363-206-285
Technical Specifications
Issue 3 June 2001
10-29
¶ One connector (0.75 dB) on each end is assumed to connect station cable to outside
plant.
∗∗ Unallocated margin, or safety margin, is typically specified from 0 dB to 3 dB.
††If the loss budget is less than 6.0 dB, use low power. Includes a 1.5 dB safety margin.
‡‡ 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.
¶¶ Full width at half maximum (FWHM) spectral width.
*** 1.0 nm for a SLM laser.
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