CN106529440A - Sectional matching and filtering method for coherent frequency diversity array radar - Google Patents

Abstract

The invention provides a sectional matching and filtering method for a coherent frequency diversity array radar. The method mainly solves the problem in the prior art that the existing radar system cannot realize the distance-angle two-dimensional matching and filtering function in the wide-area coverage condition. The method comprises the steps of 1, obtaining the receiving-end echo signal of a coherent frequency diversity array; and constructing the expression of a corresponding transmit beam pattern; 2, according to the corresponding transmit beam pattern, acquiring an illumination time period configured to point to the main lobe of a beam at a specific spatial angle, and designing a time width matched with a sub-pulse; 3, according to the time width matched with the sub-pulse of a function, uniformly dividing the time of transmitted pulses, and constructing an angle-time two-dimensional and sectional matching and filtering function corresponding to each matched sub-pulse. According to the technical scheme of the invention, the total-space coverage capability of the coherent frequency diversity array is fully utilized, so that the method can be used for designing the transmit beam patterns of low-range side lobes and low minor lobes.

Description

Coincidence frequency diversity battle array radar segmented matched filter method

Technical field

The invention belongs to signal processing technology field, more particularly to a kind of coincidence frequency diversity battle array radar segmented matched filter Method, can be used for low distance side lobe and Sidelobe direction of the launch G- Design.

Background technology

Phased array realizes the functions such as beam scanning, adaptive beam zero setting, multi-beam by the phase place for changing antenna element, It is the important milestone of radar development.But the transmitting pattern of phased array antenna is only relevant with space angle, and apart from unrelated, Therefore the two dimension matched filtering of distance-angle is difficult under phased array system.

For this problem, prior art adopts frequency diversity array.Frequency diversity battle array is by introducing the frequency between array element Difference, obtains extra distance dimension controllable degrees of freedom, forms distance-angle dependency transmitting pattern, with more flexible Wave beam is controlled and signal handling capacity.Frequency diversity battle array can be divided into orthogonal frequency division battle array and coincidence frequency diversity battle array.

Coincidence frequency diversity battle array, refers to the array element transmitting coherent signal of frequency diversity battle array.In coincidence frequency diversity battle array radar Under broad pulse system, transmitting pattern has distance verses time-angle three-dimensional dependency characteristic, can enter row distance-angle in receiving terminal The two-dimentional matched filtering of degree is processed, while realizing that equivalent launching beam is formed.

Under coincidence frequency diversity battle array radar system, the matched filtering function of receiving terminal actually by baseband signal and is sent out Penetrate what directional diagram was together decided on.In order to realize that the matching to space arbitrfary point is received, need to design one to each space angle Matched filtering function.But for given angle, the matched filtering function of receiving terminal is modulated by transmitting pattern, therefore is had The match time of effect be transmitting pattern be main lobe time be only the whole pulse duration a part, matched filtering letter Several effective bandwidth is also only the corresponding frequency bandwidth of transmitting pattern main lobe, it is impossible to complete distance under wide area coverage condition- Angle two dimensional quasi steady state matched filtering.

The content of the invention

The present invention is directed to existing issue, it is proposed that a kind of coincidence frequency diversity battle array radar segmented matched filter method, with about The corresponding time width of beam matched filtering function, realizes the distance-angle two dimensional quasi steady state matched filtering under wide area coverage condition.

The present invention technical thought be：Sky can be equally assigned to according to the transmitting burst length of coincidence frequency diversity battle array Between this principle on different directions, the corresponding broad pulse of echo-signal will be received and is evenly dividing as multiple narrow subpulses, every The quasi-steady state characteristic of analysis transmitting pattern in individual subpulse, and the distance-angle two dimension matching modulated by transmitting pattern Filter function carries out the two stage cultivation reception processing of echo-signal.Implementation step includes as follows：

(1) obtain coincidence frequency diversity array received end echo-signal：

(1a) obtain n-th antenna and receive echo-signal r launched by all array elements_n(θ, t- τ), wherein n=1,2 ..., M, M are element number of array, and θ is antenna scan angle,The time delay for being echo-signal under the conditions of narrow emission, R is signal Propagation distance, c are the light velocity, and t is signal propagation time；

(1b) echo-signal r according to n-th antenna reception_n(θ, t- τ) obtains the vector form of receiving terminal echo-signal：

Wherein, symbol []^TFor transposition computing,For impulse function, T_pFor pulse width Degree,For baseband waveform, j represents imaginary number, f₀For reference work frequency, g_T(θ, t- τ) be corresponding transmitting pattern, a (θ) it is the reception steering vector that only relies upon angle；

