lpf

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lpf

y = lpf ( x,fcut,order[=8],type[=1],dBpass[=.5],dBstop[=-40] )
y = x.lpf ( fcut,order[=8],type[=1],dBpass[=.5],dBstop[=-40] )

IIR, low-pass filtering; Apply a low-pass filter to the audio signal

arg

type

Description

Unit or Value scale

x

AUDIO

audio signal


fcut

SCAL

cut-off frequency


order

SCAL

order of the IIR filter


type

SCAL

IIR filter type (1: Butterworth, 2: Chebyshev, 3: Elliptic)


dBpass

SCAL

Passband ripple allowed


dBstop

SCAL

Stopband attenuation


Outputs

  • y is a lowpass-filterd version of x.

Notes

  • The output is not normalized; i.e., the rms of x is adjusted according to the filter gain.
  • fcut should be less than the Nyquist frequency.
  • IIR filter coefficients are designed by the specification requested in the argument list, but not guranteed. The user is responsible for making sure the output follows the spec.

Examples

  • lpf(x, 2000)
  • noise(500).lpf(500)

See Also

hpf | bpf | bsf

Algorithm

ELLF Digital Filter Calculator

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