# DPCA Canceller

Displaced phase center array (DPCA) pulse canceller for a uniform linear array

**Library:**Phased Array System Toolbox / Space-Time Adaptive Processing

## Description

The DPCA Canceller block filters clutter impinging on a uniform linear array using a displaced phase center array pulse canceller.

## Ports

### Input

`X`

— Input signal

*M*-by-*N*-by-*P*
complex-valued matrix

Input signal, specified as an
*M*-by-*N*-by-*P*
complex-valued array. *M* is the number of range
samples, *N* is the number of channels, and
*P* is the number of pulses.

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

`Idx`

— Index of range cells

positive integer

Index of range cells to compute processing weights.

**Example: **`1`

**Data Types: **`double`

`PRF`

— Pulse repetition frequency

positive scalar

Pulse repetition frequency of current pulse, specified as a positive scalar.

#### Dependencies

To enable this port, set the **Specify PRF as**
parameter to `Input port`

.

**Data Types: **`double`

`Ang`

— Targeting direction

`2`

-by-`1`

real-valued
vector

Targeting direction, specified as a
`2`

-by-*1* real-valued vector. The
vector takes the form of
`[AzimuthAngle;ElevationAngle]`

. Angle units are in
degrees. The azimuth angle must lie between –180° and 180°, inclusive,
and the elevation angle must lie between –90° and 90°, inclusive. Angles
are defined with respect to the local coordinate system of the
array.

#### Dependencies

To enable this port, set the **Specify direction
as** parameter to `Input port`

.

**Data Types: **`double`

`Dop`

— Targeting Doppler frequency

scalar

Targeting Doppler frequency of current pulse, specified as a scalar.

#### Dependencies

This port appears when the **Output pre-Doppler
result** check box is cleared and the **Specify
targeting Doppler as** parameter is set to
`Input port`

.

**Data Types: **`double`

### Output

`Y`

— Beamformed output

*M*-by-1 complex-valued vector

Processing output, returned as an
*M*-by-*1* complex-valued vector.
The quantity *M* is the number of range samples in the
input port `X`

.

**Data Types: **`double`

**Complex Number Support: **Yes

`W`

— Processing weights

length *N***P* complex-valued
vector

Processing weights, returned as Length
*N***P* complex-valued vector. The
quantity *N* is the number of channels and
*P* is the number of pulses. When the
**Specify sensor array as** parameter is set to
`Partitioned array`

or ```
Replicated
subarray
```

, *N* represents the number of
subarrays. *L* is the number of desired beamforming
directions specified in the `Ang`

input port or by the
**Beamforming direction (deg)** parameter. There is
one set of weights for each beamforming direction.

#### Dependencies

To enable this port, select the **Enable weights
output** check box.

**Data Types: **`double`

**Complex Number Support: **Yes

## Parameters

**Main Tab**

`Signal propagation speed (m/s)`

— Signal propagation speed

`physconst('LightSpeed')`

(default) | real-valued 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')`

.
Units are in meters per second.

**Example: **`3e8`

**Data Types: **`double`

`Operating frequency (Hz)`

— System operating frequency

`3.0e8`

(default) | positive real scalar

System operating frequency, specified as a positive scalar. Units are in Hz.

`Specify PRF as`

— Source of PRF value

`Property`

(default) | `Input port`

Source of PRF value, specified as `Property`

or
`Input port`

. When set to
`Property`

, the **Pulse repetition frequency
(Hz)** parameter sets the PRF. When set to ```
Input
port
```

, pass in the PRF using the `PRF`

input
port.

`Pulse repetition frequency (Hz)`

— Pulse repetition frequency

`1`

(default) | positive scalar

Pulse repetition frequency, PRF, specified as a positive scalar. Units are in Hertz.
Set this parameter to the same value set in any `Waveform`

library
block used in the simulation.

#### Dependencies

To enable this parameter, set the **Specify PRF as** parameter to
`Property`

.