(2) obtain receive Wave beam forming after signal y (θ, R, t)：

(2a) receiving terminal conventional beams weight vector w (θ are built₀)：

Wherein, d is the spacing of each array element, θ₀For beam position,For reference wavelength；

(2b) according to receiving terminal conventional beams weight vector w (θ₀) and echo-signal x (θ, R, t), obtain receive Wave beam forming Rear signal y (θ, R, t)：

Wherein, symbol []^HFor conjugate transpose computing, g_R(θ) it is receiving pattern；

(3) build segmented matched filter function：

(3a) it is θ to define beam position₀When transmitting pattern adaptation function

Wherein, frequency increments of the Δ f for coincidence frequency diversity array；

(3b) according to transmitting pattern adaptation functionObtain beam main lobe irradiation time section：

(3c) according to beam main lobe irradiation time section, selection matching subpulse time width is：

(3d) according to subpulse time width T_s, obtain the time period t of k-th matching subpulse^{k}：

Wherein, k=1,2 ..., M,For the central instant of k-th subpulse, and

(3e) central instant according to k-th subpulseObtain the corresponding angle-time 2-D of k-th subpulse With filter function h^{k}(θ₀,t)：

Wherein,For the corresponding baseband waveform of k-th subpulse,For The corresponding impulse function of k-th subpulse,For the corresponding transmitting pattern adaptation function of k-th subpulse.

The present invention has advantages below compared with prior art：

First, the present invention by array pull-in frequency stepping-in amount so that transmitting pattern have angle-when m- distance Dependency, therefore, the matched filtering function of its echo-signal is also the two-dimensional function of angle-time.

Second, it is of the invention by being multiple narrow subpulses by echo-signal corresponding burst length cutting, in every height Distance-angle two dimension matched filtering function in pulse using transmitting pattern modulation carries out two stage cultivation reception processing, can be with Exchange the covering in space using burst length resource for.

Simulation result shows, by the corresponding time width of constrained matching filter function, it is possible to achieve wide area coverage condition Under distance-angle two dimensional quasi steady state matched filtering, and the transmitting pattern of low distance side lobe and Sidelobe can be obtained.

Description of the drawings

Fig. 1 is the flowchart of the present invention；

Fig. 2 is the receiver structure figure in the present invention；

Fig. 3 is the corresponding angle-time 2-D ambiguity function analogous diagram of k-th subpulse in the present invention；

Fig. 4 is the angle dimension one-dimension slice figure of the ambiguity function in the present invention；

Fig. 5 be the present invention ambiguity function distance dimension one-dimension slice figure.

Specific embodiment

Below in conjunction with the accompanying drawings embodiments of the invention and effect are described in further detail.

The use scene of the present invention is coincidence frequency diversity array：Assume to have M array element, the spacing of each array element is d, The signal frequency of m-th array element is：

f_m=f₀+ (m-1) Δ f, m=1,2 ..., M

Wherein, f₀For reference work frequency, frequency increments of the Δ f for frequency diversity array.

With reference to Fig. 1, the present invention's realizes that step is as follows：

Step 1, obtains coincidence frequency diversity array received end echo-signal.

(1a) obtain n-th array element and receive the signal s launched by m-th array element_m,n(t-τ)：

Wherein, n=1,2 ..., M,For impulse function, T_pFor pulse width,The time delay for being echo-signal under the conditions of narrow emission, R are signal propagation distance, and c is the light velocity, when t is that signal is propagated Between,For baseband waveform, j represents imaginary number；

(1b) the signal s launched by m-th array element is received according to n-th array element in (1a)_m,n(t- τ) is obtained n-th Antenna receives echo-signal r launched by all array elements_n(θ,t-τ)：

Wherein, θ is antenna scan angle；

(1c) echo-signal r received according to n-th antenna in (1b)_n(θ, t- τ) obtains receiving terminal echo-signal Vector form：

Wherein, symbol []^TFor transposition computing, g_T(θ, t- τ) is corresponding transmitting pattern, and a (θ) is to only rely upon angle The reception steering vector of degree, its formula are expressed as：

(1d) build receiving terminal conventional beams weight vector：

Wherein, θ₀For beam position；

(1e) according to echo-signal x (θ, R, w (θ t) and in receiving terminal conventional beams weight vector (1d) in (1c)₀), Obtain receive Wave beam forming after signal y (θ, R, t)：

Wherein, symbol []^HFor conjugate transpose computing, g_R(θ) it is receiving pattern, its formula is expressed as：

Step 2, is θ to beam position₀When required adaptation function time be designed.

