363-206-295
Technical Specifications
10-12 Issue 1 December 1997
Notes:
1. Maximum 21G/21G-U/21G2-U MM Link Budget (dB) for multimode
operation is 22.0 dB for high power and 15.6 dB for low power.
2. 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.
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 (22 dB, 15.6 dB, and 12
dB, respectively) can be used to determine if the loss budget is sufficient for that
fiber.
The system is dispersion limited for all the fiber bandwidths listed in this table.
If planning a new fiber installation, the values at the end of the table, given for a
number of commercially available fiber bandwidth-distance products, can be
used. Fiber distances are calculated using the 120 MHz exit bandwidth limit,
however, actual exit bandwidths may be higher for these distances due to the
existence of splices. This may permit longer span lengths to be achieved, for the
given fiber bandwidths, than those specified in the table. In this case, however, the
span length can only be increased to the point where the system is loss-limited as
specified by the maximum multimode link budget given in the table (1 dB/km cable
is assumed).
Table 10-6. OC-3 OLIUs Link Budget — Multimode Operation
Fiber Bandwidth
Maximum Span Length (km)
21G/21G-U/21G2-U (Note 1) 21D/21D-U (Note 2)
1000 MHz-km
800 MHz-km
500 MHz-km
300 MHz-km
6.5
5.1
3.1
1.8
3.6/3.4
3.4/3.3
2.7
1.9
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