`Specify direction as`

— Specify source of targeting directions

`Property`

(default) | `Input port`

Specify whether the targeting direction for the STAP processor block comes from a block
parameter or from the `ANG`

input port. Values of this parameter
are

`Property` |
For the ADPCA Canceller and DPCA Canceller blocks, targeting direction is specified using **Receiving mainlobe direction (deg)**.For the SMI Beamformer block, targeting direction is specified using **Targeting direction**.
These parameters appear only when
the |

`Input port` | Enter the targeting directions using the |

`Receiving mainlobe direction (deg)`

— Pointing direction of main lobe of array

`[0;0]`

(default) | real-valued 2-by-1 vector

Specify the direction of the main lobe of the receiving sensor array as a
real-valued 2-by-1 vector. The direction is specified in the format of
`[AzimuthAngle; ElevationAngle]`

. The azimuth angle
should be between –180° and 180° and the elevation angle should be between
–90° and 90°.

**Example: **`[100;-45]`

#### Dependencies

To enable this parameter, set **Specify direction
as** to `Property`

.

`Number of bits in phase shifters`

— Number of phase shift quantization bits

`0`

(default) | nonnegative integer

The number of bits used to quantize the phase shift component of beamformer or steering vector weights. Specify the number of bits as a non-negative integer. A value of zero indicates that no quantization is performed.

`Specify targeting Doppler as`

— Source of targeting Doppler

`Property`

(default) | `Input port`

Specify whether targeting Doppler values for the STAP processor comes from the
**Targeting Doppler (Hz)** parameter of this block or using the
`DOP`

input port. For the ADPCA Canceller and
DPCA Canceller blocks, the **Specify targeting Doppler
as** parameter appears only when the **Output pre-Doppler
result** check box is cleared. Values of this parameter are

`Property` | Specify targeting Doppler values using the Targeting
Doppler parameter of the block. The
Targeting Doppler parameter appears only
when Specify targeting Doppler as is set to
`Property` . |

`Input port` | Specify targeting Doppler values using the `Dop`
input port. This port appears only when Specify targeting
Doppler as is set to ```
Input
port
``` . |

`Targeting Doppler (Hz)`

— Targeting Doppler of STAP processor

`0`

(default) | scalar

Targeting Doppler of STAP processor, specified as a scalar.

#### Dependencies

To enable this parameter for the SMI Beamformer block, set

**Specify targeting Doppler as**to`Property`

.To enable this parameter for the ADPCA Canceller and DPCA Canceller blocks, first clear the

**Output pre-Doppler result**check box. Then set the**Specify targeting Doppler as**parameter to`Property`

.

`Enable weights output`

— Option to output beamformer weights

off (default) | on

Select this check box to obtain the beamformer weights from the output port,
`W`

.

`Output pre-Doppler result`

— Output results before Doppler filtering

on (default) | off

Select this check box to output the results before Doppler filtering.
Clear this check box to output the processing result after Doppler
filtering. Selecting this check box will remove the **Specify
targeting Doppler as** and **Targeting Doppler
(Hz)** parameters.

`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).

**Sensor Arrays Tab**

`Specify sensor array as`

— Method to specify array

`Array (no subarrays)`

(default) | `MATLAB expression`

Method to specify array, specified as ```
Array (no
subarrays)
```

or `MATLAB expression`

.

`Array (no subarrays)`

— use the block parameters to specify the array.`MATLAB expression`

— create the array using a MATLAB expression.

`Expression`

— MATLAB expression used to create an array

Phased Array System Toolbox™ array System object

MATLAB expression used to create an array, specified as a valid Phased Array System Toolbox array System object.

**Example: **`phased.URA('Size',[5,3])`

#### Dependencies

To enable this parameter, set **Specify sensor array
as** to `MATLAB expression`

.

**Element Parameters**

`Element type`

— Array element types

`Isotropic Antenna`

(default) | `Cosine Antenna`

| `Custom Antenna`

| `Omni Microphone`

| `Custom Microphone`

Antenna or microphone type, specified as one of the following:

`Isotropic Antenna`

`Cosine Antenna`

`Custom Antenna`

`Omni Microphone`

`Custom Microphone`

`Operating frequency range (Hz)`

— Operating frequency range of the antenna or microphone element

`[0,1.0e20]`

(default) | real-valued 1-by-2 row vector

Specify the operating frequency range of the antenna or microphone
element as a 1-by-2 row vector in the form `[LowerBound,UpperBound]`

.
The element has no response outside this frequency range. Frequency
units are in Hz.

