CANOGA PERKINS 9145 Network Interface Device - Manual (Page 82)

9145 Network Interface Device 4-2
Measuring 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 9145.
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 9145. 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 9145 Tx output value to
determine the power expected at the remote cable end, which is the input power at the
remote receiver.
Measuring Receiver Input Power
If you know the link attenuation, skip this section. Otherwise, follow these steps to use the
9145 to measure the link attenuation.
1. At the local site, connect the fiber link cable to Tx on the 9145.
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 optical receiver. This power level must be within the sensitivity range listed
on the data sheet for the optical receiver.
4. Subtract the remote receive power level from the transmitter output power at the local
site. The result provides the link loss, in dB.
Note: If you cannot determine the Rx sensitivity, contact Canoga Perkins Technical
Support Department for assistance.