Re: [MSNoise] MSNoise Digest, Vol 31, Issue 1

Thanks Esteban, I have looked through the documentation extensively, as well as the SRL paper, and a bit of grepping on the source code (e.g. it took me a while to figure out why in the world I couldnt remove instrument responses using a RESP or PZ file, since it is listed on the documentation page, until I grepped the source code and saw those were not implemented.) 1) Yes. It is more efficient to compute the cross-correlation functions or Green’s functions using 30-min chunks. Although you can change this feature if you will. Segments are re-build afterwards. This is only true if the daily segments are always preloaded into memory (IO vs CC time). The SRL paper makes it sounds like this is the case, but I want to make sure that this is always the case, even for processing many stations/days or long segments. I also wasnt sure if these segmented CC were used for any statistics (e.g. uncertainty in daily CC values). 2) You need to define the filters in order to compute the cross-correlations and extract the coherent part of the ambient noise for a given frequency range. MWCS is used to compute the moving window cross spectral analysis after the cross-correlation procedure. Yes, I understand that (the way its been written) filter values should be defined before the CC (which really should only be the whiteneing band or preprocessing), however I dont understand why in the web gui the whiten and MWCS filters are put within the same group. This make me predefine a MWCS filter band, along with my whiten band, even though the MWCS doesnt happed for another two processing steps. This leads to confusion, for example; What happens if I compute the CC's with a defined filter (as written, a MWCS and whiten filter defined together) and then want to compute different MWCS's later on when I actually get to the MWCS step. Can I just define a new filter, with new mwcs_low mwcs_high values? Since the web gui forces me to define a filter high low value (whiten, I assume) does it not use these? Do I have to go back and recalculate the cross correlations everytime I want to add an MWCS filter (which I wouldnt expect I have too)? Similarly, what happens if I want to delete a set of processed MWCS or stacks? I cant just delete the folder, since their are still pointers in the sql database. Just reprocessing doesnt seem to work either. thanks again -ashton On Thu, Oct 6, 2016 at 10:17 AM, Esteban Chaves <echfisica(a)gmail.com> wrote: -- Ashton F. Flinders, Ph.D U.S. Geological Survey 345 Middlefield Road Menlo Park, CA 94025 (650) 329-5050