CANOGA PERKINS L357 Gigabit Ethernet Service Unit - Manual (Page 50)

EdgeAccess Universal Chassis System
L357 Gigabit Ethernet Service Unit 5-2
5.1.3 Measure Transmitter Output Power
To measure the output power, follow these steps:
1. Clean the connectors on the fiber optic test cable, then plug it in to the Tx connector on the L357.
2. Warm up each component for at least 30 minutes.
3. Set the optical power meter to the proper wavelength.
4. Wait two or three minutes for the power reading to stabilize, and then read the output power.
5. Subtract out the test cable loss, then record the power level and compare it to the value on the
performance sheet for that particular L357. Measurement tolerance is +/- 0.5 dBm.
Note: When referencing optical power levels with numerical values less than zero, the reading
closer to zero is the greater value; for example, -17 dBm is greater than -20 dBm.
6. If the reading is incorrect, repeat the measurement with a different test cable. If the power level is
still not within range, call Technical Support.
7. After calculating the link attenuation, subtract that value from the L357 Tx output value to
determine the power expected at the remote cable end, which is the input power at the remote
receiver.
5.1.4 Measure Receiver Input Power
If you know the link attenuation, skip this section. Otherwise, follow these steps to use the L357 to
measure the link attenuation.
1. At the local site, connect the fiber link cable to Tx on the L357.
2. At the remote site, set the optical power meter to the proper wavelength and connect it to the fiber
link cable.
3. Record the optical power level and compare it with the sensitivity level listed on the data sheet
for the link fiber type.
4. Subtract the remote power level from the value for the transmitter output power at the local site.
The result provides the link loss, in dB. The received power level must not be lower than the Rx
sensitivity nor greater than the Rx saturation listed in the optical specification for the model of
L357 or SFP used.
Note: If you cannot determine the Rx sensitivity, contact Canoga Perkins Technical Support
Department for assistance.