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Halfband decimator

`dsp.FIRHalfbandDecimator`

performs an efficient
polyphase decimation of the input signal by a factor of two. You can
use `dsp.FIRHalfbandDecimator`

to implement the analysis
portion of a two-band filter bank to filter a signal into lowpass
and highpass subbands. `dsp.FIRHalfbandDecimator`

uses
an FIR equiripple design to construct the halfband filters and a polyphase
implementation to filter the input. This object supports fixed-point
operations and ARM Cortex code generation.

To filter and downsample your data:

Define and set up your halfband decimator. See Construction.

Call

`step`

to filter the input signal according to the properties of`dsp.FIRHalfbandDecimator`

. The input signal can be a real- or complex-valued column vector or matrix. If the input signal is a matrix, each column of the matrix is treated as an independent channel. The number of rows in the input signal must be a multiple of 2.

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.

`firhalfbanddecim = dsp.FIRHalfbandDecimator`

returns
a halfband decimator, `firhalfbanddecim`

, with
the default settings. Calling `step`

with the default
property settings filters and downsamples the input data with a halfband
frequency of 11025 Hz, a transition width of 4.1 kHz, and a stopband
attenuation of 80 dB.

returns
a halfband decimator, with additional properties specified by one
or more `firhalfbanddecim`

= dsp.FIRHalfbandDecimator(`Name,Value`

)`Name,Value`

pair arguments. `Name`

is
the property name and `Value`

is the corresponding
value. `Name`

must appear inside single quotes
(' '). You can specify several name-value pair arguments in any order
as `Name1,Value1,...,NameN,ValueN`

.

reset | Reset internal states of FIR halfband decimator |

step | Filter input with FIR halfband decimator |

For additional methods, see Analysis Methods for Filter System Objects.

For a complete list of analysis methods supported for the `dsp.FIRHalfbandDecimator`

object,
enter `dsp.FIRHalfbandDecimator.helpFilterAnalysis`

at
the MATLAB^{®} command prompt.

Common to All System Objects | |
---|---|

`clone` | Create System object with same property values |

`getNumInputs` | Expected number of inputs to a System object |

`getNumOutputs` | Expected number of outputs of a System object |

`isLocked` | Check locked states of a System object (logical) |

`release` | Allow System object property value changes |

[1] Harris, F.J. *Multirate Signal
Processing for Communication Systems*, Prentice Hall, 2004,
pp. 208–209.

`dsp.Channelizer`

|`dsp.DyadicAnalysisFilterBank`

|`dsp.FIRHalfbandInterpolator`

|`dsp.IIRHalfbandDecimator`

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