CN103729485B - A kind of wideband radar coherent clutter emulation mode based on dem data - Google Patents

Abstract

The invention belongs to technical field of radar simulation, be specifically related to a kind of wideband radar coherent clutter emulation mode based on dem data.It comprises the steps: to be loaded into simulation parameter；Read in the n-th track points data；Determine radar platform position and beam direction；In conjunction with antenna radiation pattern, determine radar illumination region；With d θ andBe respectively the angle of pitch and azimuthal angle interval along orientation to pitching to carrying out ground scatter dividing elements, calculate scattering unit area；According to radar equation, the echo voltage power of computing unit and amplitude；According to the clutter amplitude obtained, in conjunction with LFM characteristics of signals, calculate the echo voltage signal of scattering unit；Calculate scattering unit echo in the position of radar return data；The echo voltage signal of all scattering units is carried out optics coherence tomography；Judge whether n ＜ N sets up, if set up, then emulation terminates；Otherwise repeat step 2.The method, under considering surface relief situation of change, does not carry out the electromagnetism Scattering Calculation of complexity.

Description

A kind of wideband radar coherent clutter emulation mode based on dem data

Technical field

The invention belongs to technical field of radar simulation, be specifically related to a kind of wideband radar phase based on dem data Dry Clutter simulation method.

Background technology

Radar system is usually operated in certain ground environment, from radar return and the echo signal on ground And noise etc. enters receiver together, form the clutter of interference radar data reduction.Along with modern radar spirit Improving constantly of sensitivity and precision, radar system is affected the most increasing by ground clutter environment.Carry out The optimization design of radar system, it is necessary to understand and grasp the interaction of electromagnetic wave and clutter environment in depth.

Modern radar system typically use broadband linear frequency modulation (LFM) signal improve distance to resolution capability, Using beam antenna that LFM signal is launched, LFM signal is made with ground target and environment With, reflected signal is received by radar receiver, obtains one-dimensional High Range Resolution through pulse compression.During reception Need that echo-signal is carried out I road and sample in Q road simultaneously, obtain coherence data.

Existing radar clutter simulation method is broadly divided into two classes, and a class is analogy method based on signal processing, Do not consider the fluctuations on ground；Another kind of is method based on electromagnetism Scattering Calculation, but amount of calculation is the biggest.

Summary of the invention

It is an object of the invention to provide a kind of wideband radar coherent clutter emulation mode based on dem data, Under considering surface relief situation of change, do not carry out the electromagnetism Scattering Calculation of complexity, it is possible to the big rule of Fast simulation The radar echo signal of mould 3 D complex scene, can be radar system design and signal processing algorithm research carry For effectively supporting.

For reaching above-mentioned purpose, the technical solution used in the present invention is:

A kind of wideband radar coherent clutter emulation mode based on dem data, the method comprises the steps:

Step one: be loaded into simulation parameter, including radar platform motion flight path, speed, antenna beam point to, Ground grid dem data, and the wavelength of radar, pulsewidth, bandwidth, operating distance and antenna radiation pattern；

Step 2: read in the data of the n-th track points；

Step 3: determine radar platform position and beam direction；

Step 4: combine antenna radiation pattern, determines the irradiation area of radar；

Step 5: with d θ andBe respectively the angle of pitch and azimuthal angle interval along orientation to pitching to entering Row ground scatter dividing elements, the area of scattering unit is

Wherein, θ andRepresenting the angle of pitch under spherical coordinate system and azimuth respectively, r represents that radar is to scattering unit Distance；

Step 6: according to radar equation, the echo voltage power of computing unit and amplitude:

$P_r=\frac{P_t{G}^2\left(\mathrm{\θ}\right){\mathrm{\λ}}^2\mathrm{\σ}}{{\left(4\mathrm{\π}\right)}^3{r}^4}---\left(2\right)$

$A_i=\sqrt{P_r}---\left(3\right)$

Wherein: P_tRepresent radar transmission power, unit W；G (θ) represents that the antenna in surface units direction increases Benefit；λ represents radar operation wavelength, unit m；σ represents the scattering resonance state of surface units；R represents ground Unit is to the distance of radar, unit m；

Step 7: the clutter amplitude A obtained according to step 6_i, in conjunction with LFM characteristics of signals, it is calculated as follows The echo voltage signal of scattering unit:

