Wideband Backscatter Radar Target

Backscatter wideband signals from radar target

• Library:

• Phased Array System Toolbox / Environment and Target

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Description

The Wideband Backscatter Radar Target block models the monostatic reflection of nonpolarized wideband electromagnetic signals from a radar target. The target radar cross-section (RCS) model includes all four Swerling target fluctuation models and a nonfluctuating model. You can model several targets simultaneously by specifying multiple RCS matrices.

Ports

Input

X — Wideband incident nonpolarized signal

N-by-M complex-valued matrix

Wideband incident nonpolarized signal, specified as an N-by-M complex-valued matrix. The quantity N is the number of signal samples, and M is the number of independent signals reflecting off the target. Each column contains an independent signal to be reflected from the target.

The size of the first dimension of the input matrix can vary to simulate a changing signal length. A size change can occur, for example, in the case of a pulse waveform with variable pulse repetition frequency.

Data Types: double
Complex Number Support: Yes

Ang — Incident signal direction

2-by-1 real-valued column vector of positive values | 2-by-M real-valued column vector of positive values

Incident signal direction, specified as a 2-by-1 or 2-by-M real-valued column matrix of positive values. Each column of Ang specifies the incident direction of the corresponding signal. The number of columns in Ang must match the number of independent signals in X. The columns take the form [AzimuthAngle;ElevationAngle]. Units are in degrees.

Data Types: double

Update — Enable update of RCS

false (default) | true

Option to enable updating of RCS values for fluctuation models, specified as false or true. When Update is true, a new RCS value is generated each time you run the block. If Update is false, the RCS remains unchanged.

Dependencies

To enable this port, set the Fluctuation model parameter to one of the Swerling models.

Data Types: Boolean

Output

Out — Wideband reflected nonpolarized signal

N-by-M complex-valued matrix

Wideband reflected nonpolarized signal, returned as an N-by-M complex-valued matrix. The quantity N is the number of signal samples, and M is the number of independent signals reflected from the target. Each column contains an independent signal reflected from the target.

Data Types: double

Parameters

Backscatter pattern frequency vector (Hz) — Wideband backscatter pattern frequencies

[0,1e20] (default) | real-valued row vector of positive values in strictly increasing order

Specify the frequencies used in the RCS matrix. The elements of this vector must be in strictly increasing order. The target has no response outside this frequency range. Frequencies are defined with respect to the physical frequency band, not the baseband. Frequency units are in Hz.

Azimuth angles (deg) — Azimuth angles

[-180:180] (default) | 1-by-P real-valued row vector | P-by-1 real-valued column vector

Azimuth angles used to define the angular coordinates of each column of the matrices specified by the RCS pattern (m^2) parameter. Specify the azimuth angles as a length P vector. P must be greater than two. Angle units are in degrees.

Example: [-45:0.1:45]

Data Types: double

Elevation angles (deg) — Elevation angles

[-90:90] (default) | 1-by-Q real-valued row vector | Q-by-1 real-valued column vector

Elevation angles used to define the angular coordinates of each row of the matrices specified by the RCS pattern (m^2) parameter. Specify the elevation angles as a length Q vector. Q must be greater than two. Angle units are in degrees.

Example: [-30:0.1:30]

Data Types: double

RCS pattern (m^2) — Radar cross-section pattern

ones(181,361) (default) | Q-by-P real-valued matrix | Q-by-P-by-K real-valued array | 1-by-P-by-K real-valued array | K-by-P real-valued matrix

Radar cross-section pattern, specified as a real-valued matrix or array.

Dimensions	Application
Q-by-P matrix	Specifies a matrix of RCS values as a function of Q elevation angles and P azimuth angles. The same RCS matrix is used for all frequencies.
Q-by-P-by-K array	Specifies an array of RCS patterns as a function of Q elevation angles, P azimuth angles, and K frequencies. If K = 1, the RCS pattern is equivalent to a Q-by-P matrix.
1-by-P-by-K array	Specifies a matrix of RCS values as a function of P azimuth angles and K frequencies. These dimension formats apply when there is only one elevation angle.
K-by-P matrix

• Q is the length of the vector specified by the Elevation angles (deg) parameter.

• P is the length of the vector specified by the Azimuth angles (deg) parameter.

• K is the number of frequencies specified by the Backscatter pattern frequency vector (Hz) parameter.

You can specify patterns for L targets by putting L patterns into a cell array. All patterns must have the same dimensions. The value of L must match the column dimensions of the signals passed as input into the block. You can, however, use one pattern to model L multiple targets.

RCS units are in square meters.

Example: [1,2;2,1]

Data Types: double

Fluctuation model — Target fluctuation model

Nonfluctuating (default) | Swerling1 | Swerling2 | Swerling3 | Swerling4

Target fluctuation model, specified as Nonfluctuating, Swerling1, Swerling2, Swerling3, or Swerling4. If you set this parameter to a value other than Nonfluctuating, you must pass either true or false into the Update Update port.

Propagation speed (m/s) — Signal propagation speed

physconst('LightSpeed') (default) | positive scalar

Signal propagation speed, specified as a real-valued positive scalar. The default value of the speed of light is the value returned by physconst('LightSpeed').

Data Types: double

Operating frequency (Hz) — Signal carrier frequency

300.0e6 (default) | positive real-valued scalar

Signal carrier frequency, specified as a positive real-valued scalar. Units are in hertz.

Inherit sample rate — Inherit sample rate from upstream blocks

on (default) | off

Select this parameter to inherit the sample rate from upstream blocks. Otherwise, specify the sample rate using the Sample rate (Hz) parameter.

Data Types: Boolean

Sample rate (Hz) — Sampling rate of signal

1e6 (default) | positive real-valued scalar

Specify the signal sampling rate as a positive scalar. Units are in Hz.

Dependencies

To enable this parameter, clear the Inherit sample rate check box.

Data Types: double

Number of subbands — Number of processing subbands

64 (default) | positive integer

Number of processing subbands, specified as a positive integer.

Example: 128

Simulate using — Block simulation method

Interpreted Execution (default) | Code Generation

Block simulation, specified as Interpreted Execution or Code Generation. If you want your block to use the MATLAB^® interpreter, choose Interpreted Execution. If you want your block to run as compiled code, choose Code Generation. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using Code Generation. Long simulations run faster with generated code than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink^® model is in Accelerator mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

Block Simulation	Simulation Behavior
	Normal	Accelerator	Rapid Accelerator
Interpreted Execution	The block executes using the MATLAB interpreter.	The block executes using the MATLAB interpreter.	Creates a standalone executable from the model.
Code Generation	The block is compiled.	All blocks in the model are compiled.

For more information, see Choosing a Simulation Mode (Simulink).