comm.HadamardCode

Generate Hadamard code

Description

The HadamardCode object generates a Hadamard code from a Hadamard matrix, whose rows form an orthogonal set of codes. You can use orthogonal codes for spreading in communication systems in which the receiver is perfectly synchronized with the transmitter. In these systems, the despreading operation is ideal, because the codes decorrelate completely.

To generate a Hadamard code:

Define and set up your Hadamard code object. See Construction.
Call step to generate a Hadamard according to the properties of comm.HadamardCode. 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) and y = obj() perform equivalent operations.

Construction

H = comm.HadamardCode creates a Hadamard code generator System object, H. This object generates Hadamard codes from a set of orthogonal codes.

H = comm.HadamardCode(Name,Value) creates a Hadamard code generator 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

`Length`	Length of generated code Specify the length of the generated code as a numeric, integer scalar value with a power of two. The default is `64`.
`Index`	Row index of Hadamard matrix Specify the row index of the Hadamard matrix as a numeric, integer scalar value in the range `[0, 1, ... , N-1]`. N is the value of the `Length` property. The default is `60`. An N $\times$ N Hadamard matrix, denoted as P(N), is defined recursively as follows: P(1) = [1] P(2N) = [P(N) P(N); P(N) –P(N)] The NxN Hadamard matrix has the property that P(N) $\times$ P(N)' = N $\times$ `eye`(N). The `step` method outputs code samples from the row of the Hadamard matrix that you specify in this property. When you set this property to an integer k, the output code has exactly k zero crossings, for k = 0, `1`, ... , N–`1`.
`SamplesPerFrame`	Number of output samples per frame Specify the number of Hadamard code samples that the `step` method outputs as a numeric, positive, integer scalar value. The default is `1`. When you set this property to a value of M, the `step` method outputs M samples of a Hadamard code of length N. N equals the length of the code that you specify in the `Length` property.
`OutputDataType`	Data type of output Specify the output data type as one of `double` \| `int8`. The default is `double`.

Methods

step	Generate Hadamard code

Common to All System Objects
`release`	Allow System object property value changes
`reset`	Reset internal states of System object

Examples

collapse all

Hadamard Code Sequence

Open Live Script

Generate 10 samples of a Hadamard code sequence having a length of 128.

hadamard = comm.HadamardCode('Length',128,'SamplesPerFrame',10)

hadamard = 
  comm.HadamardCode with properties:

             Length: 128
              Index: 60
    SamplesPerFrame: 10
     OutputDataType: 'double'

seq = hadamard()

Algorithms

This object implements the algorithm, inputs, and outputs described on the Hadamard Code Generator block reference page. The object properties correspond to the block parameters, except:

The object does not have a property to select frame based outputs.
The object does not have a property that corresponds to the Sample time parameter.