F-K Analysis, can not find the time window

This forum is dedicated to discuss all problems and suggestions related to the use of geopsy database and its plugins (array processing, H/V,...).
Post Reply
mercury
Posts: 2
Joined: Thu Apr 01, 2021 7:58 am

F-K Analysis, can not find the time window

Post by mercury »

Hello, I have compiled the seismic waves (background noise) recorded by a group of station arrays into a group file, and the waveform displayed is as follows.and the time and processing parameters are as follows.When testing, the waveform interface has no window information, I want to know why.

thanks!
Attachments
time.png
time Parameter setting
(26.04 KiB) Not downloaded yet
process.png
Parameter setting
(19.85 KiB) Not downloaded yet
grid.png
grid research Parameter setting
(17.96 KiB) Not downloaded yet
波形.png
A set of seismic signals
(143.8 KiB) Not downloaded yet
admin
Site Admin
Posts: 841
Joined: Mon Aug 13, 2007 11:48 am
Location: ISTerre
Contact:

Re: F-K Analysis, can not find the time window

Post by admin »

Hi,

For FK processing, you can see the time windows only if you press in "Test" button. It is an interactive tool to look at individual FK maps calculated for each block set (a statck of several time windows as specified by block averaging options). Usual with FK, we do not look at individual time windows, but rather process the results statistically by analysing the .max files produced when pressing on "Start" button. You can view the .max files with gphistogram or gpviewmax.

Just note that we prefer length of time windows proportional to the period of interest. Hence the option frequency dependent is generally chosen. Anti-triggering for FK processing is not helpful and even it can remove interesting part of the signal. So I would remove it.

Best regards,

Marc
mercury
Posts: 2
Joined: Thu Apr 01, 2021 7:58 am

Re: F-K Analysis, can not find the time window

Post by mercury »

I pressed the "Test" option, but the time window did not appear, and there was no data in the “.max file” generated by clicking "Start".
best regards.
admin
Site Admin
Posts: 841
Joined: Mon Aug 13, 2007 11:48 am
Location: ISTerre
Contact:

Re: F-K Analysis, can not find the time window

Post by admin »

Hi,

Sorry for this late answer. If you still have this case at hand, I noticed that the anti-trigger option was on (time.png). For FK processing, this is not recommended. If you have no output in the .max file and no window information when pressing "Test", it is likely that no time window can be added. The anti-trigger option can block time windows. On the signal plot, the available time range looks also quite small (only 2 minutes?). But with 10 s time windows you should get time windows. If you remove the anti-trigger and still get no time window, try to switch to the latest release (currently 3.4.1).
Post Reply