#### Dependencies

To enable this parameter, set **Element type** to ```
Isotropic
Antenna
```

, `Cosine Antenna`

, or ```
Omni
Microphone
```

.

`Operating frequency vector (Hz)`

— Operating frequency range of custom antenna or microphone elements

`[0,1.0e20]`

(default) | real-valued row vector

Specify the frequencies at which to set antenna and microphone
frequency responses as a 1-by-*L* row vector of increasing
real values. The antenna or microphone element has no response outside
the frequency range specified by the minimum and maximum elements
of this vector. Frequency units are in Hz.

#### Dependencies

To enable this parameter, set **Element type** to ```
Custom
Antenna
```

or `Custom Microphone`

. Use **Frequency
responses (dB)** to set the responses at these frequencies.

`Baffle the back of the element`

— Set back response of an `Isotropic Antenna`

element or an `Omni Microphone`

element to zero

off (default) | on

Select this check box to baffle the back response of the element. When back baffled, the responses at all azimuth angles beyond ±90° from broadside are set to zero. The broadside direction is defined as 0° azimuth angle and 0° elevation angle.

#### Dependencies

To enable this check box, set **Element type** to ```
Isotropic
Antenna
```

or `Omni Microphone`

.

`Exponent of cosine pattern`

— Exponents of azimuth and elevation cosine patterns

`[1.5 1.5]`

(default) | nonnegative scalar | real-valued 1-by-2 matrix of nonnegative values

Specify the exponents of the cosine pattern as a nonnegative scalar or a real-valued 1-by-2
matrix of nonnegative values. When **Exponent of cosine pattern** is a
1-by-2 vector, the first element is the exponent in the azimuth direction and the second
element is the exponent in the elevation direction. When you set this parameter to a
scalar, both the azimuth direction and elevation direction cosine patterns are raised to
the same power.

#### Dependencies

To enable this parameter, set **Element type** to ```
Cosine
Antenna
```

.

`Frequency responses (dB)`

— Antenna and microphone frequency response

`[0,0]`

(default) | real-valued row vector

Frequency response of a custom antenna or custom microphone
for the frequencies defined by the **Operating frequency vector
(Hz)** parameter. The dimensions of **Frequency responses
(dB)** must match the dimensions of the vector specified
by the **Operating frequency vector (Hz)** parameter.

#### Dependencies

To enable this parameter, set **Element type** to ```
Custom
Antenna
```

or `Custom Microphone`

.

`Input Pattern Coordinate System`

— Coordinate system of custom antenna pattern

`az-el`

(default) | `phi-theta`

Coordinate system of custom antenna pattern, specified `az-el`

or `phi-theta`

. When you specify `az-el`

, use the **Azimuth angles (deg)** and **Elevations angles (deg)** parameters to specify the coordinates of the pattern points. When you specify `phi-theta`

, use the **Phi angles (deg)** and **Theta angles (deg)** parameters to specify the coordinates of the pattern points.

#### Dependencies

To enable this parameter, set **Element type** to `Custom Antenna`

.

`Azimuth angles (deg)`

— Azimuth angles of antenna radiation pattern

`[-180:180]`

(default) | real-valued row vector

Specify the azimuth angles at which to calculate the antenna
radiation pattern as a 1-by-*P* row vector. *P* must
be greater than 2. Azimuth angles must lie between –180°
and 180°, inclusive, and be in strictly increasing order.

#### Dependencies

To enable this parameter, set the **Element type** parameter to
`Custom Antenna`

and the **Input Pattern Coordinate
System** parameter to `az-el`

.

`Elevation angles (deg)`

— Elevation angles of antenna radiation pattern

`[-90:90]`

(default) | real-valued row vector

Specify the elevation angles at which to compute the radiation
pattern as a 1-by-*Q* vector. *Q* must
be greater than 2. Angle units are in degrees. Elevation angles must
lie between –90° and 90°, inclusive, and be in strictly
increasing order.

#### Dependencies

To enable this parameter, set the **Element type** parameter to
`Custom Antenna`

and the **Input Pattern Coordinate
System** parameter to `az-el`

.

