CN1321331C - Method for array channel calibration by utilizing ocean echo wave - Google Patents

Abstract

The present invention relates to a method for using sea echo waves to carry out array passage correction. The method is characterized in that an antenna array comprising at least two translation invariant array element pairs is used for receiving sea echo waves; a single arrival direction frequency point is detected in the sea echo waves through the statistical analysis to sea echo wave two-dimensional spectra; the statistical average is carried out to the echo wave spectrum amplitude corresponding to the single arrival direction frequency point, and the amplitude characteristics of passages are estimated; amplitude correction can be realized; according to the echo wave spectrum phase positions and the known reflecting signal source echo wave information such as islands, lighthouses, drilling platforms, etc., the phase characteristics of the passages are estimated by an MUSIC(multiple signal classification) algorithm, statistical average is carried out to the multiple results, and phase correction can be realized.

Description

A kind of method of utilizing marine echo to carry out array channel calibration

Technical field

The present invention relates to a kind of method of utilizing marine echo high-frequency ground wave radar to be carried out array channel calibration.

Background technology

High-frequency ground wave radar is a kind ofly to utilize high frequency (3～30MHz) electromagnetic waves are surveyed the New Type Radar of distant object (naval vessel, low altitude aircraft, cruise missile, ocean surface etc.) along earth surface diffraction, have detection range antiradiation missile far away, anti-stealthy, anti-, anti-low-level penetration, can survey outstanding advantages (comparing) such as ocean surface state, have very big development potentiality with normal radar.

High-frequency ground wave radar adopts phased array antenna, the Applied Digital wave beam forms and the Estimation of Spatial Spectrum technology is carried out beam scanning and DOA (arrival direction) estimation to naval target, effectively moving targets such as ocean surface state such as probe wind, wave, stream and aircraft, naval vessel.

Owing to influence of various factors such as mutual coupling effect between the inconsistent and antenna of hardware itself, amplitude characteristic and the phase propetry of forming each receiving cable of radar array in the reality are discrepant, cause echoed signal inconsistent through amplitude and phase change behind the different passages.The inconsistent error that causes that beam scanning and DOA estimate of this channel characteristic increases, even complete failure, is one of key issue that influences the high-frequency ground wave radar detection performance.In order to guarantee that radar can effectively work, must take measures to make the inconsistency between array channel to be limited in certain scope: on the one hand, to make each passage when making, guarantee its consistance by adequate measures (as the components and parts screening) as far as possible; On the other hand, can be by proofreading and correct the difference of further dwindling channel characteristic.

Existing array channel calibration method can be divided into passive correction and active correction two classes.

In passive bearing calibration, need not accurately known signal source of direction, directly utilize the measured data of reception and amplitude and the phase error that some prioris (as array format) are calculated each passage, compensate correction then.Some passive bearing calibration can also realize the estimation of uniting to direction of arrival of signal and channel error.In " Estimation of Spatial Spectrum and application thereof " (publishing house of Chinese University of Science and Technology 1997) book that Liu Deshu, Luo Jingqing etc. writes, the method is elaborated.

In the active correction method, a known signal source is put to from array open area enough far away, transmit, measure the amplitude and the phase place of each receiving cable output signal, the phase differential that deduction array manifold position causes can obtain channel error information.This bearing calibration principle is simple, respond well, has obtained widespread use in practice.In high-frequency ground wave radar, the signal source that is used to proofread and correct is one and is placed on array the place ahead transponder at a distance, emission was gone back after the radar signal that is used for receiving was amplified, and the array response of answer signal is compared with desirable array response, can obtain the estimation of passage amplitude phase error.

In existing channel correcting method, passive correction needs repeatedly complicated interative computation, and calculated amount is very big, the requirement of real time surely that differs, and might converge on local minimum, rather than global minimum, thereby obtain wrong result.Though adopt the active correction principle of transponder simple, respond well, be subjected to a lot of restrictions in the application of practical matter: transponder is at sea placed and is safeguarded very difficultly, is difficult to long-term work; The influence of the multipath effect that difficult elimination island or naval vessel etc. cause, or the like.

