# fdesign.arbgrpdelay

Arbitrary group delay filter specification object

## Syntax

## Description

Arbitrary group delay filters are allpass filters that you can use to correct
the phase distortion introduced by other filters. The
`fdesign.arbgrpdelay`

function uses an iterative least
*p*-th norm optimization procedure to minimize the phase response
error [1].

The `fdesign.arbgrpdelay`

function returns a filter design
specification object containing filter specifications, such as filter order, number of
bands, frequency vector, and group delay response. You then use the `design`

function to design the filter from the filter design
specifications object.

For more control options, see Filter Design Procedure. For a complete workflow, see Design a Filter in Fdesign — Process Overview.

creates an
allpass arbitrary group delay filter design specification object with the filter
order of 10, frequency vector of [0 0.1 1], and group delay response vector of [2 3
1].`specObj`

= fdesign.arbgrpdelay

creates a filter design specification object with the specification values
`specObj`

= fdesign.arbgrpdelay(`spec`

,`value1,...,valueN`

)`value1,...,valueN`

. Set the specification options in the
expression `spec`

. After the expression, specify a value for each
option.

specifies the sample rate in Hz. If you specify a sample rate, the group delay
response values in the filter design specification object are in seconds. If you do
not specify a sample rate, the function normalizes all frequencies and the group
delay response values are in samples.`specObj`

= fdesign.arbgrpdelay(___,`Fs`

)

## Examples

## Input Arguments

## Output Arguments

## More About

## Tips

If your arbitrary group delay design produces the ```
Poorly conditioned Hessian
matrix
```

error, perform one of the following or both.

Set the

`MaxPoleRadius`

IIR lp norm design option to a number less than 1 when you`design`

your filter.For more information on thedesign(d,'iirlpnorm','MaxPoleRadius',0.95)

`MaxPoleRadius`

design option, see the Design Arbitrary Group Delay and Multiband Delay Equalization examples.Reduce the order of your filter design.

## Algorithms

The `fdesign.arbgrpdelay`

function uses a least *p*-th
norm iterative optimization described in [1].

## References

[1] Antoniou, A. *Digital Signal Processing:
Signals, Systems, and Filters.*, New York:McGraw-Hill,
2006, pp. 719–771.

## Version History

**Introduced in R2011b**

## See Also

`fdesign`

| `design`

| `iirgrpdelay`

| `designmethods`

| `designoptions`