CustomSurface
Description
CustomSurface
defines a custom surface object belonging to a radar
scenario, radarScenario
. The
object describes the extent and complex scattering response of the surface. You can use the
CustomSurface
object to update polarization scattering matrices, determine
surface heights, and test for occlusion. CustomSurface
objects are compatible with I/Q sensors generated by radarTransceiver
and
require that the scenario sensor, surface, and targets are polarized. Scattering matrices are
specific to a single frequency and viewing geometry and are therefore relevant to a single
sensor attached to the radarScenario
. Effects due to occlusion should be
modeled within the surface scattering matrix.
Creation
Create CustomSurface
objects using the customSurface
object function of the radarScenario
object.
Properties
Boundary
— Bounding rectangle of surface (degrees)
[-60 60; -60 60] (default) | finite 2-by-2 matrix
Extent of the rectangular custom surface, specified as a 2-by-2 finite matrix in units
of degrees. The bounding rectangle is defined by two 2-dimensional points in either
Cartesian or geodetic scenario coordinates. When the
IsEarthCentered
property of the radarScenario
object is specified as:
false
— Scenario coordinates are Cartesian. Specify the bounding rectangle as [minX
,maxX
,minY
maxY
].minX
andmaxX
are the minimum and maximum values in the x-direction of the reference frame, whereminX
<maxX
.minY
andmaxY
are the minimum and maximum values in the y-direction of the reference frame, whereminY
<maxY
.true
— Scenario coordinates are geodetic. Specify the bounding rectangle as [startLat
,endLat
,startLon
endLon
].startLat
andendLat
are the minimum and maximum latitudes of the geodetic frames, wherestartLat
andendLat
must lie in the interval [–90,90] andstartLat
<endLat
.startLon
andendLon
are the minimum and maximum longitudes of the geodetic frame and must lie in the interval [–180,180]. IfendLon
<startLon
, the object wrapsendLon
tostartLon
+360°
. Units are in degrees.
The resolution of surface patches within Boundary
is
given by resX
= lengthX
/
numX
for the x-dimension. Similarly, the resolution
for the y-dimension is resY
= lengthY
/
numY
. lengthX
and lengthY
are
calculated as the differences of the Boundary
coordinates in the
x- and y- dimensions, respectively. The
number of surface patches within the boundary is determined by the size of the
scattering matrix component Shh
. For the
x-dimension, numX
=
size
(Shh
,1
) and for the y-dimension, numY
=
size
(Shh
,2
). Note, the clutterGenerator
Resolution
property for the radarScenario
should
match the resolution of the custom surface to prevent resampling of the surface. For
example, if you have a surface that is 500-by-1 km in Cartesian space with a
clutterGenerator
Resolution
set to 50 m, the Boundary
could be
specified as [–200 300; 100 1100]
. For this case, the polarization
scattering matrix components (Shh
, Svv
,
Shv
, and Svh
) should be of size 20-by-10 m
because numX
= (maxX
–
minX
) / resX
, and numY
= (maxY
–
minY
) / resY
.
Data Types: double
CrossPolarization
— Polarization scattering matrix type
"full"
(default) | "symmetric"
Specify the polarization scattering matrix as either full
or
symmetric
. If CrossPolarization
is
full
, the polarization matrix components
Shh
, Svv
, Shv
, and
Svh
must all be specified. If
CrossPolarization
is set to symmetric
,
reciprocity is assumed (monostatic geometry), and the cross-polarization terms are
considered to be equivalent (Shv
= Svh
).
Therefore, Shv
is automatically set to the same value as
Svh
and cannot be modified.
Data Types: char
| string
Shh
— Polarization scattering matrix co-polarized HH
component
3-by-3-by-2 matrix of ones (default) | M
-by-N
-by-P
matrix
Specify the complex-valued polarization scattering matrix co-polarized
HH
component, where HH
represents horizontal
transmission and horizontal reception, as an
M
-by-N
-by-P
matrix.
M
indicates the number of components in the
x-direction, N
indicates the number of
components in the y-direction, and P
corresponds
to the number of elements in the Frequency
vector. The matrix is
bounded in space by the Boundary
property limits.
Data Types: double
Complex Number Support: Yes
Svv
— Polarization scattering matrix co-polarized VV
component
3-by-3-by-2 matrix of ones (default) | M
-by-N
-by-P
matrix
Specify the complex-valued polarization scattering matrix co-polarized
VV
component, where VV
represents vertical
transmission and vertical reception, as an
M
-by-N
-by-P
matrix.
M
indicates the number of components in the
x-direction, N
indicates the number of
components in the y-direction, and P
corresponds
to the number of elements in the Frequency
vector. The matrix is
bounded in space by the Boundary
property limits.
