Viavi MTS 4000 Base Unit, User Manual

Page: 94 / 254

Chapter 5 Power meter, VFL (Visual Fault Locator) and Talkset
Making a measurement
72 User Manual 77000000206 Rev. 007
Optical link loss
Setting the zero
value of the power
meter
1 Fix the plug over the optical input of the power meter so that no light
can reach the photodiode of the power meter. If the zero adjustment
is made without this plug, an error message may be displayed, as
the photodiode will detect too much light.
2 In the Results page, press the Powermeter Config. > Zero soft key
and validate.
Carrying out the
reference
measurement
1 Fix the adapter corresponding to the jumper to the optical connector
of the power meter.
2 Connect the jumper between the input of the power meter and the
output of the source.
3 Configure the same wavelength on the source and the power meter.
The power measured is displayed in the results page of the power
meter.
4 Press the Pow Reference > Standard Ref soft keys to save the
result displayed as reference value.
Measurements on
the fiber under test
After defining the reference value, proceed as follows to make the
measurement:
1 Fix the jumpers and connectors needed to connect the fiber to be
tested between the source output and the power meter input.
2 In the set-up menu, select dB units.
3 The power displayed in the Power Meter window corresponds to the
optical loss of the link tested. It can be displayed in the table (see
"Table of results" page 70 ).
It is important to set the zero of the power meter before making any
measurements where accuracy is required, as the noise from the ger-
manium photodiode fluctuates over time and with variations in tem-
perature.