CN105116241B - A kind of Novel site equivalence darkroom measuring method - Google Patents

Abstract

A kind of Novel site equivalence darkroom measuring method, first the signal received two antennas does Fourier transformation, utilizes the directional diagram of weights comprehensive two-element antenna array on frequency domain so that it is a zero point occur, this zero point is allowed to be directed at the signal arrival bearing of EUT, then array output S₀F () only comprises interference components, and the signal S that individual antenna receives₁(f) and S₂F not only including EUT component of signal but also include interference components in (), the interference components in three is height correlation, therefore can utilize and offset process, removes S₁(f) and S₂Interference components in (f), thus obtain the signal of Device under test.The present invention is based on advanced signal processing technology, uses dual pathways system, in conjunction with airspace filter and signal correlation processing method, when testing at the scene, it is possible to equivalence goes out a dark room conditions, filters the environmental disturbances at scene, it is thus achieved that the true radiation characteristic of EUT.

Description

A kind of Novel site equivalence darkroom measuring method

Technical field

The present invention relates to Electromagnetic Field and Microwave Technology field, particularly relate to environment at the scene is carried out the side of electromagnetic radiation test Method.

Background technology

For large scale electronic equipment, on-the-spot test mode is generally used to search electromagnetic interference problem.But the broadcast at scene, TV, Mobile phone and other potential radiation source can severe jamming measuring accuracies.Generally, it sends the level of signal often beyond standard limited value 30～40dB, the situation of Device under test (Equipment Under Tset, EUT) transmitting signal is flooded in this ambient noise level, Can cause that testing time length, test error are big, environmental disturbances is mistakenly considered the adverse consequencess such as EUT signal, it is impossible to accurately survey Measure the electromagnetic radiation of EUT, cause diagnostic error.Utilize darkroom or screened room to measure and can eliminate these impacts, but some dresses Standby the hugest, it is impossible to be placed on darkroom or transport is tested to standard open area test site, on-the-spot test can only be carried out.Therefore, Need effective on-the-spot test and processing method, even if in the case of EUT has been operated in very big environmental disturbances, also can be by environment In interference filtering, realize the accurate measurement to EUT electromagnetic radiation at the scene.

One of environmental disturbances suppressing method is to utilize timesharing to measure.Particularly as follows: first timesharing measuring method, closes EUT in the t1 moment, EMI receiver or audiofrequency spectrometer measurement is used to obtain the power spectrum of environmental disturbances signal；Then, open EUT in the t2 moment, this Time record environmental disturbances signal and the power spectrum of EUT signal, the result that front and back records for twice is subtracted each other, it is possible to offset environment Interference, it is thus achieved that EUT radiated signal power is composed.

American scholar Marino.J in 2005 put forward the patented technology obtaining virtual darkroom.This patent is based on adaptive noise cancellation skill Art, the time difference problem brought when specify that and overcome single channel distribution tests in twin-channel mode, thus improve measuring accuracy and Range of application.Its principle is as it is shown in figure 1, antenna A places near EUT, and distance is d, and antenna B is then away from EUT Placing, distance EUT is at least above 10d.Main channel 1 and reference channel 2 are to synchronize, and wherein main channel 1 is by antenna A Receive EUT signal and environmental disturbances signal, and reference channel 2 only receives environmental disturbances signal, due to two by antenna B The environmental disturbances signal height that channel reception arrives is correlated with, and utilizes and wants closing property processing method, it is possible to filtering environmental interference signal.

Also have a kind of measuring method based on Array Signal Processing, receive as in figure 2 it is shown, place a set of antenna around radiation source Array, each antenna element all can receive the mixed signal being made up of EUT radiation signal and background noise, permissible Utilize the direction of arrival (direction of arrival, DOA) of MUSIC Estimation of Spatial Spectrum each signal of technical limit spacing.According to signal Estimation of Spatial Spectrum result, utilize MVDR criterion, to each array element receive signal make optimal weighting, ensure EUT radiation letter On the premise of number undistorted, array beams is made to form " zero falls into " the arrival bearing of interference signal, it is achieved the sky to interference signal Territory filters, and accurately reflects the true radiation characteristic of EUT.

