weight d according to this variation relation, so that system is in side peaks suppression with the variation relation of weight d
Balance can be reached between signal-to-noise ratio, rather than sacrifice signal-to-noise ratio simply to improve the side peaks suppression performance of system.
Embodiment 5
Doppler ties up fuzzy side peaks suppression method with embodiment 1-4 in external illuminators-based radar, in step 4 and step 4.1 point
It indescribably arrives and defines snr loss SNRL and peak sidelobe ratio PSLR, specifically comprise the following steps:
4.1.1, the result A of snr loss SNRL and the matched filtering in peak sidelobe ratio PSLRmatIt may be expressed as:
In formula, l indicates that delay unit, p indicate Doppler frequency shift unit, SrIndicate the signal received in echo channel, Sd
Indicate the signal received in reference channel.
The result A of matched filteringmatIn,
A in formularIndicate that the complex magnitude of received direct-path signal in echo channel, d (t) indicate the complex envelope of direct wave, NCIndicate echo
The number of received multi-path signal, c in channeliAnd τiRespectively indicate the complex magnitude and delayed data of i-th of multi-path signal.
NTIndicate the number of received target echo in echo channel, am、τmAnd fmIt respectively indicates the complex magnitude of m-th of target echo, prolong
When and doppler information.nr(t) channel noise in echo channel is indicated.
4.1.2, the result A of snr loss SNRL and the mismatch filter in peak sidelobe ratio PSLRmisIt may be expressed as:
In formula, W is the mismatch filter factor, is represented by
In formula,Indicate that Doppler ties up frequency displacement, the range of m value is-Dfr,(-D+1),L,fr,fr,L,
Dfr, the number for Doppler's dimension submaximum that D expression needs to inhibit；frIndicate Doppler tie up submaximum repetition rate, d indicate weight because
Son.
Mismatch filter factor W reduces, the result A of mismatch filter with the increase of weight d in formulamisWith the reduction of W
And reduce, PLSR is with AmisReduction and increase, so weight d increases, peak sidelobe ratio PLSR increased with it；Conversely, public
Mismatch filter factor W increases, the result A of mismatch filter with the reduction of weight d in formulamisIncrease with the increase of W,
PLSR is with AmisIncrease and reduce, so weight d reduces, peak sidelobe ratio reduces therewith.
Meanwhile mismatch filter factor W reduces, the result A of mismatch filter with the increase of weight d in formulamisWith W
Reduction and reduce, SNRL is with AmisReduction and increase, so weight d increases, snr loss SNRL increased with it；
Conversely, mismatch filter factor W increases, the result A of mismatch filter with the reduction of weight d in formulamisWith the increase of W
Increase, snr loss SNRL is with AmisIncrease and reduce, so weight d reduces, snr loss SNRL subtracts therewith
It is small；
After defining snr loss and peak sidelobe ratio, make SNRL's and d respectively in MATLAB emulation platform
The relation curve of relation curve and PSLR and d obtains the property that Doppler in external illuminators-based radar ties up fuzzy side peaks suppression method
It can there are certain relationships with weight d.
A more detailed example is given below, in conjunction with attached drawing, to further instruction of the present invention
Embodiment 6
Doppler ties up fuzzy side peaks suppression method with embodiment 1-5 in external illuminators-based radar,
As shown in Figure 1, third party's external sort algorithm is placed on the far field of external illuminators-based radar receiving station as transmitting station,
Carry out transmission of electromagnetic signals with this, when electromagnetic wave signal is radiated in the target in the area of observation coverage, target echo letter can be reflected
Number.
In addition, some electromagnetic wave understands direct irradiation on external illuminators-based radar, to form reference signal.Outer spoke
It penetrates source radar and direct-path signal is received by the reference channel of aerial array, and target is returned using Radar Signal Processing algorithm
Wave signal and direct-path signal are handled, thus to detect the information such as the speed of target, distance and bearing.
Since external illuminators-based radar generally comprises two-way echo-signal, wherein signal is echo channel all the way, mainly use
The reflection echo from target is received, but inevitably multi-path signal by direct wave and through ground return is dry
It disturbs；In addition it is all the way reference channel, is mainly used to receive the direct-path signal from radiation source, for eliminating in echo channel
Direct wave and multipath interfere and pass through the energy that distance-doppler processing improves target echo.
