lowpass#

gwpy.signal.filter_design.lowpass(

frequency: QuantityLike,

sample_rate: QuantityLike,

fstop: QuantityLike | None = None,

gpass: float = 2,

gstop: float = 30,

type: Literal['iir'] = 'iir',

output: Literal['zpk'] = 'zpk',

**kwargs,

) → ZpkType[source]#

gwpy.signal.filter_design.lowpass(

frequency: QuantityLike,

sample_rate: QuantityLike,

fstop: QuantityLike | None = None,

gpass: float = 2,

gstop: float = 30,

type: Literal['iir'] = 'iir',

output: Literal['ba'] = 'ba',

**kwargs,

) → BAType

gwpy.signal.filter_design.lowpass(

frequency: QuantityLike,

sample_rate: QuantityLike,

fstop: QuantityLike | None = None,

gpass: float = 2,

gstop: float = 30,

type: Literal['iir'] = 'iir',

output: Literal['sos'] = 'sos',

**kwargs,

) → SosType

gwpy.signal.filter_design.lowpass(

frequency: QuantityLike,

sample_rate: QuantityLike,

fstop: QuantityLike | None = None,

gpass: float = 2,

gstop: float = 30,

type: Literal['fir'] = 'fir',

**kwargs,

) → TapsType

Design a low-pass filter for the given cutoff frequency.

Parameters:

frequencyfloat: Corner frequency of low-pass filter (Hertz).
sample_ratefloat: Sampling rate of target data (Hertz).
fstopfloat, optional: Edge-frequency of stop-band (Hertz).
gpassfloat, optional, default: 2: The maximum loss in the passband (dB).
gstopfloat, optional, default: 30: The minimum attenuation in the stopband (dB).
typestr, optional, default: 'iir': The filter type, either 'iir' or 'fir'.
outputstr, optional, default: 'zpk': The output format for an IIR filter, either 'zpk', 'ba', or 'sos'.
kwargs: Other keyword arguments are passed directly to iirdesign() or firwin().

Returns:

filter: The formatted filter. The output format for an IIR filter depends on the input arguments, default is a tuple of (zeros, poles, gain).

Notes

By default a digital filter is returned, meaning the zeros and poles are given in the Z-domain in units of radians/sample.

Examples

To create a low-pass filter at 1000 Hz for 4096 Hz-sampled data:

>>> from gwpy.signal.filter_design import lowpass
>>> lp = lowpass(1000, 4096)

To view the filter, you can use the BodePlot:

>>> from gwpy.plot import BodePlot
>>> plot = BodePlot(lp, sample_rate=4096)
>>> plot.show()

(png)

../../_images/gwpy-signal-filter_design-lowpass-1.png