Note: This page has been translated by MathWorks. Please click here

To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

Signal envelope

`[yupper,ylower] = envelope(x)`

`[yupper,ylower] = envelope(x,fl,'analytic')`

`[yupper,ylower] = envelope(x,wl,'rms')`

`[yupper,ylower] = envelope(x,np,'peak')`

`envelope(___)`

`[`

returns
the upper and lower envelopes of the input sequence, `yupper,ylower`

] = envelope(`x`

)`x`

,
as the magnitude of its analytic signal. The analytic signal of `x`

is
found using the discrete Fourier transform as implemented in `hilbert`

. The function initially removes
the mean of `x`

and adds it back after computing
the envelopes. If `x`

is a matrix, then `envelope`

operates
independently over each column of `x`

.

`[`

returns
the envelopes of `yupper,ylower`

] = envelope(`x`

,`fl`

,'analytic')`x`

determined using the magnitude
of its analytic signal. The analytic signal is computed by filtering `x`

with
a Hilbert FIR filter of length `fl`

. This syntax
is used if you specify only two arguments.

`[`

returns
the upper and lower root-mean-square envelopes of `yupper,ylower`

] = envelope(`x`

,`wl`

,'rms')`x`

.
The envelopes are determined using a sliding window of length `wl`

samples.

`[`

returns
the upper and lower peak envelopes of `yupper,ylower`

] = envelope(`x`

,`np`

,'peak')`x`

. The
envelopes are determined using spline interpolation over local maxima
separated by at least `np`

samples.

`envelope(___)`

with no output
arguments plots the signal and its upper and lower envelopes. This
syntax accepts any of the input arguments from previous syntaxes.

Was this topic helpful?