surfaceReflectivityLand

Normalized reflectivity of land surface

Since R2022a

Description

This System object™ computes the normalized reflectivity of a land surface. Normalized reflectivity is the radar cross-section of a unit area of a surface. Multiplying by the total area of a surface or the illuminated area of a surface gives the total radar cross-section. Normalized reflectivity is also referred to as surface σ⁰ and is a function of frequency and grazing angle.

To compute the normalized reflectivity:

1. Create the surfaceReflectivityLand object and set its properties.

2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

Creation

Syntax

refl = surfaceReflectivityLand

refl = surfaceReflectivityLand(Name=Value)

Description

refl = surfaceReflectivityLand creates a normalized reflectivity object refl for a land surface. Use this object to generate a normalized radar cross section (NRCS). This syntax creates a normalized reflectivity object with a 'Barton' land Model and a 'Flatland' LandType.

It is not recommended to use models outside of their defined validity regions. See the Model property description for more information about available models and at what frequency and grazing angles the models are valid. See the LandType property help for information about applicable land types for each model.

refl = surfaceReflectivityLand(Name=Value) creates a normalized reflectivity object for a land surface with the specified property Name set to the specified Value. You can specify additional name-value pair arguments in any order as (Name1=Value1, … ,NameN=ValueN).

Example: refl = surfaceReflectivityLand(Model="GIT",LandType="Soil",SurfaceHeightStandardDeviation=1) creates a normalized reflectivity object for land using the GIT model with a LandType of Soil and a SurfaceHeightStandardDeviation of 1.

Properties

Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

EnablePolarization — Enable polarization

false (default) | true

Enable polarization, specified as false or true.

• When true, the System object enables the specification of cross-polarization components to help form a complete polarimetric normalized radar cross-section (NRCS) reflectivity matrix σ⁰ of the form

  $${\sigma }^0=\left[\begin{array}{cc}{\sigma }_{HH}^0& {\sigma }_{HV}^0\\ {\sigma }_{VH}^0& {\sigma }_{VV}^0\end{array}\right]$$

  where σ⁰_HV and σ⁰_VH are the cross-polarization components specified by the ReflectivityHV and ReflectivityVH properties, respectively. The remaining components, σ⁰_HH and σ⁰_VV, are determined by the particular model set by the Model property.

• When false, the System object lets you specify the mean polarization using the Polarization property based on the selected Model.

CrossPolarization — Cross-polarization components

'Full' (default) | 'Symmetric'

Cross-polarization components, specified as 'Full' or 'Symmetric'.

When the CrossPolarization property is set to 'Full':

• If the Model property is not set to 'ConstantGamma', the ReflectivityHV and ReflectivityVH properties are applicable, and unique speckle values are generated for all reflectivity components (σ⁰_HH, σ⁰_HV, σ⁰_VH, and σ⁰_VV).

• If the Model property set to 'ConstantGamma', the CrossPolarization property only affects speckle generation.

When the CrossPolarization property is set to 'Symmetric' then reciprocity applies for monostatic geometry and the cross-polarization terms are equal, σ⁰_HV = σ⁰_VH.

• If the Model property is not 'ConstantGamma', only the ReflectivityHV property can be set. The ReflectivityVH property is assumed to be equal to the ReflectivityHV property. In addition, speckle values corresponding to the HV and VH components are equal.

• If the Model property is 'ConstantGamma', setting the CrossPolarization property to 'Symmetric' requires that the HV and VH components of the Gamma property are equal and the object returns equal HV and VH speckle values.

Dependencies

To enable this property, set the EnablePolarization property to true.

Data Types: char | string

Model — Land reflectivity model

'Barton' (default) | 'APL' | 'Billingsley' | 'GIT' | 'Morchin' | 'Nathanson' | 'UlabyDobson' | 'ConstantGamma'

Land reflectivity model, specified as 'Barton', 'APL', 'Billingsley', 'GIT', 'Morchin', 'Nathanson', 'Nathanson', 'UlabyDobson', or 'ConstantGamma'. Descriptions of the models and land types are shown in the table Land Reflectivity Models and Land Types.

LandType — Land type

char | string

Land type, specified as a char or string. The allowable land type and their default values depend on the Model property. If the Model property is not specified, the default land type is 'Flatland'. Descriptions of the models and land types are shown in the table Land Reflectivity Models and Land Types.

Data Types: char | string

SurfaceHeightStandardDeviation — Surface height standard deviation

0 (default) | scalar

Standard deviation of the surface height, specified as a positive scalar. Units are in meters.

