bfil infile itype npoles fcenter bwidth ifaz infile =input file name itype 0=low-pass filter, cut off freq= fc (-3dBv) 1=band-pass filter, center frequency= fc 2=high-pass filter, cut off freq= fc (-3dBv) npoles =number of poles in filter (6dB/octave)/(pair of poles) fcenter =center frequency Hz bwidth =band-pass filter bandwidth (-3dB) Hz ifaz 1=minimum phase 0=zero phase filter
Examples of filtering with BFIL are shown in Figure 93:
bfil c008.seg 0 4 12. 1
bfil c008.seg 2 4 48. 1
bfil c008.seg 1 4 24. 24. 1
Another way to band-pass filter is to run the data twice, once through a low-pass, and then through a high-pass filter, choosing cut-off frequencies to produce a band-pass.