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comm.BinarySymmetricChannel System object

Introduce binary errors


The BinarySymmetricChannel object introduces binary errors to the signal transmitted through this channel.

To introduce binary errors into the transmitted signal:

  1. Define and set up your binary symmetric channel object. See Construction.

  2. Call step to introduces binary errors into the signal transmitted through this channel according to the properties of comm.ACPR. The behavior of step is specific to each object in the toolbox.


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.


H = comm.BinarySymmetricChannel creates a binary symmetric channel System object, H, that introduces binary errors to the input signal with a prescribed probability.

H = comm.BinarySymmetricChannel(Name,Value) creates a binary symmetric channel 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).



Probability of binary error

Specify the probability of a binary error as a scalar with a value between 0 and 1. The default is 0.05.


Enable error vector output

When you set this property to true, the step method outputs an error signal, ERR. This error signal, in vector form, indicates where errors were introduced in the input signal, X. A value of 1 at the i-th element of ERR indicates that an error was introduced at the i-th element of X. Set the property to false if you do not want the ERR vector at the output of the step method. The default is true.


Data type of output

Specify output data type as one of double | logical. The default is double.


stepIntroduce binary errors
Common to All System Objects

Create System object with same property values


Expected number of inputs to a System object


Expected number of outputs of a System object


Check locked states of a System object (logical)


Allow System object property value changes


expand all

Add binary errors with a probability of 0.2 to a binary input signal

binSymChan = comm.BinarySymmetricChannel('ErrorProbability',0.2);
data = randi([0 1],1000,1);
[~,err] = binSymChan(data);

Confirm that the number errors is approximately equal to the 0.2 multiplied by the number of symbols.

[sum(err) 0.2*length(data)]
ans = 

   188   200


This object implements the algorithm, inputs, and outputs described on the Binary Symmetric Channel block reference page. The object properties correspond to the block parameters, except:This object uses the MATLAB® default random stream to generate random numbers. The block uses a random number generator based on the V5 RANDN (Ziggurat) algorithm. An initial seed, set with the Initial seed parameter initializes the random number generator. For every system run that contains the block, the block generates the same sequence of random numbers. To generate reproducible numbers using this object, you can reset the MATLAB default random stream using the following code.

For more information, see help for RandStream.

Extended Capabilities

Introduced in R2012a

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