Backscatter wideband signals from radar target

**Library:**Phased Array System Toolbox / Environment and Target

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.

`X`

— Wideband incident nonpolarized signalWideband 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 direction2-by-1 real-valued column vector of positive values | 2-by-

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.

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

**Data Types: **`Boolean`

`Out`

— Wideband reflected nonpolarized signalWideband 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`

`Backscatter pattern frequency vector (Hz)`

— Wideband backscatter pattern frequencies`[0,1e20]`

(default) | real-valued row vector of positive values in strictly increasing
orderSpecify 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-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-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) | 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 scalarSignal 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 scalarSignal carrier frequency, specified as a positive real-valued scalar. Units are in hertz.

`Inherit sample rate`

— Inherit sample rate from upstream blockson (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 scalarSpecify the signal sampling rate as a positive scalar. Units are in Hz.

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

**Data Types: **`double`

`Number of subbands`

— Number of processing subbands`64`

(default) | positive integerNumber 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).

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