363-206-305
Technical Specifications
10-22
Issue 3 June 2000
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).
Long Reach OC-1 Interface (26G2-U OLIU)
10
■
Optical Specification
The multilongitudinal mode laser transmitter supplies a non-return to zero
(NRZ)-coded signal. For direct optical loopbacks, at least 7.0 dB (use 10
dB of attenuation) is needed for the 26-type.
The 26-type OLIU long reach OC-1 interfaces support span lengths up to
44 km, assuming 0.45 dB/km single-mode fiber and the span engineering
rules outlined in Table 10-11. Transmit and receive powers are referenced
to Points S and R as shown in Figure 10-2. Table 10-9 and Table 10-10
provide detailed specifications and link budget information for the 26-type
OLIU.
■
Alarm Thresholding
The following parameters are monitored at the OC-1 interface:
— Loss of signal
— Loss of frame
— Loss of pointer
— Line AIS
— B2 thresholding signal fail
— B2 thresholding signal degrade. (B2 signal degrade thresholds are
user settable in the range from 10
-5
to 10
-9
BER.)
■
Performance Monitoring (See Table 10-3 and Table 10-23.)
— Section severely errored frame seconds (SEFS)
— Line parameter B2
— STS pointer justification (OC-3 R11.0 and later).
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