Field Tool

OTDR Splice Average

Average bidirectional OTDR readings for splice loss, with pass or fail against the owner's threshold.

Events

OTDR Loss Readings in Both Directions
#	Event or fiber	A→B (dB)	B→A (dB)
1	Row 1 event name	Row 1 loss A to B in decibels	Row 1 loss B to A in decibels
2	Row 2 event name	Row 2 loss A to B in decibels	Row 2 loss B to A in decibels
3	Row 3 event name	Row 3 loss A to B in decibels	Row 3 loss B to A in decibels
4	Row 4 event name	Row 4 loss A to B in decibels	Row 4 loss B to A in decibels

A negative value is allowed: it marks a gainer in that direction.

Paste from a SpreadsheetTwo columns (A→B, B→A) or three (event, A→B, B→A)

Acceptance

Threshold (optional)Per owner spec

decibels

Maximum average splice loss from the owner's specification. Leave empty to see averages only.

Not graded: enter the owner's threshold. Mean 0.085 dB, maximum 0.20 dB.

Warning: Not graded: enter the owner's threshold

Events: 4
Mean: 0.085 dB
Maximum: 0.20 dB
Over threshold: –

Bidirectional Average per Event
Event	A→B	B→A	Average	Result
Splice 1	0.12	-0.04 gainer	0.04	Not graded
Splice 2	0.05	0.07	0.06	Not graded
Splice 3	0.30	0.10	0.20	Not graded
Splice 4	-0.02 gainer	0.10	0.04	Not graded

A negative reading in one direction is a "gainer": the fibers on each side of the splice backscatter light differently, so one direction shows a false gain. The two-direction average cancels it.

Reading the Trace

To see how a splice, a connector and a gainer look on a trace, with the gainer shot from each end, read Reading OTDR Traces.

Show the Math

average = (A→B + B→A) ÷ 2

A→B and B→A are the event losses in dB read from OTDR traces shot from each end. One-way readings include the difference in backscatter between the two fibers; averaging both directions cancels it and gives the splice loss used for acceptance (the common bidirectional method; the owner's test specification governs).

Gainers

A negative reading in one direction is a "gainer": the fibers on each side of the splice backscatter light differently, so one direction shows a false gain. The two-direction average cancels it.

Summary and Status

Count, mean of the averages, maximum average and the number over the threshold.
An average at or under the threshold passes; above it fails.
All events pass: good. Any event fails: critical. No threshold entered: warning (averages only, not graded).

Threshold

The acceptance threshold is the owner's: maximum average splice loss. The field is empty by default; FAHMY does not supply a pass value.

Assumptions

Each row pairs the same event (splice) from both directions, at the same wavelength.
Pasted rows have exactly two columns (A→B, B→A) or three (event, A→B, B→A), split by tabs, semicolons, commas or spaces. Any other column count is skipped and reported by line number, so a four-column export (with an average column) is never read as shifted columns.
A decimal comma (0,12) is read only when columns are split by tabs or semicolons. The first line is ignored as a header only when every cell has letters and none is a number; the tool says so when it does.

Sources

Bidirectional OTDR splice-loss measurement and its acceptance values come from the owner's test specification: test method per owner spec. FAHMY does not yet cite a standard test method for this tool; it is on the SME review list.

FAHMY tools give planning estimates. The owner's specifications, the authority having jurisdiction and the manufacturer's data govern every job. Values marked "Planning assumption", "Planning default", "Typical maximum", "Rule of thumb" or "Example" are editable starting points, not requirements; "Per owner spec" fields take the owner's value.