Dear WG-II members,
Please find the following proposal made by IRIS DMC, USGS/ASL and BSL/NCEDC for changes to the
SEED documentation for blockette 62 (Polynomial). A lot of work has been done by Chad to formulate
the new description - thanks! If you have any further comments please let me know within 1 week.
Reinoud
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Proposed changes to SEED Blockette 62 (IRIS DMC, USGS/ASL, BSL/NCEDC)
For consistent and expanded usage of blockette 62 (Polynomial) clarification is needed in the documentation. The largest change is the ability to use a blockette 62 to describe a total system response, this is now the preferred usage of a 62; the ability to use a 62 to describe a single component remains. Also clarified is that a total system sensitivity (blockette 58 in stage 0) should NOT be used when a 62 is present. And finally the units are clarified.
An example SEED RESP file describing a total system response using a blockette 62 is included after the proposed wording changes.
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[62] Response (Polynomial) Blockette
Use this blockette to characterize the response of the entire system or a a component (e.g. sensor) of the system. When used in stage 0 the polynomial should describe the conversion from the sample values to Earth units. When used within the response cascade (stages >= 1) the polynomial should represent a single component of the system. A stage 0 polynomial should always be present to facilitate conversion of the data to Earth units when any component of the system is described using a polynomial. Conversely, a complete response may be specified with only a polynomial specified in stage 0. When any system is described using a polynomial, a blockette 58 should not be present in stage 0 (sensitivity); unless the polynomial describes a linear transform a total sensitivity scalar cannot be correct. Unlike most other response blockettes that describe a filter representing a component during data acquisition, the polynomial describes a function to be applied to the data.
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Further clarification is needed for the units, the new field descriptions are proposed as follows:
5 A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming signal to this stage from the system perspective. These are the units of the dependent variable (e.g. Earth units) that result from applying the polynomial.
6 A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the output signal from this stage from the system perspective. These are the units of the independent variable (e.g. Counts, Volts) that are used as inputs to the polynomial.
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Example of a blockette 62 in stage 0 used to describe a complete system:
#
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#
B050F03 Station: ANTO
B050F16 Network: IU
B052F03 Location: 30
B052F04 Channel: LDO
B052F22 Start date: 2010,204,00:00:00
B052F23 End date: 2599,365,23:59:59
#
# +-----------------------------------+
# | Response (Polynomial) |
# | IU ANTO 30 LDO |
# | 07/23/2010 to 12/31/2599 |
# +-----------------------------------+
#
B062F03 Transfer function type: P
B062F04 Stage sequence number: 0
B062F05 Response in units lookup: PA - Pressure in Pascals
B062F06 Response out units lookup: COUNTS - Digital Counts
B062F07 Polynomial Approximation Type: M
B062F08 Valid Frequency Units: B
B062F09 Lower Valid Frequency Bound: +0.00000E+00
B062F10 Upper Valid Frequency Bound: +5.00000E-01
B062F11 Lower Bound of Approximation: +8.00000E+04
B062F12 Upper Bound of Approximation: +1.10000E+05
B062F13 Maximum Absolute Error: +0.00000E+00
B062F14 Number of coefficients: 2
# Polynomial coefficients:
# i, coefficient, error
B062F15-16 0 +8.00000E+04 +0.00000E+00
B062F15-16 1 +1.43050E-02 +0.00000E+00