`Phi Angles (deg)`

— Phi angle coordinates of custom antenna radiation pattern

`0:360`

| real-valued 1-by-*P* row vector

Phi angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-*P* row vector. *P* must be greater than 2. Angle units are in degrees. Phi angles must lie between 0° and 360° and be in strictly increasing order.

#### Dependencies

To enable this parameter, set the **Element type** parameter to `Custom Antenna`

and the **Input Pattern Coordinate System** parameter to `phi-theta`

.

`Theta Angles (deg)`

— Theta angle coordinates of custom antenna radiation pattern

`0:180`

| real-valued 1-by-*Q* row vector

Theta angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-*Q* row vector. *Q* must be greater than 2. Angle units are in degrees. Theta angles must lie between 0° and 360° and be in strictly increasing order.

#### Dependencies

To enable this parameter, set the **Element type** parameter to `Custom Antenna`

and the **Input Pattern Coordinate System** parameter to `phi-theta`

.

`Magnitude pattern (dB)`

— Magnitude of combined antenna radiation pattern

`zeros(181,361)`

(default) | real-valued *Q*-by-*P* matrix | real-valued *Q*-by-*P*-by-*L* array

Magnitude of the combined antenna radiation pattern, specified as a
*Q*-by-*P* matrix or a
*Q*-by-*P*-by-*L* array.

When the

**Input Pattern Coordinate System**parameter is set to`az-el`

,*Q*equals the length of the vector specified by the**Elevation angles (deg)**parameter and*P*equals the length of the vector specified by the**Azimuth angles (deg)**parameter.When the

**Input Pattern Coordinate System**parameter is set to`phi-theta`

,*Q*equals the length of the vector specified by the**Theta Angles (deg)**parameter and*P*equals the length of the vector specified by the**Phi Angles (deg)**parameter.

The quantity *L* equals the length of the
**Operating frequency vector (Hz)**.

If this parameter is a

*Q*-by-*P*matrix, the same pattern is applied to*all*frequencies specified in the**Operating frequency vector (Hz)**parameter.If the value is a

*Q*-by-*P*-by-*L*array, each*Q*-by-*P*page of the array specifies a pattern for the*corresponding*frequency specified in the**Operating frequency vector (Hz)**parameter.

#### Dependencies

To enable this parameter, set **Element type** to
`Custom Antenna`

.

`Phase pattern (deg)`

— Custom antenna radiation phase pattern

`zeros(181,361)`

(default) | real-valued *Q*-by-*P* matrix | real-valued *Q*-by-*P*-by-*L* array

Phase of the combined antenna radiation pattern, specified as a
*Q*-by-*P* matrix or a
*Q*-by-*P*-by-*L* array.

When the

**Input Pattern Coordinate System**parameter is set to`az-el`

,*Q*equals the length of the vector specified by the**Elevation angles (deg)**parameter and*P*equals the length of the vector specified by the**Azimuth angles (deg)**parameter.When the

**Input Pattern Coordinate System**parameter is set to`phi-theta`

,*Q*equals the length of the vector specified by the**Theta Angles (deg)**parameter and*P*equals the length of the vector specified by the**Phi Angles (deg)**parameter.

The quantity *L* equals the length of the
**Operating frequency vector (Hz)**.

If this parameter is a

*Q*-by-*P*matrix, the same pattern is applied to*all*frequencies specified in the**Operating frequency vector (Hz)**parameter.If the value is a

*Q*-by-*P*-by-*L*array, each*Q*-by-*P*page of the array specifies a pattern for the*corresponding*frequency specified in the**Operating frequency vector (**

#### Dependencies

To enable this parameter, set **Element type** to
`Custom Antenna`

.

`MatchArrayNormal`

— Rotate antenna element to array normal

`on`

(default) | `off`

Select this check box to rotate the antenna element pattern to align with the array normal. When not selected, the element pattern is not rotated.

When the antenna is used in an antenna array and the **Input Pattern Coordinate System** parameter is `az-el`

, selecting this check box rotates the pattern so that the *x*-axis of the element coordinate system points along the array normal. Not selecting uses the element pattern without the rotation.

When the antenna is used in an antenna array and **Input Pattern Coordinate System** is set to `phi-theta`

, selecting this check box rotates the pattern so that the *z*-axis of the element coordinate system points along the array normal.

