363-206-305
Technical Specifications
Issue 3 June 2000
10-21
Table 10-8. OC-3 OLIU Link Budget - Multimode Operation
Notes
:
1. When two numbers are given, the number before the slash is the specification for
operating under controlled environmental conditions. The number following the slash is
the specification for uncontrolled environmental conditions. If only one number is given,
it applies to both controlled and uncontrolled environmental conditions.
2. Maximum 22F-type MM Link Budget (dB) for multimode operation is 12.0 dB.
3. The 22G4-U will replace the 22F-type and the 22G-U/22G2-U/22G3-U OLIUs.
The system is dispersion limited for all the fiber bandwidths listed in Table 10-8.
Multimode fiber operation on the DDM-2000 OC-3 Multiplexer requires a minimum exit
bandwidth of 120 MHz to ensure that dispersion loss is kept below acceptable levels. If the
fiber is already installed and the exit bandwidth is measured to be 120 MHz or greater, then
the maximum link budget values (see Note 2) can be used to determine if the loss budget is
sufficient for that fiber.
∗∗
Unallocated margin, or safety margin, is typically specified from 0 dB to 3 dB.
‡‡ Budget available for both station and transmission cable and splices.
§§
***
Attenuation and dispersion can be the limiting factors in span length. For OC-3
single-mode fiber systems, dispersion is not a factor and all applications are
attenuation limited. For OC-12 systems, the maximum distance could be either
attenuation limited or dispersion limited. The limits must be calculated based on both
factors and the lesser of the two defines the actual maximum span length. A rough
rule of thumb for attenuation-limited systems is 0.45 dB/km. This estimate includes
typical cable loss (0.4 dB/km) and splice loss (0.2 dB per splice, 11 total splices)
associated with single-mode fiber.
Maximum span length can be calculated more precisely based on particular fiber
and splice characteristics and local engineering rules.
The 22G4-U OLIU is fully compliant with SONET Long Reach applications. The
22G4-U will replace the 22F-type and the 22G-U/22G2-U/22G3-U OLIUs.
Maximum Span
Length (km)
Maximum Span
Length (km)
Maximum Span
Length (km)
Fiber
Bandwidth
22D-U
(Note 1)
22F/22F-U/22F2-U
(Note 2)
22G-U/22G2-U/22G3-U/22G4-U
(Note 3)
1000 MHz-km
800 MHz-km
500 MHz-km
300 MHz-km
3.6/3.4
3.4/3.3
2.7
1.9
6.5
5.1
3.1
1.8
6.5
5.1
3.1
1.8
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