363-206-285
Technical Specifications
Issue 3 June 2001
10-23
Long Reach OC-1 Interface (26G2-U/27G-U/27G2-U OLIU) 10
■ Optical Specification
The multilongitudinal mode (MLM
*
) laser transmitter supplies an NRZ-coded signal.
For direct optical loopbacks, at least 13.8 dB (use 15.0 dB, attenuator, see
Table 10-21) of attenuation is needed for the 26G2-U/27G-U/27G2-U.
The 26G2-U/27G-U/27G2-U OLIU long reach OC-1 interface supports span
lengths up to 44 km, assuming 0.45 dB/km single-mode fiber and the span
engineering rules outlined in Table 10-13. Transmit and receive powers are
referenced to Points S and R as shown in Figure 10-2. Table 10-12, Table 10-13,
and Table 10-14 provide detailed specifications and link budget information for the
26G2-U/27G-U/27G2-U OLIU.
■ Alarm Thresholding
The following parameters are monitored at the OC-1 interface.
— Loss of signal (LOS)
— Loss of frame (LOF)
— Loss of pointer (LOP)
—LineAIS
— 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 10-23)
— Section SEFS
— Line parameter B2
— STS pointer justifications (Release 11.0 and later).
* A higher quality SLM laser may be used instead of an MLM laser.
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