Above-mentioned existing three kinds of measuring methods, are also individually present following defect:

The method using timesharing to measure carries the environmental disturbances power spectrum of twice measurement of moment being EUT startup and shutdown and is all close to phase With, say, that environmental disturbances belongs to time stationary signal.It is true that many times the interference signal under conventional environment all has The intermittent feature with amplitude fluctuations, such as when test environment exists short-term burst signal, the ring measured during EUT shutdown The environmental disturbances signal measured when border interference signal and EUT start cannot effectively be offset.

The method measured during virtual darkroom method score based on noise cancellation has a bigger improvement, but effect is not in actual use Ideal, is mainly reflected in: 1. in order to reach preferable precision, one of them reception antenna needs to be remotely from the position of EUT Put, owing to the inconsistent meeting of two reception antenna present position environmental disturbances brings bigger test error；2. antenna is put at a distance Put, cause test cable long, infeasible in operation, also have impact on certainty of measurement；3. when environment existing and EUT radiation When signal is with the component that frequency and intensity are the biggest, interference suppressioning effect is inconspicuous.

Disturbance restraining method based on Array Signal Processing have employed multichannel system, and its structural system is complex, and design realizes Difficulty is big, and hardware development cost is high, limits it and extensively applies.

Summary of the invention

In order to relatively accurately obtain the radiation-emitting characteristic of electronic equipment on Large-Scale Equipment platform under complex electromagnetic environment at the scene, The present invention provides a kind of Novel site equivalence darkroom measuring method.

The technical scheme is that

As it is shown on figure 3, the signal first received two antennas of the present invention does Fourier transformation (FFT), exploitation right on frequency domain It is worth the directional diagram of comprehensive two-element antenna array so that it is a zero point occurs, allows this zero point be directed at the signal arrival bearing of EUT, Then array output S₀F () only comprises interference components, and the signal S that individual antenna receives₁(f) and S₂F () had both included EUT component of signal Including again interference components, the interference components in three is height correlation, therefore can utilize and offset process, removes S₁(f) and S₂Interference components in (f), thus obtain the signal of Device under test.

Specifically, one Novel site equivalence darkroom of the present invention measuring method, comprise the following steps:

(1) angle of the DOA of EUT signal, i.e. EUT sense and aerial array normal direction is first determined.Here can be in order to Realize with existing instruments such as laser angle meter；

(2) angle measured according to step (1), utilizes broadband MVDR Beamforming Method, calculates weighted value, exhibition by combination method side Xiang Tu so that the zero point alignment EUT sense of directional diagram, thus extract the frequency spectrum of interference signal；Detailed process is as follows:

1. being sampled by the signal that two antennas receive, obtain discrete data x (t), then carry out segmentation respectively, each segment data is long Degree is L；

2. two antennas are designated as the data of n-th section(l=0,1 ... L-1, m=1,2), it is done L point quick Fourier and becomes Change (Fast Fourier Transform, FFT), obtain frequency domain narrow band data:

$\begin{array}{cc}{X}_m^{\left(n\right)}\left(k\right)=\underset{l=0}{\overset{L-1}{\Σ}}{x}_m^{\left(n\right)}\left(l\right)e^{-j2\mathrm{\π}l/L}& k=0,1,\mathrm{...},L-1\end{array}---\left(1\right)$

Wherein j refers to that imaginary unit, e are the nature truth of a matter, and π is pi.