Use the parameter in conjunction with the **Array normal** parameter of the `URA`

and `UCA`

arrays.

#### Dependencies

To enable this parameter, set **Element type** to `Custom Antenna`

.

`Polar pattern frequencies (Hz)`

— Polar pattern microphone response frequencies

1e3 (default) | real scalar | real-valued 1-by-*L* row vector

Polar pattern microphone response frequencies, specified as a real scalar, or a
real-valued, 1-by-*L* vector. The response frequencies lie within the
frequency range specified by the **Operating frequency vector (Hz)**
vector.

#### Dependencies

To enable this parameter, set **Element type** set to
`Custom Microphone`

.

`Polar pattern angles (deg)`

— Polar pattern response angles

`[-180:180]`

(default) | real-valued -by-*P* row vector

Specify the polar pattern response angles, as a 1-by-*P* vector.
The angles are measured from the central pickup axis of the microphone
and must be between –180° and 180°, inclusive.

#### Dependencies

To enable this parameter, set **Element type** to ```
Custom
Microphone
```

.

`Polar pattern (dB)`

— Custom microphone polar response

`zeros(1,361)`

(default) | real-valued *L*-by-*P* matrix

Specify the magnitude of the custom microphone element polar patterns as an
*L*-by-*P* matrix. *L* is the
number of frequencies specified in **Polar pattern frequencies (Hz)**.
*P* is the number of angles specified in **Polar pattern
angles (deg)**. Each row of the matrix represents the magnitude of the
polar pattern measured at the corresponding frequency specified in **Polar
pattern frequencies (Hz)** and all angles specified in **Polar
pattern angles (deg)**. The pattern is measured in the azimuth plane. In
the azimuth plane, the elevation angle is 0° and the central pickup axis is 0°
degrees azimuth and 0° degrees elevation. The polar pattern is symmetric around the
central axis. You can construct the microphone response pattern in 3-D space from the
polar pattern.

#### Dependencies

To enable this parameter, set **Element type** to ```
Custom
Microphone
```

.

### Array Parameters

`Specify sensor array as`

— Type of array

`Array (no subarrays)`

(default) | `MATLAB expression`

Specify a ULA sensor array directly or by using a MATLAB expression.

**Types**

`Array (no subarrays)` |

`MATLAB expression` |

`Number of elements`

— Number of array elements in U

`2`

(default) | positive integer greater than or equal to two

The number of array elements for ULA arrays, specified as an integer greater than or equal to two.

**Example: **`11`

**Data Types: **`double`

`Element spacing`

— Distance between ULA elements

`0.5`

(default) | positive scalar

Distance between adjacent ULA elements, specified as a positive scalar. Units are in meters.

**Example: **`1.5`

`Array axis`

— Linear axis direction of ULA

`y`

(default) | `x`

| `z`

Linear axis direction of ULA, specified as `y`

, `x`

,
or `z`

. All ULA array elements are uniformly
spaced along this axis in the local array coordinate system.

#### Dependencies

To enable this parameter, set

**Geometry**to`ULA`

.This parameter is also enabled when the block only supports ULA arrays.

`Taper`

— ULA array taper

`1`

(default) | complex-valued vector

Tapers, also known as *element weights*, are applied to sensor elements in the array. Tapers are used to modify both the amplitude and phase of the transmitted or received data.

Specify element tapering as a complex-valued scalar or a complex-valued 1-by-*N* row vector. In this vector, *N* represents the number of elements in the array. If **Taper** is a scalar, the same weight is applied to each element. If **Taper** is a vector, a weight from the vector is applied to the corresponding sensor element. A weight must be applied to each element in the sensor array.

**Example: **[0.5;1;0.5]

**Data Types: **`double`

**Complex Number Support: **Yes

`Expression`

— MATLAB expression used to create an array

Phased Array System Toolbox array System object

MATLAB expression used to create a ULA array, specified as a valid Phased Array System Toolbox array System object.

**Example: **`phased.ULA('NumElements',13)`

#### Dependencies

To enable this parameter, set **Specify sensor array
as** to `MATLAB expression`

.

## See Also

**Introduced in R2014b**

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