As shown in Fig. 2, the fuzzy side peaks suppression method of Doppler's dimension includes in a kind of external illuminators-based radar provided by the invention
Following steps:
S1: obtaining the data based on CDMA echo signal data and reference channel of actual measurement, and it is more to make distance-to two signals
General Le two-dimensional correlation processing, generates ambiguity function to be processed.In external illuminators-based radar, target echo signal is usually very micro-
It is weak, so needing to handle using distance-Doppler's two-dimensional correlation to return to carry out long-time energy accumulation with this to improve target
The energy of wave signal.For reference signal and echo signal, the processing of distance-Doppler's two-dimensional correlation are as follows:
In formula, l indicates that delay unit, p indicate Doppler frequency shift unit, Amat[l, p] is matched filtering result.
Due to the influence of pilot tone and cyclic prefix in external sort algorithm signal, can go out in distance-Doppler two-dimensional correlation result
Now periodic Doppler ties up submaximum, these Doppler's submaximums can indicate are as follows:
Wherein, D indicates that Doppler ties up submaximum number, frIt indicates that Doppler ties up the repetition rate of submaximum, due to pilot tone and follows
The relative position of ring prefix is fixed, therefore the repetition rate of Doppler's dimension submaximum is fixed.
S2: to the fuzzy submaximum figure of Doppler's dimension of generation, following cost function is constructed
In formula, W indicates the mismatch filter factor for needing to solve, W0It indicates match filter, is signal itself.D is indicated
Weight, [g]HConjugate transposition operation is asked in expression.Indicate Doppler frequency shift.In formula the range of m value be-
D fr, (- D+1) fr... ,-fr, fr... D fr, the number for Doppler's dimension submaximum that D expression needs to inhibit.Cost function is by two
Part forms: first part is the difference of the mismatch filter factor and matching attribute, and difference is smaller, then mismatch filter snr loss
It is smaller；Second part be Doppler's submaximum energy and, be worth it is smaller, then Doppler tie up side peaks suppression performance it is better.But submaximum
While rejection is better, the snr loss of mismatch filter is bigger, and usual weight d is bigger, and side peaks suppression performance is got over
Good, synchronous signal is bigger than losing, and solution is can to make side peaks suppression performance and noise by adjusting weight d
Reach balance than loss.
S3: prove cost function be convex function, then according to optimal solution be cost function conjugate gradient be 0 when value come
Acquire optimal mismatch filter factor W.The Hai Sai (Hessian) for acquiring cost function J first is represented by
In formula, INFor the unit matrix of N-dimensional.
Cost function is convex function as evidence, and card E first is a positive semidefinite matrix, i.e., to make for any one 1 × N
Complex vector located x, inequality xExH>=0 all sets up.So having
Above-mentioned inequality is clearly to set up, therefore E is a positive semidefinite matrix, i.e. cost function J is a convex function.
For convex function, as functional minimum value when conjugate gradient is equal to 0.
Acquiring the conjugate gradient of cost function and enabling it is 0, i.e.,
Solution above formula obtains the optimal mismatch filter factor are as follows:
S4: snr loss and peak sidelobe ratio are defined, and verifies the performance of suppressing method.Define snr lossPeak sidelobe ratioWherein AmatAnd Amis
Respectively indicate the result of matched filtering and mismatch filter.
Doppler ties up fuzzy side peaks suppression method in a kind of external illuminators-based radar provided by the invention, passes through actual measurement first
Ambiguity function figure based on CDMA signal, generates ambiguity function to be processed, then acquires mismatch filter by solving cost function J
The wave factor, wherein cost function can be regarded as and consist of two parts, and to solve ionic size mismatch optimal value, then first prove cost function
For convex function, value when being then 0 according to the conjugate gradient that optimal solution is cost function acquires optimal mismatch filter factor W.
Then it in actual treatment, chooses the fuzzy submaximum of P Doppler dimension nearest from main lobe and handles, can reduce computationally intensive
The problem of.To effectively realize to Doppler tie up ambiguity function submaximum inhibition, reduce due to obscure submaximum presence and band
Carry out the probability of false dismissal, to realize effective detection of target.
Technical effect of the invention is explained again below by emulation:
Embodiment 7
Doppler ties up fuzzy side peaks suppression method with embodiment 1-6 in external illuminators-based radar,
Simulated conditions
The present invention experiment in using actual acquisition to CDMA signal mentioned algorithm performance is verified, the sampling of signal
Rate is 1.25MHz, and it is 1221Hz that the Doppler of CDMA signal ambiguity function, which ties up repetition rate,.The handled fuzzy pair of Doppler's dimension
Peak number is P, P 3, therefore cost function can be rewritten as in the present invention:
In formula, P belongs to set { P≤D }, indicates that the Doppler for needing to inhibit ties up the quantity of minor lobe.
It solves above formula to obtain, the optimal mismatch filter factor are as follows:
Because the value that P value is 3, m is ± 3, ± 2, ± 1.