3. two antenna frequency domain narrow band data matrixes are extracted:

$X^{\left(n\right)}\left(k\right)=\[X_1^{\left(n\right)}\left(k\right),X_2^{\left(n\right)}\left(k\right)\]---\left(2\right)$

If 4. the DOA of EUT radiation signal is θ, it is assumed that array main beam be oriented to θ₀, and θ₀As far as possible away from θ, it guides Vector is α (θ₀) be represented by

$\mathrm{\α}\left({\mathrm{\θ}}_0\right)=\left[\begin{array}{c}\exp (-j\mathrm{\ω})\\ \exp (-j\mathrm{\ω}\mathrm{\τ})\end{array}\right]---\left(3\right)$

In formula, $\mathrm{\ω}=2\mathrm{\π}f=2\mathrm{\π}\frac{c}{\mathrm{\λ}},\mathrm{\τ}=\frac{{\mathrm{dcos\θ}}_0}{c},$ C is the light velocity, and λ is wavelength.

5. the design of the undistorted response of minimum variance (Minimum Variance Distortionless Response, MVDR) method is used Corresponding beam weight vector.

If the output of array signal is expressed as:

P_out=E{ | y |²}=E{ (w^Hx)·(w^Hx)^H}=w^HR_xxw (4)

In formula, y=w^HX is the output signal after array weight, w=w (f_k)=[w₁(f_k),w₂(f_k)], x=[x₁(t),x₂(t)], H is the meaning taking conjugate transpose.The MVDR criterion of optimality is represented by:

$\begin{array}{cc}\min & P_{out}=w^H{R}_{xx}w\\ s.t.& w^H\mathrm{\α}\left({\mathrm{\θ}}_0\right)=1\end{array}---\left(5\right)$

This constraints is also called wave beam " zero setting condition ", because it forces " zero point " of receiving array beam pattern to point to All EUT senses.Wherein Pout refers to that array output power, min are meant that the meaning minimized, i.e. array output work Rate Pout wants minimum, and the implication of s.t. refers to meet condition, R simultaneously_xxRefer to input signal x=[x₁(t),x₂(t)] covariance square Battle array.

6. Lagrangian is constructed:

L (w, λ)=w^HR_xxw+λ(α(θ₀)^Hw-1)+λ^*(w^Hα(θ₀)-1) (6)

In view of w ∈ C^M×1, the conjugate gradient making L (w, λ) is 0, i.e.

$\∂L(w,\mathrm{\λ})/\∂w^{*}=0---\left(7\right)$

Obtain

w^H=-λ α (θ₀)^HR_xx ^-1 (8)

Substitute into w α (θ₀)=1, available

λ=-(α (θ₀)^HR_xx ^-1α(θ₀))^-1 (9)

Thus best initial weights can be obtained:

w_opt=R_xx ^-1α(θ₀)(α^H(θ₀)R_xx ^-1α(θ₀))^-1=R_xx ^-1α(θ₀)P_{o min} (10)

P in formula_{o min}=(α^H(θ₀)R_xx ^-1α(θ₀))^-1For minimum output power.

(3) each frequency domain narrow band data is weighted summation, obtain each subband wave beam output data:

$Y^{\left(n\right)}\left(k\right)=w^H\left(f_k\right)X^{\left(n\right)}\left(k\right)=\underset{m=1}{\overset{M}{\Σ}}{w}_m^{*}\left(f_k\right)X_m^{\left(n\right)}\left(k\right)---\left(11\right)$

The array output S of whole test frequency range has been become by the output data groups of each frequency range₀(f), i.e. S₀(f)=[Y (1), Y (2) ..., Y (k)].