Dependencies

To enable this property, set the Model property to 'GIT' and specify the LandType.

Data Types: double

Polarization — Mean polarization of reflectivity model

'H' (default) | 'V'

Mean polarization of reflectivity model, specified as 'H' or 'V'. 'H' designates horizontal polarization and 'V' designates vertical polarization.

Dependencies

To enable this property, set the Model property to 'UlabyDobson' and set the EnablePolarization property to false.

Data Types: char | string

Gamma — Terrain gamma value

-20 (default) | real scalar | 2-by-2 real-valued matrix

Gamma value used in the constant gamma clutter reflectivity model, specified as a scalar or 2-by-2 real-valued matrix. The gamma value depends on both terrain type and operating frequency. The default value is representative of flat land. Units are in dB.

• If EnablePolarization is false, specify Gamma as a scalar.

• If EnablePolarization is true, specify Gamma as a scalar or a 2-by-2 matrix, such that Gamma = [GammaHH GammaHV; GammaVH GammaVV]. When specified as a scalar, it is assumed that all polarimetric components are equal.

  To control the speckle values for the polarimetric Gamma case, set the CrossPolarization property to 'Full' for unique speckle values for all components or 'Symmetric' to set the speckle value for HV = VH.

Example: -15

Dependencies

To enable this property, set the Model property to 'ConstantGamma'.

Data Types: double

ReflectivityHV — HV normalized radar cross section

zeros(91,2) (default) | Q-by-R real-valued matrix

Normalized radar cross section (NRCS), for the cross-polarized σ⁰_HV component, where HV represents horizontal transmission and vertical reception. Q corresponds to the number of angles in either the GrazingAngle or DepressionAngle property. R corresponds to the number of frequencies in the Frequency property. The σ⁰_HH and σ⁰_VV components are derived from the selected model designated by the Model property and associated properties. Units are m²/m².

Dependencies

To enable this property, set the EnablePolarization property to true and set the Model property is anything other than 'ConstantGamma'.

Data Types: double

ReflectivityVH — VH normalized radar cross section

zeros(91,2) (default) | Q-by-R real-valued matrix

Normalized radar cross section (NRCS), for the cross-polarized σ⁰_VH component, where VH represents horizontal transmission and vertical reception. Q corresponds to the number of angles in either the GrazingAngle or DepressionAngle property. R corresponds to the number of frequencies in the Frequency property. The σ⁰_HH and σ⁰_VV components are derived from the selected model designated by the Model property and associated properties. Units are m²/m².

Dependencies

To enable this property, set the CrossPolarization property to 'Full'.

Frequency — Radar frequency

[0 1e20] (default) | length-R row vector

Valid frequencies for the normalized reflectivity, specified as a length-R row vector. Frequency units are in Hz.

Example: [1e6,10e6]

Dependencies

To enable this property, set the EnablePolarization property to true and set the Model property to any value except 'Constant Gamma'.

Data Types: double

GrazingAngle — Grazing angles

[0:90] (default) | length-Q row vector

Grazing angles, as a length-Q row vector. Units are in degrees.

Example: [45:60]

Dependencies

To enable this property, set the EnablePolarization property to true and set the Model property any value except 'Billingsley' or 'Constant Gamma'.

Data Types: double

DepressionAngle — Depression angles

[0:90] (default) | length-Q row vector

Depression angles, specified as a length-Q row vector. Units are in degrees.

Example: [10:5:80]

Dependencies

To enable this property, set the EnablePolarization property to true and set the Model property to 'Billingsley'.

Data Types: double

Speckle — Speckle distribution type

'None' (default) | 'Lognormal' | 'Rayleigh' | 'Weibull'

Speckle distribution type, specified as 'None', 'Lognormal', 'Rayleigh', or 'Weibull'. Speckle is a multiplicative factor used to make clutter data appear noisier and is especially applicable to imaging applications.

Speckle is correlated with clutter RCS and is applied as I = σ*n, where σ represents the clutter RCS and n represents random numbers, which are often drawn from an independent identically-distributed unity mean noise statistical distribution.

• None – No speckle is applied.

• Lognormal – Speckle has a lognormal distribution. Define the distribution using the SpeckleMean and SpeckleStandardDeviation properties. Default values of these properties create speckle with a normalized mean lognormal distribution.

• Rayleigh – Speckle has a Rayleigh distribution. Define the distribution using the SpeckleScale property. The default value of this property creates speckle with a unit mean Rayleigh distribution.

