What is an optical loss budget?

The expected total light loss over a fibre section: cable attenuation plus every splice and connector, compared against what the equipment can tolerate.

Why: If the real loss is higher than the equipment's budget the link won't work, so it's calculated at design and checked against test results.

Where: Calculated for each core-to-core section and each core-to-access or access-to-access sub-section, using set figures for cable, splice and connector loss.

Where the rules are

• NR/L2/TEL/30160 cl 11.1what the loss budget is and why it matters
• NR/L2/TEL/30160 cl 11.2cable attenuation figures
• NR/L2/TEL/30160 cl 11.3splice loss
• NR/L2/TEL/30160 cl 11.4connector loss
• NR/L2/TEL/30160 cl 11.5calculating expected section loss
• NR/L2/TEL/30160 cl 11.6calculating expected sub-section loss

On the drawing

Usually issued as a loss calculation sheet alongside the splicing drawings.

• NR/L2/TEL/31200 cl 6.1straight joint spacing to minimise loss

Also called: link budget, section loss, attenuation budget

Guidance in our words. Read the current issue of each standard before you design to it.