Measurement Application Of Otdr; Measurement Contents Of Otdr; Trace Analysis Of Otdr - ADInstruments AD1000 User Manual

Information relating to distance is obtained through time information (That's the
reason why there is "Time Domain" in the name of OTDR). Fresnel reflection occurs
at the boundary between two media of different IOR (For example, connections of
faults, connectors, or optic fiber end). This reflection is used to locate the
discontinuous points on optic fiber. The magnitude of reflection depends on the
difference between IOR and the smoothness of boundary.
OTDR sends out a light pulse into the connected optic fiber, and receive reflections
of events and backward scattering power of pulse in time. Locus will be displayed on
LCD. The Y-axis is dB value of backward scattering power, and the X-axis is the
distance.

4.2 Measurement Application of OTDR

OTDR displays power relating to distance of returning signals. This information can
be used to identify the main properties of an optic fiber chain.

4.2.1 Measurement Contents of OTDR

Ø Event location (Distance),end or rupture of optic fiber chain
Ø Attenuation coefficient of fiber
Ø Loss of a single event (e.g. one optic tie-in), or total loss from upper end to end
Ø Range of a single event like reflection of connectors (Or grade of reflection)
Ø Auto measurement of cumulative loss of a single event

4.2.2 Trace Analysis of OTDR

The trace analysis of OTDR is fully automatic. The trace locates:
Ø Reflection events of connections and mechanic tie-ins
Ø Non-reflection events (usually at welding tie-ins)
Ø End of optic fiber
Through scanning the first loss event that is larger than end threshold, end
of optic fiber can be identified.
Ø Events list: event type, loss, reflection and distance.
AD1000 User's Manual
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