Fiber optic budget considerations
ATTENTION
Fitting terminations to fiber optic cable requires special equipment and techniques. In order
to obtain the best results, a trained person should perform this operation in accordance with
the manufacturer's instructions. For these reasons, the following installation instructions do
not include detailed procedures for this process.
Testing of the quality (loss) of the terminations should be carried out at each stage.
13.4.9 Standard I/O link extender maximum cable span calculation
The following calculation MUST be used to ensure that the number of planned splices and the
cable choice supports the necessary cable span distance.
The maximum cable span calculation (in km) is as follows:
Max Span = (Available Optical Power - Losses in Splices)/(Max Loss per Cable
Type)
The calculations or values for each of the above variables are described below.
13.4.10 Available standard I/O link extender optical power
The available optical power calculation is as follows:
Transmit Power - Minimum Receiver Sensitivity - Power Loss Over Time =
Available Optical Power
where for a Standard I/O Link Extender:
Transmit Power = - 16.0 dB
Minimum Receiver Sensitivity = - 24.0 dB
Power Loss Over Time = 2.5 dB
Example calculation for a Standard I/O Link Extender using 62.5
micron cable:
(- 16.0 dB) - (- 24.0 dB) - (2.5 dB) = 5.5 dB Available Optical Power
ATTENTION
Because the maximum transmitter output level is -7 dB, and the maximum receiver input
level is -10 dB, the receiver may be overdriven on a short link and may require a 3 dB
attenuator. Connector allowances for the transmitter and receiver are included in the above
power declaration.
