Thread: guidelines for band code assignment

Dear WG II members,



During the preparation for the next WG II meeting inMelbourne I noticed

the following request made by Doug Neuhauser, upon which our WG never took

further action (?).



A pragmatic solution would be to keep the current band code in place for the

seismometers and define new ones for accelerometers and other geophysical instruments

based on the sample rate only, for example:



I sr>= 1000 Hz

J sr: 250 Hz– 1000 Hz

K sr: 100 Hz– 250 Hz

N sr: 1 Hz– 10 Hz

P sr: ~ 1 Hz

W sr: ~ 0.1 Hz

X sr: ~ 0.01 Hz

Y sr< 0.01 Hz



Please let me know your thoughts.



I will send you a draft agenda for the WG II meeting today or tomorrow.



Cheers,

Reinoud

From: Doug Neuhauser<doug at 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.

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