What does the red line under the channel heading in a Geosoft database (*.GDB) mean? What does a blue line mean?
Problem/Symptom:
I have a red or blue line in a channel heading in my GDB. What do these coloured lines mean? How do they affect my data?
Environment:
Any version of Oasis Montaj, Target, or Target for ArcGIS. This resolution applies to Geosoft databases (*.GDB's) only.
Resolution:
The 'red line' under the channel name means that the data is (or has been) sampled at different fiducial increments/rates than the original data. Basically, fiducials are the rows in your database. Normally they are sampled at an even interval (0 - 1 - 2 - etc), but can be re-sampled at any interval (or fiducial increment/rate).
The data that you see in the channel with the red line underneath the channel header has been resampled to the fiducials that are displayed in the fiducial channel. In order to see the true values, right click on your data channel with the red underline and select "Master Sample". As well, if you hide the channel(s) with a red line, the other (or original) fiducial rate (and corresponding channels) will be displayed.
The Master Sample channel is denoted by a blue line underneath the channel header, and is used to force all other database channels to be sampled at the same fiducial increment/rate as the selected channel. The other channels will now have red underlines indicating that they are showing re-sampled data (i.e. at a different fiducial rate than the Master Sample). This feature is useful when you want to edit data from a channel that has a larger fiducial rate (data which is sampled less often) then other channels in the database. By default, the spreadsheet window displays data using the channel with the smallest fiducial (most frequent sampling) rate.
For example, consider a database with two channels. Channel 1 has a fiducial sampling rate of 10 readings/second. This channel is considered to be smaller (more frequent) than Channel 2, which was sampled at 1 reading/second. By making Channel 2 the Master Sample channel, Channel 1 is displayed at the same rate so that only every tenth fiducial is displayed.
To get back to the original sampling rate, right click on your data channel and select "No master sample". Then the channel will be displayed as a resampled channel. Note that you cannot edit the values in a resampled channel because the values displayed are not the real data values. They are simply representations of the true data values.