For the present invention will be described better, the principle of work to high-frequency ground wave radar is introduced below.High-frequency ground wave radar adopts FMCW (linear frequency modulation continuous wave) system, under the situation that transmitting-receiving is stood altogether, interrupted becoming FMICW (linear frequency modulation interruption continuous wave) system for solving the transmitting-receiving isolating problem, people such as Rafaat Khan deliver is entitled as " high-frequency ground wave radar target detection and tracking " (Target Detection and Tracking With a High Frequency Ground WaveRadar IEEE Journal of Oceanic Engineering, 1994,19 (4): in the paper 540～548) this is had a detailed description.

Radar Signal Generator produces the FMCW local oscillation signal, can be expressed as

f ₀Be Carrier Frequency on Radar Signal, α is a sweep rate, and T is a frequency sweep cycle, and A and  are respectively signal amplitude and first phase.Local oscillation signal is had no progeny to become in gating pulse and is transmitted

S _T(t)＝S(t)g(t) (2)

Gating pulse g (t) can be expressed as

$g\left(t\right)=\underset{p=0}{\overset{p-1}{\mathrm{\&Sigma;}}}\mathrm{rect}\left[\frac{t-\mathrm{pq}-\frac{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">T</figure-callout>}}_0}{2}}{T_0}\right]---\left(3\right)$

P is the gating pulse number in the frequency sweep cycle T, T ₀, q is respectively pulse width and cycle. Representing width is T ₀, the center is at the rect.p. of initial point.

If target is sentenced radial velocity v (away from radar for just) motion at distance r, then the time delay of the target echo of radar reception is

$\mathrm{\&tau;}=\frac{2(r+\mathrm{vt})}{c}---\left(4\right)$

Wherein c is the light velocity.The radar received signal is

S _R(t)＝K _RS _T(t-τ) (5)

K _RBe the propagation attenuation factor.After received signal and the local oscillation signal mixing, obtain baseband signal through the low-pass filtering demodulation and be

$S_I\left(t\right)=\mathrm{lowpass}\{S\left(t\right)\&CenterDot;S_R\left(t\right)\}$

$=A_I\cos \left(2\mathrm{\&pi;}(\mathrm{\&alpha;\&tau;t}-{\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">f</figure-callout>}}_0\mathrm{\&tau;}-\frac{{\mathrm{\&alpha;\&tau;}}^2}{2})\right)---\left(6\right)$

A ₁It is the baseband signal amplitude.Low-pass filtering has been removed pulsed modulation and has been made baseband signal become continuous wave, therefore do not had in (6) formula gating pulse g (t) this.To launch after (4) formula substitution (6) formula, omitting some very little phase masses can get

$S_I\left(t\right)\&ap;A_I\cos \left(2\mathrm{\&pi;}(2\left(\frac{\mathrm{\&alpha;r}-f_{0}v}{c}\right)t+\frac{2\mathrm{\&alpha;v}}{c}{t}^2-\frac{2f_{0}r}{c}-\frac{2\mathrm{\&alpha;}{r}^2}{c^2})\right)=A_I\cos \left({\mathrm{\&phi;}}_{\mathrm{\&tau;}}\right)---\left(7\right)$

The baseband signal instantaneous frequency is

$f_{\mathrm{\&tau;}}\left(t\right)=\frac{1}{2\mathrm{\&pi;}}\frac{d{\mathrm{\&phi;}}_{\mathrm{\&tau;}}}{\mathrm{dt}}=\frac{2\mathrm{\&alpha;r}}{c}-\frac{2f_{0}v}{c}+\frac{4\mathrm{\&alpha;vt}}{c}---\left(8\right)$

Wherein first is caused that by target range second and third is caused by target radial speed.In higher-frequency radar

$\left|\frac{2\mathrm{\&alpha;r}}{c}\right|>>|-\frac{2f_{0}v}{c}+\frac{4\mathrm{\&alpha;vt}}{c}|,$ Thereby have $f_{\mathrm{\&tau;}}\left(t\right)\&ap;\frac{2\mathrm{\&alpha;r}}{c}.$

The analysis showed that more than can obtain the discrete spectrum corresponding with distance to carrying out FFT after the baseband signal A/D conversion, current FFT is called range conversion, the gained distance spectrum is

