source: SH_SHM/trunk/doc/recfilters.txt @ 373

Revision 16, 1.2 KB checked in by marcus, 14 years ago (diff)

r1 | svn | 2007-12-13 11:10:29 +0100 (Do, 13 Dez 2007) | 2 lines

Initial import

Line 
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2
3Recursive filters from poles and zeros files using MATLAB:
4
5- type the FFT filter file (e.g. GRSN_S+G_WWSSN_SP.FLF)
6! file GRSN_S+G_WWSSN_SP.FLF
7!      =====================
8!
9! version 1, 25-Nov-94
10!
11! simulation filter for
12! seismometer  h1 (0.670000), T1 (1.250000)
13! galvanometer h2 (0.840000), T2 (0.750000)
14! recorded at instrument
15! seismometer  h0 (0.707000), T0 (120.900002)
16! K. Stammler, 25-Nov-94
171357913578
181
197.018386e+01
202
21(-3.674286e-02,-3.675396e-02)
22(-3.674286e-02,3.675396e-02)
234
24(-3.367788e+00,-3.731514e+00)
25(-3.367788e+00,3.731514e+00)
26(-7.037168e+00,-4.545562e+00)
27(-7.037168e+00,4.545562e+00)
28
29- call MATLAB and define column vectors with complex zeros and poles:
30>> Z = [
31-0.0367 - 0.0368i
32-0.0367 + 0.0368i
33]
34>> P = [
35-3.3678 - 3.7315i
36-3.3678 + 3.7315i
37-7.0372 - 4.5456i
38-7.0372 + 4.5456i
39]
40
41- define gain K and sample frequency Fs
42K = 7.018386e+01
43Fs = 20
44
45- compute transfer function using zp2tf:
46[num,den] = zp2tf( Z, P, K )
47
48- compute recursive coefficients using bilinear
49[NUMd,DENd] = bilinear( num, den, Fs )
50
51- create FLR-file:
521. line '1357913578'
532. line '3'
543. line sample distance in s
554. line gain factor
565. line number of NUMd elements
57from 6. line: list NUMd elements
58N. line: number of DENd elements
59from N+1. line: list DENd elements
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