POSC Specifications: Epicentre Version 3.0 | Logical Data Model |
A wavelet (W) or digital filter (F) are differentiated in terms of their effects on a physical process and to data representing it. In seismic, the physical process is a reflection series (R) and the data are the seismic trace values (T). The wavelet is defined by W*R = T and the digital filter by R = F*T, where * represents convolution. A filter is the inverse of a wavelet. Either a wavelet or a filter can be described in terms of both its frequency spectrum and time spectrum. A parametric description of a "notch" response will have a negative value for low cut rate and a positive value for high cut rate.
- identifier (M, K: ndt_identifier) (C037)
- A name which identifies the wavelet or filter.
- ref_wavelet_or_filter (M, K: ref_wavelet_or_filter(wavelet_or_filter)) (C138)
- Indicates a wavelet or a type of filter represented by the instance. Recognized values include wavelet, bandpass filter, lowpass filter, highpass filter, notch filter. Indicates whether the waveform described is the wavelet "in" the data or a filter applied "to" the data. Each wavelet_or_filter must be a kind of one ref_wavelet_or_filter.
- activity (O, K, I: activity(process_data))
- Defines the activity which created this instance. Each wavelet_or_filter may be the result of one activity. Inherited from process_data.
- description (O, I: ndt_comment) (C117)
- A remark or comment about the instance. Inherited from e_and_p_data.
- dominant_period (O: ndt_time)
- The dominant period of the wavelet.
- dominant_wavelength (O: ndt_length)
- The dominant wavelength of the wavelet.
- frequency_index (O: ndt_frequency_1d_index)
- Defines the frequency axis associated with a frequency spectrum.
- frequency_spectrum (O: ndt_frequency_spectrum_1d_value)
- The amplitude and-or phase values of the frequency spectrum for the wavelet or filter. The corresponding frequency values are defined by the frequency index.
- high_cut (O: ndt_frequency)
- The frequency designator specific to a frequency where the response of the filter is attenuated 3 decibels (to 70% amplitude, or half power) of the total signal amplitude. Frequencies greater than the high cut are reduced by more than 3 decibels, and frequencies less than the high cut are reduced by less.
- high_cut_rate (O: ndt_decibel_per_octave)
- The rate, in decibels per octave, at which the amplitude spectrum changes with respect to increasing frequency at the high cut. Positive indicates a high cut (or top of a band pass) response. The power spectrum will change at twice this value.
- impulse_response (O: ndt_amplitude_1d_value)
- The amplitude values of the time spectrum for the wavelet or filter. The time axis of the grid is defined by time index.
- instance_create_date (O, I: ndt_date_tod) (C126)
- This is the date that this instance was created. This date is defined by the source if imported, or is the date the instance is created if a new instance. Inherited from e_and_p_data.
- instance_creator (O, I: ndt_identifier) (C126)
- This is the person, company or application that created this instance. This identifies the party responsible for loading this instance. Inherited from e_and_p_data.
- last_updated (O, I: ndt_date_tod) (C126)
- This is the date that this instance was last updated. This value should be updated when any part of this instance is altered (except for inverse relationships). Inherited from e_and_p_data.
- last_updated_by (O, I: ndt_identifier) (C126)
- This records the person or application making the update to this instance. Inherited from e_and_p_data.
- low_cut (O: ndt_frequency)
- The frequency designator specific to a frequency where the response of the amplitude filter is attenuated 3 decibels (to 70% amplitude or half power) of the total signal amplitude. Frequencies less than the low cut are reduced by more than 3 decibels, and frequencies greater than the low cut are reduced by less.
- low_cut_rate (O: ndt_decibel_per_octave)
- The rate, in decibels per octave, at which the amplitude spectrum of the wavelet/filter changes with respect to increasing frequency at the low cut. Positive indicates a low cut (or bottom of a band pass) response. The power spectrum changes at a value twice the low cut rate.
- peak_amplitude (O: ndt_real4)
- The peak amplitude in the frequency domain representation of the wavelet or filter.
- peak_frequency (O: ndt_plane_angle)
- The frequency at which the peak amplitude value occurs.
- source (O, I: ndt_identifier) (C126)
- The provider of this instance, which is usually a data provider for imported/purchased data. If this instance is provided by POSC, then this attribute must be "POSC". Inherited from e_and_p_data.
- time_index (O: ndt_time_1d_index)
- Defines the time axis of the impulse response.
- data_collection (I, V: SET[0:?] data_collection_content(collection_part)) (C020)
- Indicates the data collections that include this instance of E and P data. Each wavelet_or_filter may be a member of one or more data_collection_content. Inherited from e_and_p_data.
- document_information_content (I, V: SET[0:?] document_information_content(e_and_p_data)) (C136)
- These are the document specification parts that include this data value and define its meaning within a document specification. Each use may define a different meaning, and many uses are allowed. Each wavelet_or_filter may be included in one or more document_information_content. Inherited from e_and_p_data.
- geophysical_facility (V: SET[0:?] geophysical_fcl_spectral_desc(wavelet_or_filter))
- The utilization characterized by this wavelet or filter. Each wavelet_or_filter may characterize one or more geophysical_fcl_spectral_desc.
- graphical_element (I, V: SET[0:?] graphical_element(depicted_object))
- Specifies one or more graphical elements which are depicting this data item. Each wavelet_or_filter may be depicted by one or more graphical_element. Inherited from e_and_p_data.
- process_data_item (I, V: SET[0:?] process_data_item(process_data))
- Defines where this data was used by an activity. Each wavelet_or_filter may be the value for one or more process_data_item. Inherited from process_data.
- ref_wavelet_filter_algorithm (O: ref_wavelet_filter_algorithm(wavelet_or_filter)) (C112, C138)
- The algorithm for calculating the wavelet or filter. Examples are minimum phase wavelet, Ricker wavelet, Butterworth filter, etc. Each wavelet_or_filter may be characterized by one ref_wavelet_filter_algorithm.
Local rules:
- Uniqueness Constraint (C056)
- identifier, ref_wavelet_or_filter, activity
- Instance Value Constraint
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For each instance, if LOW CUT RATE is defined then LOW CUT must also be defined.
- Instance Value Constraint
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For each instance, if HIGH CUT RATE is defined then HIGH CUT must also be define d.
- Instance Value Constraint (C050)
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For each instance, if REF WAVELET OR FILTER is WAVELET, then IMPULSE RESPONSE must be defined.
- Instance Value Constraint (C050)
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For each instance, if REF WAVELET OR FILTER is not WAVELET, then neither DOMINANT PERIOD nor DOMINATE WAVELENGTH can be defined.
Supertype path(s):
Referenced in Diagrams:
Generated on Tue Jul 10 15:55:37 2001
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