Thread: Mustang/noise-pdf frequencies

Hi webservices team,

I wanted to confirm what the frequencies in the text output of
Mustang/noise-pdf web service exactly represent.

In the following I'm referring to the output of:
Text:

http://service.iris.edu/mustang/noise-pdf/1/query?network=IU&station=ANMO&location=00&channel=LHZ&quality=*&starttime=2010-01-01&endtime=2010-01-03&plot.interpolation=none&plot.period.min=2.1&plot.period.max=2.3&format=plot
Plot:

http://service.iris.edu/mustang/noise-pdf/1/query?network=IU&station=ANMO&location=00&channel=LHZ&quality=*&starttime=2010-01-01&endtime=2010-01-03&plot.interpolation=none&plot.period.min=2.1&plot.period.max=2.3&format=text

Comparing tabulated output and the plot, it looks like the lowest period
data point given in text output (in this case: 0.475683 Hz == 2.1022 s)
coincides with the left edge of the first pixel in the plot (as opposed
to the bin being centered at this period value), while on the other hand
the curves for Min/Max/Mode start at this period value.

What exactly are those tabulated values? Is it the center of the
full-octave smoothing window (i.e. geometric mean of left/right edge),
which is what I would expect.. in that case the bin-pixels in the plot
should be shifted half a bin width to the left.
Or.. is it indeed the left edge of the pixel, which would be very
surprising.. and in that case the min/max/mode curves should be shifted
to the right by half a bin-pixel width.

In any case I could not find information on this detail in the
webservice documentation, so this piece of information should be added.


best,
Tobias




--
Dipl.-Geophys. Tobias Megies

Geophysikalisches Observatorium
Ludwigshöhe 8
82256 Fürstenfeldbruck

Ludwig-Maximilians-Universität
Department für Geo- und Umweltwissenschaften
Sektion Geophysik
Theresienstrasse 41/IV
80333 München

Tel: +49 (0) 89 2180-73981
+49 (0) 89 2180-4326
Mail: tobias.megies<at>geophysik.uni-muenchen.de