EXFO FTB-8100 Series Transport Blazer for FTB-500 - Manual (Page 428)

Advanced Tabs
414 FTB-8100 Series Transport Blazer
Service Disruption Time (SDT)
³
Service Disruption: Indicates the time (in seconds) during which
there is a disruption of service due to the absence of traffic or to the
detection of defects. The H and C LEDs indicate respectively the
current (C) and history (H) SDT measurement states.
The C (Current) LED is green when there is no SDT. The C LED is red if
there is an SDT, and last until the next No Defect Time has been met or
the test period is elapsed.
The H (History) LED indicates if any SDT occurred in the past (LED is
red) or not (LED is green).