Emulation content
Emulation content is divided into following three parts:
1. utilizing measured data early period, target, the fuzzy submaximum of Doppler's dimension and its energy size to be detected are determined, it will be outer
The result of emitter Signals ambiguity function is drawn on the three-dimensional constituted with distance (X-axis)-Doppler frequency shift (Y-axis)-amplitude (Z axis)
In coordinate system.
2. Doppler ties up fuzzy side peaks suppression method in a kind of external illuminators-based radar provided using the embodiment of the present invention
The inhibition for carrying out submaximum determines that target to be detected, Doppler tie up fuzzy submaximum and its energy size, selected distance main lobe are nearest
Several submaximums handled, then by result be drawn on distance (X-axis)-Doppler frequency shift (Y-axis)-amplitude (Z axis) constituted
Three-dimensional system of coordinate in.
3. being further verification algorithm performance, simulating, verifying snr loss (Signal to Noise Rate
Loss, SNRL) and peak sidelobe ratio (Peak Side Lobe Ratio, PSLR) and weight d relationship, result is drawn
In the two-dimensional coordinate system constituted with weight (X-axis)-amplitude (Y-axis).
Analysis of simulation result
Fig. 3 show the testing result of the 1. partial simulation content of emulation experiment.It is to be generated using detection data early period
Ambiguity function figure.X-axis is distance dimension (unit: km) in figure, and Y-axis is that Doppler ties up (unit: Hz), and Z axis is echo signal amplitude
(unit: dB)；It can be seen from the figure that being the target to be detected in Doppler fibrillar center, have around target a series of fuzzy
The presence of submaximum, fuzzy submaximum makes that target can not be accurately positioned, this is because including pilot tone and circulation in external sort algorithm signal
The information such as prefix and caused by.
Fig. 4 show the testing result of the 2. partial simulation content of emulation experiment.And it is obtained using the present invention fuzzy
Functional arrangement, X-axis is distance dimension (unit: km) in figure, and Y-axis is that Doppler ties up (unit: Hz), and Z axis is that echo signal amplitude is (single
Position: dB)；It can be seen from the figure that after mismatch filter is handled, only target energy is maximum, other submaximums by
Inhibit to function.Therefore fuzzy side peaks suppression method is tieed up using Doppler in a kind of external illuminators-based radar of offer of the invention to carry out
The inhibition of submaximum can preferably inhibit fuzzy submaximum, thus reduce the presence due to obscuring submaximum and bring the probability of false dismissal,
The final effective detection for realizing target.
Embodiment 8
Doppler ties up fuzzy side peaks suppression method with embodiment 1-6, simulated conditions and emulation content in external illuminators-based radar
With embodiment 7
Fig. 5 show the testing result of the 3. partial simulation content of emulation experiment.And the result obtained using the present invention
Scheme, X-axis is weight in figure, and Y-axis is amplitude (unit: dB)；It can be seen from the figure that the value and power of snr loss SNRL
It is worth factor d correlation, the value of peak sidelobe ratio PSLR increases with the increase of weight d.The value of PSLR is got over
Greatly, then the side peaks suppression performance of algorithm is better, and the value of SNRL is bigger, then the snr loss of algorithm is bigger.From figure also
As can be seen that the side peaks suppression performance of algorithm is better, the snr loss of system is bigger.Therefore need to weigh snr loss and
Side peaks suppression performance adjusts weight d, to obtain better mismatch filter performance according to the actual needs.
Those of ordinary skill in the art will appreciate that: realize that all or part of the steps of above method embodiment can pass through
The relevant hardware of program instruction is completed, and program above-mentioned can store in computer-readable storage medium, which exists
When execution, step including the steps of the foregoing method embodiments is executed；And storage medium above-mentioned includes: ROM, RAM, magnetic or disk
Etc. the various media that can store program code.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain
Lid is within protection scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.
The invention discloses Doppler in a kind of external illuminators-based radar to tie up fuzzy side peaks suppression method.Solves mismatch filter
The problem of to fuzzy side peaks suppression.Realize step have: obtain actual measurement based on CDMA (CDMA) echo channel data and ginseng
Channel data is examined, ambiguity function to be processed is generated；Submaximum energy is tieed up by minimizing mismatch filter snr loss and Doppler
The sum of amount construction cost function；Cost function J is solved, the sea plug battle array E by proof cost function is a Semidefinite Matrices to demonstrate,prove
Cost function is convex function, seeks mismatch filter factor W according to the first order necessary condition of convex optimization；Define snr loss SNRL and
Peak sidelobe ratio PSLR exports the relational expression of the two factors Yu weight d respectively, more in external illuminators-based radar for adjusting
Pu Lewei obscures the performance of side peaks suppression method.The present invention is by construction cost function without obtaining signal prior information, letter
The process for having changed side peaks suppression can achieve the purpose for reducing false-alarm or false dismissed rate, effectively to the how general of signal ambiguity function
It strangles the submaximum in dimension near main lobe to be inhibited, in field of radar, ambiguity function to be tieed up in Doppler in the presence of fuzzy submaximum
Inhibition.
