Cisco GS7000 Installation And Configuration Manual page 112

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 EDFAs.
At the headend, dual 1550 nm transmitters and EDFAs are used, each carrying
broadcast specific channel plans to the GS7-OH. The two independent links each
feed into field-hardened EDFAs within the optical hub for amplification. Each of
the amplified signals are injected into the secondary BC input 1x4 "A" and "B"
connectors of the NCBC8D4-BC18-NCxxxxF passive module. Each NCBC module
feeds eight GainMaker fiber deep nodes or the Model GS7000 4-way segmentable
node. The primary 1x8 broadcast input is not used.
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 modules
and GS7000 field-hardened gain-flattened EDFA's.
Narrowcast signals originating at the headend are transported over a point-to-point
fiber path to the Model GS7000 Optical Hub using DWDM for maximum fiber
efficiency. The single fiber 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 NCBC8D4-BC18-NCxxxxF modules,
one for each group of eight forward wavelengths. The output of the gain-flattened
EDFA is inserted into the narrowcast insertion port of the NCBC8D4-BC18-NCxxxxF
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.
Node Return Transport
The Prisma II analog CWDM technology is used to transport node returns on a
single wavelength from the node to the headend. Multiple node laser options
available: Analog DWDM/CWDM, BDR DWDM/CWDM.
At the node, the 5 to 42 MHz analog reverse path signals are input to the CWDM
transmitter module. Each node is assigned a unique CWDM wavelength that is
multiplexed within the Model GS7000 Optical Hub with a 1x8 CWDM multiplexer.
The 8-node multiplexed group is transported to the headend where the CWDM
signals are demultiplexed and then feed into Prisma analog return receiver modules
for O/E conversion.
90 OL-29936-01