Thread: Band-pass filter

Hi Rehman,

I do not understand because you applied a filter repeatedly, anyway.

I attach a plot when is applied your filter four times to an impulse,
sac command: sac> funcgen.

Obviously the results that the filter modify slightly the amplitude of
signal and also a delay (time axe)
in each instance.

In sac I do:

SAC> funcgen

SAC> bp c 0.01 .1 n 4 p 2

SAC> w 1.sac

SAC> bp c 0.01 .1 n 4 p 2

SAC> w 2.sac

SAC> bp c 0.01 .1 n 4 p 2

SAC> w 3.sac

SAC> bp c 0.01 .1 n 4 p 2

SAC> w 4.sac

SAC> p2

SAC> r ./1.sac ./2.sac ./3.sac ./4.sac

SAC> p2

SAC> color on inc

SAC> p2

Cheers,

Milton






************************************
Milton P. PLASENCIA LINARES

Centro di Ricerche Sismologiche (CRS)
OGS - Istituto Nazionale di Oceanografia e di Geofisica Sperimentale

Borgo Grotta Gigante 42/C
(34010) Sgonico - Trieste - Italia
Tel: +39 040 2140 156 (Udine)
Tel: +39 040 2140 256 (Trieste)
Cel.: +39 331 6481 935

E-mail: mplasencia<at>inogs.it
GPG key: 22FCFFA8

ASAIN (Antarctic Seismographic Argentinean Italian Network)
*********************************

On 20 September 2017 at 17:05, Rehman . <rehman.techgeophy<at>gmail.com> wrote:

Hello,
I have band passed a teleseismic event waveform with ( bp c
0.01 0.1 n 4 p 2), It filtered the noise and given a nice waveform shape.
But buy applying multiple times band-pass filter ( bp c 0.01 0.1 n 4 p 2)
to same waveform I observed slight change in waveform every time. Why it is
so? Can I work with multiple times filtered waveform?


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