Operation
B
GX2 EA1000C*/* Multi-Wavelength DWDM 1550 nm Laser Transmitter
•
User Guide
34
589569-001-a
The GX2-EA1000C*/* reads the quick-swap message from the GX2-CM100B,
automatically resets, and re-initializes itself to the same configuration as contained in the
message.
•
If the GX2-EA1000C*/* is in Preset mode, it uses the factory default optimum OMI
setting to determine the RF level at the laser.
•
If the GX2-EA1000C*/* is in Set mode, the laser RF input level control (OMI offset)
determines the RF level at the laser. If the GX2-EA1000C*/* is in Manual mode, the
attenuator setting determines the RF level at the laser.
•
If the quick-swap message intended for the GX2-EA1000C*/* is sent to another
type of module, the command is rejected and the module information is not
replaced.
Instructions for selecting and implementing the quick-swap mode are provided in the
GX2-CM100B Control Module Installation and Operation Manual.
Implementing a Reduced Channel Load
The GX2-EA1000C*/* performance is optimized during manufacturing for a full load of 79
NTSC channels (52 through 550 MHz) and 450 MHz of digital at –6 dBc (550 through
1002 MHz). However, some CATV systems begin optical-link operations with a reduced
channel load and later add additional channels.
Operating with a reduced channel load can be advantageous, as it improves the c/n ratio.
This is the method used in supertrunk applications. The c/n ratio improvement is
approximately 10 x log
10
(ratio of channels). For example, a 79-channel laser operating
with a 40-channel input improves the c/n ratio by approximately 3.0
dB [10 x log
10
(40/79)] and requires a 3.0 dB higher input level.
By carefully implementing the GX2-EA1000C*/* and additional distribution equipment,
you can avoid costly field trips to reset node levels after adding channels. The following
subsection presents several options to meet individual system requirements.
