Table 59: Example of calculating the optical budget (maximum distance)
Type of LDCM Short range (SR) Short range (SR) Medium range (MR) Long range (LR)
Type of fibre Multi-mode fiber
glass 50/125 μm
Multi-mode fiber
glass 62.5/125 μm
Single-mode fiber
glass 9/125 μm
Single-mode fiber
glass 9/125 μm
Modem type 1MRK0002122-AB 1MRK0002122-AB 1MRK002311-AA 1MRK002311-BA
Maximum distance 2 km 3 km 80 km 120 km
Attenuation in
fibre-optic cables
6 dB 9 dB 25.6 dB 25.2 dB
2 contacts 2 dB 3 dB 0.6 dB 0.6 dB
Factory splice
attenuation
0.3 dB 0.45 dB 0.64 dB 0.96 dB
Repair splices 0.1 dB 0.3 dB 0.8 dB 1.2 dB
Fiber margin for
aging
0.2 dB 0.3 dB 0.8 dB 1.2 dB
Total attenuation 8.6 dB 12.05 dB 26.04 dB 28.56 dB
Optical link budget 9 dB 13 dB 26.8 dB 28.7 dB
Link margin 0.4 dB 0.95 dB 0.76 dB 0.14 dB
ComAlarmDel
defines the time delay for communication failure alarm. In communication
systems, route switching can sometimes cause interruptions with a duration of up to 50 ms.
Too short a time delay can thus cause nuisance alarms.
ComAlrmResDel
defines the time delay for communication failure alarm reset.
RedChSwTime
defines the time delay before switching over to a redundant channel in case of
primary channel failure.
RedChRturnTime
defines the time delay before switching back to the primary channel after
channel failure.
AsymDelay
denotes asymmetry which is defined as transmission delay minus receive delay. If
fixed asymmetry is known,
Echo
synchronization method can be used, provided that
AsymDelay
is properly set. From the definition follows that asymmetry is always positive at
one end and negative at the other end.
MaxTransmDelay
indicates maximum transmission delay. Data for maximum 40 ms
transmission delay can be buffered up. Delay times in the range of some ms are common. If
data arrive in wrong order, the oldest data is disregarded.
MaxtDiffLevel
indicates the maximum time difference allowed between internal clocks in
respective line ends.
64 kbit mode specific settings
TransmCurr
is used to select among the following:
• one of the two possible local currents is transmitted
• sum of the two local currents is transmitted
• channel is used as a redundant backup channel
1MRK 505 370-UEN D Section 18
Remote communication
Busbar protection REB670 425
Application manual
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