(4) utilization offsets process and removes environmental disturbances；

After above-mentioned signal processing, now array output S₀F () comprises only interference signal, and the output S of individual antenna₂In (f) then Both contained EUT signal, and also contained interference signal, now carry out offseting process, can obtain

S_EUT(f)=S₂(f)-S₀(f)。

Beneficial effects of the present invention:

The present invention is based on advanced signal processing technology, uses dual pathways system, in conjunction with airspace filter and signal cancellation processing method, When testing at the scene, it is possible to equivalence goes out a dark room conditions, filter the environmental disturbances at scene, it is thus achieved that the true spoke of EUT Penetrate characteristic.A following unique advantage is had compared with other inventions above-mentioned:

1, the remote discrete placement of antenna and the baroque defect of multichannel system are overcome.The present invention only needs two-element antenna array Row coordinate two-channel receiver, considerably increase the suitability and ease for operation；

2, precision is higher.Relative to macrotype platform, the size of aerial array almost can be ignored, bay on test position The signal received does not haves background noise and disturbs inconsistent situation, thus helps in raising certainty of measurement；

3, co-channel interference inhibition is more preferably.The limitation of the virtual darkroom measuring method of Marino.Jr design causes it to locate Reason co-channel interference.And utilize the present invention, as long as interference signal is inconsistent with the DOA of EUT signal, it is possible to effectively suppress Co-channel interference；

4, the time is measured shorter.The present invention is the mode measured based on time-domain signal, to necessarily when the most only needing to test at the scene Signal in time does Digital Signal Processing after sampling, it is not necessary to carry out long frequency domain test, thus can be big Promote greatly measuring speed.

Accompanying drawing explanation

Fig. 1 is virtual darkroom principle schematic.

Fig. 2 is anti-interference radiation-emitting in-site measurement schematic diagram based on Array Signal Processing.

Fig. 3 is equivalent virtual darkroom measuring method schematic diagram.

Fig. 4 is the flow chart of the present invention a kind of Novel site equivalence darkroom measuring method.

Fig. 5 is the simulation configurations schematic diagram of the embodiment of the present invention 1

Fig. 6 is the comparison diagram of frequency spectrum and the original signal spectrum utilizing the inventive method to recover in embodiment 1

Fig. 7 is the experimental field configuration figure of embodiment 2

Fig. 8 is the signal graph that in embodiment 2, dual channel oscilloscope receives

Fig. 9 is the spectral contrast figure in embodiment 2 before and after EUT target signal filter

Figure 10 is the comparison diagram offseting before and after's signal spectrum in embodiment 2

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described further.

The present invention provides a kind of Novel site equivalence darkroom measuring method, comprises the following steps:

(1) angle of the DOA of EUT signal, i.e. EUT sense and aerial array normal direction is first determined.The most permissible The existing instruments such as laser angle meter are utilized to realize；

(2) angle measured according to step (1), utilizes broadband MVDR Beamforming Method, calculates weighted value, comprehensive battle array Column direction figure so that the zero point alignment EUT sense of directional diagram, thus extract the frequency spectrum of interference signal；Detailed process is such as Under:

1. being sampled by the signal that two antennas receive, obtain discrete data x (t), then carry out segmentation respectively, each segment data is long Degree is L；

2. two antennas are designated as the data of n-th section(l=0,1 ... L-1, m=1,2), it is done L point quick Fourier and becomes Change (Fast Fourier Transform, FFT), obtain frequency domain narrow band data:

$\begin{array}{cc}{X}_m^{\left(n\right)}\left(k\right)=\underset{l=0}{\overset{L-1}{\Σ}}{x}_m^{\left(n\right)}\left(l\right)e^{-j2\mathrm{\π}l/L}& k=0,1,\mathrm{...},L-1\end{array}---\left(1\right)$

Wherein j refers to that imaginary unit, e are the nature truth of a matter, and π is pi.

