Cisco GS7000 Installation And Configuration Manual page 108

Chapter 3 Setup and Operation
Transport for Broadcast Services
The Prisma II 1550 nm Optical Transport System is used for delivering broadcast
video and broadcast digital services from a headend to the Model GS7000 Optical
Hub and nodal service area. This system utilizes externally modulated 1550 nm
transmitters in conjunction with erbium-doped fiber amplifiers (EDFAs).
At the headend a 1550 nm transmitter and EDFA are used to carry broadcast
payloads for transport to the Model GS7000 Optical Hub via a ringed network. The
two paths are fed into the optical hub that is configured with an optical switch
(OPSW) that detects loss or drop of light. The output of the OPSW is fed into a
field-hardened EDFA within the optical hub for amplification. The amplified signal
is split and feeds up to four NCBC8-BC18-NCxxxxFR passive modules. Each
NCBC module feeds eight GainMaker fiber deep nodes or the Model GS7000 4-way
segmentable node.
The flexible design is built on the building block concept adding
NCBC8-BC18-NCxxxxFR passive modules only when the service area requires
additional nodes or node segmentation.
Transport for Narrowcast Services
The Prisma II 1550 nm Optical Transport System QAM Transmitter is used for
delivering narrowcast digital services from the headend to the Model GS7000
Optical Hub and nodal service area. This system utilizes directly modulated 100
GHz spaced 1550 nm ITU transmitters (40 available wavelengths) in conjunction
with Prisma and GS7000 Optical Hub multiplexer/demultiplexer passive devices
and GS7000 field-hardened gain-flattened EDFAs.
Narrowcast signals originating at the headend are transported over a protected fiber
ringed to the Model GS7000 Optical Hub using DWDM for maximum fiber
efficiency. The two paths are fed into the Model GS7000 Optical Hub that is
configured with an OPSW that detects loss or drop of light. The output of the
OPSW is fed into a field-hardened gain-flattened EDFA within the optical hub for
amplification prior to injection into the optical hub passive devices
The passive devices consist of up to four distinct NCBC8-BC18-NCxxxxFR modules,
one for each group of eight forward/return wavelengths, and 4-band BWDM
module that is used to multiplex/demultiplex the individual 1x8 DWDM channel
groups (ITU 21-27, ITU 28-35, ITU 36-43 and ITU 44-51). Other options are
available. Each 8-wavelength channel group is inserted into the narrowcast
insertion port of the NCBC8-BC18-NCxxxxFR passive module where the narrowcast
DWDM wavelengths are demultiplexed and then multiplexed with the broadcast
wavelength providing each node or service area with broadcast content and
area-specific narrowcast content for advanced services such as HSD, VOD, and
voice.
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