2.0 Circuit Description
CX28394/28395/28398
2.4 Transmitter
Quad/x16/Octal—T1/E1/J1 Framers
Yellow Alarm Generation
Yellow Alarm, also referred to as RAI (Remote Alarm Indication), is a bit pattern
inserted into the transmit stream to alert far-end equipment that the local receiver
cannot recover data. Yellow Alarm/RAI is typically transmitted during receive
loss of frame and is defined differently depending upon the transmit frame format
configured [TFRAME; addr 070]. Table 2-6 describes the Yellow Alarm/RAI
transmitted for each frame format.
Table 2-6. Yellow Alarm Generation
Frame Format
Yellow Alarm Transmitted
Mode
SF
Bit 2 of every time slot set to zero
Bit 2 of every time slot set to zero
YB2
YB2
(1)
ESF
SLC-96
SF/JYEL
T1DM
E1
Bit 2 of every time slot set to zero
F-bit 12 of every superframe set to one
Y bit of the sync byte set to zero
The A bit of TS0 set to one
YB2
YJ
Y24
Y0
NOTE(S):
(1)
Yellow Alarm/RAI for T1-ESF framing is defined as a BOP priority codeword in the FDL
channel. T1-ESF Yellow Alarm/RAI is not transmitted using the procedure described
below. Instead, T1- ESF Yellow Alarm/RAI is generated by configuring DL1 to
continuously transmit an all zeros BOP priority codeword. Refer to Section 2.4.2,
Transmit Data Links.
Transmission of Yellow Alarm/RAI is controlled by these register bits:
Bit Name
Register
INS_YEL
TYEL
AUTO_YEL
RLOF
TFRM; addr 072]
TALM; addr 075]
TALM; addr 075]
ALM1; addr 047]
RALM; addr 045]
RLOF_INTEG
Insertion of Yellow Alarm/RAI into the transmit stream is controlled by
INS_YEL. Yellow Alarm/RAI is inserted only when INS_YEL is set, otherwise
these bit positions are supplied by data from TPCMI. Yellow Alarm/RAI
generation can be done manually or automatically.
Manual generation of Yellow Alarm/RAI is controlled by TYEL. Setting this
bit will immediately and unconditionally overwrite the Yellow Alarm/RAI signal
bit(s) in the transmitted data stream with the appropriate pattern.
Automatic generation of Yellow Alarm/RAI is controlled by AUTO_YEL,
RLOF, and RLOF_INTEG. If AUTO_YEL is set, Yellow Alarm/RAI is generated
during a receive loss of frame alignment (RLOF = 1). Optionally, RLOF
integration can be enabled by setting RLOF_INTEG. In this case, both RLOF
indication and Yellow Alarm/RAI generation are delayed for approximately 2.5
seconds if a continuous out-of-frame condition exists. Yellow Alarm/RAI
generation continues for at least 1 second after RLOF clears.
2-48
Conexant
100054E
CONEXANT [ CONEXANT SYSTEMS, INC ]
