Entity wavelet_or_filter

• 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.

Attribute                                 Flags   Data Type

From technical_object:
   data_collection                        IV      set[0 .. N] of (data_collection)

                                          Indicates the data collections that include this
                                          instance of E and P data. 

   graphical_element                      IV      set[0 .. N] of (graphical_element)

                                          Specifies one or more graphical elements which
                                          are depicting this data item. 

   datum_for_ranking                      IV      set[0 .. N] of (object_ranking)

                                          Indicates that an object is being used as a basis
                                          for comparison with another object. 

   object_of_ranking                      IV      set[0 .. N] of (object_ranking)

                                          Indicates that an object is being classified in
                                          a rank order based on its characteristics. 


description                                       ndt_comment

                                          A comment about this wavelet or filter. 

dominant_period                           N       ndt_time

                                          The dominant period of the wavelet. 

dominant_wavelength                       N       ndt_length

                                          The dominant wavelength of the wavelet. 

frequency_index                           N       ndt_frequency_1d_index

                                          Defines the frequency axis associated with a frequency
                                          spectrum. 

frequency_spectrum                        N       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                                  N       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                             N       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                          N       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. 

low_cut                                   N       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                              N       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. 

name                                      MU      ndt_name

                                          A name which identifies the wavelet or filter.

peak_amplitude                                    ndt_real4

                                          The peak amplitude in the frequency domain
                                          representation of the wavelet or filter. 

peak_frequency                            N       ndt_plane_angle

                                          The frequency at which the peak amplitude value
                                          occurs. 

ref_wavelet_or_filter                     MU      ref_wavelet_or_filter

                                          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. 

ref_wavelet_or_filter_algorithm                   ref_wavelet_or_filter_algorithm

                                          The algorithm for calculating the wavelet or filter.
                                          Examples are minimum phase wavelet, Ricker wavelet,
                                          Butterworth filter, etc. 

time_index                                N       ndt_time_1d_index

                                          Defines the time axis of the impulse response.

seismic_processing_activity               U       seismic_processing_activity

                                          The activity which created this characterization
                                          and which forms part of its identity. A
                                          characterization such as a 60 hertz notch filter
                                          with a particular slope can be defined independent
                                          of an activity and can be "globally" used. 

seismic_facility                          V       set[0 .. N] of (seismic_facility)

                                          The utilization characterized by this wavelet
                                          or filter. 

End of entity wavelet_or_filter

M - mandatory, U - unique, I - inherited, V - inverse, N - named type