[MSNoise] QUESTIONS ABOUT ALL PROCESS WITH MSNOISE

[Thomas Lecocq]

Fernando,


the parameters look mostly OK, except:

if

cc_sampling_rate = 20

and your data is 125 Hz, you can't use Decimation by factor=125 ! You have to either

cc_sampling_rate = 25
decimation factor = 5

or
cc_sampling_rate = 20
method=Resample

In a future version, we will use the Trace.decimate() function from obspy which automatically lowpass the signal, but that would not solve your problem there !

Anyway, that should work better already (I'm surprised you even have results ... it should crash at step 3)... Are the CCF looking OK ? when you plot them manually ?



THEN:
for the MWCS, you need to remember that, for each time lag, the dt is calculated by a weighted linear regression, which needs at least several (>10?) points to work. So: if you have 0.1 to 0.2 Hz frequency band, you need 10 points there, which is equivalent to 100 points for 1 Hz --> you need to have a mwcs_wlen of ~100s !! (except if you hack a little the FFT and add zeros to the time series, but I don't recommend it without being really willing to dive deep in the maths/science of fft).


Cheers,

Thomas



Le 11/02/2015 18:17, Fernando Salazar Monroy a écrit :
>
>
>
>
>
> Hello Thomas,
>
>
> I'm trying again run msnoise in my computer, however I want to do some questions about the processing.
>
> I have all records in SAC format, and I have processed these with the next specifications:
>
> The sampling rate for the correlations is 1 sps
>
> startdate : 2009-01-01
> enddate : 2013-01-01
> analysis duration : 86400
> cc_sampling_rate : 20
> resampling_method : Decimate
> decimation_factor : 125
> preprocess_lowpass : 1
> preprocess_highpass : 0.0125
> maxlag : 120
> corr_duration : 1800
> windsorizing : 3
> crondays : -1
> autocorr : N
> keep_all : Y
> keep_days : Y
> ref_begin :2009-01-01
> ref_end : 2013-01-01
> export_format : MSEED
> sac_format : doublets
>
> I don't know why, but the mwcs.py don't stimate and s06compute_dtt.py the compiler don't function.
>
> One of the filter for the correlations is:
> correlations is low=0.1, low_mwcs=0.1, high_mwcs=0.2, high=0.2
> Someone could tell me if some parameter is wrong?
>
>
>
> Edilson Salazar
> Master in Earth Sciences
> National Autonomus University of Mexico
>
>
>
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