After a fiber link has been installed, optical attenuation (or loss) should be measured to determine the quality
of the installation. When compared to a pre-calculated link budget, a simple comparison of power values can
be used to determine if the link will perform as installed. A light source and two patch cords are also required
for this test. Use the following steps to perform an attenuation test in SIMPLE METER:
Calculate Maximum System Attenuation.
1) Use the link budget calculation worksheet at the end of this manual to calculate the Maximum System
Attenuation. This is the first section on the worksheet.
2) Record the Maximum System Attenuation.
Set the optical reference (or ”ZERO”).
3) Power on the FiberMeter and select SIMPLE METER.
4) Power on the light source being used for the test, and allow it to warm up according to manufacturer’s
specifications.
5) Set the FiberMeter and light source to matching wavelengths.
6) Connect the FiberMeter to the light source using a single patch cord of the appropriate type. The
core size of the patch cord should match the core size of the fiber link under test. If the fiber link under
test is multimode, the patch cord must be wrapped and secured around a mandrel. Please see the
appendix at the end of this manual for more information about setting optical references.
7) Press or to set the optical reference. The power units will automatically change to dB, and
the power reading should be very close to 0.00 dB. The optical reference in dBm will also appear
below the power reading.
Measure attenuation (or loss) of the fiber link under test.
8) Disconnect the patch cord from the FiberMeter, taking great care to
leave the patch cord connected to the light source.
9) Take the FiberMeter and light source to opposite ends of the fiber link
under test.
10) Connect the FiberMeter and light source to the corresponding fiber
connector using appropriate patch cords.
11) Record the power value that appears in the upper left hand corner of the
display without the minus (-) sign. This is the amount of loss across the
link.
12) Remove the patch cords from the fiber connector.
13) Repeat steps 10 through 12 for each fiber in the fiber link under test.
Repeat this procedure for each wavelength to be tested.
Interpreting the results.
Compare the Total System Attenuation from the link budget to the actual recorded loss. If the Maximum
System Attenuation exceeds the actual recorded loss, the link passes.
For example, if the Maximum System Attenuation is 2.0 dB, and the actual recorded loss is 1.54 dB (like the
display above), then the link is said to pass, and has a margin of 0.46 dB.
NOTE: the memory in the FiberMeter allows for permanent storage of data, including reference and
power readings. Data will remain in the meter, even when the unit is powered off, until it is removed
by the user.
2-2
SIMPLE METER - Attenuation Test
SIMPLE METER
UNIT 2
UNITS
_____________________
-
ZERO
54
(-20 12dBm Ref)
1
82
68%
dB
WAVE
850nm
Optical Loss
Displayed in dB
F2F2
0
. - /