3. two antenna frequency domain narrow band data matrixes are extracted:

$X^{\left(n\right)}\left(k\right)=\[X_1^{\left(n\right)}\left(k\right),X_2^{\left(n\right)}\left(k\right)\]---\left(2\right)$

If 4. the DOA of EUT radiation signal is θ, it is assumed that array main beam be oriented to θ₀, and θ₀As far as possible away from θ, it guides Vector is α (θ₀) be represented by

$\mathrm{\α}\left({\mathrm{\θ}}_0\right)=\left[\begin{array}{c}\exp (-j\mathrm{\ω})\\ \exp (-j\mathrm{\ω}\mathrm{\τ})\end{array}\right]---\left(3\right)$

In formula, $\mathrm{\ω}=2\mathrm{\π}f=2\mathrm{\π}\frac{c}{\mathrm{\λ}},\mathrm{\τ}=\frac{{\mathrm{dcos\θ}}_0}{c},$ C is the light velocity, and λ is wavelength.

5. the design of the undistorted response of minimum variance (Minimum Variance Distortionless Response, MVDR) method is used Corresponding beam weight vector.If the output of array signal is expressed as:

P_out=E{ | y |²}=E{ (w^Hx)·(w^Hx)^H}=w^HR_xxw (4) In formula, y=w^HX is the output signal after array weight, w=w (f_k)=[w₁(f_k),w₂(f_k)], x=[x₁(t),x₂(t)], H It it is the meaning taking conjugate transpose.The MVDR criterion of optimality is represented by:

$\begin{array}{cc}\min & P_{out}=w^H{R}_{xx}w\\ s.t.& w^H\mathrm{\α}\left({\mathrm{\θ}}_0\right)=1\end{array}---\left(5\right)$

This constraints is also called wave beam " zero setting condition ", owns because it forces " zero point " of receiving array beam pattern to point to EUT sense.Wherein Pout refers to that array output power, min are meant that the meaning minimized, i.e. array output power Pout Wanting minimum, the implication of s.t. refers to meet condition, R simultaneously_xxRefer to input signal x=[x₁(t),x₂(t)] covariance matrix.

6. Lagrangian is constructed:

L (w, λ)=w^HR_xxw+λ(α(θ₀)^Hw-1)+λ^*(w^Hα(θ₀)-1) (6)

In view of w ∈ C^M×1, the conjugate gradient making L (w, λ) is 0, i.e.

$\∂L(w,\mathrm{\λ})/\∂w^{*}=0---\left(7\right)$

Obtain

w^H=-λ α (θ₀)^HR_xx ^-1 (8)

Substitute into w α (θ₀)=1, available

λ=-(α (θ₀)^HR_xx ^-1α(θ₀))^-1 (9)

Thus best initial weights can be obtained:

w_opt=R_xx ^-1α(θ₀)(α^H(θ₀)R_xx ^-1α(θ₀))^-1=R_xx ^-1α(θ₀)P_{o min} (10)

P in formula_{o min}=(α^H(θ₀)R_xx ^-1α(θ₀))^-1For minimum output power.

(3) each frequency domain narrow band data is weighted summation, obtain each subband wave beam output data:

$Y^{\left(n\right)}\left(k\right)=w^H\left(f_k\right)X^{\left(n\right)}\left(k\right)=\underset{m=1}{\overset{M}{\Σ}}{w}_m^{*}\left(f_k\right)X_m^{\left(n\right)}\left(k\right)---\left(11\right)$

The array output S of whole test frequency range has been become by the output data groups of each frequency range₀(f), i.e. S₀(f)=[Y (1), Y (2) ..., Y (k)].

(4) utilization offsets process and removes environmental disturbances；

After above-mentioned signal processing, now array output S₀F () comprises only interference signal, and the output S of individual antenna₂In (f) then Both contained EUT signal, and also contained interference signal, now carry out offseting process, can obtain

S_EUT(f)=S₂(f)-S₀(f)。

Embodiment 1

The effectiveness of the inventive method is described with a computer simulation example.

As it is shown in figure 5, be the simulation configurations schematic diagram of the present embodiment.

