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spectral analysi
Posted: Mon Jun 17, 2024 5:23 pm
by Yasin_Janem
Greetings dears,
Hope you are doing well,
How can I make a spectral analysis for each component to judge if the resulting frequency is the resonance frequency or not as shown in the attached images?
And what are the best parameters for spectral analysis, considering that I'm using the following parameters for HVSR analysis
1- Taper window type (Cosine)
2- Smoothing window type (Konno - Ohmachi width log 40% - Y scale type linear)
3- Anti-triggering on raw signal
![Image]()
![Image]()
Best regards.
Yasin Janem.
Re: spectral analysi
Posted: Mon Jun 17, 2024 9:17 pm
by admin
Hi Yasin,
The images are missing.
If I properly understood your question, you can get the spectra by running the Spectrum tool which is provided in the same plugin library as the HV tool (see menu Tools). Select the same parameters in the Spectrum tool as in the HV tool.
Best regards,
Marc
Re: spectral analysi
Posted: Tue Jun 18, 2024 3:38 pm
by Yasin_Janem
Greetings Mark,
Thanks for your reply and I really appreciate your efforts.
Sorry for the missing images, could you please have a look at the attached images?
I tried the spectrum tool which is provided in the same plugin library of H/V, as shown in (Geopsy spectrum image) the units were different than the (Example 1 and Example 2 images), moreover, it's not clear in (Geopsy spectrum image) that each line in the graph related to which component.
Best regards.
Yasin Janem.
Re: spectral analysi
Posted: Wed Jun 19, 2024 1:18 pm
by admin
The units depends upon the unit of the signals. By default, the signals have no unit ("count"). If the conversion factor "count2volt" is different from 1, the signal are shown in volt. The same applies to "volt2unit". These values can be set for each signal in a table (direct editing after unlocking edition in menu "Edit") or with menu "Edit/
Set header".
To change the line types, right-click on the plot and select "Properties". Inside "Layers" tab, change the legend, put your own style to distinguish the lines. The order is the same as in the sheet with the individual results.
Re: spectral analysi
Posted: Fri Jun 21, 2024 6:14 pm
by Yasin_Janem
Thanks for your reply and clarification regarding the legend. I still have one problem that wasn't solved and thought that maybe I didn't clarify the problem properly.
my problem is as follows:
when I use the spectrum analysis tool, it calculates and presents a graph that shows the unit "(counts^2)/Hz" on the Y-axis, and that is not the required output in my situation, what I need for the Y-axis to represent is the unit "(mm/s)/Hz" but I still have some difficulty doing exactly that.
it should be noted that the X-axis represents the unit I need, and I don't plan on changing it.
thanks in advance,
Yasin Janem.
Re: spectral analysi
Posted: Fri Jun 28, 2024 10:10 am
by admin
If CountPerVolt and VoltPerUnit fields have a value of 1, signal units are assumed to be Counts. If you want to plot your spectra in mm/s, you have to change the values of these fields with menu Edit/Set header. For example you can use these scripts.
If your signals are originally in Count (adjust the correction factors):
Code: Select all
for(i=0; i<signals.length; i++) {
signals[i].countPerVolt=10000
signals[i].voltPerUnit=2000
signals[i].amplitudeUnit="Velocity"
}
If your signals are already in m/s but Geopsy does not know it, use this trick:
Code: Select all
for(i=0; i<signals.length; i++) {
signals[i].countPerVolt=0.5
signals[i].voltPerUnit=2
signals[i].amplitudeUnit="Velocity"
}
The amplitude of the signal is not affected. Geopsy uses only m/s for Velocity. You have to edit the Y axis of your results to set them to (mm/s)^2/Hz. This is valid only if the original signals are in mm/s. Note the square because this is a spectrum power. The spectrum amplitude would be in mm/s/sqrt(Hz).