Programming Documents for Pre-K for SA - The City of San Antonio

Appendix B: Calculating The Loss
Budget For A Fiber Optic Cable Plant
Calculating the loss budget for a fiber optic link determines what is the maximum loss expected in a
normal installation. The loss measured by an OLTS (Optical Loss Test Set) should be less than the loss
calculated by the following method:
B.1 Information Necessary:
Length of the link
Number of connectors Number of splices.
B.2 Process:
Calculate the loss of the fiber
Calculate the loss of all connections
Calculate the loss of all splices
Add all losses to get the total loss
B.3 To calculate the fiber loss:
Multiply the length of the fiber times the attenuation at each wavelength:
850 nm: (length in km) X (3.5 dB/km @ 850 nm) = fiber dB loss @ 850 nm
1300 nm: (length in km) X (1.5 dB/km @ 1300 nm) = fiber dB loss @ 1300 nm
B.4 To calculate the connector loss:
Multiple the number of connectors times the maximum allowable loss of 0.75 dB (count the connectors
on each end as one each and each mated pair as one connector loss)
(Number of connectors) X (0.75 dB) = Connector loss in dB
B.5 To calculate the splice loss:
Multiple the number of splices times the maximum allowable loss of 0.3 dB
(Number of splices) X (0.3 dB) = Splice loss in dB
B.6 To calculate the total cable loss, add the losses
calculated above:
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