$R_I\left[m\right]=\mathrm{FFT}\left\{S_I\left(t\right)\right\}$

${=A}_I\&CenterDot;\mathrm{FFT}\left\{\cos \left(2\mathrm{\&pi;}(\mathrm{\&alpha;\&tau;t}-{\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">f</figure-callout>}}_0\mathrm{\&tau;}-\frac{{\mathrm{\&alpha;\&tau;}}^2}{2})\right)\right\}$

$=A_I\&CenterDot;R\left[m\right]---\left(9\right)$

With the distance spectrum that obtains in the frequency sweep cycle as delegation, l continuously then _MaxThe distance spectrum that individual frequency sweep cycle obtains can constitute a l _Max* m _MaxMatrix

m _MaxBe maximum distance unit ordinal number.

Analyze the Changing Pattern of the phase place of each row among the R now with frequency sweep cycle ordinal number (row ordinal number) l.During l frequency sweep cycle, target range is

r _l＝r+v(l-1)T (11)

Then l frequency sweep cycle baseband signal phase place is

${\mathrm{\&phi;}}_{\mathrm{l\&tau;}}=2\mathrm{\&pi;}(2\left(\frac{{\mathrm{\&alpha;r}}_l-f_{0}v}{c}\right)t+\frac{2\mathrm{\&alpha;v}}{c}{t}^2-\frac{2f_0{r}_l}{c}\text{-}\frac{{2\mathrm{\&alpha;r}}_l^2}{c^2})---\left(12\right)$

In 100 frequency sweep cycles, i.e. l _Max≤ 100 o'clock, omit some little phase terms, continuous two frequency sweep cycle baseband signal phase differential are

$\mathrm{\&Delta;\&phi;}\&ap;2\mathrm{\&pi;}(-\frac{{2f}_{0}v}{c})T---\left(13\right)$

Approximate according to this, l is capable among the R only differs a phase factor e with the 1st row ^{-j2 π (l-1)-(2f0v/c)}, can approximate representation be

Each row to (14) formula carry out a FFT again and just can obtain the Doppler frequency spectrum corresponding with speed, and FFT is called Doppler-shift specifically.This shows, to getting the discrete two-dimensional echo spectrum through twice FFT processing after a plurality of frequency sweep cycle baseband signal samplings

Z(m，n)＝FFT{FFT{S _I(t)}} (15)

Wherein m is the discrete frequency on the distance dimension, and n is the discrete frequency on speed (Doppler frequency) dimension.Target echo is f in the frequency that peak value appears in the distance dimension _τ=2 α r/c, the frequency that occurs peak value in the speed dimension is f _v=-2f ₀V/c carries out the peak value detection to two-dimentional echo spectrum and can obtain target range and speed.

From above argumentation to the high-frequency ground wave radar principle of work as can be known, in fact twice FFT separate the target echo signal of different distance and speed, makes it corresponding to frequencies different in the two-dimentional echo spectrum.High-frequency ground wave radar receives the very strong sea echo signal of big energy, is dispersed on a lot of frequencies of two-dimentional echo spectrum, wherein must some have only single arrival direction.Statistical study by to the output of specific array two dimension echo spectrum can detect single arrival direction frequency wherein, and then estimate the magnitude-phase characteristics of each passage according to known reflection sources echo information, and carries out statistical average to improve precision.

Summary of the invention

Defective at existing method, the objective of the invention is to utilize the marine echo information of high-frequency ground wave radar reception, a kind of real-time, accurate, cheap and more reliable and more stable array channel calibration method is provided,, has improved the radar system performance to reduce the passage amplitude phase error.

To achieve these goals, the array correcting method that the present invention adopts is: receive marine echo with the aerial array that contains at least two translation invariant array element idols, by the statistical study to the marine echo two-dimensional spectrum, detect single arrival direction frequency wherein; Echo spectrum amplitude to single arrival direction frequency correspondence is carried out statistical average, estimates the amplitude characteristic of each passage, realizes amplitude correction; Echo spectrum phase place and known reflected signal source echo information according to single arrival direction frequency correspondence, as island, beacon, drilling platform etc., employing MUSIC (multiple signal classification) algorithm estimates the phase propetry of each passage, and a plurality of results are carried out statistical average, realizes phase correction.

