comm.ConvolutionalDeinterleaver

Restore ordering of symbols using shift registers

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Description

The ConvolutionalDeinterleaver object recovers a signal that was interleaved using the convolutional Interleaver object. The parameters in the two blocks should have the same values.

To recover convolutionally interleaved binary data:

  1. Define and set up your convolutional deinterleaver object. See Construction.

  2. Call step to convolutionally deinterleave according to the properties of comm.ConvolutionalDeinterleaver. The behavior of step is specific to each object in the toolbox.

Note

Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Construction

H = comm.ConvolutionalDeinterleaver creates a convolutional deinterleaver System object, H. This object restores the original ordering of a sequence that was interleaved using the convolutional interleaver System object.

H = comm.ConvolutionalDeinterleaver(Name,Value) creates a convolutional deinterleaver System 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

NumRegisters

Number of internal shift registers

Specify the number of internal shift registers as a scalar, positive integer. The default is 6.

RegisterLengthStep

Symbol capacity difference of each successive shift register

Specify the difference in symbol capacity of each successive shift register, where the last register holds zero symbols as a positive, scalar integer. The default is 2.

InitialConditions

Initial conditions of shift registers

Specify the values that are initially stored in each shift register as a numeric scalar or vector, except the last shift register, which has zero delay. If you set this property to a scalar, then all shift registers, except the last one, store the same specified value. You can also set this property to a column vector with length equal to the value of the NumRegisters property. With this setting, the i-th shift register stores the (N–i+1)-th element of the specified vector. The value of the first element of this property is unimportant because the last shift register has zero delay. The default is 0.

Methods

resetReset states of the convolutional deinterleaver object
stepRestore ordering of symbols using shift registers
Common to All System Objects
release

Allow System object property value changes

Examples

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Open Live Script

Create convolutional interleaver and deinterleaver objects.

interleaver = comm.ConvolutionalInterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);
deinterleaver = comm.ConvolutionalDeinterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);

Generate data, and pass the data through the convolutional interleaver. Pass the interleaved data through the convolutional deinterleaver.

data = (0:20)';
intrlvData = interleaver(data);
deintrlvData = deinterleaver(intrlvData);

Display the original sequence, interleaved sequence and restored sequence.

[data intrlvData deintrlvData]
ans = 21×3

     0     0     0
     1     0     0
     2     2     0
     3     0     0
     4     4     0
     5     0     0
     6     6     0
     7     1     1
     8     8     2
     9     3     3
      ⋮

The delay through the interleaver and deinterleaver pair is equal to the product of the NumRegisters and RegisterLengthStep properties. After accounting for this delay, confirm that the original and deinterleaved data are identical.

intrlvDelay = interleaver.NumRegisters * interleaver.RegisterLengthStep
intrlvDelay = 6

numSymErrors = symerr(data(1:end-intrlvDelay),deintrlvData(1+intrlvDelay:end))
numSymErrors = 0

Algorithms

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

Extended Capabilities

See Also

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Introduced in R2012a

Communications Toolbox Documentation
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