Time-Step Change

02-Analytical capabilities
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yildirimarda
Posts: 4
Joined: 04 Oct 2020, 21:32

Time-Step Change

Post by yildirimarda »

Good night everyone.

I have 25 sec earthquake data which time interval is 0.005.

First i filtered+baseline correction to it and looked for the instensity parameters. I saw max acc is 0.525 and time of max acc is 10.585
Then i changed time step to 0.02 and again looked for the instensity parameters. This time i saw the max acc is 0.527 and time of max acc is 9.5

My first question is why the acc is increased?

Secondly i saved filtered+baseline correctioned data to my desktop for 0.005 interval. Re-opened the seismosignal and firstly opened this filtered data and then change time step to 0.02 (i didnt do filtering second time again). This time i saw max acc is 0.509 and time of max acc is 10.58

My second question is i want to ask which one i did correct?

Thank you very much.
huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Time-Step Change

Post by huffte »

Increasing the time step will actually omit some of the data. Decreasing the time step will increase the resolution by linear interpolation between original points.

When you multiplied the time step by 4 you actually omitted a large section of the data. That is why it changed.

You can load an accelerogram with any time step you wish by specifying the correct options during the initial loading.

So to use the same data (acceleration values) with a modified (from the original) time step, specify "Single Acceleration Value per Line" (as an example, if your data is such) and the acceleration column (usually 2). Manually input your desired, artificial time step.
Tim Huff
yildirimarda
Posts: 4
Joined: 04 Oct 2020, 21:32

Re: Time-Step Change

Post by yildirimarda »

thanks for your responding sir.

I know when time step changes data will change. But i cant understand why increases. Why the original data cant reach that max acceleration which i found in larger time step?
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seismosoft
Posts: 860
Joined: 06 Jul 2007, 04:55

Re: Time-Step Change

Post by seismosoft »

Can it be the effect of filtering and / or baseline correction?
Seismosoft Support
yildirimarda
Posts: 4
Joined: 04 Oct 2020, 21:32

Re: Time-Step Change

Post by yildirimarda »

Thanks for your responding sir.

I'm using linear baseline correction and butterworth filtering with bandpass configuration.

Actually i dont know how can affect this situation for max acc?

Is it possible to talk about the subject a little bit? Under what conditions could this happen?
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Time-Step Change

Post by seismosoft »

This is not something that can be explained through a support forum, which anyway all is only about the use of our programs.
Some details are provided in the help of the program, but for a better understanding you need to read the details of baseline correction and filtering from a good textbook.
Seismosoft Support
yildirimarda
Posts: 4
Joined: 04 Oct 2020, 21:32

Re: Time-Step Change

Post by yildirimarda »

I could not express myself well.

I know what these options do. It's just the first time I've seen it increase the acceleration.
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