Difference between revisions of "Geopsy: Waveform Units"
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| − | In [[Geopsy]], informations for '''Data Conversion''' are stored in the signal [[Geopsy: Database|Database]] in various fields. These values are automatically set in the database when a signal is imported only if this information appears in the signal file. However, this information can be manually set by | + | In [[Geopsy]], informations for '''Data Conversion''' are stored in the signal [[Geopsy: Database|Database]] in various fields. These values are automatically set in the database when a signal is imported only if this information appears in the signal file. However, this information can be manually set by [[Geopsy: Table#Table editing|editing a Table]] or automatically using [[Geopsy: Edit menu#Set_headers|Set headers in the Edit menu]]. |
A digitizer writes integer values called Counts on a digital support. In order to retrieve the physical unit of the recorded signal (velocity or acceleration), ''Counts'' should be converted to ''Units''. The ''Unit'' type (m/s, m/s<math>^2</math>...) is defined in the [[Geopsy: Database#Field:AmplitudeUnit|AmplitudeUnit]] field. The first step is to correct from the digitizer that wrote a current in ''Volts'' coming from the sensor on the digital support in ''Counts''. This conversion factor is defined in the [[Geopsy: Database#Field:CountPerVolt|CountPerVolt]] and redundantly in the [[Geopsy: Database#Field:VoltPerCount|VoltPerCount]] (inverse) fields. This information is more likely to be be given by the digitizer in the signal file than the following. The second step is to correct from the sensor response that turns vibrations (velocity or acceleration) into an electric current in Volt. This response factor is defined in the [[Geopsy: Database#Field:VoltPerUnit|VoltPerUnit]] and redundantly in the [[Geopsy: Database#Field:UnitPerVolt|UnitPerVolt]] fields. The multiplication of these factors is stored in the [[Geopsy: Database#Field:CountPerUnit|CountPerUnit]] and redundantly in the [[Geopsy: Database#Field:UnitPerCount|UnitPerCount]] fields. These fields cannot be modified by the user (read-only). | A digitizer writes integer values called Counts on a digital support. In order to retrieve the physical unit of the recorded signal (velocity or acceleration), ''Counts'' should be converted to ''Units''. The ''Unit'' type (m/s, m/s<math>^2</math>...) is defined in the [[Geopsy: Database#Field:AmplitudeUnit|AmplitudeUnit]] field. The first step is to correct from the digitizer that wrote a current in ''Volts'' coming from the sensor on the digital support in ''Counts''. This conversion factor is defined in the [[Geopsy: Database#Field:CountPerVolt|CountPerVolt]] and redundantly in the [[Geopsy: Database#Field:VoltPerCount|VoltPerCount]] (inverse) fields. This information is more likely to be be given by the digitizer in the signal file than the following. The second step is to correct from the sensor response that turns vibrations (velocity or acceleration) into an electric current in Volt. This response factor is defined in the [[Geopsy: Database#Field:VoltPerUnit|VoltPerUnit]] and redundantly in the [[Geopsy: Database#Field:UnitPerVolt|UnitPerVolt]] fields. The multiplication of these factors is stored in the [[Geopsy: Database#Field:CountPerUnit|CountPerUnit]] and redundantly in the [[Geopsy: Database#Field:UnitPerCount|UnitPerCount]] fields. These fields cannot be modified by the user (read-only). | ||
'''Important warning''': Conversion from Counts to physical Unit DOES NOT correct for the non-flat response of the sensor at low or high frequencies. This feature is currently not implemented in Geopsy. | '''Important warning''': Conversion from Counts to physical Unit DOES NOT correct for the non-flat response of the sensor at low or high frequencies. This feature is currently not implemented in Geopsy. | ||
Latest revision as of 15:17, 12 March 2010
In Geopsy, informations for Data Conversion are stored in the signal Database in various fields. These values are automatically set in the database when a signal is imported only if this information appears in the signal file. However, this information can be manually set by editing a Table or automatically using Set headers in the Edit menu.
A digitizer writes integer values called Counts on a digital support. In order to retrieve the physical unit of the recorded signal (velocity or acceleration), Counts should be converted to Units. The Unit type (m/s, m/s...) is defined in the AmplitudeUnit field. The first step is to correct from the digitizer that wrote a current in Volts coming from the sensor on the digital support in Counts. This conversion factor is defined in the CountPerVolt and redundantly in the VoltPerCount (inverse) fields. This information is more likely to be be given by the digitizer in the signal file than the following. The second step is to correct from the sensor response that turns vibrations (velocity or acceleration) into an electric current in Volt. This response factor is defined in the VoltPerUnit and redundantly in the UnitPerVolt fields. The multiplication of these factors is stored in the CountPerUnit and redundantly in the UnitPerCount fields. These fields cannot be modified by the user (read-only).
Important warning: Conversion from Counts to physical Unit DOES NOT correct for the non-flat response of the sensor at low or high frequencies. This feature is currently not implemented in Geopsy.
