User Manual CXE85X
59300464 Rev.005
9.12.2013 11(44)
Optical input selection
The CXE852 optical input selection can be set to 3 modes: Automatic, Manual
1, Manual 2.
When the input selection is set to the “Automatic” mode, the node automatically
selects the optical input according to signal conditions. If the optical input power
at the main input is out of major alarm limits, input 2 will be selected provided
that its optical input power is inside major alarm limit + deadband. Input 1 is
selected when its optical input power is above low major alarm limit +
deadband. This fully automatic input selection between the two inputs offers a
useful redundancy mode for critical applications.
In “Manual: RX #1” mode input 1 is always used, regardless of the optical input
power. In “Manual: RX #2” mode input 2 is always used, regardless of the
optical input power.
Forward path adjustment
The following are instructions to be used for a normal adjustment procedure.
1. Test the optical input power present on the fibre using an optical power
meter. The CXE85x optical input power range is from -7 dBm to +2 dBm.
2. Optical Level Control (OLC) circuitry provides gain control that
compensates for changes in input level caused by external variations. The
available gain reserve is factory-set for optimum operation. If needed the
output level can be adjusted with the mid stage attenuator. It is possible to
disable the OLC with a jumper (Figure 4 pos. 8) or via software. This makes
it possible to operate the CXE85x at full gain for applications that do not
require gain stabilization.
3. Use the mid stage attenuator to get wanted output level. The network plan
should specify exact signal levels. Refer to the "Table 3. Mid stage
attenuator selection and output level".
4.
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