Ideal Networks Serie 33-960 Cable tester, cable tester 33-960-3MB Manual De Usuario

Introducing the IDEAL OTDR

6

IDEAL

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. An 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

8

 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

c

n

---

t

2

---

×

=

Distance