User`s guide

Definition of Terms / Measurement Conditions CSpecifications

E6000C Mini-OTDR User’s Guide, E0302

199

OTDR

= the distance measured with the OTDR, at the

given OTDR group index setting

T = time of flight between the two locations on the fiber,

measured at the wavelength of the OTDR

N = OTDR group index setting

NOTE Relatively long lengths of fibers, for example, 10 km, are

to be used to evaluate the distance scale error, in order to

remove the influence from finite distance sampling

spacing.

NOTE The distance scale error excludes the uncertainty of the

fiber’s group index, N, because the same N is used in the

calculation of L and L

OTDR

Measurement: Measure the time of flight, T, with a pulse

generator, a laser source, an opto-electronic converter,

and a time interval counter by determining the time

difference with and without the fiber of length L inserted.

The laser source should have the same wavelength as the

OTDR.

Dynamic range (RMS)

The amount of fiber attenuation that causes the

backscatter signal to equal the

→noise level (RMS).

Measurement: It is recommended to connect a standard

single mode fiber with a length of more than 20 times the

pulse width in meters to the OTDR. Then determine the

difference between the extrapolated backscatter trace (as

in Figure 2) and the

→noise level (RMS).

Conditions: standard single mode fiber, at specified

averaging time, ambient temperature and instrument

settings.