step

System object: phased.ADPCACanceller
Package: phased

Perform ADPCA processing on input data

Syntax

Y = step(H,X,CUTIDX)
Y = step(H,X,CUTIDX,ANG)
Y = step(___,DOP)
[Y,W] = step(___)

Description

Y = step(H,X,CUTIDX) applies the ADPCA pulse cancellation algorithm to the input data X. The algorithm calculates the processing weights according to the range cell specified by CUTIDX. This syntax is available when the DirectionSource property is 'Property' and the DopplerSource property is 'Property'. The receiving mainlobe direction is the Direction property value. The output Y contains the result of pulse cancellation either before or after Doppler filtering, depending on the PreDopplerOutput property value.

Y = step(H,X,CUTIDX,ANG) uses ANG as the receiving mainlobe direction. This syntax is available when the DirectionSource property is 'Input port' and the DopplerSource property is 'Property'.

Y = step(___,DOP) uses DOP as the targeting Doppler frequency. This syntax is available when the DopplerSource property is 'Input port'.

[Y,W] = step(___) returns the additional output, W, as the processing weights. This syntax is available when the WeightsOutputPort property is true.

    Note:   H specifies the System object™ on which to run this step method.

    The object performs an initialization the first time the step method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first call the release method to unlock the object.

Input Arguments

H

Pulse canceller object.

X

Input data. X must be a 3-dimensional M-by-N-by-P numeric array whose dimensions are (range, channels, pulses).

CUTIDX

Range cell.

ANG

Receiving mainlobe direction. ANG must be a 2-by-1 vector in the form [AzimuthAngle; ElevationAngle], in degrees. The azimuth angle must be between –180 and 180. The elevation angle must be between –90 and 90.

Default: Direction property of H

DOP

Targeting Doppler frequency in hertz. DOP must be a scalar.

Default: Doppler property of H

Output Arguments

Y

Result of applying pulse cancelling to the input data. The meaning and dimensions of Y depend on the PreDopplerOutput property of H:

  • If PreDopplerOutput is true, Y contains the pre-Doppler data. Y is an M-by-(P–1) matrix. Each column in Y represents the result obtained by cancelling the two successive pulses.

  • If PreDopplerOutput is false, Y contains the result of applying an FFT-based Doppler filter to the pre-Doppler data. The targeting Doppler is the Doppler property value. Y is a column vector of length M.

W

Processing weights the pulse canceller used to obtain the pre-Doppler data. The dimensions of W depend on the PreDopplerOutput property of H:

  • If PreDopplerOutput is true, W is a 2N-by-(P-1) matrix. The columns in W correspond to successive pulses in X.

  • If PreDopplerOutput is false, W is a column vector of length (N*P).

Examples

Process the example radar data cube, STAPExampleData.mat, using an ADPCA processor. The weights are calculated for the 71st cell of a collected radar data cube. The look direction is [0; 0] degrees and the Doppler frequency is 12980 Hz. After constructing the phased.ADPCACanceller object, use step to process the data.

load STAPExampleData;   % load radar data cube
Hs = phased.ADPCACanceller('SensorArray',STAPEx_HArray,...
    'PRF',STAPEx_PRF,...
    'PropagationSpeed',STAPEx_PropagationSpeed,...
    'OperatingFrequency',STAPEx_OperatingFrequency,...
    'NumTrainingCells',100,...
    'WeightsOutputPort',true,...
    'DirectionSource','Input port',...
    'DopplerSource','Input port');
[y,w] = step(Hs,STAPEx_ReceivePulse,71,[0; 0],12980);
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