CANOGA PERKINS 9161 Network Interface Device - Manual (Page 51)

Maintenance 9161 Ethernet Network Interface Device User’s Manual
Check Optical Power Levels
39/(42 Blank)
Figure 5-2. Measuring Receiver Input Power
5.2.3 Calculating Fiber Link Attenuation
Link attenuation measurement identifies potential problems with links that are on the threshold of
receiver sensitivity. Measure optical fiber links at the shortest wavelength of operation, as it is the
limiting factor in the loss budget. 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 9161 and the local
device. (Each fiber connection can generate 0.5 dB of additional loss.)
NOTE: If you cannot determine the Rx sensitivity, contact Canoga Perkins
Technical Support for assistance.
Follow these steps to calculate fiber link attenuation:
1. Determine transmitter output power as described in paragraph 6.2.1 above.
2. Determine receiver input power as described in paragraph 6.2.2 above.
3. Subtract receiver input power from transmitter output power. The result is the fiber link
attenuation.
Transmit Output Power -7.0 dBm
Receiver Input Power -28.2 dBm
Fiber Link Attenuation 21.2 dB
FIBER OPTIC
TRANSMITTER
FIBER OPTIC
RECEIVER
OPTICAL POWER METER -24dBm λ = 1300 nm
FIBER OPTIC
TRANSMITTER
FIBER OPTIC
RECEIVER
OPTICAL POWER METER
-24dBm λ = 1300 nm
LOCAL SITE
REMOTE SITE