SAC Help

A forum for SAC users to exchange ideas and ask questions about SAC usage, installation, portability, etc.

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Active Message Threads for March 2008

Andreas Wuestefeld
2008-03-31 21:52:43
Hi again. Athur Snoke just pointed out to me, that the ghostscrip package might be of interest for some users (SGFTOPS...) In the CYGWIN setup, it's located in Grahics: * ghostscript Andy
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Andreas Wuestefeld
2008-03-31 18:58:55
Hi everybody As of SAC version 101.1 the SAC development team made some adoptions to ease installation under CYGWIN (http://www.cygwin.com/) If you want to compile SAC under CYGWIN, you mainly need to have installed several packages. Use the CYGWIN setup utility! I list the necessary packages here by category (as of CYGWIN1.5): ===================================================== 1) Packages which *need* to be installed Devel: * gcc-g++ * libncurses-devel * make * readlin... [more]
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Rick Benson
2008-03-31 03:35:43
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Onur Tan
2008-03-28 03:34:59
Dear Xu SAC uses omega convention. so you must multiply every poles and zeros with 2*pi*f ( in general, f=1Hz for Guralp seismometers). Do not use the values in Guralp Cal-Doc. Add one Zero for integration. And you have to calculate Constant using sensor and digitizer gain values. You can use this document: http://www.le.ac.uk/seis-uk/downloads/seisuk_data_manage.pdf I edit more detailed document, but in Turkish. If you want to read only numbers :) in this document I can send you. ... [more]
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Xuefeng Shang
2008-03-27 20:47:26
Hi all, I use command "transfer from EVALRESP to BBDISP" to deconvolve the instrument response, and get error below: Extracting evresp response for YKW1, BHE... EVRESP ERROR (YKW1.CN..BHE [File: ./RESP.CN.YKW1..BHE; Start date: 1989,025,00:00:00; Stage: 4]): check_channel; decimation blockette with no associated filter, skipping to next response now EVRESP ERROR (YKW1.CN..BHE [File: ./RESP.CN.YKW1..BHE; Start date: 1989,025,00:00:00; Stage: 4]): check_channel; de... [more]
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wwxu
2008-03-26 17:01:58
Dear ALL, I am using function "transfer" to deconvolve the instrument response in SAC, the usage is as "transfer from polezero subtype cmg3esp.response to none", and the file "cmg3esp.response" is in the format as SAC mannual told(poles, zeros, constant), here I want to know what is the unit of poles and zeros, radian/sec or Hz? it is very different as we know, can anyone help me? Your sincerely, Xu W. ************************************************ Dr. WeiWei Xu Institute of Geology a... [more]
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sac-help@iris.washington.edu
2008-03-26 13:41:51
(no body)
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Sribharath Kainkaryam
2008-03-21 03:12:13
(no body)
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Sribharath Kainkaryam
2008-03-20 23:07:41
(no body)
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Geo .
2008-03-14 00:09:29
Greetings everyone, I am in the process of writing a little macro to deconvolve the instrument response using poles zeroes files. For this I have to set a blackboard variable equal to the name of the poles zeros file for each instrument. Example of such a file name is as follows, SAC_PZs_US_JFWS_BHZ__1995.257.00.00.00.0000_2001.181.24.60.60.9999 I can set the first few characters of this file name using SETBB but the probelm is "1995.257.00.00.00.0000_2001.181.24.60.60.9999" part. Does anyo... [more]
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Robert Herrmann
2008-03-11 21:44:39
sac-help-request@iris.washington.edu wrote: The simple test of the FFT is to see the effect of an impulse: fg impulse delta 0.1 npts 1024 w impulse.sac *1. Test of sac2000 FFT *Sac creates a time series with a centered impulse of height 1.0 and not a unit area pulse. fft writesp am This creates a series of the amplitude spectrum, which has values of 0.1, e.g., 1 (from the time series) * DT from the fft ifft This creates a time series consisting of a centered impulse with height 1.0 ... [more]
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wwxu
2008-03-11 14:53:16
Hi, ALL We suppose that x[n] and y[k] are a DFT pairs, i.e. y[k]=1/N*sum_n(x[n]*exp(-2*pi*j*k*n/N)) n=0,1,...,N-1 where sum_n means the sum for n=0,1,N-1(similar for sum_k), and dt is the sampling interval, df is the sampling frequency, N is the sampling number. To obey Parseval's theorem, we get sum_n(x[n]*x[n])*dt=sum_k(y[k]*y[k])*df since sum_n(x[n]*x[n])=N*sum_k(y[k]*y[k]) and df=1/(N*dt), also consider the amplitude symmetry of the real series, we should multiply a coef... [more]
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Brian Savage
2008-03-11 02:20:54
For an forward FFT (fft) in SAC the output series is scaled by the time sampling or delta For an inverse FFT (ifft) in SAC the output series is scaled by 1/ (delta * npts) See below for a further discussion, but simply fg sine 5 npts 1024 delta 0.01 # Put the delta back in div 0.01 # Scale the FFT by the length of the signal div 1024 fft psp am # Maximum should be around 0.5 writesp tmp read tmp.am lh depmax # depmax should be about 4.671955e-01 (not exactly 0.5, but close) Cheers Bri... [more]