Advantage of the present invention is: do not adopt complicated interative computation, calculated amount is little, can satisfy the requirement of channel correcting real-time; A large amount of echoed signals are adopted statistical method, improved the accuracy of channel correcting; Utilize a large amount of continual marine echos and known reflection sources information, avoided the placement and the maintenance issues of transponder, make channel correcting cheap more, and can long-term stability carry out reliably; Adopted and to have carried out the MUSIC algorithm that multi-source DOA estimates, eliminated the influence of multipath effect.

Below in conjunction with drawings and Examples, the present invention is done more detailed explanation.

Description of drawings

Fig. 1 high-frequency ground wave radar fundamental diagram

Fig. 2 high-frequency ground wave radar two dimension echo spectrum synoptic diagram

Fig. 3 is used for detecting the specific array synoptic diagram of the single arrival direction frequency of two-dimentional echo spectrum

Fig. 4 uniform linear array synoptic diagram

Embodiment

Key of the present invention is to detect single arrival direction frequency in the two-dimentional echo spectrum, and this needs to contain in the aerial array specific array format, as shown in Figure 3.

Suppose that high-frequency ground wave radar has M antenna element, coordinate is (x _i, y _i), i=1,2 ... M.The specific array that is used to detect single arrival direction echo spectrum frequency is made of array element 1～4, and wherein 1 and 2 have constituted array element idol A ₁, 3 and 4 have constituted array element idol A ₂A ₁With A ₂Between have translation invariance, i.e. A ₁After the translation can with A ₂Overlap fully, (x is then arranged ₂, y ₂)=(x ₁+ d, y ₁), (x ₄, y ₄)=(x ₃+ d, y ₃).If the passage complex gain of array element i is g _ie ^{J φ i}, be true origin with array element 1, then array two dimension echo spectrum is

$Z_i(m,n)=g_i{e}^{\mathrm{j\&phi;i}}[\underset{k=1}{\overset{k}{\mathrm{\&Sigma;}}}{S}_k(m,n){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^j+N_i(m,n)]---\left(16\right)$

Wherein, S _k(m, n) (arrival direction is θ to k the echoed signal that receives for array element 1 _k) two-dimentional echo spectrum, N _i(m is a noise contribution in the two-dimentional echo spectrum of array element i n), and λ is a signal wavelength, and K is an echoed signal arrival direction number.Order ${\mathrm{\&eta;}}_1=\frac{Z_2(m,n)Z_3(m,n)}{Z_1(m,n)Z_4(m,n)},$ As K=1 and N _i(m n)=0 o'clock, has ${\mathrm{\&eta;}}_1=\frac{g_2{g}_3}{g_1{g}_4}{e}^{J({\mathrm{\&phi;}}_2+{\mathrm{\&phi;}}_3-{\mathrm{\&phi;}}_1-{\mathrm{\&phi;}}_4)},$ This shows

(m n), is having only an arrival direction and noiseless composition ideally, η for a certain frequency in the two-dimentional echo spectrum ₁It is an only fixed amount relevant with the passage complex gain.Noise is inevitably in the real system, corresponding η ₁Be distributed near this fixed amount.By simple analysis as can be known, the η of the frequency correspondence of arrival direction number K 〉=2 ₁Be a variable quantity relevant, on complex plane, present disperse state with echo strength and arrival direction, and the η of the frequency correspondence of arrival direction number K=1 ₁Then accumulate on the complex plane certain a bit near.With all surpass the η of the frequency correspondence of certain signal-noise ratio threshold in the two-dimentional echo spectrum ₁Be marked on the complex plane, then have and only have a zone η to occur ₁The phenomenon of assembling, wherein most of η ₁The value frequency points corresponding has only an arrival direction.

