PBS Automates

Net develops compact multicast system


PBS announced that it has developed a highly automated multistream television station that fits in just six equipment racks, which the network expects to place with several of its member stations in the near future.

The system, dubbed ACE by the network, provides an entire control, storage and playout system for a television station-everything that goes between a studio and the transmitter. Designed for operation in a centralcasting DTV world, the system has the capability to broadcast four standard-definition channels and one high-definition channel simultaneously, with a sixth SD channel available for backup in the event of a failure.

An ACE system will be installed at a PBS member station in the next few months and other stations are considering the technology. PBS management sees ACE as one way for member stations to get the most from their challenging budgets and limited manpower.

"Because 96 percent of our content is in the can, and if we can ensure that upstream both the content and the metadata are absolutely accurate, why do we need somebody watching over master control [at the station]?" said André Mendes, chief technology integration officer at PBS, whose job encompasses both information technology and broadcast engineering.

"I assumed that broadcast could be run as a supply chain management environment, [where] content moves from the producers, through the distributors, through the retail system and on to the end users," Mendes said.


The ACE system-which is a standalone name and not an acronym-is based on other technologies developed at PBS, notably the network's NGIS bi-directional content distribution system. Member stations now use NGIS to acquire content from the network and to share homegrown programming with other stations.

The network's experience from manipulating metadata over IP networks with its NGIS system provided a solid foundation for developing an automated storage, control and playout package for individual broadcasters. One of the challenges was to keep the signal as unchanged as possible as it passed from one point to another.

"If we could optimize the process of getting it from point A to point Z, with the minimum amount of replication, with no transcoding, using one ingest process, one codec and moving the files all the way through the station without any further changes or handling," Mendes said, "we could improve the quality of the product and [gain] tremendous efficiencies."

Started after NAB2003, the ACE project joined some of the network's best engineering talent with several vendors to develop a smoothly operating test bed at PBS' headquarters in Alexandria, Va. The chosen vendors span the capability spectrum from IP experts to broadcast equipment manufacturers-the main criteria was that they all had to be willing to work together and not step on each other's technical toes.

Although the project went together very quickly-construction on the ACE system didn't start until the summer of 2003-the test was so successful that a PBS member station is now installing an ACE system. Mendes credits the teamwork among the various PBS engineers and vendors as the force behind the successful test and first rollout of ACE.


The resulting system is a complete multistream television station in six equipment racks, including extensive video storage and playout capability, automated ingest, channel branding, local and remote monitoring, station automation, traffic and billing, and a manual override. The system is so integrated with automation that it does not require a local operator, and all aspects of ACE can be remotely monitored and controlled over an IP network-a variation on the typical centralcasting model.

Vendors for the ACE system include BroadView Software (traffic and scheduling software); Intel (computer servers and desktop technology); Microsoft (software and operating systems); Miranda Technologies (switchers, routers and signal processing equipment); Omneon Video Networks (video storage and servers); OmniBus Systems (station automation); and SES Americom (satellite communications). Assisting in the overall integration of the system was Accenture.

Equipment from Miranda Technologies is salted across the six equipment racks that comprise the ACE system. The company's products also will be used for channel branding, master control, remote control and monitoring, and interfacing, distribution and format conversion. A Miranda Presmaster master control switcher is the heart of the ACE signal flow and the company's glass cockpit monitoring concept is in some ways a forerunner of the centralized monitoring feature of ACE.

Michel Proulx, vice president of product development for Miranda, said that his company has a unique capability with respect to remote monitoring and that's what first attracted the attention of PBS. Being on the ACE team had its rewards, he said.

"It's an interesting opportunity to work with these vendors," Proulx said. "We have the opportunity to go above and beyond the usual interface with vendors like OmniBus and Omneon."

Managing the system is the task of automation software from OmniBus Systems.

"PBS was investigating automation and saw that we used the Microsoft.net platform," said Mike Oldham, CEO of OmniBus Systems.

The network was also interested in the highly scalable nature of the OmniBus software and the fact that the automation system needed minimal customization to meet the needs of the project.


The ACE system has 2 TB of video storage from the 16 Omneon MediaStore disk modules, organized as a single drive. In addition to the storage, Omneon provided MediaPorts for system I/O and ingest/playout is overseen by the company's MediaServer system.

"[This] is a great example of bringing together technology companies who excel at applying IT techniques to solve the demanding requirements of broadcasters like PBS," said Geoff Stedman, vice president of Omneon Networks.

The current version of ACE uses MPEG-2 for distribution and storage, but PBS' Mendes said that the team is looking hard at other codecs that would maintain quality while reducing bandwidth requirements and increasing storage capacity. The system design allows for field upgrading of features, even those as critical as the codec.

ACE has drawn the attention of commercial broadcasters, several of which have toured the test facility. Mendes said that the tight integration of all the components was essential to making this a practical system.

"The cooperation and interoperability that we've gotten from our consortium members has been absolutely key in driving this process," Mendes said. "All of them bought into our vision of creating an environment that operates at a very high level of reliability."

Bob Kovacs

Bob Kovacs is the former Technology Editor for TV Tech and editor of Government Video. He is a long-time video engineer and writer, who now works as a video producer for a government agency. In 2020, Kovacs won several awards as the editor and co-producer of the short film "Rendezvous."