, a government-backed R&D organization that is part of a major consortium developing set-top boxes. "It's also a business issue," notes Chao, adding, "How much are customers willing to pay for them?"
What's in the Box
But most analysts concur that, when it finally develops, the market for set-top boxes and related services will be tremendous. Companies are beginning to rush their products to market, at prices ranging from $200 to $300. Today's first- generation set-top boxes offer more than a multitude of TV channels; they're flexible platforms that connect to various networking architectures and consumer-electronics gear. Follow-up products will contain a slot for a smart card, which will give users a secure way to conduct transactions over cable networks.
Standard set-tops are stand-alone units that connect directly to a TV. Other models will support wireless
transmissions; direct broadcast satellite (DBS) services, such as DirecTV; and the Multichannel Multiport Distribution System (MMDS), which uses multiple local terrestrial microwave transmitters located in metropolitan areas to get a signal to homes. Other box vendors are taking different approaches. For instance, aside from their standard set-top lines, NEC and Samsung are integrating set-top-box functions into some of their PC lines.
In what appears to be a collision -- or conversion -- course between PCs and TVs, some set-tops also run real-time OSes and Java applets, which allows the boxes to double as TV Internet surfers if they're connected to the Web. Since some cable companies offer broadband data connections on their networks, some set-tops also feature Ethernet connectors that allow you to download information from the Net.
Asian countries are expected to embrace a combination of standard and wireless set-top boxes that will connect to current and future consumer-electronics devices as the
home moves from analog to digital. Future set-tops will support the emerging IEEE-1394 digital interface standard, which specifies the way PCs and consumer-electronics devices exchange data.
The Network Connection
According to analysts, the major issue in Asia is how to link a set-top box to disparate (and sometimes poor) networking infrastructures. Future set-tops will incorporate so-called network interface modules (NIMs), which will allow them to support a bevy of protocols: Asymmetric Digital Subscriber Line (ADSL), hybrid-fiber-coaxial (HFC), and Fiber to the Curb (FTTC, also known as switch digital video). Wireless boxes will support DBS and MMDS.
Basically, ADSL uses specialized modems to transmit signals over an existing twisted-pair telephone wire. A typical ADSL system supports a downstream rate of 6 Mbps and an upstream rate of 64 Kbps. Meanwhile, HFC uses an existing cable-TV network; however, this bandwidth must be shared among several hundred subscribers using intera
ctive services.
Switch digital video calls for fiber-optic cable to be strung to a neighborhood, with a portion connected by coaxial or twisted-pair wire. Such a network might require the use of asynchronous transfer mode (ATM), a cell-switching technology with data rates starting at 1544 Kbps. For interactive-TV services, a set-top box requires several components: a CPU, an NIM, an MPEG-2 audio/video decoder, a real-time OS, main and graphics memory for use in displaying menus and/or bit-mapped images, modulation/demodulation chips, and forward-error-correction ICs.
According to the Interactive Multimedia Association, there are six types of set-top boxes. Below are some details about these six types.
Class 1 and 2 boxes are low-end, analog-based units built around a CISC microprocessor unit (MPU), usually a 386 or a 68020/30. These boxes have little or no capacity for transmitting, but they support cable channels and pay-per-view TV.
Class 3 and 4 boxes also employ CISC MPUs. They provide mor
e functionality by retaining some return-channel bandwidth capabilities while splitting the download channel between analog and encoded video. Class 4 units offer more digital interactive services.
Class 5 and 6 boxes are all-digital units that support a full range of interactive-TV services. Class 5 units have a downstream path that's wider than the upstream path, while Class 6 units have equal bandwidth for sending and receiving. Class 5 and 6 boxes use embedded RISC CPUs, such as the PowerPC, from Motorola and IBM; R4000 variants, from LSI Logic or others; and the MicroSparc, from Sun.
Many RISC MPUs integrate the CPU core, analog descrambler, and network-security interface. Like Class 3 and 4 units, the high-end boxes use MPEG-2 for audio/video compression. Many MPEG-2 chips enable PAL-format video, with a full-screen, 16-color on-screen display and only 16 Mb of DRAM.
Set-tops will also support one or more real-time OSes, including Integrated Systems' pSOS, Microware's OS-9, and the Thomson-S
un Interactive Alliance's OpenTV. These boxes must also support several international standards, which are being devised by a new consortium, the Digital Audio/Visual Council (DAVIC).
A Special OS
Set-top OSes are generally
kernel-based
, scalable software platforms that offer support for CISC and RISC processors as well as provide multitasking functions in real time. This is important for embedded applications, explains Doug Lewis, manager of Asian business development for Microware Systems (Des Moines, IA).