Order ${\mathrm{\&eta;}}_2=\frac{Z_2(m,n){\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1^{*}(m,n)}{Z_4(m,n)Z_3^{*}(m,n)},$ With the same analysis in front as can be known, η ₂Also aggregation zone can appear, wherein most of η on complex plane ₂The value frequency points corresponding has only an arrival direction.Because the η of single arrival direction frequency correspondence ₁And η ₂All concentrate in the accumulation area separately, and the η of many arrival directions frequency correspondence ₁And η ₂Be to disperse to distribute, the possibility that drops on simultaneously in the accumulation area is very little, therefore can use η ₁And η ₂Whether fall into accumulation area simultaneously as the criterion that detects single arrival direction frequency.

By above analysis as can be known, as long as contain at least two translation invariant array element idols in the aerial array, just can detect the single arrival direction frequency in the two-dimentional echo spectrum.The array that channel correcting method of the present invention was suitable for all contains this specific array form.

Suppose that single arrival direction frequency is (m ', n '), K=1 is arranged again, substitution (16) formula can get the two-dimentional echo spectrum output of this frequency correspondence

$Z_i(m^{\&prime;},n^{\&prime;})=g_i{e}^{j{\mathrm{\&phi;}}_i}[S_1(m^{\&prime;},n^{\&prime;}){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^j+N_i(m^{\&prime;},n^{\&prime;})]---\left(17\right)$

Work as N _i(m ', n ')=0 o'clock, have

g _i＝|Z _i(m′，n′)|/|S ₁(m′，n′)| (18)

Receiving cable with array element 1 is benchmark, then g ₁=1, | S ₁(m ', n ') |=| Z ₁(m ', n ') |, substitution (18) formula obtains

g _i＝|Z _i(m′，n′)|/|Z ₁(m′，n′)| (19)

Actual two-dimentional echo spectrum is noisy, the g that tries to achieve according to different single arrival direction frequencies _iHave some random fluctuations, can carry out statistical average and improve estimated accuracy.Estimate channel amplitude gain g _iAfter, with the echo data of each passage divided by separately g _i, can realize amplitude correction.

Through behind the amplitude correction, channel amplitude gain g _i=1, according to (17) formula, work as N _i(m ', n ')=had in 0 o'clock

$e^{J{\mathrm{\&phi;}}_i}=[Z_i(m^{\&prime;},n^{\&prime;})/S_1(m^{\&prime;},n^{\&prime;})]e^{-\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">J</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}\left(x_i\sin {\mathrm{\&theta;}}_1{y}_i\cos {\mathrm{\&theta;}}_1\right)}---\left(20\right)$

Receiving cable with array element 1 is a benchmark, and its position is a true origin, promptly $e^{j\mathrm{\&phi;}1}=1$ , (x ₁, y ₁)=(0,0), S is then arranged ₁(m ', n ')=Z ₁(m ', n '), substitution (20) formula obtains

$e^{J{\mathrm{\&phi;}}_i}=[Z_i(m^{\&prime;},n^{\&prime;})/Z_1(m^{\&prime;},n^{\&prime;})]e^{-\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">J</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(X_i{\sin \mathrm{\&theta;}}_1+y_i\cos {\mathrm{\&theta;}}_1)}---\left(21\right)$

Write (16) formula as matrix form

Z(m，n)＝GAS(m，n)+GN(m，n) (22)

Wherein, and Z (m, n)=[Z ₁(m, n), Z ₂(m, n) ..., Z _M(m, n)] ^T

$G=\mathrm{diag}(g_1{e}^{j{\mathrm{\&phi;}}_1},g_2{e}^{{\mathrm{j\&phi;}}_2},...,g_M{e}^{j{\mathrm{\&phi;}}_M})$

A＝[a(θ ₁)，a(θ ₂)，…，a(θ _K)]

$a\left(\mathrm{\&theta;}\right)=[{\mathrm{<figure-callout\; id="2"\; label="e\; J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^J,{\mathrm{<figure-callout\; id="2"\; label="e\; J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^J,...,{\mathrm{<figure-callout\; id="2"\; label="e\; J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^J{]}^T$

S(m，n)＝[S ₁(m，n)，S ₂(m，n)，…，S _K(m，n)] ^T

N(m，n)＝[N ₁(m，n)，N ₂(m，n)，…，N _M(m，n)] ^T

Passage is through g behind the amplitude correction _i=1, promptly $G=\mathrm{diag}(e^{j{\mathrm{\&phi;}}_1},e^{j{\mathrm{\&phi;}}_2},...,e^{{\mathrm{j\&phi;}}_M}).$

