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# comm.MatrixHelicalScanInterleaver System object

Package: comm

Permute input symbols by selecting matrix elements along diagonals

## Description

The MatrixHelicalScanInterleaver object performs block interleaving by filling a matrix with the input symbols row by row and then outputs the matrix contents helically. The number of rows and number of columns properties are the dimensions of the matrix that the object uses internally for computations.

To interleave the input signal by filling a matrix row-by-row with the input symbols and then outputting the matrix contents helically:

1. Define and set up your matrix helical scan interleaver object. See Construction.

2. Call step to interleave the input signal according to the properties of comm.MatrixHelicalScanInterleaver. The behavior of step is specific to each object in the toolbox.

## Construction

H = comm.MatrixHelicalScanInterleaver creates a matrix helical scan interleaver object, H. This object permutes the input by filling a permutation matrix with the input symbols row by row and then outputs the matrix contents helically.

H = comm.MatrixHelicalScanInterleaver(Name,Value) creates a matrix helical scan interleaver object, H, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

## Properties

 NumRows Number of rows of permutation matrix Specify the number of rows in the permutation matrix as a scalar, positive integer. The default is 64. NumColumns Number of columns of permutation matrix Specify the number of columns in the permutation matrix as a scalar, positive integer. The default is 64. StepSize Slope of diagonals Specify slope as a scalar integer between 0 and the value you specify in the NumRows property. The slope value represents the amount by which the row index increases as the column index increases by 1. When you set the value of this property to 0, the object does not interleave and the output matches the input. The default is 1.

## Methods

 clone Create matrix helical scan interleaver object with same property values getNumInputs Number of expected inputs to step method getNumOutputs Number of outputs from step method isLocked Locked status for input attributes and nontunable properties release Allow property value and input characteristics changes step Permute input symbols by selecting matrix elements along diagonals

## Examples

Interleave and deinterleave random data.

```    hInt = comm.MatrixHelicalScanInterleaver('NumRows', 4, ...
'NumColumns', 4);
hDeInt = comm.MatrixHelicalScanDeinterleaver('NumRows', 4, ...
'NumColumns', 4);
data = randi(7, 16, 1);
intData = step(hInt, data);
deIntData = step(hDeInt, intData);

% compare the original sequence, interleaved sequence and restored sequence.
[data, intData, deIntData]
```

## Algorithms

This object implements the algorithm, inputs, and outputs described on the Matrix Helical Scan Deinterleaver block reference page. The object properties correspond to the block parameters.