Wherein,Represent initial phase, k_rRepresent the modulation rate of LFM signal, f_dRepresent Doppler frequency；

Step 8: calculate scattering unit echo in the position of radar return data

m_i=(int) { (r-R_start)/bin+0.5} (6)

Wherein, (int) represents rounding operation, R_startRepresenting the starting sample distance of radar, bin represents range gate Width；

Step 9: the echo voltage signal to all scattering units, carries out optics coherence tomography, the n-th track points Echo-signal is:

$S_n\left(t\right)=\underset{i}{\Σ}{S}_i\left(t\right)---\left(8\right)$

Step 10: judge whether n < N (N represents that whole flight path is counted) sets up, if set up, then imitative Really terminate；Otherwise repeat step 2.

In described step 6, the scattering resonance state σ following formula of surface units calculates

σ=σ₀ds (4)

Wherein, σ₀Represent the backscattering coefficient on ground.

In described step 8, bin calculates according to following formula

Bin=c/2/f_s (7)

Wherein, c represents the light velocity, and value is 3 × 10⁸m/s；f_sFor A/D sample rate；If r is ＜ R_start, then should The echo of unit is outside receiving window, it is impossible to is received, can directly give up.

Having the beneficial effect that acquired by the present invention

Wideband radar coherent clutter emulation mode based on dem data of the present invention, is considering surface relief Under situation of change, do not carry out the electromagnetism Scattering Calculation of complexity, it is possible to Fast simulation extensive 3 D complex scene Radar echo signal, can be radar system design and signal processing algorithm research provides and effectively supports.

Fig. 2 gives the Radar Clutter Signal simulation result of a typical environment, its I road and Q road signal tool Having typical LFM signal intensity characteristic, Fig. 3 gives and carries out the knot after pulse compression with frequency matching function Really, after the narrowest peak value fluctuations shows pulse compression, LFM signal has been removed by.

Accompanying drawing explanation

Fig. 1 is wideband radar coherent clutter emulation mode flow chart based on dem data of the present invention；

Fig. 2 is the Radar Clutter Signal simulation result of typical environment；

Fig. 3 is to carry out the result after pulse compression with frequency matching function；

Fig. 4 is that surface units divides geometric graph；

Fig. 5 is scatter echo superposition schematic diagram.

Detailed description of the invention

The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.

As it is shown in figure 1, wideband radar coherent clutter emulation mode based on dem data of the present invention includes Following steps:

Step one: be loaded into simulation parameter, mainly include that radar platform motion flight path, speed, antenna beam refer to To, ground grid dem data, and the wavelength of radar, pulsewidth, bandwidth, operating distance and antenna direction Figure etc.；

Step 2: read in the data of the n-th track points；

Step 3: determine radar platform position and beam direction；

Step 4: combine antenna radiation pattern, determines the irradiation area of radar；

Step 5: with d θ andBe respectively the angle of pitch and azimuthal angle interval along orientation to pitching to entering Row ground scatter dividing elements, as shown in Figure 4, the area of scattering unit is

Wherein, θ andRepresenting the angle of pitch under spherical coordinate system and azimuth respectively, r represents that radar is to scattering unit Distance；

Step 6: according to radar equation, the echo voltage power of computing unit and amplitude:

$P_r=\frac{P_t{G}^2\left(\mathrm{\&theta;}\right){\mathrm{\&lambda;}}^2\mathrm{\&sigma;}}{{\left(4\mathrm{\&pi;}\right)}^3{r}^4}---\left(2\right)$

$A_i=\sqrt{P_r}---\left(3\right)$

Wherein: P_tRepresent radar transmission power, unit W；G (θ) represents that the antenna in surface units direction increases Benefit；λ represents radar operation wavelength, unit m；σ represents the scattering resonance state of surface units；R represents ground Unit is to the distance of radar, unit m；

Wherein, the scattering resonance state σ following formula of surface units calculates

σ=σ₀ds (4)

Wherein, σ₀Represent the backscattering coefficient on ground.

Step 7: the clutter amplitude A obtained according to step 6_i, in conjunction with LFM characteristics of signals, it is calculated as follows The echo voltage signal of scattering unit:

Wherein,Represent initial phase, k_rRepresent the modulation rate of LFM signal, f_dRepresent Doppler frequency.

