Poor Frequency Response - Cisco GS7000 Troubleshooting Manual

Poor Frequency Response

Note
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Poor Frequency Response
Follow this troubleshooting flowchart. Also see the notes following the chart.
Troubleshooting
8
Description
For standard receiver
The range for optical light input level is -6 to
+2 dBm which converts to 0.25 to 1.6 V DC.
The optimum operating range is -3 dBm to +2
dBm which converts to 0.5 to 1.6 V DC. Levels
higher than +2 dBm can cause the photo diode
to generate distortions, which add to the
distortion performance of the link, effectively
degrading the distortion performance.
Attenuate the light to simulate the amount of light that should be at the 1.2 GHz GS7000 Node
and rerun the distortion performance. If the distortion performance improves, there is too much
light. An inline optical attenuator or a coupler with a higher loss can reduce the light, or the laser
may have to be replaced with a lower launch power.
Attenuate the RF input level into the amplifier by increasing the pad value at the OIB. If the
distortion perform improves, there is too much RF.
For low input receiver
The range for optical light input level is -10 to
-2 dBm which converts to 0.1 to 0.6 V DC. The
optimum operating range is -6 dBm to -2 dBm
which converts to 0.25 to 0.6 V DC. Levels
higher than -2 dBm can cause the photo diode
to generate distortions, which add to the
distortion performance of the link, effectively
degrading the distortion performance.
Troubleshooting