Blue Alarm (AIS)
(see note 1 below) |
when over a 3ms window, 5 or less zeros are received |
when over a 3ms window, 6 or more zeros are received |
| 1. D4 bit 2 mode (RCR2.2 = 0) |
when bit 2 of 256 consecutive channels is set to zero for at least 254 occurrences |
when bit 2 of 256 consecutive channels is set to zero for less than 254 occurrences |
| 2. D4 12th F–bit mode (RCR2.2 = 1; this mode is also referred to as the "Japanese Yellow Alarm") |
when the 12th framing bit is set to one for two consecutive occurrences |
when the 12th framing bit is set to zero for two consecutive occurrences |
| 3. ESF mode |
when 16 consecutive patterns of 00FF hex appear in the FDL |
when 14 or less patterns of 00FF hex out of 16 possible appear in the FDL |
| Red Alarm (RCL) (this alarm is also referred to as Loss Of Signal) |
when 192 consecutive zeros are received |
when at least 12.5% one's density is received |
