
Data Sheet
61
Rev. 1.0, 2005-06-02
OctalLIU
TM
PEF 22508 E
Functional Description
Figure 22
Long Haul Redundancy Application using the Analog Switch (shown for one line)
3.7.5
Loss-of-Signal Detection
There are different definitions for detecting Loss-Of-Signal (LOS) alarms in the ITU-T G.775 and ETS 300233. The
OctalLIU
TM covers all these standards. The LOS indication is performed by generating an interrupt (if not masked)
and activating a status bit. Additionally a LOS status change interrupt is programmable by using register GCR.SCI.
Detection: An alarm is generated if the incoming data stream has no pulses (no transitions) for a certain
number (N) of consecutive pulse periods. A pulse with an amplitude less than Q dB below nominal is the criteria
for “no pulse” in the analog receive interface (LIM1.DRS = 0) (LIM1). The receive signal level Q is
programmable by three control bits LIM1.RIL(2:0) see Table 50. The number N can be set by an 8-bit register
(PCD). The contents of the PCD register is multiplied by 16, which results in the number of pulse periods, i.e.
the time which has to suspend until the alarm has to be detected. The programmable range is 16 to 4096 pulse
periods. ETS300233 requires detection intervals of at least 1 ms. This time period results always in a LFA
(Loss of Frame Alignment) before a LOS is detected.
Table 17
Redundancy Application using the Analog Switch, switching with only one board signal
Configuration
Register Bits
Channel 1
(active/stand-by)
Channel 2
(stand-by/active)
XLT, XLT
PC1.XPC1(3:0)
1000
1110
RTDMT
PC1.RPC1(3:0)
1101
Receive framer interface
DIC3.RRTRI
0
1
RLT
PC2.RPC2(3:0)
1000
Receive line termination
LIM0.RTRS
0
E1/T1/J1
Receive
Line
RL1
RL2
RDOP
RL1
RL2
RDOP
XL1
XL2
E1/T1/J1
Transmit
Line
XDIP
XL1
XL2
XDIP
XLT
(XPA)
active/stand-by
stand-by/actice
FCLKR
XLT
(XPA)
OctalLIU_Receiver_6
RTDMT
DIC3.RRTRI = 0
LIM0.RTRS= 0
DIC3.RRTRI = 1
LIM0.RTRS= 1
(RPA)
FCLKX
Framer
1/8OctalLIUTM
low/high
(RPB)
RLT
(RPB)
RLT
RLS