EXFO FTB-800 Series for FTB-1 - Manual (Page 323)

Test Results
NetBlazer 313
Performance Monitoring

UAS (Unavailable Second): Gives the count of the seconds
corresponding to the periods of unavailable time that begins at the
onset of 10 consecutive SES events, including these 10 seconds. A
period of available time shall begin at the onset of 10 consecutive
non-SES events, including these 10 seconds.

ESR (Errored Second Ratio) (G.821, G.826, G.828, and G.829): Gives
the ratio of the number of ES in available time (AS) during a fixed
measurement interval.
ESR = ES ÷ AS

SESR (Severely Errored Second Ratio) (G.821, G.826, G.828, and
G.829): Gives the ratio of the number of SES in available time (AS)
during a fixed measurement interval.
SESR = SES ÷ AS

BBER (Background Block Error Ratio) (G.826, G.828, G.829, and
M.2101): Gives the ratio of BBE in available time (AS) to total blocks in
available time during a fixed measurement interval. The count of total
blocks excludes all blocks during SESs.

DM (Degraded Minutes) (G.821 only): A Degraded Minute is the
number of minutes in which the estimated error rate exceeds 10
-6
but
does not exceed 10 -3 . DM is determined by collecting all of the
Available Seconds, removing any SES grouping the result in 60-second
long groups and counting a 60-second long group as degraded if the
cumulative errors during the seconds present in the group exceed 10
-6
.