• Weibull – Speckle has a Weibull distribution. Define the distribution using the SpeckleScale and SpeckleShape properties. The default values of these properties create speckle with a unit mean Rayleigh distribution.

Data Types: char | string

SpeckleMean — Mean of value of lognormal-distributed speckle

-0.5*log(2) (default) | scalar

Mean value of lognormal-distributed speckle, specified as a scalar.

Dependencies

To enable this property, set the Speckle property to 'Lognormal'.

Data Types: double

SpeckleStandardDeviation — Standard deviation of lognormal-distributed speckle

sqrt(log(2)) (default) | non-negative scalar

Standard deviation of lognormal-distributed speckle, specified as a non-negative scalar.

Dependencies

To enable this property, set the Speckle property to 'Lognormal'.

Data Types: double

SpeckleScale — Scale parameter for Weibull and Rayleigh speckle distribution

sqrt(4/π) (default) | non-negative scalar

Scale parameter for speckle for the Rayleigh and Weibull distributions, specified as a positive scalar.

Dependencies

To enable this property, set the Speckle property to 'Rayleigh' or 'Weibull'.

Data Types: double

SpeckleShape — Shape value for Weibull distribution

2 (default) | positive scalar

Shape value for the Weibull speckle distribution, specified as a positive scalar.

Dependencies

To enable this property, set the Speckle property to 'Weibull'.

Data Types: double

Usage

Syntax

nrcs = refl(ang,freq)

[nrcs,speck] = refl(graz,freq)

Description

nrcs = refl(ang,freq) returns the normalized radar cross section nrcs of a surface at angle ang and frequency freq. When the Model property is not set to 'Billingsley', ang is interpreted as a grazing angle. Then, it is interpreted as a depression angle.

[nrcs,speck] = refl(graz,freq) also returns the multiplicative speckle speck.

Input Arguments

graz — Grazing or depression angle

Q-length vector of real values

Grazing or depression angle of a surface relative to the radar, specified as a Q-length row vector of real values. When the land Model property is set to 'Billingsley', the angle is interpreted as a depression angle depressionang between –90° and 90°. For all other models, the angle is interpreted as a grazing angle grazingang ranging from 0° to 90°. Units are in degrees.

freq — Transmitted frequencies

R-length vector of positive values

Transmitted frequencies, specified as a positive scalar or R-length vector of positive values. Units are in Hz.

Example: freq = 70e9

Output Arguments

nrcs — Normalized surface reflectivity

real-valued Q-by-R matrix | real-valued 2-by-2-by-Q-by-R array

Normalized surface reflectivity , returned as a real-valued Q-by-R matrix or a real-valued 2-by-2-Q-by-R array. Q is the length of the grazing angle graz or, for land surfaces only, depression angle. R is the length of the frequency vector freq. nrcs is dimensionless but often expressed as m²/m². Normalized reflectivity is also called normalized radar cross section (NRCS).

• For the non-polarimetric reflectivity case, nrcs is returned as a real-valued Q-by-R matrix.

• For the polarimetric reflectivity case, nrcs is returned as a real-valued 2-b-2-byQ-by-R array. For each value of Q and R, NRCS forms a polarimetric normalized radar cross-section (NRCS) reflectivity matrix s of the form

  $${\sigma }^0=\left[\begin{array}{cc}{\sigma }_{HH}^0& {\sigma }_{HV}^0\\ {\sigma }_{VH}^0& {\sigma }_{VV}^0\end{array}\right]$$

  where S_HV and S_VH are the cross-polarization components specified by the ReflectivityHV and ReflectivityVH properties. The σ⁰_HH and σ⁰_VV components are derived from the specified model as set by the Model property

The returned normalized reflectivity for cross-polarization components σ⁰_HV and σ⁰_VH is calculated using nearest neighbor interpolation at a given grazing angle and frequency. To avoid interpolation errors, the normalized reflectivity values in the ReflectivityHV and ReflectivityVH properties should cover grazing angles from 0–90 degrees and all expected frequencies.

Dependencies

To enable the polarimetric reflectivity, set the EnablePolarization to true.

speck — Multiplicative speckle

Q-by-R matrix | 2-by-2-by-Q-by-R MATLAB^® array

Multiplicative speckle, returned as a Q-by-R matrix where Q is the length of the angles vector in ang and R is the length of the frequency vector in freq. For the polarimetric reflectivity case, speckle is returned as a 2-by-2-by-Q-by-R MATLAB array.

