butfilt {RSEIS}R Documentation

Butterworth filter

Description

design and apply butterworth low/high/band pass filters.

Usage

butfilt(a, fl=0, fh=50, deltat=1, type="BP", proto="BU", npoles=5, chebstop=30.0, trbndw=0.3)

Arguments

a vector signal
fl low frequency cut-off, default=0
fh high frequency cut-off, DEFAULT=1/2dt
deltat sample rate, s, deFAULT=1
type type of filter, one of c("LP", "HP","BP" ,"BR" ), DEFAULT="BP"
proto prototype, c("BU", "BE" , "C1" ,"C2"), DEFAULT="BU"
npoles number of poles or order, DEFAULT=5
chebstop Chebyshev stop band attenuation, DEFAULT=30.0
trbndw Chebyshev transition bandwidth, DEFAULT=0.3

Details

creation of butfilt is a described by the following arguments:

LP
low pass
HP
high pass
BP
band pass
BR
band reject
BU
Butterworth
BE
Bessel
C1
Chebyshev type 1
C2
Chebyshev type 2

Arguments chebstop , trbndw are ignored for non-chebyshev filters. LP and HP filters are seet by specifying fl for HP filters and fh for LP filters, the other argumentin each case is ignored.

Value

filtered time series

Author(s)

Jonathan M. Lees<jonathan.lees.edu>

Examples

data(CE1)

ts1 = CE1$y
zz = butfilt(ts1, 1, 15,  CE1$dt, "LP" ,  "BU")


[Package RSEIS version 2.1-6 Index]