Ok, thanks Lukas!
I brought up a similar question last week about how the cross-correlation
segmenting was done and after talking to Esteban/Thomas my impression was
that corr_duration simply split the time segments into chunks, and did the
cross correlation in chunks PURELY for efficiency reasons, and then rebuilt
the total daily time cross correlation afterwards, and did not stack them.
But this seems to not be true then?
-ashton
On Thu, Oct 13, 2016 at 3:09 AM, Lukas Preiswerk <preiswerk(a)vaw.baug.ethz.ch
wrote:
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(a)usgs.gov>ov>:
> 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(a)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(a)usgs.gov>ov>:
>>> 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(a)mailman-as.oma.be
>
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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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