EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 148)

Setting Up the Instrument in Drift Mode
140 FTB-5240S/5240BP
Setting Up Drift Analysis Parameters
5. Press OK to return to the Channels window, which now lists the added
channels.
Note: When new channels are added, the Use Default thresholds will be applied
to the channel parameters.
Note: A warning message will be displayed if any channels are overlapping, but
the analysis can still be performed on overlapping channels. If any
duplicate channels are added, a confirmation message will be displayed to
overwrite the existing channels with the duplicate channels.
6. Press OK to save the changes and close the window, or press Cancel to
exit without saving.
Note: The application displays a message if more than 1000 channels are added.
You can exit the Analysis Setup window only after deleting the extra
channels from the channel list. You can delete the channels manually as
required.