EXFO FTB-8500 Series for FTB-500 - Manual (Page 398)

System Tabs
384 FTB-8500 Series and FTB-8120NGE/8130NGE
Clock Synchronization

Line Coding: Allows the selection of the interface line coding. Choices
are:
For DS1: AMI and B8ZS. The default setting is B8ZS.
For E1: AMI and HDB3. The default setting is HDB3.

Framing: Allows the selection of the interface framing. Choices are:
For DS1: SF, and ESF. The default setting is SF.
For E1: PCM30, PCM30 CRC-4, PCM31, and PCM31 CRC-4. The default
setting is PCM30.
Alarm Analysis
Note: Only LOPPS-L alarm is available with 1PPS signal.

LOS (Loss Of Signal): The LOS alarm indicates absence of an input
signal or an all-zeros signal is received.

AIS (Alarm Indication Signal): The AIS alarm is declared when an
unframed all-ones signal is received.

LOF (Loss Of Frame):
For DS1:

With SF Framing: The Loss-of-Frame condition will be assumed
when 2 terminal frame and/or signaling frame errors in 5
consecutive frames have been received.

With ESF Framing: The Loss-of-Frame condition will be assumed
when 2 FPS frame errors in 5 consecutive frames have been
received.
For E1: The Loss-Of-Frame condition will be assumed when three
consecutive incorrect frame alignment signals have been received.