CN104914410B - A kind of clutter channel blind discrimination method suitable for passive bistatic system - Google Patents

A kind of clutter channel blind discrimination method suitable for passive bistatic system Download PDF

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Publication number
CN104914410B
CN104914410B CN201510179675.1A CN201510179675A CN104914410B CN 104914410 B CN104914410 B CN 104914410B CN 201510179675 A CN201510179675 A CN 201510179675A CN 104914410 B CN104914410 B CN 104914410B
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mrow
msub
mtd
clutter
channel
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CN104914410A (en
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王峰
蒋德富
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Hohai University HHU
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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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0215—Interference

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

Abstract

The invention discloses a kind of clutter channel blind discrimination method suitable for passive bistatic system, belong to the passive bistatic radar systems technology field based on frequency modulation broadcasting.This method comprises the following steps：（1）Recover direct-path signal in the signal received using ARMA blind balance methods from the reference channel of passive bistatic radar；（2）By monitoring ARMA balanced device excess mean-square error estimates, judge to start the startup time of normalization minimum mean-square error identification wave filter, when mean square error is less than set thresholding, start normalization minimum mean-square error identification wave filter；（3）Adaptive-filtering processing, the clutter channel response after being recognized are carried out to monitoring channel signal using normalization minimum mean-square error identification wave filter.The present invention can realize the clutter channel blind discrimination of passive bistatic radar.

