Optical budgets and measurement records

Calculate optical loss from a circuit's saved path, retain a calculation snapshot and link field measurements.

Last updated: 10 November 2026

What is the calculation based on?

Optical budget in a circuit card assesses the saved path's cables, connections and equipment using selected profiles. It uses transmitter/receiver, loss and design profiles, cable lengths and connection losses. The current calculation shown when opening the card is not saved automatically.

Suitability is calculated only for Path complete. Missing profiles, missing loss information or an unsupported path may produce could not be assessed. Supported suitability assessment covers outside-plant cables; a path containing Inside building installation or Building drop cable class is not assessed for suitability. A cable-specific profile does not extend that scope.

Select profiles

An organisation administrator manages project profiles and defaults in Optical profiles. Under Project selection, choose transmitter/receiver, loss and design profiles, then Save selection. Copy from library (optional) copies a library entry into a project profile.

Payload (JSON) in the profile creation form requires technical information. To support suitability assessment, a loss/fiber profile requires maximum-loss band information covering the transmitter band; a value at a single wavelength alone is not a suitability basis.

Optical profiles in the circuit's Edit form overrides project selections. Cable optical profile in a cable card customises that cable's loss/fiber basis. For a Dark fiber circuit, the project default transmitter/receiver profile is not applied automatically; select one for the circuit if needed.

Review and retain a budget

1. Open the circuit in Technical circuits and check Path status.
2. Under Optical budget, review Result, Profiles and Loss / cable basis.
3. For the displayed directions, read Transmitter band, Source wavelength band, Remaining slack and check results.
4. Expand Items to inspect fiber, splice, connector, ODF passage and splitter contributions.
5. Select Freeze calculation to retain this calculation.

Results may be suitable, borderline, unsuitable or could not be assessed. A display containing only Loss table is informational, not a suitability result. L_max / L_min are loss boundaries in dB, not distances.

Frozen calculations retains inputs and results from the calculation time. Changes to paths, lengths, connections or profiles may mark an earlier calculation old, with the reason beside it. Review a new calculation to assess the current state. For multiple circuits, use Save optical calculations in bulk in Technical circuits.

Use Optical loss in the splice diagram for connection-specific loss. Record the design/measurement distinction correctly through Loss (dB) and Loss classification. A calculation does not replace measurement or field acceptance.

Add a measurement to a circuit

1. Select Add measurement under Measurements in the circuit card.
2. Choose OPM power (dBm), LSPM loss (dB) or OTDR (dB) as Measurement type.
3. Complete Wavelength (nm), Value, Direction, Measured by and Date. Add uncertainty, reference method and a note if needed.
4. Check Calculation to compare. It defaults to the latest frozen calculation; No link (comparison unavailable) is also available.
5. Select an optional file and Save. Check the file upload result too.
6. Review Comparison (with linked calculation) in the measurement table.

Measurements are recorded within 1,260–1,660 nm. Measurement files may be .sor, .pdf or .csv, up to 5 MB each. Supported SOR contents are read to display events and measurement suggestions. Fields selected in SOR contents are applied with Fill from SOR; uploading does not automatically change existing fields. PDF and CSV files are retained as attachments. Use Upload file to attach a file later and File to download the saved file.

Comparison shows compatible, deviation or could not compare, with a reason. A measurement does not automatically link to a calculation created later. OPM power suitability depends on direction and receiver boundaries; it does not verify data communication quality or field acceptance. Obtain a report with Measurement report (CSV).

Fiber and port measurements

Use Fiber measurements in the cable card to select a fiber number and cable endpoint; use Port measurements on equipment to select a port number and face. Open records through Show measurements. Fiber loss is compared with cable length and fiber attenuation. A port measurement can be compared with the frozen calculation of its linked circuit.

Check Circuit calculation (optional) for a port measurement. If blank on a new measurement, the latest calculation for a single active circuit may be suggested. If several active circuits or no calculation exist, inspect the comparison explanation. Fiber power measurements lack transmitter information, so no power suitability result is inferred.

A fiber measurement belongs to a specific cable and endpoint. Splitting, merging or moving an endpoint may therefore be blocked if it changes that cable's physical scope. Measurement files themselves are not carried in project packages; a restored record may show file is outside the package.

P2P profiles with separately assessed directions

The transmitter/receiver profile form in Optical profiles includes Profile directions. Asymmetric P2P (a_b + b_a) defines wavelength and transmitter/receiver values separately for each direction. The other options are Symmetric P2P (iki_yon) and PON (downstream / upstream).

1. As an authorised administrator, open or create the relevant transmitter/receiver profile.
2. Choose the arrangement under Profile directions.
3. Verify each direction's wavelength and transmitter/receiver values in Payload (JSON).
4. Save and select the profile for the project or circuit.
5. Inspect each direction's result separately in the circuit's optical budget; retain the current calculation with Freeze calculation if needed.

For paths containing WDM and OADM equipment, saved insertion losses contribute to the optical items. Do not infer suitability before completing missing or invalid loss information. See OTDR files and fault location for SOR events and fault positioning.