Signal and noise contribution in the wig two dimension echo spectrum are ergodic zero-mean stationary stochastic processes, and signal and noise are separate, and the noise of each passage is uncorrelated mutually, and for having identical variances sigma ²White Gaussian process, then the array covariance matrix of two-dimentional echo spectrum is

R _ZZ＝E[Z(m，n)Z ^H(m，n)]＝GAR _SSA ^HG ^H+σ ²I (23)

Wherein, R _SS=E[S (m, n) S ^H(m, n)].To R _ZZCarrying out characteristic value decomposition can get

R _ZZ＝UDU ^H (24)

D is by R _ZZThe diagonal matrix that constitutes of eigenwert

D＝diag(λ ₁，λ ₂，…，λ _M)λ ₁≥λ ₂≥…≥λ _M (25)

U be by with eigenvalue ₁The matrix that the characteristic of correspondence vector constitutes

U＝[μ ₁，μ ₂，…，μ _M]＝[U _S，U _N] (26)

Wherein, U _S=[μ ₁, μ ₂..., μ _K] corresponding with K eigenwert of representation signal, the space that its column vector is opened is called signal subspace; U _N=[μ _K+1, μ _K+2..., μ _M] corresponding with the M-K that represents a noise eigenwert, the space that its column vector is opened then is called noise subspace.

MUSIC algorithm (the R.O.Schmidt that adopts Schmidt to propose, Multiple emitter location and signalparameter estimation, IEEE Trans.Antennas Propagation, 1986, Vol.34 pp.276-280.) obtains the spatial spectrum function that DOA estimates and is

$R_{\mathrm{MU}}=\frac{1}{{\left[\mathrm{Ga}\left(\mathrm{\&theta;}\right)\right]}^H{\mathrm{\&Pi;}}^{\&perp;}\left[\mathrm{Ga}\left(\mathrm{\&theta;}\right)\right]}---\left(27\right)$

Wherein, ∏ ^⊥Be the projection operator on the noise subspace

${\mathrm{\&Pi;}}^{\&perp;}=U_N{U}_N^H=I-A{\left(A^{H}A\right)}^{-1}{A}^H---\left(28\right)$

Make Z in (22) formula that (m n) for the two-dimensional spectrum array output of the corresponding frequency of known reflection sources echo (can detect according to information such as the distance of reflection sources, speed), can obtain ∏ thus in two-dimentional echo spectrum ^⊥By (21) formula as can be known, G is actually θ ₁Function, can be expressed as G (θ ₁), reflection sources echo arrival direction θ=θ ₀Known, P then _MUBecome θ ₁Function

$P_{\mathrm{MU}}\left({\mathrm{\&theta;}}_1\right)=\frac{1}{\left[G\left({\mathrm{\&theta;}}_1\right)a\left({\mathrm{\&theta;}}_0\right){]}^H{\mathrm{\&Pi;}}^{\&perp;}\right[G\left({\mathrm{\&theta;}}_1\right)a\left({\mathrm{\&theta;}}_0\right)]}---\left(29\right)$

With P _MU(θ ₁) θ of spectrum peak correspondence ₁Value estimates that as the DOA of single arrival direction frequency in the two-dimentional echo spectrum substitution (21) formula can get channel phases gain e ^{J φ 2}In the actual ghosts spectrum is noisy, the e that tries to achieve according to the single arrival direction frequency of difference ^{J φ 2}And inequality, can carry out statistical average to improve estimated accuracy.After estimating channel phases gain, the echo data of each passage divided by separately phase gain, can be realized that channel phases proofreaies and correct.

Fig. 4 is a high-frequency ground wave radar uniform linear array synoptic diagram commonly used, in this case, will be more accurate to the detection of single arrival direction frequency in the echo spectrum, more than active method for correcting phase also can simplify.

M unit uniform linear array can be divided into M-1 translation invariant array element idol A ₁-A _M, combine and may be used to detect single arrival direction frequency, gathered accordingly for wherein any two.To whether fall into a plurality of this intersection of sets collection as criterion, and make the detection of single arrival direction frequency more accurate.

