Thread: Ascii to SAC

Hello Barney, 
Why not do the FFT in Matlab and pick the peak frequencies if that's the only thing you want to do without converting your data to .SAC? If you are not familiar with its use you could use positiveFFT.m program from Jake Blanchard's website: http://blanchard.ep.wisc.edu/PublicMatlab/
Note that your inputs are thermal data vector and sampling frequency. 

If things are still not clear you could look at his tutorial here: http://www.youtube.com/watch?v=Oi2vFowjYiY
Note that positiveFFT.m part starts at 3:15. 

Januka.
 
_______________
Serenity isn't freedom from the storm, but peace within the storm

Januka Attanayake 
Earthquake Seismology & Economics
The University of Connecticut
354, Mansfield Road
Storrs, CT 06269-2045
Tel:860 486 3914 (Lab - P405)

Home page: http://sites.google.com/site/janukaattanayake/
Research group: http://www.phys.uconn.edu/research/geophysics/index.html








________________________________
From: Thomas Barningham <stbarningham<at>googlemail.com>
To: sac-help<at>iris.washington.edu
Sent: Monday, June 4, 2012 6:00 PM
Subject: [SAC-HELP] Ascii to SAC


Dear all,

I'm trying to convert an ascii file into a sac file so that it can be read by a matlab program that i'm using. I have a time series of thermal data from several fumaroles that i'm trying to analyse, the current ascii file looks like this:

Measurement definition file: 
Nevado_1001300245-Nevado_1001300890.mdf
Sequence start time: 
13-feb-2010 13:13:53 
Index X01 MaxX02 MaxX03 MaxA04 MaxR05 AvgR06 Avg
013,94210,8432,04741,8535,6227,276
114,66310,96529,60331,4015,847,431
214,30510,44537,22741,8315,8327,503
314,32410,80537,95942,9415,8827,558
414,39910,62531,83532,5185,8557,566
514,68211,57636,2945,1645,957,578
615,0212,93136,52945,2316,0267,651
714,45611,10537,19845,076,0057,627

etc

What I want to do is process this through a program constructed from matlab scripts that have been designed to analyse seismic data with a graphical interfere, it's called "Seismo_volcanalysis" if any of you have used it. Specifically these scripts will enable me to perform a fast Fourier transform in order to pick out periodic temperature fluctuations from the fumaroles. But to do this I need my ascii file in sac format so that it can be read by the program, can anyone help?! I realise the program is designed for seismic analysis, but I figured the scripts could also be used to analyse thermal data...

Cheers
Barney
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sac-help<at>iris.washington.edu
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Dear Barney -

See the SAC manual for the ASCII file format, here:

http://www.iris.edu/software/sac/manual/file_format.html

As a quick and dirty solution, I'd suggest that you copy and paste the header info from the example, change NPTS (last field on line 16) and then substitute your own data values at the end by copy/paste or an awk script. Then read it in and modify the header values to what you need by CH commands. Watch out for the strict field widths, however.

On 4 Jun 2012, at 23:00, Thomas Barningham wrote:

Dear all,

I'm trying to convert an ascii file into a sac file so that it can be read by a matlab program that i'm using. I have a time series of thermal data from several fumaroles that i'm trying to analyse, the current ascii file looks like this:

Measurement definition file:
Nevado_1001300245-Nevado_1001300890.mdf
Sequence start time:
13-feb-2010 13:13:53
Index X01 Max X02 Max X03 Max A04 Max R05 Avg R06 Avg
0 13,942 10,84 32,047 41,853 5,622 7,276
1 14,663 10,965 29,603 31,401 5,84 7,431
2 14,305 10,445 37,227 41,831 5,832 7,503
3 14,324 10,805 37,959 42,941 5,882 7,558
4 14,399 10,625 31,835 32,518 5,855 7,566
5 14,682 11,576 36,29 45,164 5,95 7,578
6 15,02 12,931 36,529 45,231 6,026 7,651
7 14,456 11,105 37,198 45,07 6,005 7,627

etc

What I want to do is process this through a program constructed from matlab scripts that have been designed to analyse seismic data with a graphical interfere, it's called "Seismo_volcanalysis" if any of you have used it. Specifically these scripts will enable me to perform a fast Fourier transform in order to pick out periodic temperature fluctuations from the fumaroles. But to do this I need my ascii file in sac format so that it can be read by the program, can anyone help?! I realise the program is designed for seismic analysis, but I figured the scripts could also be used to analyse thermal data...

Cheers
Barney
_______________________________________________
sac-help mailing list
sac-help<at>iris.washington.edu
http://www.iris.washington.edu/mailman/listinfo/sac-help

George Helffrich
george.helffrich<at>bris.ac.uk

Hi folks,

What is the sign convention for radial and tangential components if I
use the "rotate to gcp" command? My guess is away from the event is
positive radial, and positive tangential will be 90deg clockwise of the
positive radial. "help rotate" is a little vague, so I figured it
couldn't hurt to check.

Thanks,

Derek

--
Derek Schutt
Assistant Professor
Geosciences
Colorado State University
970-491-5786