CANOGA PERKINS 9155 Network Interface Device - Manual (Page 45)

5.3.3 Measure Fiber Link Attenuation
Determine and record link attenuation before starting normal link traffic. The attenuation factor
identifies potential problems with links that are on the threshold of receiver limitations.
Measure optical fiber links at the shortest wavelength of operation to determine the limiting factor in
the loss budget. Each device that transmits to an 9155 has a loss budget that is specified by the
manufacturer and recorded on a data sheet provided with the equipment. That loss budget must be
greater than the total of the measured loss of the fiber link and the attenuation of the 9155s.
Use a power meter calibrated for the laser source, then factor in approximately 1 dB for the connector
loss from the patch cables between the 9155 and the local device. (Each fiber connection can
generate 0.5 dB of additional loss.)
Note: Consider this measurement when extending the link at WWDM wavelengths because the
shorter wavelengths have a greater loss.
To measure attenuation:
1. Attach the transmit fiber to the local and remote ends of the link.
Note: To avoid damage, do not over-tighten or force-fit the optical connectors.
2. With a properly calibrated optical power meter, measure the optical power on the fiber that will
be connected to the Rx connector at one site. Record this reading.
Note: Use either a hand-held power meter or other similar measuring device.
3. Repeat this process at the other site.
5.4 Troubleshooting
This section describes fault conditions and corrective action. The multifunction LEDs and the alarms
display all failures.
Whenever there is a significant signal loss, first check the fiber path and the minimum bend radius for
problems. Remove and inspect the cable connectors, being careful not to damage the fiber end-face
surface or the connector housing. Clean all optical connectors before reinstalling them.
5.4.1 LED Indicators
For details on the LED status during a normal start-up, see Chapter 3.
The front panel LEDs show both normal and fault conditions. Additional information about fault
conditions appears in various status and information screens. To aid troubleshooting, Tables 1 and 2
list the functions of the front panel LEDs.
9155 Network Interface Device 5-3