It's an IP/TV world. Opal looks like a winner.............
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Broadcast IP Is Here To Stay: Two Approaches
By George Maier
(August 16, 1999) One of the more noticeable buzzes around NAB was the interest in IP video. The interest is not new; its been on everyone's mind as DTV rolls out and as broadcasters look at datatcasting opportunities. A few new product developments and some new thinking are likely to push IP more to the forefront this year. One such development was announced at the Thomcast NAB press conference this year; a new IP broadcast product called Opal.
Opal is an IP to MPEG-2 Gateway for broadcasting data within MPEG-2 transport streams. The gateway supports ATSC or DVB compliant software multiplexing in real time, based on Thomcast's "OpenMux’" technology. From an application standpoint, Opal can manage up to 50 different IP inputs for broadcasting Internet or data files within ATSC or DVB MPEG-2 transport streams. The platform is Windows-NT based, and the real-time multiplexer has an optional live MPEG-2 transport stream input, and provides MPEG-2 transport streams at a rate of up to 40 Mbps. Other options include DVB-PI, LVDS, or ASI output signals.
The Opal platform is a client/server architecture consisting of two clients, the Configurator and the IP Manager. The Configurator offers global supervision of the server, and features a complete display of all MPEG-2 ATSC and DVB parameters. The IP Manager is dedicated to the configuration, management, and supervision of all IP inputs within the Opal Gateway, and features an SNMP agent. The IP Manager can be run on a remote platform.
At NAB, Thomcast teamed with Microsoft and the LG Electronics Research Center of America to demonstrate data broadcasting applications. The Microsoft demonstration incorporated applications based on the Advanced Television Enhancement Forum (ATVEF) specification for Interactive Television. Microsoft conducted a similar demonstration utilizing Opal at the WinHEC conference just before NAB. The demonstration with LG showed a variety of potential business applications as well program related content from the WGBH Education Foundation. The IP data for both of these demonstrations was multiplexed into a single ATSC/MPEG stream by the Opal Gateway.
In a recent conversation with Jim Kutzner, Director of Engineering at Thomcast's CDS group, it was confirmed that broadcasters are showing strong interest in getting IP data into their DTV bitstream. "Opal is a product that fills a need," said Kutzner, "it will fulfill the possibilities that data broadcasting allows within the DTV signal," he added.
Certainly, the first users of IP will be experimenting with any number of services to feel their way around the market and the technology, but eventually, it will be a major part of every DTV plant. One issue is the return data. Thomcast has chosen land-line for the moment, but other possibilities are looming, as we shall see later.
Harris also introduced an IP product called the Dataplus DP-100 MPEG Data Encapsulator. The Dataplus DP-100 is a push mode encapsulator for bit streams, byte streams, ATVEF, and IP into MPEG-2 packets for insertion into an ATSC transport stream. In addition to IP, Dataplus also supports ATM, RS-232 asynchronous, and RS422 synchronous data. Harris uses a process called Null Packet Optimaztion to replace null packets in the ATSC stream with encapsulated MPEG-2 packets. The technique is so unique, that Harris has applied for a patent.
Using Dataplus, a broadcaster can create and schedule data based services that will be encapsulated in the ATSC stream. For example, one of the services might be to broadcast page two of a financial info web page, with a three minute refresh rate, from noon to 4:00 PM. If a viewer has selected this service, the info is cached automatically on the viewer's computer, which could be the TV or a PC. The viewer may elect to specify a visible flag being raised whenever certain parameters are met with respect to new information. Once a flag is raised, the viewer will be asked if they wish to connect to the site via their normal ISP.
Harris sources have hinted that Dataplus will become much more powerful as more applications software is developed, but for now they are pleased with the basic results.
Another interesting, and very different approach to datacasting was discussed by the folks at ADC Broadcast Systems Division; the former ITS. Just about a year ago, an ITS UHF transmitter went on the air in Houston, on Channel 43. From day one, it has never carried video in the broadcast sense, but has been devoted totally to IP. Channel 43, better known as AccelerNet, is an on air high speed Internet carrier. According to AccelerNet president Dean Mosely, the 6 MHz TV channel provides a total of 30 Mbps of aggregate downstream bandwidth, splitting the channel into three subchannels using 64 QAM modulation, each delivering 10 Mbps. A single 6 MHz TV channel can support up to 18,000 subscribers based on average usage, with up to 1,800 active users on line at any given instant. The actual number of possible subscribers varies according to the type of traffic and user requirements.
The service area is a 50-mile radius, which is quite respectable given that the transmitter power output is around 1 kW average. What would normally be the studio, is a network operations center. At the subscriber, the interface is an asymmetrical cable modem with a UHF receiving antenna to pick up the Channel 43 signal, and a telco interface for the upstream return data. The cable modem (which is tuned to a given frequency) demodulates the signal that is received by the transmitter and routes it to a PC using TCP/IP as its networking protocol, this frequency is determined at the network operations center, or POP, on each cable modem installed. The function of the cable modem is to connect broadband (i.e. IF wireless network) to Ethernet. The cable modem sends the data request to the upstream channel, and once the upstream destination is reached from the Internet, the data is sent to the UHF transmitter for the completion of the request.
AccelerNet is an LPTV allocation, the first of its type, but it will not be the last. According to Mosely, "We can bring high speed Internet service to rural communities faster and with less expense than any competitive solution." And with plans to install more than a dozen additional systems from Hawaii to New York, AccelerNet is betting that broadcast IP will capture a significant share of the market.
One improvement that AccelerNet hopes to see working in the near future is the upstream return channel. They are working on a microwave solution that should provide better performance, and freedom from copper. As for ADC, they think this is just the tip of the iceberg.
With this perspective in mind, and with thirst for ways to generate revenue using DTV channels, this is a hot topic to stay in tune with, and we promise we'll come back to it again soon.
George Maier, founder of Orion Broadcast Solutions, a broadcast & telco consulting firm, can be reached at 978-443-9659, or gmaier@ultranet.com.
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