Data Types: double

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

Common to All System Objects

step	Run System object algorithm
release	Release resources and allow changes to System object property values and input characteristics
reset	Reset internal states of System object

Examples

Surface Reflectivity of Default Land Model

Plot the normalized radar cross-section for grazing angles from 5 to 90 degrees. Assume the default 'Barton' land Model and 'Flatland' LandType. Set the radar frequency to 1 GHz.

grazAng = 5:90;
freq = 1e9;
reflectivity = surfaceReflectivityLand;
nrcs = reflectivity(grazAng,freq);
plot(grazAng,pow2db(nrcs))
grid on
xlabel('Grazing Angle (deg)')
ylabel('NRCS (dB m^2/m^2)')
title('Barton Land Model with Flat Land Type')

Create Reflective Land Surface in Radar Scenario

Configure a radarscenario to simulate a reflective land surface. Add a land surface object to define the physical properties of the scenario surface. The surface is a simple 200-by-200 meter rectangle. Use the surfaceReflectivityLand function to create a constant-gamma reflectivity model with a gamma value of -10 dB. Use the scenario landSurface method to add the rectangular land region and the radar reflectivity model to the scenario. Use a surface reference height of 16 meters.

scene = radarScenario(UpdateRate = 0, IsEarthCentered = false);
refl = surfaceReflectivityLand(Model = "ConstantGamma", Gamma = -10);
srf = landSurface(scene,RadarReflectivity = refl, ...
    Boundary=[-100 100; -100 100],ReferenceHeight = 16)

srf = 
  LandSurface with properties:

        RadarReflectivity: [1x1 surfaceReflectivityLand]
    ReflectionCoefficient: [1x1 radar.scenario.SurfaceReflectionCoefficient]
          ReflectivityMap: 1
          ReferenceHeight: 16
                 Boundary: [2x2 double]
                  Terrain: []

Surface Reflectivity of GIT Land Model

Create a normalized reflectivity object using the GIT 'Model' and a 'Soil' land type. Obtain the normalized radar cross-section at a frequency of 3 GHz over grazing angles from 20 to 60 degrees. Assume a surface height standard deviation of two meters. Plot the surface reflectivity.

grazAng = 20:60;
freq = 10e9;
reflectivity = surfaceReflectivityLand(Model="GIT", ...
    LandType="Soil",SurfaceHeightStandardDeviation=2);
nrcs = reflectivity(grazAng,freq);
plot(grazAng,pow2db(nrcs))
grid on
xlabel('Grazing Angle (deg)')
ylabel('NRCS (dB m^2/m^2)')
title('GIT Model')

Surface Reflectivity of Billingsley Land Model

Create a normalized reflectivity object using the Billingsley 'Model' and a 'LowReliefRural' land type. Obtain the normalized radar cross-section at a frequency of 3 GHz over depression angles from 0.1 to 3 degrees. Plot the surface reflectivity.

    depAng = 0.1:0.1:2;
    freq = 3e9; 
    reflectivity = surfaceReflectivityLand(Model="Billingsley", ...
         LandType="LowReliefRural");
    nrcs = reflectivity(depAng,freq);
    plot(depAng,pow2db(nrcs))
    grid on
    xlabel('Depression Angle (deg)')
    ylabel('NRCS (dB m^2/m^2)')
    title('Billingsley Model')

Surface Reflectivity of Ulaby-Dobson Land Model

Create a normalized reflectivity object using the Ulaby-Dobson model for a grass land type. Obtain the normalized radar cross-section for both vertical and horizontal polarizations at a frequency of 10 GHz over grazing angles from 1 to 10 degrees. Plot the surface reflectivities.

grazAng = 1:0.1:10;
freq = 10e9;
reflectivity_v = surfaceReflectivityLand(Model="UlabyDobson", ...
    LandType="Grass",Polarization="V");
nrcs_v = reflectivity_v(grazAng,freq);
reflectivity_h = surfaceReflectivityLand(Model="UlabyDobson", ...
    LandType="Grass",Polarization="H");
nrcs_h = reflectivity_h(grazAng,freq);
plot(grazAng,pow2db(nrcs_v))
hold on
plot(grazAng,pow2db(nrcs_h))
grid on
legend('Vertical Polarization','Horizontal Polarization')
xlabel('Grazing Angle (deg)')
ylabel('NRCS (dB m^2/m^2)')
title('Ulaby-Dobson Model')

Create Land Surface in Radar Scenario

Create a surface with two hills. Plot the surface on a 200-by-200 meter grid with grid points one meter apart. Add the surface to a radar scenario. Assume the surface has a radar reflectivity defined by a constant gamma model.