Microware's OS-9 is bundled with Spyglass's Web Technology Kit. This allows Microware's OS-9 to support Internet-access capabilities for several types of electronic appliances: Web-enabled TVs, network computers, pagers, digital cameras, cellular phones, and others. Microware's OS is also bundled with the Java programming environment, enabling the use of Java applets on OS-9.
One of the first VOD trials in Japan is a collaboration between Nippon Teleg
raph and Telephone (NTT) and cable-TV operators in Tokyo, Chiba, and Kanagawa. The trial, which started in July 1995 and runs through March 1997, calls for 300 households to use a set-top box via NTT's fiber-optic network. Telephone services use a 64-Kbps ISDN network.
A separate VOD trial now taking place near Tokyo, which will also run through March 1997, is being conducted by NTT and Silicon Graphics, Inc. (SGI). This trial uses SGI's set-top box, a custom unit built around a Mips R4000 RISC CPU. Last spring, NTT, CATV Yokosuka, and Microsoft launched a similar program.
NEC, Pioneer, and Toshiba are among the major set-top-box vendors in Japan. NEC's new box, the Broadband Access System-2000, is based on a PowerPC chip that runs OS-9 and supports switch digital video, ADSL, MMDS, DBS, and HFC. It handles NTSC/PAL video signals, while decoding is done via MPEG-2 over a 15-Mbps transport stream.
NEC's box can support narrowband services, such as plain old telephone service (POTS), narrowband ISDN
, and Internet access. The optical network unit can support narrowband signals via T1 or E1 interfaces. NEC's ADSL system can transport signals via ATM cells using the ADSL format. The downstream bit rate is 6 Mbps; the upstream rate is 64 Kbps. A typical price for a set-top box in Japan runs from 20,000 to 30,000 yen.
Karaoke on Demand
Late last year, NEC was picked as the set-top-box vendor for a major VOD contract in Hong Kong. NEC's box is built around IBM's PowerPC. Hong Kong's VOD provider, Hongkong Telecom-IMS, has delayed its VOD trials until 1997, when it will offer VOD, karaoke on demand, electronic commerce, home shopping, and pay-per-view TV.
Hongkong Telecom-IMS will carry its interactive-TV services via an ATM or broadband ISDN network. Applications servers will supply Java over dial-up connections across the ATM network. Two-way communications will take place across this ATM connection via TCP/IP protocols. Video content sent out from the server will be in MPEG-2 fo
rm. It will then be decoded by a hardware chip in the set-top box and turned into an analog signal for transmission to the TV, according to William Lo, president of Hongkong Telecom-IMS.
Meanwhile, Taiwan is also endorsing the PowerPC in a set-top-box/VOD pilot program. This set-top box comes from a newly formed consortium led by Acer, CCL, and Tatung. Taiwan's Interactive TV consortium consists of some of the island's other PC and consumer-electronics vendors: ADI, First International Computer, Mitac, and Sampo, as well as some multinational corporations, including Philips and Matsushita.
Acer's box, the AcerStar, will ship early next year. It's built around IBM's 403 version of the embedded PowerPC, and it runs OS-9. Once it hits mass production in 1997, the Acer box will sell for about $300. It includes an MPEG-2 chip and 3 MB of memory, and it supports the European Digital Video Broadcast (DVB) standard. "DVB, which is getting support in the U.S., has a good descrambler system for encryption and d
ecryption purposes," says Carlie Wang, R&D director for Acer's set-top-box project.
Tatung, one of Taiwan's largest consumer-electronics companies, also has a new set-top box, the TDS-403D. Like the AcerStar, the TDS-403D is based on the PowerPC and uses an MPEG-2 chip for compression/decompression.
Samsung is playing a major role in Korea Telecom's (KT's) VOD pilot project, which is taking place in Seoul. Fifty subscribers in the Yoido area have been able to enjoy movies, drama, documentaries, and karaoke by placing an order through a telephone line to KT's VOD server. In the trial, Samsung is developing and providing an ATM switching system, an ATM multiplexer, ADSL, set-top boxes, and other systems. Meanwhile, Digital Equipment provides the video server, consulting, and systems integration.
The set-top box may take yet another form in the future. Like NEC, Samsung, and others, Acer may integrate set-top functions into its PCs. "The PC will likely integrate the set-top, the DVD [digital videodis
c] player, and other devices," Acer's Wang says. "But eventually, we see the stand-alone set-top becoming the home server for distributing information to the PC or other appliances in the home. With the set-top, you can receive video information or telephone signals. In a sense, the set-top becomes the cornerstone in the home."
Where to Find
Acer, Inc.
Taipei, Taiwan, R.O.C.
Phone: +886 2 545 5288
Fax: +886 2 545 5308
Internet:
http://www.acer.com/
Set-Top Madness
