RSEIS (version 2.1-6)

butfilt: 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

Value

• filtered time series

Details

creation of butfilt is a described by the following arguments: [object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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.

Examples

data(CE1)

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