(2a) it is θ to define beam position₀When transmitting pattern adaptation function

(2b) according to the transmitting pattern adaptation function in (2a)Order T is solved, so as to solve Use t₁When representing Between section starting point, t₂Time segment endpoint is represented, therefore obtains beam main lobe irradiation time section [t₁,t₂]；

(2c) according to the beam main lobe irradiation time section [t in (2b)₁,t₂], the time width for obtaining matching subpulse is：

Step 3, builds segmented matched filter function.

With reference to Fig. 2, being embodied as this step is as follows：

(3a) burst length will be launched with the T in (2c)_sFor interval, be divided into M match subpulse, obtain k-th it is sub The central instant of pulse：

Wherein, k=1,2 ..., M；

(3b) central instant according to k-th subpulse in (3a)And the matching subpulse time width in (2c) Degree T_s, obtain withFor starting point,For the time period t of k-th matching subpulse of terminal^{k}：

Wherein,

(3c) by impulse function in (1a)Baseband waveformAnd the transmitting pattern g in (1c)_T τ in (θ, t- τ) is usedReplacement, by impulse function in (1a)In T_pUse T_sReplacement, obtains k-th subpulse Corresponding baseband waveformThe corresponding impulse function of k-th subpulse And the corresponding transmitting pattern adaptation function of k-th subpulse

(3d) time period t of subpulse is matched at k-th^{k}It is interior, according to the central instant of k-th subpulse in (3a)(3c) inAndObtain the corresponding angle of k-th subpulse Degree-time 2-D matched filtering function：

The effect of the present invention is described further below by emulation experiment.

1. simulation parameter：

Receiving angle is assumed for 0 degree, i.e. normal direction, remaining simulation parameter such as table 1：

1 simulation parameter of form

2. emulation content：

Emulation 1, under above-mentioned simulation parameter, using the inventive method, to k-th subpulse correspondence of coincidence frequency diversity battle array Angle-time 2-D ambiguity function emulated, as a result as shown in Figure 3.

As seen from Figure 3, the process of coincidence frequency diversity battle array segmented matched filter of the present invention had actually both completed biography System time domain matched filtering, the launching beam for completing spatial domain again are formed, therefore, coincidence frequency diversity battle array segmented matched filter is empty When-time two-dimensional filtering.

Emulation 2, under above-mentioned simulation parameter, using the inventive method, ties up to the angle of angle-time 2-D ambiguity function One-dimension slice figure is emulated, as a result as shown in Figure 4.

As seen from Figure 4, tie up in angle, due to irradiating corresponding subpulse time construction matched filtering only with main lobe Function, the secondary lobe ignored corresponding burst length, the main-side lobe ratio after equivalent launching beam is formed are less than -19dB.

Emulation 3, under above-mentioned simulation parameter, using the inventive method, ties up to the distance of angle-time 2-D ambiguity function One-dimension slice figure is emulated, as a result as shown in Figure 5.

As seen from Figure 5, in distance dimension, for using the corresponding ambiguity function of subpulse, due to the damage of match time Lose, adaptation function main lobe is slightly wider, and the first sidelobe level is in -36dB or so.

The correctness of the above-mentioned simulating, verifying present invention, validity and reliability.

Claims (4)

1. a kind of coincidence frequency diversity battle array radar segmented matched filter method, including：

(1) obtain coincidence frequency diversity array received end echo-signal：

(1a) obtain n-th antenna and receive echo-signal r launched by all array elements_n(θ, t- τ), wherein n=1,2 ..., M, M are Element number of array, θ are antenna scan angle,The time delay for being echo-signal under the conditions of narrow emission, R be signal propagate away from From c is the light velocity, and t is signal propagation time；

(1b) echo-signal r according to n-th antenna reception_n(θ, t- τ) obtains the vector form of receiving terminal echo-signal：

Wherein, symbol []^TFor transposition computing,For impulse function, T_pFor pulse width,For baseband waveform, j represents imaginary number, f₀For reference work frequency, g_T(θ, t- τ) be corresponding transmitting pattern, a (θ) For only relying upon the reception steering vector of angle；

(2) obtain receive Wave beam forming after signal y (θ, R, t)：

(2a) receiving terminal conventional beams weight vector w (θ are built₀)：

$w\left({\mathrm{\θ}}_0\right)={\[1,\exp \left\{j2\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}sin\left({\mathrm{\θ}}_0\right)\right\},...,\exp \left\{j2\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}(M-1)sin\left({\mathrm{\θ}}_0\right)\right\}\]}^T$

Wherein, d is the spacing of each array element, θ₀For beam position,For reference wavelength；

(2b) according to receiving terminal conventional beams weight vector w (θ₀) and echo-signal x (θ, R, t), obtain receive Wave beam forming after letter Number y (θ, R, t)：

Wherein, symbol []^HFor conjugate transpose computing, g_R(θ) it is receiving pattern；