The coordinate of each array element of uniform linear array is (x _i, y _i)=((i-1) d, 0), substitution (21) Shi Kede

$e^{J{\mathrm{\&phi;}}_i}=[Z_i(m^{\&prime;},n^{\&prime;})/Z_1(m^{\&prime;},n^{\&prime;})]e^{-\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">J</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(i-1)d\sin {\mathrm{\&theta;}}_1}---\left(30\right)$

When i=2, ${\mathrm{<figure-callout\; id="2"\; label="e\; J"\; filenames="C0312823800111.png"\; state="\{\{state\}\}">e</figure-callout>}}^J=[Z_2(m^{\&prime;},n^{\&prime;})/Z_1(m^{\&prime;},n^{\&prime;})]e^{-J{\mathrm{\&phi;}}_2},$ The substitution following formula can get

$e^{j{\mathrm{\&phi;}}_1}=Z_1(m^{\&prime;},n^{\&prime;})\left[Z_2(m^{\&prime;},n^{\&prime;}){]}^{1-i}\right[Z_1(m^{\&prime;},n^{\&prime;}){]}^{i-2}{e}^{J(i-1){\mathrm{\&phi;}}_2}=B_i{e}^{J(i-1){\mathrm{\&phi;}}_2}---\left(31\right)$

Wherein, $B_i=Z_i(m^{\&prime;},n^{\&prime;})\left[Z_2(m^{\&prime;},n^{\&prime;}){]}^{1-i}\right[Z_1(m^{\&prime;},n^{\&prime;}){]}^{i-2}=e^{J[{\mathrm{\&phi;}}_i-(i-1){\mathrm{\&phi;}}_2]}$ , be the irrelevant amount of an echo bearing corresponding with single arrival direction frequency.Contain noise and disturbance in the real system, the B that tries to achieve according to different single arrival direction frequencies _iAnd inequality, can carry out statistical average and obtain Substitution (31) formula has

$e^{J{\mathrm{\&phi;}}_i}={\stackrel{\&OverBar;}{B}}_i{e}^{j(i-1){\mathrm{\&phi;}}_2}---\left(32\right)$

According to following formula as can be known, G is φ ₂Function, can be expressed as G (φ ₂), reflection sources echo arrival direction θ=θ ₀, P then _MUBecome φ ₂Function

$P_{\mathrm{MU}}\left({\mathrm{\&phi;}}_2\right)=\frac{1}{\left[G\left({\mathrm{\&phi;}}_2\right)a\left({\mathrm{\&theta;}}_0\right){]}^H{\mathrm{\&Pi;}}^{\&perp;}\right[G\left({\mathrm{\&phi;}}_2\right)a\left({\mathrm{\&theta;}}_0\right)]}---\left(33\right)$

With P _MU(φ ₂) φ of spectrum peak correspondence ₂Value is as the estimation of the channel phases error (is benchmark with array element 1) of array element 2, and substitution (32) formula can get channel phases gain e ^{J φ 2}

This active method for correcting phase at uniform linear array has only carried out once spectrum search, and statistical average places before the spectrum search, thereby calculated amount is less.

Claims (2)

1. method of utilizing marine echo to carry out array channel calibration, it is characterized in that receiving marine echo with the aerial array that contains at least two translation invariant array element idols, by statistical study, detect single arrival direction frequency wherein to the marine echo two-dimensional spectrum; Echo spectrum amplitude to single arrival direction frequency correspondence is carried out statistical average, estimates the amplitude characteristic of each passage, realizes amplitude correction; According to the echo spectrum phase place and the known reflected signal source echo information of single arrival direction frequency correspondence, employing multiple signal classification MUSIC algorithm estimates the phase propetry of each passage, and a plurality of results are carried out statistical average, realizes phase correction.

2. the method for utilizing marine echo to carry out array channel calibration as claimed in claim 1, it is characterized in that aerial array is a uniform linear array, M unit uniform linear array is divided into M-1 translation invariant array element idol A1～AM, combine and be used to detect single arrival direction frequency for wherein any two, gathered accordingly, will whether be fallen into a plurality of this intersection of sets collection as criterion.

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