Step 8: calculate scattering unit echo in the position of radar return data

m_i=(int) { (r-R_start)/bin+0.5} (6)

Wherein, (int) represents rounding operation, R_startRepresenting the starting sample distance of radar, bin represents range gate Width, bin calculates according to following formula

Bin=c/2/f_s (7)

Wherein, c represents the light velocity, and value is 3 × 10⁸m/s；f_sFor A/D sample rate；If r is ＜ R_start, then this is single The echo of unit is outside receiving window, it is impossible to is received, can directly give up.

Step 9: the echo voltage signal to all scattering units, carries out optics coherence tomography, the n-th track points Echo-signal is:

$S_n\left(t\right)=\underset{i}{\&Sigma;}{S}_i\left(t\right)---\left(8\right)$

During optics coherence tomography, it should be noted that the scattering unit echo calculated in step 8 position in radar return data Put, as shown in Figure 5.

Step 10: judge whether n < N (N represents that whole flight path is counted) sets up, if set up, then imitative Really terminate；Otherwise repeat step 2.

Claims (3)

1. a wideband radar coherent clutter emulation mode based on dem data, it is characterised in that:

The method comprises the steps:

Step one: be loaded into simulation parameter, including radar platform motion flight path, speed, antenna beam point to, Ground grid dem data, and the wavelength of radar, pulsewidth, bandwidth, operating distance and antenna radiation pattern；

Step 2: read in the data of the n-th track points；

Step 3: determine radar platform position and beam direction；

Step 4: combine antenna radiation pattern, determines the irradiation area of radar；

Step 5: with d θ andBe respectively the angle of pitch and azimuthal angle interval along orientation to pitching to entering Row ground scatter dividing elements, the area of scattering unit is

Wherein, θ andRepresenting the angle of pitch under spherical coordinate system and azimuth respectively, r represents that radar is to scattering unit Distance；

Step 6: according to radar equation, the echo voltage power of computing unit and amplitude:

$P_r=\frac{P_t{G}^2\left(\mathrm{\&theta;}\right){\mathrm{\&lambda;}}^2\mathrm{\&sigma;}}{{\left(4\mathrm{\&pi;}\right)}^3{r}^4}---\left(2\right)$

$A_i=\sqrt{P_r}---\left(3\right)$

Wherein: P_tRepresent radar transmission power, unit W；G (θ) represents that the antenna in surface units direction increases Benefit；λ represents radar operation wavelength, unit m；σ represents the scattering resonance state of surface units；R represents ground Unit is to the distance of radar, unit m；I represents ground scatter unit number；

Step 7: the clutter amplitude A obtained according to step 6_i, in conjunction with LFM characteristics of signals, it is calculated as follows The echo voltage signal of scattering unit:

Wherein,Represent initial phase, k_rRepresent the modulation rate of LFM signal, f_dRepresent Doppler frequency；J table Show imaginary unit；

Step 8: calculate scattering unit echo in the position of radar return data

m_i=(int) { (r-R_start)/bin+0.5} (6)

Wherein, (int) represents rounding operation, R_startRepresenting the starting sample distance of radar, bin represents range gate Width；

Step 9: the echo voltage signal to all scattering units, carries out optics coherence tomography, the n-th track points Echo-signal is:

$S_n\left(t\right)=\underset{i}{\&Sigma;}{S}_i\left(t\right)---\left(8\right)$

Step 10: judge whether n < N sets up, N represents that whole flight path is counted, if set up, then emulation Terminate；Otherwise repeat step 2.

A kind of wideband radar coherent clutter emulation side based on dem data the most according to claim 1 Method, it is characterised in that: in described step 6, the scattering resonance state σ following formula of surface units calculates

σ=σ₀ds (4)

Wherein, σ₀Represent the backscattering coefficient on ground.

A kind of wideband radar coherent clutter emulation side based on dem data the most according to claim 1 Method, it is characterised in that: in described step 8, bin calculates according to following formula

Bin=c/2/f_s (7)

Wherein, c represents the light velocity, and value is 3 × 10⁸m/s；f_sFor A/D sample rate；If r is ＜ R_start, then should The echo of unit is outside receiving window, it is impossible to is received, can directly give up.