Exfo OTDR 2 Manual do Utilizador descarregar pdf (Página 15)

Introducing the OTDR

OTDR 7

OTDR Basic Principles

An OTDR sends short pulses of light into a fiber. Light scattering occurs in

the fiber due to discontinuities such as connectors, splices, bends, and

faults. The OTDR then detects and analyzes the backscattered signals. The

signal strength is measured for specific intervals of time and is used to

characterize events.

The OTDR calculates distances as follows:

where

c = speed of light in a vacuum (2.998 x 10

m/s)

t = time delay from the launch of the pulse to the reception of the

pulse

n = index of refraction of the fiber under test (as specified by the

manufacturer)

Distance

-- -

=

1 2 ... 10 11 12 13 14 15 16 17 18 19 20 ... 218 219

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Exfo OTDR 2 Manual do Utilizador Página 15