ARLINGTON, VA.—The decade-long buildout of the
Next Generation Interconnection System at PBS was on track to mark its latest milestone
Sept. 17 when the public network converted the totality
of its satellite distribution equipment from
MPEG-2 to MPEG-4. The overall NGIS project is projected
to be fully completed by late 2016.
“The primary goal of NGIS is to take ‘public television
interconnection’ to the next level,” said PBS
Chief Technology Officer John McCoskey. “That included
a significant technology refresh and an architecture
that would drive both efficiency and flexibility
over a 10-year period that encompasses multiple
elements and technology cycles.”
Remember that NGIS was conceived in the era of
tape-based origination analog TV and standard definition, and so it needed to take us through the digital
transition, [including] file-based workflows and
high definition,” McCoskey said.
CARRIER ID
Stefan Petrat, vice president of Distribution
Operations & Engineering at PBS,
is leading the NGIS initiative from the
network’s Arlington, Va. headquarters. “An
important part of the MPEG-4 upgrade is
the support of Carrier ID in the Ericsson
8190 encoders and Newtec M6100 modulators,”
Petrat said. “Carrier ID is a ‘stamp’
on uplink signals that will enable satellite
operators to identify transmissions to
their satellites and coordinate with earthstation
operators in the event of signal
interference.” PBS is supporting the World
Broadcasting Unions-International Satellite
Operations Group and others to promote
global Carrier ID standardization.
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| Al Nunez |
Al Nunez, president/Americas at Ericsson
Television, said since radio frequency
interference negatively impacts qualityof-
service for broadcasters, operators and
at-home consumers, Ericsson has been
working with PBS and other industry
leaders in the development of Carrier ID.
“Using this identification method allows
satellite operators to identify and quickly
contact the source of interference, which
directly affects and can increase qualityof-
service by providing faster resolution
to signal disruptions,” Nunez said. “Switching
to MPEG-4 enables PBS to deliver more
content with higher video and audio quality,
using the same bandwidth limitations.
And any bandwidth savings could enable
PBS to add new services.”
Nunez said deployment of more than
1,500 Integrated Receiver Decoders to
PBS stations was a highly coordinated
event: “Each RX8200 IRD was shipped
from the factory to Duluth, [Ga.], where
[each unit] was loaded with the specific
PBS configuration—and then thoroughly
tested by running them for 24 hours. Presetting
and pre-soaking the receivers before
they’re put into the field provides a
more reliable deployment,” Nunez said.
(Ericsson’s MPEG-4 distribution system
also has been tapped by ABC/ESPN, NBC
Universal, Telemundo and Univision,
among others.)
As for public TV viewers, Petrat said
“they can clearly see and hear the significant
technical quality improvements
of MPEG-4. NGIS allowed us to create a
state-of-the-art playout and distribution
system, enabling stations to pass on superior
quality images and sound to consumers.”
Nunez said for viewers with largescreen
HD sets, “the visual resolution may
be dramatically improved and images
will have less compression artifacts. The
side-by-side comparisons of programs
compressed in MPEG-4 and MPEG-2 are
impressive. It doesn’t take a golden eye
to see MPEG 4 delivers higher quality at
lower bit rates.”
NRT ROLLOUT UNDERWAY
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| PBS shipped more than 1,500 Ericsson RX8200 IRDs to member stations. |
Petrat said the NGIS also centers on
Ku-band satellite transponder-leasing and
a wide variety of sub-projects—such as
Non-Real Time, a file-based delivery system
to stations via satellite. He said NRT
has been rolled out to more than 70 percent
of local PTV outlets, with the remaining
ops sites scheduled to receive NRT
equipment by late 2012.
 |
| John McCoskey |
“NRT is an efficient way to deliver content
that can be recorded, stored and played
at a later date,” Petrat said. “It leverages an
IP-based system to transmit programs as an
AS03 MXF-wrapped file by satellite to ‘catchservers’
at stations, instead of sending the
content in baseband as real-time program
feeds that need to be physically recorded
by a video server or tape deck. NRT delivery
reduces the number of encode cycles,
thus reducing concatenation artifacts. This
catch-server communicates with a station’s
traffic system and playout server to push
content to air,” Petrat said. Each catch-server
has 12 terabytes of storage (typically
enough for about 10
days of content).
CTO McCoskey said a key advantage
to NRT distribution is “it eliminates the
manual step of trimming the beginning
and end of a recorded program that station
personnel would normally have to
do. That may seem like a small thing, but
multiplied by hundreds of stations and
thousands of shows each year, the labor
reduction across the system is significant.
NGIS is designed to increase workflow efficiency,”
he said.
The last major project on the current
NGIS agenda is a broadcast disaster recovery
facility. The goal of DDMS (Disaster
Recovery, Diversity and Maintenance
Site) is to construct a replicated backup
of the PBS Tech Center in Northern
Virginia at PTV’s Nebraska Educational
Telecommunications facilities in Lincoln.
McCoskey said the DDMS will be a standalone
“lights-out” operation built on an
all-IP platform remotely—and monitored
and controlled by PBS staffers in Virginia.
DDMS is scheduled for completion by the
end of this year.