Description

A kind of clutter channel blind discrimination method suitable for passive bistatic system
Technical field
The present invention relates to a kind of clutter channel blind discrimination method suitable for passive bistatic system, belong to wide based on frequency modulation The passive bistatic radar systems technology field broadcast.
Background technology
Passive bistatic radar based on frequency modulation broadcasting is faced with serious direct wave and disturbed with multipath clutter.These are through Ripple enters the reference channel or monitoring passage of system with multi-path jamming so that direct wave recovers to become to be stranded very much with signal detection It is difficult.Wherein direct wave recovers the matched filtering performance for being related to passive bistatic system.When multipath enters together with direct-path signal Enter reference channel, then false-alarm will be produced during matched filtering, influence the normal detection of target.Passive bistatic system face actually why The clutter environment of sample be system application person it should be understood that.Current industry lacks research for the analysis of clutter environment, not See the noise performance discrimination method for passive bistatic radar.
The content of the invention
In order to clearly provide the clutter channel circumstance that passive bistatic system is faced, the present invention proposes one kind , can be in the case where not knowing transmission signal, by certainly suitable for the clutter channel blind discrimination method of passive bistatic system Regressive averaging model（ARMA）The method that blind equalization is combined with Adaptive Identification, the clutter characteristic of channel is successfully extracted, is System researchers provide the coefficient information of clutter channel.
The present invention adopts the following technical scheme that to solve its technical problem：
A kind of clutter channel blind discrimination method suitable for passive bistatic system, comprise the following steps：
（1）Recover direct wave in the signal received using ARMA blind balance methods from the reference channel of passive bistatic radar Signal；
（2）By monitoring ARMA balanced device excess mean-square error estimates, judge that starting normalization minimum mean-square error distinguishes Know the startup time of wave filter, when mean square error is less than set thresholding, start the filtering of normalization minimum mean-square error identification Device；
（3）Adaptive-filtering processing is carried out to monitoring channel signal using normalization minimum mean-square error identification wave filter, Clutter channel response after being recognized.
Beneficial effects of the present invention are as follows：
1st, the present invention can realize the clutter channel blind discrimination of passive bistatic radar.
2nd, blind identification algorithm proposed by the present invention, solves the noise performance estimation of the passive bistatic radars such as frequency modulation broadcasting Problem, the noise performance for solving passive bistatic radar is studied a question significant.
Brief description of the drawings
Fig. 1 passive bistatic radar clutter channel identifying process charts.
Fig. 2 ARMA structural constant mould blind equalization algorithm schematic diagrams.
Fig. 3 blind identification algorithms and the combined method schematic diagram of adaptive normalization minimum mean-square calculation.
The checking of Fig. 4 computers adds clutter channel modulus value figure.
Output signal modulus value variation diagram after Fig. 5 ARMA algorithms.
The least mean square algorithm output signal modulus value figure of Fig. 6 the inventive method.
The coefficient modulus value figure for the channel estimation that Fig. 7 is obtained.
Coefficient modulus value figures of the Fig. 8 after normalized.
Embodiment
The invention is described in further details below in conjunction with the accompanying drawings.
Passive biradical land clutter channel blind discrimination proposed by the present invention based on ARMA blind equalizations and adaptive channel identification Handling process is as shown in Figure 1.
For passive bistatic radar system, the influence of echo signal is not considered when measuring clutter, mainly target is believed Number due to energy it is smaller, measurement that can not be on clutter, which is formed, to be influenceed.If transmission signalPass through spatial for FM signal With reaching monitoring passage together with multipath clutter
(1)
In formulaThe multipath clutter channel response of monitoring passage is represented,Product computing is represented,For Discrete time,Take natural number,To monitor channel noise,Represent monitoring channel receiving signal；
The signal that reference channel receives is
(2)
In formula,Reference channel and phase difference and amplitude difference existing for monitoring passage are represented,, its In：Represent plural number,Represent phase,Complex envelope coefficient is represented,For reference channel noise.
2.1 ARMA blind equalizations
Before adaptive channel identification is carried out, it is necessary to first recover direct-path signal.Due to direct-path signal be mixed into it is more Footpath signal, therefore, according to the reception direct wave and multipath of reference channel, using a kind of ARMA based on constant mould Blind Equalization Criteria Type algorithm carries out direct-path signal recovery.The blind equalization algorithm of ARMA structures compared with the blind equalization algorithm of linear filtering structure, There are good convergence capabilities for the zero point of deep fading.The algorithm principle block diagram is shown in Fig. 2.
The forward direction power balanced device weight vector of the algorithmForVector
(3)
Wherein,Represent theIndividual equalizer coefficients,Value 0,1,,；Take natural number；
Using normalized lowest mean square criterion is based on, its iterative formula is constant mould blind equalization
(4)
In formulaFor the iteration step length factor,It is small positive number,Conjugate transposition computing is represented,For recurrence to Amount,Represent iteration error.
(5)
Feedback filter weight vector is iterative to be
(6)
Represent conjugate operation.In formulaIt is that it inputs recursive vector,For its step factor,Expression changes For error,ForDimension feedback weight vector
(7)
Wherein：Represent theIndividual feedback filter coefficient,Value 0,1,,,Take natural number.
It is that it inputs recursive vector, there is following form
(8)
In formulaFor equalizer output signal,Obtained by the output of balanced device by nonlinear transformation,
(9)
In formulaFor the coefficient of kurtosis of transmission signal, calculated using following formula
(10)
Mathematic expectaion is asked in expression,Represent transmission signal.
The direct-path signal of acquisition, i.e. equalizer output signal are
(11)
The 2.2 clutter channel identifyings based on normalization minimum mean-square calculation
The signal that blind equalization algorithm exports is input to least-mean-square error algorithm and completes clutter channel identifying.Using normalizing Change least mean square algorithm.Adaptive-filtering output has following form
(12)
Weight vector more new-standard cement
(13)
In formulaFor small positive number.ForSef-adapting filter vector recurrence input vector
(14)
ForFilter coefficient
(15)
The expression formula is the clutter channel identifying result of required monitoring passage, whereinRepresent theIndividual filter coefficient,Value 0,1,,；Take natural number.
The combined method of 2.4 ARMA types blind equalization algorithms and adaptive normalization minimum mean-square calculation
Because ARMA types blind equalization algorithm has a convergence process, when the algorithm fails to complete convergence, if started Lowest mean square identification algorithm, then the latter's convergence can not ensure.Therefore the present invention adds to lowest mean square clutter channel identifying algorithm Start control.Only after the mean square error of the output of blind equalization algorithm, which reaches certain, to be required, just start lowest mean square and distinguish Know convergence of algorithm.Algorithm principle block diagram is shown in Fig. 3.
Judge that the condition that lowest mean square clutter channel identifying algorithm starts is as follows：
（1）Per iterationIt is secondary, whereinNatural number is taken, then for formula（9）Carry outThe mean square error statistics of point
(16)
WhereinRepresent mean square error,Take natural number；Take
(17)
WhereinRepresent the root mean square of mean square error；
（2）Empirical thresholds are set
In order to verify the channel identifying of given ARMA types blind equalization algorithm and adaptive normalization minimum mean-square calculation The performance of method, using carrying out performance verification exemplified by the external illuminators-based radar based on fm broadcast signal.Frequency modulation broadcast system band Wide to be set to 50 kHz, sample rate is arranged to 200 kHz.The signal integration time takes 2s.Reception clutter noise ratio is 50dB.From The clutter channel for being transmitted into reference channel is as follows：,,Take iteration time Number takesFor 10000 points, mean square error is calculated.It is 21 to set least-mean-square error algorithm weight vector length, sets iteration step A length of 0.001.Select thresholdingFor 48dB, the sample of mean square error is calculated=1500。
The clutter channel modulus value that Computer Simulation checking adds is shown in Fig. 4, and channel multi-path crosses over 6 sampling intervals, and multipath Coefficient energy mainly the 1st, 4,6 taps, remaining tap energies is 0.The present invention gives the ARMA type blind equalization algorithms of method Output signal modulus value is as shown in Figure 5 after convergence, it is seen that algorithmic stability converges to constant modulus signals state, and this is due to frequency modulation broadcasting letter Number it is constant amplitude signal, only phase is modulated.After the algorithmic statement, then direct-path signal is stably recovered.Adaptive normalizing The convergence result for changing least mean square algorithm is shown in Fig. 6, and algorithm converges to stable state after iteration, and error steady section correspond to channel by just Really identification.It can be seen that two kinds of algorithm all stable convergences.
After the new method processing of the present invention, the clutter channel result of estimation is shown in Fig. 7.As a result of ARMA blind equalizations Algorithm carries out de-convolution operation, the absolute value information of channel is lost, so coefficient output valve is larger.Normalized using maximum Output result afterwards is shown in Fig. 8.Comparison diagram 8 is visible with Fig. 3, estimated that coefficient value relative result is accurate.As long as obtain clutter letter Road relativeness, you can obtain the characteristic of clutter channel.

