# dwtfilterbank

Discrete wavelet transform filter bank

## Description

Use `dwtfilterbank`

to create a discrete wavelet transform
(DWT) filter bank

Visualize wavelets and scaling functions in time and frequency.

Measure the 3-dB bandwidths of the wavelet and scaling functions. You can also measure energy concentration of the wavelet and scaling functions in the theoretical DWT passbands.

Create a DWT filter bank using your own custom filters. You can determine whether the filter bank is orthogonal or biorthogonal.

Determine the frame bounds of the filter bank.

## Creation

### Description

create a discrete
wavelet transform (DWT) filter bank. The default filter bank is designed for a
signal with 1024 samples. The default filter bank uses the analysis
(decomposition) sym4 wavelet and scaling filter with seven resolution
levels.`fb`

= dwtfilterbank

creates a DWT filter bank `fb`

= dwtfilterbank(`Name,Value`

)`fb`

with properties specified by
one or more `Name,Value`

pair arguments. Properties can be
specified in any order as `Name1,Value1,...,NameN,ValueN`

.
Enclose each property name in quotes.

For example, ```
fb =
dwtfilterbank('SignalLength',1000,'Wavelet','bior4.4')
```

creates a
DWT filter bank for signals of length 1000 using the biorthogonal
`bior4.4`

wavelet.

**Note**

You cannot change a property value of an existing filter bank. For
example, if you have a filter bank `fb`

for the
`sym4`

wavelet, you must create a second filter
bank `fb2`

for the `coif5`

wavelet.
You cannot assign a different `Wavelet`

to
`fb`

.

## Properties

## Object Functions

`dwtpassbands` | DWT filter bank passbands |

`filters` | DWT filter bank filters |

`framebounds` | DWT filter bank frame bounds |

`freqz` | DWT filter bank frequency responses |

`isBiorthogonal` | Determine if DWT filter bank is biorthogonal |

`isOrthogonal` | Determine if DWT filter bank is orthogonal |

`powerbw` | DWT filter bank power bandwidth |

`qfactor` | DWT filter bank quality factor |

`scalingfunctions` | DWT filter bank time-domain scaling functions |

`wavelets` | DWT filter bank time-domain wavelets |

`waveletsupport` | DWT filter bank time supports |

## Examples

## References

[1] Daubechies, I. *Ten
Lectures on Wavelets*. CBMS-NSF Regional Conference Series in Applied
Mathematics. Philadelphia, PA: Society for Industrial and Applied Mathematics,
1992.

## Version History

**Introduced in R2018a**