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Hi Fiona, I realize you are short of time, but perhaps these workarounds could be helpful... I don't know if this would be helpful, but (like a lot of folks), I have a matlab m-file that reads in SAC time series files. Likewise there is another that can write from Matlab to SAC. Perhaps this would be useful in that you could read in the SAC files and then convert them to the proper format for the surf. wave code to do it's stuff. I also have matlab code to do multi-channel cross-correla... [more]
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Fiona Darbyshire
2008-03-10 22:09:57 - 2008-03-10 22:58:44
Dear All, I think I have identified the issues regarding the SAC input/output associated with the cross-correlation program, but that has raised more questions before I can actually solve the problem. Some of the libraries called by the program are fairly standard ones that appear in the regular "sacio.a" (and in Computer Programs in Seismology...) - namely get*hv, set*hv, rsac*, wsac*. However, there are still 4 outstanding subroutine calls that are a problem. I downloaded the most recent ... [more]
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Tuna Eken
2008-03-09 07:03:38 - 2008-03-10 16:44:51
To message 3: Hi Onur, when I tried the same commands with the same parameters onto my example sac file it did worked out ... It actually gave the same error messae when i used different time values (whis is not included by the data) ... So problem may be caused by applying wrong values for your data. have you ever checked starting end ending points of the data ? regards tuna eken Message: 3 Date: Sat, 8 Mar 2008 13:29:51 +0200 From: "Onur Tan" <Onur.Tan@mam.gov.tr> Subject: [SAC-... [more]
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Onur Tan
2008-03-09 19:15:37 - 2008-03-09 20:31:55
Hi Tuna, exactly, my data length is 1800 sec. if you look the sample again, cutting limits is 600-700 sec. the problem is the first variable ( %a ) when echo on, the second variable can not writen to the screen ! SAC> cut %a %b cut %a %b ==> cut 600 Do you use the version 101.0? I have no problem with old version. onur -----Original Message----- From: sac-help-bounces@iris.washington.edu [mailto:sac-help-bounces@iris.washington.edu] On Behalf Of Tuna Eken Sent: ... [more]
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Onur Tan
2008-03-08 21:29:51
Hi, When I use a blackboard variable as the first parameter of the cut command in SAC new version (101.0), it gives error. I tried this (echo on): -------------------- SAC> setbb a 600 setbb a 600 SAC> setbb b 700 setbb b 700 SAC> cut %a %b cut %a %b ==> cut 600 SAC> r r WARNING: Start cut greater than stop cut for file 08010_0707_CEV.1 ERROR 1301: No data files read in. SAC> ----------------------------- the cut command do not understand the second variable. This does also n... [more]
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wwxu
2008-03-08 10:59:07
Hi ALL, In SAC, I generate a 5Hz sine wave and do fft transforming as follows: sac> funcgen sine 5 npts 1024 delta 0.01 sac> fft sac> psp am loglin and I find that the maximum absolute amplitude is greater than 4 near frequency 5Hz, but in theory, it should be 0.5 because of amplitude spectrum symmetry of real series, so could you tell me why? B.T.W., I also compute the amplitude spectrum using fft program I wrote and find that the result is not the same with SAC generated, I checked the ... [more]
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Hello, I have 2 SAC-related queries that are causing me problems on a couple of fairly urgent projects currently: i) I inherited a Matlab program for surface wave analysis. The seismogram files that it reads are in PITSA ASCII format. Is there any existing software to convert standard SAC to PITSA ASCII? Or will I have to convert SAC binary to alpha, and try to reformat the resulting ascii files? ii) Another inheritance: this time I have been given the source code (fortran) for John VanDec... [more]
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Sonia Castro Alarcon
2008-03-06 19:21:36 - 2008-03-07 17:32:57
Hi, I'm not sure if this is the email to write to find help but I didn't find other. I'm trying to make a macro for ploting with the sgftops options. I use the command sgftops f001.sgf file.eps 1 si to set the options *x translation :1 *y translation :1 *rotation angle:0 *scale...........:0.9 but I couldn't find the way to make the macro answer for this variables by itself and that makes I couldn't run it easy and in a loop for all the files. Can you help me please? thanks Sonia Castro Al... [more]
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Hersh, The error you are seeing > SAC> rbbf wndbbf_all > ERROR 1203: Could not find VARS section is because the blackboard files you are trying to read into SAC are in a different byte order than the machine you are on. The files can be swapped with a little effort, but being able to read blackboard variable files of either byte order should be available in the next release of SAC. Cheers, Brian On Mar 3, 2008, at 12:49 PM , Hersh Gilbert wrote: > Hi SAC help, > > I am having ... [more]
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Geo .
2008-03-01 18:16:46
Thanks Rob, I don't have a Mac, so I guess I'll have to revert to traditional rdseed, On Fri, Feb 29, 2008 at 3:26 PM, <sac-help-request@iris.washington.edu> wrote: > Send sac-help mailing list submissions to > sac-help@iris.washington.edu > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.iris.washington.edu/mailman/listinfo/sac-help > or, via email, send a message with subject or body 'help' to > sac-help-request@iris.washington.edu > > You can... [more]
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