Data Types: double
Complex Number Support: Yes
Shv
— Polarization scattering matrix cross-polarized HV
component
3-by-3-by-2 matrix of ones (default) | M
-by-N
-by-P
matrix
Specify the complex-valued polarization scattering matrix cross-polarized
HV
component, where HV
represents horizontal
transmission and vertical reception, as an
M
-by-N
-by-P
matrix.
M
indicates the number of components in the
x-direction, N
indicates the number of
components in the y-direction, and P
corresponds
to the number of elements in the Frequency
vector. The matrix is
bounded in space by the Boundary
property limits.
Data Types: double
Complex Number Support: Yes
Svh
— Polarization scattering matrix cross-polarized VH
component
3-by-3-by-2 matrix of ones (default) | M
-by-N
-by-P
matrix
Specify the complex-valued polarization scattering matrix cross-polarized
VH
component, where VH
represents vertical
transmission and horizontal reception, as an
M
-by-N
-by-P
matrix.
M
indicates the number of components in the
x-direction, N
indicates the number of
components in the y-direction, and P
corresponds
to the number of frequencies in Frequency
. The matrix is bounded in
space by the Boundary
property limits.
Dependencies
To enable this property, set the CrossPolarization
property
to "full"
.
Data Types: double
Complex Number Support: Yes
Frequency
— Frequencies for the scattering matrix (Hz)
[0 1e20] (default) | length-P
row vector
Valid frequencies for the scattering matrix components
specified as a length-P
row
vector, where P
is the number of
frequencies. Frequency units are in hertz
(Hz).
Data Types: double
ReferenceHeight
— Surface reference height (m)
0 (default) | scalar
Reference height of surface height data, specified as a scalar. Surface heights are relative to the reference height. Units are in meters.
Data Types: double
Object Functions
updateScatteringMatrix | Update scattering matrices |
height | Height of point on surface |
occlusion | Test for occlusion of point by a surface |
Examples
Create Co-Polarized and Cross-Polarized Custom Surfaces
This example shows how to create a custom surface and update the polarization scattering matrices. Co-polarized and cross-polarized surfaces are compared.
Create Custom Surface
Create a co-polarized custom surface.
% Create a radar scenario rng('default'); scenario = radarScenario(IsEarthCentered=false); % Create a co-polarized custom surface bnds = [-600 570; 0 1.17e3]; Shh = zeros(40,40,2); Svv = ones(40,40,2); Shv = zeros(size(Shh)); srf = customSurface(scenario,Boundary=bnds, ... CrossPolarization='symmetric',Shh=Shh,Svv=Svv,Shv=Shv);
Collect I/Q Data
Create a vertically polarized radar I/Q sensor and collect data.
% Create a vertically polarized radar IQ sensor and attach to % a platform freq = 500e6; sweepBW = 5e6; fs = 2*sweepBW; wav = phased.LinearFMWaveform(SampleRate=fs, ... SweepBandwidth=sweepBW); rdr = radarTransceiver(Waveform=wav, ... MountingAngles=[-90 10 0], ... RangeLimits=[0 1.2e3]); element = phased.ShortDipoleAntennaElement; ula = phased.ULA(Element=element); configureAntennas(rdr,Combined=ula); rdr.TransmitAntenna.OperatingFrequency = freq; rdr.ReceiveAntenna.OperatingFrequency = freq; rdr.Receiver.SampleRate = fs; rdrplat = platform(scenario,Position=[0 0 10],Sensors=rdr); % Create clutter generator cluttergen = clutterGenerator(scenario,rdr,Resolution=30, ... RangeLimit=1.2e3); % Advance scenario and collect IQ advance(scenario); iq = receive(scenario); % Pulse compress mf = getMatchedFilter(rdr.Waveform); rngresp = phased.RangeResponse(SampleRate=fs); [iqPC,rngGrid] = rngresp(iq{1}(:,1),mf); figure nexttile plot(rngGrid,mag2db(abs(iqPC))) title(['Pulse 1, Element 1' newline 'Co-Polarized Surface']) xlabel('Range (m)') ylabel('Magnitude (dB)') grid on axis tight ylim([-80 60])
Update Scattering Matrix Values
Update scattering matrix values for HH and VV components to make the surface cross-polarized and collect I/Q data.
% Update scattering matrix values for HH and VV components. % Make the surface cross-polarized. Shh = ones(40,40,2); Svv = zeros(40,40,2); updateScatteringMatrix(srf,Shh=Shh,Svv=Svv) % Collect IQ iq = receive(scenario); [iqPC,rngGrid] = rngresp(iq{1}(:,1),mf); nexttile plot(rngGrid,mag2db(abs(iqPC))) title(['Pulse 2, Element 1' newline ... 'Cross-Polarized Surface']) xlabel('Range (m)') ylabel('Magnitude (dB)') grid on axis tight ylim([-80 60])
Version History
Introduced in R2024a
See Also
customSurface
| SurfaceManager
| radarScenario
| landSurface
| seaSurface
| clutterGenerator
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