Special Focus: Cabling Infrastructure
Backbone carries digital signal
Television station installs a single-mode fiber solution to accommodate new broadcast technology.
When TVW moved into its new broadcast center, the Jeannette C. Hayner Media Center, it needed to make a major overhaul of the network’s equipment, from outdated analog equipment to state-of-the-art digital broadcast technology. Photograph by Kristin K. Zwiers.
Migrating from an analog
to digital television infrastructure has, in
recent years, led to some unexpected–and
major–headaches for broadcasters and their
engineering staffs. This was a situation
that TVW, the Washington state public
affairs television network, recently faced.
TVW provides
gavel-to-gavel coverage of Washington state
legislative sessions, Washington Supreme
Court hearings and other public affairs
events. The network produces more than 2,000
hours of programming annually, modeling its
coverage on the federal-level
C-SPAN network by providing unbiased,
unfiltered access to state government
deliberations.
TVW has one of the
largest robotic camera facilities in the
nation, with 39 remotely operated cameras
located in the legislative building, the
Temple of Justice, and the State House and
Senate office buildings in Olympia, the
state capital.
When TVW moved into its
new broadcast center, the Jeannette C.
Hayner Media Center, it needed to make a
major overhaul of the network’s equipment,
from outdated analog equipment to
state-of-the-art digital broadcast
technology. Up until the move and the
transition to digital video technology, the
four buildings on the Capitol campus were
connected to TVW’s broadcast facilities by a
network backbone approximately a mile in
length. The traffic on the backbone
typically includes four SDI video feeds
multiplexed into a single channel, 12 audio
channels and control channels for the
robotic camera systems on the campus.
According to Marc
Gerchak, TVW director of engineering, this
backbone used a legacy multimode fiber
technology that was adequate for the
previous analog platform. Its performance
with the media center’s digital platform,
however, was not acceptable.
"The video signal would
actually just break up and not make it back
to TVW on a lot of the lines," Gerchak says.
"We determined that the multimode wasn’t
able to accommodate the signals without
reflective effects disrupting the signal."
After analyzing the
problem and isolating it to the multimode
limitations, Gerchak worked with TVW’s
networking infrastructure contractor,
Intracommunication Network Systems (INSI),
to develop a new solution. INSI project
manager Ari Shackell realized that TVW
needed a single-mode backbone fiber solution
that could be designed, tested and installed
swiftly and cost-effectively.
Decision considerations
The solution chosen was
Corning Cable Systems’ Plug & Play AnyLAN
Systems. Several conditions helped decide in
favor of using Corning’s solution for the
new backbone:
- Existing
pathways through steam tunnels and other
utility conduits had limited space and
difficult access for cable pulling and
splicing.
- TVW
needed a flexible system that could be
quickly installed in a short time frame,
with minimal disruption of the Capitol
campus, a high-security area.
- Its
availability in singlemode fiber, which
provided the signal stability necessary
for multiplexed digital video transport.
"We had to obtain
permissions from multiple state agencies
from a security perspective to gain access
to those tunnels," Gerchak says.
AnyLAN Systems is a
preterminated local area network cabling
solution that can be installed up to 50
percent faster per splice or termination
point than traditional field installations.
Available in singlemode and 50 µm multimode
fiber, AnyLAN Systems incorporates standard
optical-fiber cables that feature
pre-installed tether attachment points
(TAPs) placed along the length of the cable
at customer-specified points. These
preterminated TAPs replace standard bulky,
manually installed splice closures and the
need to midspan access and splice the
backbone cable to drop to locations.
Factory-terminated and
-tested distribution trunk cables, tethers
and harnesses enable quick, reliable
installation, and each TAP supports up to
two tethers (24 fibers) per location for
added flexibility. Harnesses are terminated
with the OptiTip MT Connector on one end and
up to 12 single-fiber connectors on the
other end.
The main trunk is a
144-fiber AnyLAN Systems distribution cable,
approximately 3,000 feet in length, running
from the main distribution frame at the
media center to a distribution point on the
Capitol campus. From this point, multiple
12-fiber tethers of various lengths connect
the backbone trunk to each of the four
buildings in the network: four 12-fiber
tether assemblies to the legislative
building, two to the Temple of Justice and
two each to the Senate and House office
buildings. In addition, a new tether was
connected to the general administration
building to support future video feeds
planned for that location.
The backbone trunk
interfaces with the media center’s main
distribution frame using Corning Cable
Systems’ Pretium Connector Housing. Designed
for LAN and data center applications, they
provide convenient, open access to
connectors for moves, adds and changes.
Modularity, speed important
According to Gerchak, the
principal appeal of the Corning solution was
the speed with which TVW’s network could be
manufactured and installed, coupled with the
system’s modular ability to handle future
growth.
"In case I had any
changes on the Capitol campus, or a new
building needed to be added to the network,
I knew all I had to do was purchase a
harness to plug into the backbone
infrastructure," Gerchak says.
"There are already plans
in place by the state to build a new
Heritage Center on the site of an existing
general administration building, which will
be demolished," Gerchak adds. This facility
is expected to host activities that TVW will
need to cover, so the new fiber
infrastructure will make adding the site to
the TVW network easier to accomplish.
To help confirm that the
AnyLAN Systems single-mode solution would
correct TVW’s video issues, Corning Cable
Systems provided a simulator platform so TVW
could test the product’s ability to fully
support the network. TVW ran a week-long
test sending the SDI video signal through
this platform and was satisfied the solution
was stable and delivered the required signal
quality.
TVW faced two major
challenges with installing the new network.
First, a new conduit needed to be run
underground from TVW to the tether drop
point on campus. This path had to be bored
under the main lawn of the Capitol,
requiring further rounds of permissions from
multiple agencies. Once the permissions were
obtained and the conduit installed, Corning
and INSI were able to complete the upgrade
quickly.
Since the AnyLAN System
has pre-installed tether attachment points,
technicians did not need to spend hours in
steam tunnels splicing and testing
connections, installing splice enclosures
and other time-consuming tasks. For example,
the main cable pull–close to 3,000 feet–from
the campus to the media center, was
accomplished in one afternoon.
Since the new backbone
was installed, TVW has had no video signal
issues that could be attributed to the
Corning system or the single-mode fiber,
with stable digital video coming from the
campus to the media center.
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