(3) build segmented matched filter function：

(3a) it is θ to define beam position₀When transmitting pattern adaptation function

${\tilde{g}}_T({\mathrm{\θ}}_0,t)=\exp \left\{j(M-1)\mathrm{\π}\mathrm{\Δ}ft\right\}\frac{sin\left(M\mathrm{\π}\right(\mathrm{\Δ}ft+\frac{d}{{\mathrm{\λ}}_0}sin\left({\mathrm{\θ}}_0\right)\left)\right)}{sin\left(\mathrm{\π}\right(\mathrm{\Δ}ft+\frac{d}{{\mathrm{\λ}}_0}sin\left({\mathrm{\θ}}_0\right)\left)\right)}$

Wherein, frequency increments of the Δ f for coincidence frequency diversity array；

(3b) according to transmitting pattern adaptation functionObtain beam main lobe irradiation time section：

$\[-\frac{1}{2M\mathrm{\Δ}f}-\frac{1}{\mathrm{\Δ}f}\frac{d}{{\mathrm{\λ}}_0}sin\left({\mathrm{\θ}}_0\right),\frac{1}{2M\mathrm{\Δ}f}-\frac{1}{\mathrm{\Δ}f}\frac{d}{{\mathrm{\λ}}_0}sin\left({\mathrm{\θ}}_0\right)\]$

(3c) according to beam main lobe irradiation time section, selection matching subpulse time width is：

$T_s=\frac{1}{M\mathrm{\Δ}f},$

(3d) according to subpulse time width T_s, obtain the time period t of k-th matching subpulse^{k}：

$\[{\mathrm{\τ}}_0^{\left\{k\right\}}-\frac{T_s}{2},{\mathrm{\τ}}_0^{\left\{k\right\}}+\frac{T_s}{2}\]$

Wherein, k=1,2 ..., M,For the central instant of k-th subpulse, and

(3e) central instant according to k-th subpulseObtain the corresponding angle of k-th subpulse-time 2-D matching filter Wave function h^{k}(θ₀,t)：

Wherein,For the corresponding baseband waveform of k-th subpulse,For k-th The corresponding impulse function of subpulse,For the corresponding transmitting pattern adaptation function of k-th subpulse.

2. method according to claim 1, wherein echo-signal r in step (1a)_n(θ, t- τ), its formula is as follows：

$r_n(\mathrm{\θ},t-\mathrm{\τ})=\underset{m=1}{\overset{M}{\Σ}}{s}_{m,n}(t-\mathrm{\τ})$

Wherein,Receive by m-th array element for n-th array element The signal launched, m=1,2 ..., M, f_m=f₀+ (m-1) Δ f are the operating frequency of m-th array element, f₀For reference work frequency Rate, frequency increments of the Δ f for frequency diversity array.

3. method according to claim 1, wherein the transmitting pattern g in step (1b)_T(θ, t- τ) and receive guiding arrow Amount a (θ), its formula are respectively：

$g_T(\mathrm{\θ},t-\mathrm{\τ})=\exp \left\{j(M-1)\mathrm{\π}\left(\mathrm{\Δ}f\right(t-\mathrm{\τ})+\frac{d}{{\mathrm{\λ}}_0}sin(\mathrm{\θ}\left)\right)\right\}\frac{sin\left(M\mathrm{\π}\right(\mathrm{\Δ}f\left(t-\mathrm{\τ}\right)+\frac{d}{{\mathrm{\λ}}_0}sin\left(\mathrm{\θ}\right)\left)\right)}{\sin \left(\mathrm{\π}\right(\mathrm{\Δ}f\left(t-\mathrm{\τ}\right)+\frac{d}{{\mathrm{\λ}}_0}sin\left(\mathrm{\θ}\right)\left)\right)},$

$a\left(\mathrm{\θ}\right)={\[1,\exp \left\{j2\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}sin\left(\mathrm{\θ}\right)\right\},...,\exp \left\{j2\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}(M-1)sin\left(\mathrm{\θ}\right)\right\}\]}^T.$

4. method according to claim 1, wherein the receiving pattern g in step (2b)_R(θ), its formula is：

$g_R\left(\mathrm{\θ}\right)=\exp \left\{j\left(M-1\right)\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}\left(\sin \left(\mathrm{\θ}\right)-\sin \left({\mathrm{\θ}}_0\right)\right)\right\}\frac{\sin \left(M\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}\left(\sin \left(\mathrm{\θ}\right)-\sin \left({\mathrm{\θ}}_0\right)\right)\right)}{\sin \left(\mathrm{\π}\frac{d}{{\mathrm{\λ}}_0}\left(\sin \left(\mathrm{\θ}\right)-\sin \left({\mathrm{\θ}}_0\right)\right)\right)}.$