# powerbw

Power bandwidth

## Syntax

## Description

specifies the frequency interval over which to compute the reference level. This
syntax can include any combination of input arguments from previous syntaxes, as
long as the second input argument is either `bw`

= powerbw(___,`freqlims`

,`r`

)`fs`

or
`f`

. If the second input is passed as empty,
`powerbw`

assumes a normalized frequency. The
function computes the difference in frequency between the points where the
spectrum drops below the reference level by `r`

dB or reaches
an endpoint.

`powerbw(___)`

with no output
arguments plots the PSD or power spectrum in the current figure window
and annotates the bandwidth.

## Examples

## Input Arguments

## Output Arguments

## Algorithms

To determine the 3-dB bandwidth, `powerbw`

computes
a periodogram power spectrum estimate using a rectangular window and
takes the maximum of the estimate as a reference level. The bandwidth
is the difference in frequency between the points where the spectrum
drops at least 3 dB below the reference level. If the signal reaches
one of its endpoints before dropping by 3 dB, then `powerbw`

uses
the endpoint to compute the difference.

## Extended Capabilities

## Version History

**Introduced in R2015a**

## See Also

`bandpower`

| `obw`

| `periodogram`

| `plomb`

| `pwelch`