[x,y] = meshgrid(linspace(-100,100,201));
ht1 = 40*exp(-(x.^2 + y.^2)/30^2);
ht2 = 100*exp(-((x-60).^2 + y.^2)/25^2);
ht = ht1 + ht2;
p = surfc(x(1,:),y(:,1),ht);
axis equal
axis tight
shading interp
simTime = 3;
scene = radarScenario(UpdateRate = 1, ...
    IsEarthCentered = false,StopTime = simTime);
gammaDB = surfacegamma('Flatland');
refl = surfaceReflectivityLand(Model = 'ConstantGamma',Gamma = gammaDB);
srf = landSurface(scene,RadarReflectivity = refl, ...
    Terrain = ht,Boundary = [-100,100;-100,100]);

Use surface manager to identify the surface.

scene.SurfaceManager

ans = 
  SurfaceManager with properties:

    EnableMultipath: 0
       UseOcclusion: 1
           Surfaces: [1x1 radar.scenario.LandSurface]

scene.SurfaceManager.Surfaces

ans = 
  LandSurface with properties:

        RadarReflectivity: [1x1 surfaceReflectivityLand]
    ReflectionCoefficient: [1x1 radar.scenario.SurfaceReflectionCoefficient]
          ReflectivityMap: 1
          ReferenceHeight: 0
                 Boundary: [2x2 double]
                  Terrain: [201x201 double]

Obtain and plot the height of the surface at the point (50,-30).

xt = 50;
yt = -30;
htx = height(srf,[xt,yt])

htx = 
21.1046

hold on
plot3(xt,yt,htx+5,'ow','MarkerFaceColor','r')
xlabel('x')
ylabel('y')
hold off

Display Reflectivity Matrix for Land

Create a land normalized reflectivity object using the Ulaby-Dobson model and a grass land type. Enable polarization and specify the cross-polarization reflectivity. Obtain the NRCS at a frequency of 10 GHz over grazing angles from 1 to 10 degrees. Plot the reflectivities.

grazAng = 0:0.1:20; 
freq = 10e9;
surf = surfaceReflectivityLand(Model='UlabyDobson', ...
    LandType='Grass',EnablePolarization=true, ...
    GrazingAngle=0:.1:90,Frequency=[100,1e6,11e6], ...
    ReflectivityHV=0.05*sind(0:.1:90)'*[1 1 1], ...
    ReflectivityVH=0.04*sind(0:.1:90)'*[1 1 1])

surf = 
  surfaceReflectivityLand with properties:

    EnablePolarization: 1
     CrossPolarization: 'Full'
                 Model: 'UlabyDobson'
              LandType: 'Grass'
        ReflectivityHV: [901x3 double]
        ReflectivityVH: [901x3 double]
             Frequency: [100 1000000 11000000]
          GrazingAngle: [0 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1 1.1000 1.2000 1.3000 1.4000 1.5000 1.6000 1.7000 1.8000 1.9000 2 2.1000 2.2000 2.3000 2.4000 2.5000 2.6000 2.7000 2.8000 2.9000 3 3.1000 ... ] (1x901 double)
               Speckle: 'None'

nrcs = surf(grazAng,freq);
plot(grazAng,pow2db(squeeze(nrcs(1,1,:))), ...
    grazAng,pow2db(squeeze(nrcs(2,2,:))), ...
    grazAng,pow2db(squeeze(nrcs(1,2,:))), ...
    grazAng,pow2db(squeeze(nrcs(2,1,:))))
legend('HH','VV','HV','VH');
grid on
xlabel('Grazing Angle (deg)')
ylabel('NRCS (dB m^2/m^2)')
title('Ulaby-Dobson Model for Land Surface')

