SEED band code clarification requested

[Tim Knight]

forwarded message:
> From: Doug Neuhauser <do...@seismo.berkeley.edu>
> Date: December 24, 2008 12:36:07 PM PST
> Subject: SEED band code clarification requested
>
> The SEED manual (Appendix A) provides some guidelines for band code
> assignment based on sample rate, and for higher sampling rate, based
> on corner frequency. These have recently been extended to define
> band codes for higher sample rates based on the same corner frequency
> guidelines.
>
> Band Band type Sample rate Corner period
> code (sec)
> ---------------------------------------------------------------------
> B Broad band >= 10 to < 80 >= 10 sec
> H High Broad Band >= 80 to < 250 >= 10 sec
> C ... >= 250 to < 1000 >= 10 sec
> F ... >= 1000 to < 5000 >= 10 sec
>
> S Short Period >= 10 to < 80 < 10 sec
> E Extreme Short Period >= 80 to < 250 < 10 sec
> D ... >= 250 to < 1000 < 10 sec
> G ... >= 1000 to < 5000 < 10 sec
>
> I and others in the SEED community would like some clarification and
> guidance
> on what the term "Corner period (sec)" refers to. Specifically, it
> is not
> clear into which of the above "corner period" categories data from
> accelerometers and other geophysical instruments such as electric
> and magnetic
> field sensors should be classified.
>
> For traditional accelerometers:
> If the "corner period in seconds" refers to the lower corner of the
> flat
> passband of the measured observation (eg acceleration for an
> accelerometer),
> then I would infer that accelerometers should be classified along with
> "broadband" sensors in the first group of band codes where the
> corner period
> of >= 10 seconds, since the response of acceleromters is flat to ~
> DC (0 Hz ~=
> infinity seconds). However, if the corner period in seconds refers
> to the
> natural period of the actual sensor, most accelerometers have a
> natural period
> of several Hz (< 1 second), from which I would infer that they
> should be
> classified with "short period" on the second group of band codes
> with a corner
> period of < 10 seconds. If the corner period is based on the
> characteristics
> of the physical sensor, and not of the property of the data produced
> by the
> sensor, it is unclear how this may change for non-traditional
> sensors such as
> silicon-based or fluid sensors.
>
> It sould be extremely helpful to have additional guidelines to help
> the SEED community standardize on channel names. Currently, I have
> seen both E and H bandcodes uses for 100 Hz accelerometer data,
> and the same confusion exists for higher sample rates.
>
> For other geophysical data channels such as electric and magentic
> field
> sensors, the same question arises. For both electric and magnetic
> field data
> channels, the response of data channels are often flat to close to
> DC, so I
> would infer that they should be classified along with the broad band
> sensors.
> However, if the classification is based on the senor
> characteristics, it is is
> not clear what characteristics of the actual sensor you would use for
> classification.
>
> - Doug N
>
> --
> ------------------------------------------------------------------------
> Doug Neuhauser University of California, Berkeley
> do...@seismo.berkeley.edu Berkeley Seismological Laboratory
> Office: 510-642-0931 215 McCone Hall # 4760
> Fax: 510-643-5811 Berkeley, CA 94720-4760
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