Taking array element distance d=300mm, if there being four signals in space, one of them is EUT radiation signal (measured signal), remaining Three is the environmental disturbances signal that system is different, and mathematical form is as follows:

$\left\{\begin{array}{c}{S}_{EUT}\left(t\right)=A_{0}sin2{\mathrm{\πf}}_{0}t+A_{0}sin2{\mathrm{\πf}}_{1}t+n\left(t\right)\\ S_{jam1}\left(t\right)=A_{1}sin2{\mathrm{\πf}}_{1}t+n\left(t\right)\\ \begin{array}{cc}{S}_{jam2}\left(t\right)=A_2\exp (j2{\mathrm{\πf}}_{2}t+j2{\mathrm{\πkt}}^2)+n\left(t\right)& k=band/t_{total}\end{array}\\ S_{jam3}\left(t\right)=-A_{3}cos\left(j2{\mathrm{\πf}}_{3}t\right)\exp (-4\mathrm{\π}{\left(t-t_0\right)}^2/{\mathrm{\τ}}^2)+n\left(t\right)\end{array}\right.$

In formula, containing f in EUT radiation signal₀=300MHz and f₁Two frequency contents of=600MHz, angle of incidence is θ_EUT=-45 °.Interference signal 1 simulates mono-tone interference, frequency f₂=300MHz, angle of incidence is θ_jam1=-15 °；Interference signal 2 Analog linearity frequency modulation disturbs, frequency modulation initial frequency f₃=500MHz, modulation bandwidth band=100MHz, angle of incidence is θ_jam2=15 °； The Gauss broadband interference of interference signal 3 simulation burst, angle of incidence is θ_jam3=60 °, mid frequency f₄=700MHz, time delay t₀=256ns, modulates time τ=10ns.A₀=A₁=A₂=1, A₃=100.Signal to noise ratio snr=20dB, the signal record time A length of t_total=512ns.

The inhibition of the environmental disturbances after utilizing this patent method to process as shown in Figure 6, is come from the contrast of input with output spectrum Seeing, the interference at 400MHz receives the suppression of 80dB, and linear frequency hopping and Gauss broadband interference receive the pressure of more than 60dB System, it is often more important that the EUT component of signal of 600MHz is also recovered from the frequency spectrum of aliasing.

Embodiment 2

Introduce the detailed process being carried out this method validation verification by experiment the most again.Experimental field configuration as it is shown in fig. 7, In order to ensure the accuracy of result, experiment is carried out in microwave dark room, it is therefore an objective to the interference beyond screening experiment frequency range.Demarcating Position places transmitting antenna and reception antenna, and the working frequency range of antenna is 200MHz-1GHz.The principle of location position is to allow mould Intend EUT launch antenna be on the discovery direction of receiving antenna array, simulation interference source transmitting antenna then with receiving antenna array Normal direction has a certain degree.Antenna utilizes laser range finder and clinometer to carry out position correction after placing.Signal source 1 and letter Number source 2 simulates generation EUT signal and interference signal respectively, and wherein EUT signal is set to impulse modulation, and the pulse period is 240ns, Pulse width is 120ns, and carrier frequency is 400MHz, and output is 15dBm.And disturb signal to be set to the pulse period to be 400ns, pulse width is 200ns, and carrier frequency is 700MHz, and output is 15dBm.The center distance of two reception antennas D=0.3m, is connected on dual pathways sampling oscilloscope by the shielded cable of equal length respectively, and oscillographic temporal resolution is arranged For 5ps, the concordance of two passages is calibrated before testing.

Fig. 8 is that the one piece of data of dual channel oscilloscope sampling shows, is 33 degree by the reset of array compound direction figure, and Fig. 9 is After using broadband MVDR to carry out filtering out EUT signal after spatial beams is formed, the frequency spectrum of only surplus interference signal receives with individual antenna The contrast of the signal spectrum arrived, it can be seen that EUT signal has been filtered out the level of background noise, only remains in frequency spectrum Interference signal.

As shown in Figure 10, then after offseting process, interference signal is then suppressed near the end makes an uproar, with pure EUT signal frequently Spectrum is compared, and after this method processes, the spectrum signature of the EUT signal recovered is basically identical with former EUT signal spectrum, EUT Signal has almost obtained undistorted recovery.