Claims (5)

  1. A kind of 1. clutter channel blind discrimination method suitable for passive bistatic system, it is characterised in that comprise the following steps：
    (1) direct wave letter is recovered in the signal received using ARMA blind balance methods from the reference channel of passive bistatic radar Number；
    (2) by monitoring ARMA balanced device excess mean-square error estimates, judge to start the filter of normalization minimum mean-square error identification The startup time of ripple device, when mean square error is less than set thresholding, start normalization minimum mean-square error identification wave filter；
    (3) adaptive-filtering processing is carried out to monitoring channel signal using normalization minimum mean-square error identification wave filter, obtained Clutter channel response after identification.
  2. 2. a kind of clutter channel blind discrimination method suitable for passive bistatic system according to claim 1, its feature It is, the signal that reference channel receives in the step (1) is
    <mrow> <msub> <mi>x</mi> <mi>R</mi> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> <mo>=</mo> <mi>&amp;zeta;</mi> <mo>&amp;CenterDot;</mo> <mi>h</mi> <mo>&amp;CircleTimes;</mo> <mi>a</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>n</mi> <mn>2</mn> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </mrow>
    In formula, ζ represents reference channel and phase difference and amplitude difference existing for monitoring passage,Wherein：ej[·]Represent Plural number,Phase is represented, κ represents complex envelope coefficient, n2(k) it is reference channel noise,Represent prison Survey the multipath clutter channel response of passage, []TRepresent transposition computing, h0Represent the 0th clutter channel response coefficient, h1Represent 1st clutter channel response coefficient, hiI-th of clutter channel response coefficient is represented,Represent Lλ-1Individual clutter channel response Coefficient.
  3. 3. a kind of clutter channel blind discrimination method suitable for passive bistatic system according to claim 1, its feature It is, direct-path signal is in the step (1)
    yR(k)=fT(k)XR(k)-dT(k)YR(k) (11)
    In formula, f (k) is to be preceding to power balanced device weight vector, XR(k) it is recursive vector, YR(k) it is that it inputs recursive vector, d (k) is Feedback filter weight vector.
  4. 4. a kind of clutter channel blind discrimination method suitable for passive bistatic system according to claim 3, its feature It is, the f (k) is Nf× 1 vector
    <mrow> <mi>f</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> <mo>=</mo> <msup> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <mrow> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mn>...</mn> </mtd> <mtd> <mrow> <msub> <mi>f</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mn>...</mn> </mtd> <mtd> <mrow> <msub> <mi>f</mi> <mrow> <msub> <mi>N</mi> <mi>f</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> </mtable> </mfenced> <mi>T</mi> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow>
    Wherein, fi(k) i-th of equalizer coefficients, i values 0,1 ..., N are representedf-1；NfTake natural number.
  5. 5. a kind of clutter channel blind discrimination method suitable for passive bistatic system according to claim 3, its feature It is, the d (k) is Nd× 1 dimension feedback weight vector
    <mrow> <mi>d</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> <mo>=</mo> <msup> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <mrow> <msub> <mi>d</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mrow> <msub> <mi>d</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mn>...</mn> </mtd> <mtd> <mrow> <msub> <mi>d</mi> <mi>i</mi> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> <mtd> <mn>...</mn> </mtd> <mtd> <mrow> <msub> <mi>d</mi> <mrow> <msub> <mi>N</mi> <mi>d</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> </mtable> </mfenced> <mi>T</mi> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>7</mn> <mo>)</mo> </mrow> </mrow>
    Wherein：di(k) i-th of feedback filter coefficient, i values 0,1 ..., N are representedd- 1, NdTake natural number.
CN201510179675.1A 2015-04-16 2015-04-16 A kind of clutter channel blind discrimination method suitable for passive bistatic system Expired - Fee Related CN104914410B (en)

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