EXFO FTB-8510B Guia Del Usuario página 866

SONET Tabs
Section TX (SONET)
Alarm Generation
Allows Continuous or Burst alarm generation methods.
Type
LOF (Loss Of Frame): Generates non-valid framing bytes (A1 and A2).
SEF (Severely Errored Framing): Generates four consecutive errored
framing patterns.
For Continuous method:
On/Off button: The On/Off button is used to activate/deactivate the
selected alarm. This setting is disabled (Off) by default. Exceptionally
for continuous SEF alarm, the On/Off button turns Off once the SEF
alarm has been sent.
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FTB-8100 Series Transport Blazer