Claims (5)
1. Doppler ties up fuzzy side peaks suppression method in a kind of external illuminators-based radar, which is characterized in that external illuminators-based radar includes
Two paths, the first via are echo channel, and the second tunnel is reference channel, Doppler tie up side peaks suppression method the following steps are included:
S1: generate ambiguity function figure to be processed: CDMA (CDMA) external sort algorithm signal based on the actual measurement obtains back
The data of wave signal data and reference channel are made the processing of distance-Doppler two-dimensional correlation to the signal in two channels, are generated wait locate
The ambiguity function figure of reason；In ambiguity function, the matching attribute of echo signal itself is W0；
S2: construction cost function J: tieing up the sum of submaximum energy, construction by minimizing mismatch filter snr loss and Doppler
The cost function J of echo-signal；Cost function is to consist of two parts, and first part is the mismatch filter factor and matching attribute
Difference, second part be Doppler's submaximum energy and；
S3: it solves the optimal mismatch filter factor W of cost function J: the solution of cost function J being converted into optimal value and is solved, is led to
The first order necessary condition theorem for crossing the optimization of unconstrained optimization convexity solves optimal mismatch filter factor W；It is completed with mismatch filter more
Pu Lewei obscures side peaks suppression；
S4: defining snr loss SNRL and peak sidelobe ratio PSLR, exports snr loss SNRL and peak sidelobe ratio respectively
The relational expression of PSLR and weight d tie up the performance of fuzzy side peaks suppression method to adjust Doppler in external illuminators-based radar.
2. Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar according to claim 1, it is characterised in that: step
Construction cost function J described in rapid S2 is to construct cost function for the ambiguity function figure that there is fuzzy submaximum:
In formula, W indicates the mismatch filter factor for needing to solve, W0Indicate that match filter, d indicate weight, [g]HIt indicates
Conjugate transposition operation is asked,Indicate Doppler frequency shift, the range of m value is-Df in formular,(-D+1),L,
fr,fr,L,Dfr, the number for Doppler's dimension submaximum that D expression needs to inhibit.
3. Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar according to claim 1, it is characterised in that: step
The optimal mismatch filter factor W that cost function J is solved described in rapid S3, comprises the following steps that
3.1, Hai Sai (Hessian) matrix E is first asked to the cost function；
3.2, it proves that Hai Sai (Hessian) matrix E is a positive semidefinite matrix, that is, proves that the cost function is convex function；
3.3, according to the optimal solution of convex function be cost function conjugate gradient be 0 when value, acquire the optimal mismatch filter factor
W；
3.4, when echo signal is by having the mismatched filter of the filtering factor, fuzzy submaximum is inhibited, and is reached at this time
The purpose of side peaks suppression is arrived.
4. Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar according to claim 1, it is characterised in that: step
Doppler ties up the performance of fuzzy side peaks suppression method in verifying external illuminators-based radar described in rapid S4, has specifically included following step
It is rapid:
4.1, snr loss is defined
Define peak sidelobe ratio
In formula, AmatIndicate matched filtering as a result, AmisIndicate the result of mismatch filter；
4.2, snr loss SNRL increases with the increase of weight d, and the value of SNRL is bigger, i.e. system signal noise ratio loss is got over
Greatly；
4.3, peak sidelobe ratio PSLR increases with the increase of weight d, and PSLR value is bigger, and side peaks suppression performance is better；
4.4, weight d in practical applications, as needed, is adjusted, the performance of side peaks suppression is changed.
5. Doppler ties up fuzzy side peaks suppression method in external illuminators-based radar according to claim 4, it is characterised in that: fixed
Adopted snr loss SNRL and peak sidelobe ratio PSLR,
4.1.1, the result A of matched filteringmatIt may be expressed as:
In formula, l indicates that delay unit, p indicate Doppler frequency shift unit, SrIndicate the signal received in echo channel, SdIt indicates
The signal received in reference channel；
4.1.2, the result A of mismatch filtermisIt may be expressed as:
In formula, W is the mismatch filter factor, is represented by
In formula,Indicate that Doppler ties up frequency displacement, the range of m value is-Dfr,(-D+1),L,fr,fr,L,Dfr, D
Indicate that the Doppler for needing to inhibit ties up the number of submaximum；frIndicate that Doppler ties up the repetition rate of submaximum, d indicates weight.
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