This attribute indicates whether an AIS (Alarm Indication Signal)
alarm has been entered. The AIS Alarm state is entered when AIS
defects have been observed and accumulated for 2.5 seconds +/- 0.5
second. An AIS defect is detected after having received less than 3
zeros in a 2048 bit period. If the AIS defects are intermittently
occurring, the AIS defect accumulator is decremented at a rate of 1/
10 of the incrementing rate (alarm integration ratio of 1/10), with all
measurement based on a 200 ms polling cycle. The port goes into
an operational state of disabled for the duration of an AIS alarm
state. The AIS alarm state is cleared when AIS defects are absent
for 10 seconds +/- 0.5 second.