More About

Land Reflectivity Models and Land Types

Model	Land Type	Range of Validity	Settable Properties
'Barton' – Constant-gamma mathematical model generally applicable over medium grazing angles. 'Barton' is the default model. See [1] [2], and [3].	'RuggedMountains' 'Mountains' 'Metropolitan' 'Urban' 'WoodedHills' 'RollingHills' 'Woods' 'Farm' 'Desert' 'Flatland' (default for model) 'Smooth'	Grazing angle 20 – 60 degrees Frequency 1 – 10 GHz	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'APL' – This model also known as the ADSAM model. Low-fidelity constant-gamma mathematical model that includes specular scattering. See [4].	'Urban' 'HighRelief' 'LowRelief' (default for model)	Grazing angle 0 – 90 degrees Frequency 1 – 100 GHz	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'Billingesley' – High-validity empirical model generally applicable for low depression angles less than 2 degrees. See [5].	'LowReliefRural' (default for model) 'LowReliefForest' 'Farm' 'Desert' 'Marsh' 'Grassland' 'HighReliefRural' 'HighReliefForest' 'Mountains' 'Urban' 'LowReliefUrban'	Depression angle -0.75 – 2 degrees Frequency – VHF (0.030 – 0.3), UHF (0.3 – 1), L (1 -- 2), S (2 - 4), X (8 - 12) GHz	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'GIT' – Georgia Institute of Technology semi-empirical model that takes into account terrain roughness. Generally applicable for medium grazing angles. See [6]	'Soil' (default for Model) 'Grass' 'TallGrass' 'Trees' 'Urban'	Grazing angle 20 – 65 degrees Frequency 3 – 15 GHz	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape SurfaceHeightStandardDeviation
'Morchin' – Mathematical model generally applicable for high grazing angles for frequencies from UHF to C-band. See [7].	'Desert' 'Farm' (default for Model) 'Woods' 'Mountains'	Grazing angle 70 – 90 degrees Frequencies UHF (0.3 – 1) L (1 – 2) S (2 – 4) C (4 – 8)	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'Nathanson' – Applicable up to Ka band for low grazing angle surface radars and medium grazing angle airborne radars for low mountains, farmland, and wooded areas. See [3].	'Desert' 'Farm' (default for Model) 'Woods' 'Jungle' 'RollingHills' 'Urban'	Grazing angle 0 – 60 degrees Frequency L (1 – 2). S ( 2 – 4), C (4 – 8), X (8 --12), Ku (12 --18), Ka (32 -- 36) GHz	LandType Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'UlabyDobson' – High-validity semi-empirical model for low to medium grazing angles covering L-band to Ku, taking into account polarization. See [8].	'Soil' (default for Model) 'Grass' 'Shrubs' 'ShortVegetation'	Grazing angle 0 – 60 degrees Frequency L (1 – 2), S ( 2 – 4), C (4 – 8), X (8 --12), Ku (12 --18) GHz	LandType Polarization Speckle SpeckleMean SpeckleStandardDeviation SpeckleScale SpeckleShape
'ConstantGamma' – Mathematical model for the normalized reflectivity. See Constant Gamma Model.			Gamma

Constant Gamma Model

The constant-gamma model expresses a simple analytic relationship between the normalized radar cross-section and grazing angle.

σ = 10^(γ/10)sin(θ)

γ is defined by the Gamma property and θ is the grazing angle input argument graz given in degrees. The default value of Gamma is –20, which is representative of flat land.

Speckle Model

Speckle is modeled as an uncorrelated, multiplicative factor I = σ∙n, where σ represents the clutter RCS and n are independent identically distributed (IDD) mean noise samples with unity mean. Because speckle is correlated with underlying terrain RCS, it is usually applied to radar intensity. The speckle noise models include Weibull, Rayleigh, and lognormal.

References

[1] Barton, David Knox. Radar Equations for Modern Radar. Artech House, 2013.

[2] Long, Maurice W. Radar Reflectivity of Land and Sea. 3rd ed, Artech House, 2001.

[3] Nathanson, Fred E., et al. Radar Design Principles: Signal Processing and the Environment. 2. ed., Repr, Scitech Publ, 2004.

[4] Reilly, J. P., R. L. McDonald, and G. D. Dockery. "RF-Environment Models for the ADSAM Program." Report No. A1A97U-070, Laurel, MD: Johns Hopkins University Applied Physics Laboratory, August 22, 1997.

[5] Billingsley, J. Barrie. Low-Angle Radar Land Clutter: Measurements and Empirical Models. William Andrew Pub. : SciTech Pub. ; Institution of Electrical Engineers, 2002.

[6] Richards, M. A., et al., editors. Principles of Modern Radar. SciTech Pub, 2010.

[7] Morchin, Fred E., J. Patrick Reilly, and Marvin Cohen. Radar Design Principles: Signal Processing and the Environment. 2nd ed. New York: McGraw-Hill, 1991.

[8] Ulaby, Fawwaz T., and M. Craig Dobson. Handbook of Radar Scattering Statistics for Terrain. Artech House, 1989.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2022a