[MSNoise] One more clarification

[Lukas Preiswerk]

Ashton,

> I think the part that is throwing me off a bit is the "Daily NCFs were then
> obtained by stacking 30-min NCFs".
> This sound like to be, they took their individual 30 min NCFs and stacked
> them, so that each day is represented by the stacked summation of 48
> independent NCFs.

Agreed. If you set corr_duration to 1800 and leave analysis_duration
in the standard 86400, this is exactly what you get in the 1-Day
stacks.

> I assumed that meant that both corr_duration and analysis duration were set
> to 3600, but maybe not.

As I mentioned, if you set analysis_duration to 3600,
then you only use 1 hour of data each day and leave the rest
untouched… Try it for yourself with the keep_all option enabled and by
looking at the data in the h5 files.

Lukas




2016-10-12 18:08 GMT+02:00 Flinders, Ashton <aflinders at usgs.gov>:
> Thanks Lukas!
>
> I think the part that is throwing me off a bit is the "Daily NCFs were then
> obtained by stacking 30-min NCFs".
>
> This sound like to be, they took their individual 30 min NCFs and stacked
> them, so that each day is represented by the stacked summation of 48
> independent NCFs.
>
> I assumed that meant that both corr_duration and analysis duration were set
> to 3600, but maybe not.
>
> I'll probably just send an email out to them to see what parameters they
> used.
>
>
> On Tue, Oct 11, 2016 at 11:35 PM, Lukas Preiswerk <
> preiswerk at vaw.baug.ethz.ch> wrote:
>
>> Hi Ashton,
>>
>> I can partly answer 1) and 3). First, corr_duration would be 30*60 in
>> their paper (corr_duration is in seconds). As far as I understand,
>> analysis_duration should almost always be 86400. Setting the
>> analysis_duration
>> smaller could be used to prevent loading a full day of data for
>> specific cases, like super high frequency data (8kHz or more). The
>> remaining processing still works on days and not multiples of
>> analysis_duration. For examplem if you set analysis_duration to 3600,
>> then you only use 1 hour of data each day…
>>
>> Hope that helps!
>>
>> Lukas
>>
>>
>> 2016-10-11 18:57 GMT+02:00 Flinders, Ashton <aflinders at usgs.gov>:
>> > Hi all, I was just reading through Taka'aki and Forents new paper using
>> > MSNoise, and was hoping just for a wee bit more clarification on the
>> > MSnoise processing scheme (wasnt quite clear in the docs).
>> >
>> >
>> > The paper says;
>> > "We first removed the instrument response from 1-day-long waveform to
>> > obtain ground motion in displacement. Daily displacement data were
>> > bandpassed between 0.08 and 2.0 Hz, down-sampled into 10  Hz, and split
>> > into 30-min-long data. Those 30-min-long data were spectral whitened in a
>> > frequency range of 0.1–0.9  Hz and then one-bit normalized. With those
>> > one-bit normalized data, the NCFs were computed for all possible
>> > combinations of components. Daily NCFs were then obtained by stacking
>> > 30-min NCFs."
>> >
>> >
>> > Q1) So just in terms of implementation in msnoise admin, the 30-min-long
>> > duration would be controlled by "analysis_duration" correct?
>> >
>> > Q2) If you remove the instrument response, is it always removed from a 1
>> > day chunk, or is it removed from a chunk equal in size to
>> > "analysis_duration"? (the docs say 1 day, but I wasnt sure if this was
>> just
>> > referencing the default "analysis_duration" time).
>> >
>> > Q3) This probably isnt the intended usage, but if you used
>> > "analysis_duration" longer than a day, would you expect things to behave?
>> >
>> > Thanks as always!
>> >
>> > -ashton
>> >
>> >
>> > p.s. paper;
>> > http://earth-planets-space.springeropen.com/articles/10.
>> 1186/s40623-016-0538-6
>> >
>> > --
>> > Ashton F. Flinders, Ph.D
>> > U.S. Geological Survey
>> > 345 Middlefield Road
>> > Menlo Park, CA 94025
>> > (650) 329-5050
>> > _______________________________________________
>> > MSNoise mailing list
>> > MSNoise at mailman-as.oma.be
>> > http://mailman-as.oma.be/mailman/listinfo/msnoise
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>
>
>
> --
> Ashton F. Flinders, Ph.D
> U.S. Geological Survey
> 345 Middlefield Road
> Menlo Park, CA 94025
> (650) 329-5050
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