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Measuring Cabling Loss
Loss measurements are performed to certify a cabling link meets certain
criteria for attenuation. Loss (dB) can be manually calculated by subtracting
the power (dBm) through the cabling under test from the power (dBm) of the
light source when connected directly to the meter. To make this process easier
FiberMASTER includes a calibration function that stores the light source power
level and compares it to future readings and directly displays loss in dB on the
LCD panel.
1. With the dust cap on the power meter, press
the power button. The meter will display 'null',
indicating that it is ready to measure and
is currently receiving no power. Press the
wavelength 'λ' button to change to the desired
wavelength.
2. Set the light source to the desired wavelength.
3. Remove the dust cap and connect the
reference jumpers between the power meter
and light source. The meter will display the
current power dBm from the light source.
4. Press the 'dB/Cal' button on the power meter
to store the current value into memory. The
display will now indicate 0.00dB.
5. Remove the coupler from the two reference
jumpers, connect to the cabling under test and
begin making measurements. The display will
indicate the attenuation (dB) compared to the
initial calibration power (dBm).
See diagrams on the following page.
Do not disconnect the reference jumper from the
light source after calibrating the test set. Doing so
will cause inaccuracies and requires recalibration.
6
nm
nm
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nm
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dBm
dBm
dB
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