DSP-FOM
Fiber Optic Meter
4
4.
Set the FOM switch to the wavelength position
being tested. Press
T
on the CableMeter test
tool; then verify that the second line of the test
tool message displays the following:
Multimode
(wavelength setting)
nm A-B
.
5.
Use the patch cable from step 2 to connect the
FOM to the light source. Press
#
Power
.
Allow a few seconds for the reading to
stabilize; then verify that the reading shows the
power level recorded in step 3
±
0.25 dB.
6.
Press
e
on the CableMeter test tool.
Disconnect the light source from the FOM.
DSP-FOM -50 dBm Checkout
1.
Connect the 1300 nm light source to the optical
attenuator. Use a second fiber optic patch cable
to connect the optical attenuator to the
reference power meter.
2.
Verify that the reference power meter is
configured to measure the wavelength of the
light source. Adjust the optical attenuator for a
reading of -50.00 dBm
±
0.05 dBm. Record the
power reading for later use.
3.
Use the patch cable connected to the reference
power meter to connect the FOM to the optical
attenuator.
4.
On the CableMeter test tool, press
#
Power
. Allow a few seconds for the
reading to stabilize; then verify that the reading
shows the power level recorded in step 2
±
0.4 dBm.
Turn off the test tool, FOM, and the light sources.
Disconnect the FOM and 2-meter UTP patch cable
from the test tool. Disconnect the fiber optic patch
cables from the attenuator, source, and FOM.
Disassembling and Reassembling
the FOM
W
Caution
While servicing the FOM, always follow
guidelines for preventing electrostatic
discharge (ESD). Otherwise, ESD can
damage sensitive components,
causing immediate or delayed failure
of the FOM.
A Phillips-head screwdriver is required for
disassembling and reassembling the FOM. To
disassemble the FOM, proceed as follows:
1.
Set the FOM switch to OFF.
2.
Remove the battery door; then disconnect the
battery.
3.
Remove the two Phillips screws found under
the battery door; then separate the top and
bottom cases.
4.
To remove the pca, remove the Phillips screw
near SW1; then lift out the pca.
To reassemble the FOM, proceed as follows:
1.
Reinsert the pca; then replace the screw that
holds the pca.
2.
Tuck the battery wires into the notch at the side
of the battery compartment.
3.
Tuck the battery wires down against the pca so
they will not interfere with SW1.
4.
Set SW1 to the off position.
5.
Set the slide switch actuator on the top case to
the OFF position.
6.
Put the top and bottom cases together; then
replace the two screws under the battery door.
Calibration Adjustments
To ensure that the FOM performs to specifications,
calibrate it annually using the procedure that
follows.
Always perform the complete calibration
adjustment procedure.
Step 1: Preparing for Calibration
To prepare for calibration, proceed as follows:
1-1. Remove the dust cap from the DSP-FOM.
1-2. Connect a voltage supply of 8 V dc
±1.0 V dc to the FOM battery strap.
1-3. Set the FOM switch to the 1300 nm position.
Allow the unit to warm up for 10 minutes.
1-4. Connect the 1300 nm light source to the
attenuator input.
1-5. Turn on the 1300 nm light source. Allow the
unit to warm up for 10 minutes.