3Com 7000 manual Numerical Aperture

ATM Cabling 113

Table 25 Standard Multi-mode Fiber Specification (continued)

Maximum distance between nodes	2 km
Output power (from transmitter)	19 dB minimum
	14 dB maximum
Receive power	30 dB minimum sensitivity
	14 dB maximum sensitivity

*Maximum attenuation includes cable attenuation and the loss induced by other components such as connectors, splices, and the mating of unlike fiber types. Although some 2 km cable plants have a total attenuation of less than 11.0 dB, the 2 km interstation distance must be maintained to comply with modal bandwidth requirements.

Table 26 Alternate Multi-mode Fiber Types

Core (µ m)	Cladding (µ m)	Numerical Aperture
50	125	0.20
50	125	0.22
85	125	0.28
100	140	0.29

Calculating Insertion If unlike fibers are mated in the cable plant, calculate insertion losses to Losses for Unlike be certain that the cable plant does not exceed the maximum attenuation

Fibers value listed in Table 25. To calculate the insertion loss, consider the types of fiber in the cable plant and the connectors or splices used to join them. Compare the result to the maximum attenuation value listed in Table 25. If the result is greater than the value in the table, use only like fibers in the cable plant.

Refer to Table 27 for the insertion losses of the fibers themselves. Use Table 28, which lists the losses for connectors, cables, and splices, if the specifications for these components are not available.

Use Table 27 for fiber-to-fiber connections only, not for power launched from a transmitter.