The explanation of the preferred embodiment of the present invention contained above, this is the technical characteristic in order to describe the present invention in detail, is not intended to Summary of the invention is limited in the concrete form described by embodiment, other amendments carried out according to present invention purport and change Type is also protected by this patent.The purport of present invention is to be defined by the claims, rather than by the specific descriptions institute of embodiment Define.

Claims (1)

1. a Novel site equivalence darkroom measuring method, it is characterised in that: comprise the following steps:

(1) angle of the DOA of EUT signal, i.e. EUT sense and aerial array normal direction is first determined；

(2) angle measured according to step (1), utilizes broadband MVDR Beamforming Method, calculates weighted value, exhibition by combination method directional diagram so that the zero point alignment EUT sense of directional diagram, thus extracts the frequency spectrum of interference signal；Detailed process is as follows:

1. the signal that two antennas receive is sampled, obtain discrete data x (t), then carry out segmentation respectively, a length of L of each segment data；

2. two antennas are designated as the data of n-th sectionIt is done the conversion of L point quick Fourier, obtains frequency domain narrow band data:

Wherein j refers to that imaginary unit, e are the nature truth of a matter, and π is pi；

3. two antenna frequency domain narrow band data matrixes are extracted:

If 4. the DOA of EUT radiation signal is θ, it is assumed that array main beam be oriented to θ₀, and θ₀As far as possible away from θ, its steering vector is α (θ₀) be represented by

In formula,C is the light velocity, and λ is wavelength；

5. the beam weight vector that the design of minimum variance undistorted response method is corresponding is used；

If the output of array signal is expressed as:

P_out=E{ | y |²}=E{ (w^Hx)·(w^Hx)^H}=w^HR_xxw (4)

In formula, y=w^HX is the output signal after array weight, w=w (f_k)=[w₁(f_k),w₂(f_k)], x=[x₁(t),x₂(t)], H represents the meaning taking conjugate transpose；The MVDR criterion of optimality is represented by:

This constraints is also called wave beam " zero setting condition ", because it forces " zero point " of receiving array beam pattern to point to all EUT sense；Wherein Pout refers to that array output power, min are meant that the meaning minimized, i.e. array output power Pout want minimum, and the implication of s.t. refers to meet condition, R simultaneously_xxRefer to input signal x=[x₁(t),x₂(t)] covariance matrix；

6. Lagrangian is constructed:

L (w, λ)=w^HR_xxw+λ(α(θ₀)^Hw-1)+λ^*(w^Hα(θ₀)-1) (6)

In view of w ∈ C^{M × 1}, the conjugate gradient making L (w, λ) is 0, i.e.

Obtain

w^H=-λ α (θ₀)^HR_xx ^-1 (8)

Substitute into w α (θ₀)=1, available

λ=-(α (θ₀)^HR_xx ^-1α(θ₀))^-1 (9)

Thus best initial weights can be obtained:

w_opt=R_xx ^-1α(θ₀)(α^H(θ₀)R_xx ^-1α(θ₀))^-1=R_xx ^-1α(θ₀)P_omin (10)

P in formula_omin=(α^H(θ₀)R_xx ^-1α(θ₀))^-1For minimum output power；

(3) each frequency domain narrow band data is weighted summation, obtains the wave beam output data of each subband；

The array output S of whole test frequency range has been become by the output data groups of each frequency range₀(f), i.e.

S₀(f)=[Y (1), Y (2) ..., Y (k)]；

(4) utilization offsets process and removes environmental disturbances；

After above-mentioned signal processing, now array output S₀F () comprises only interference signal, and the output S of individual antenna₂F () was the most both contained EUT signal, also contain interference signal, now carry out offseting process, can obtain

S_EUT(f)=S₂(f)-S₀(f)。