THE FUTURES MARKET
At midnight on December 31, 2000, we will enter the third millennium A.D. While it may be a bit early to buy your party hats and noisemakers for that gala occasion (which most people will mistakenly celebrate a year early), audio companies are already well along in terms of research and development for the 21st century. During a recent visit to Tokyo, I was privileged to enter the inner sanctum at Sony and discuss new product development with their chief engineers. As you might expect, most, in fact virtually all of the discussion centered on digital technology. If this column were entitled "Analog Adventures" or something, I don't think Sony's engineers and I would have had very much in common. Their emphasis is clearly on digital, and their product development programs promise high-technology times for consumers.
During an introductory meeting, Sony President Norio Ohga stressed his company's sense of historical perspective and its declared ambition to pioneer audio developments and preserve for itself a place in audio history. For example, it was on the 100th anniversary of Edison's cylinder that Sony decided to develop the next consumer audio medium. That decision, of course, culminated in the introduction of the Sony-Philips Compact Disc in 1982. That now-familiar disc is just the beginning of an ambitious format expansion called CD ROM (Read Only Memory). As a low-cost memory, CD ROM would use the 550-megabyte storage space on a Compact Disc for a variety of applications, including 2 or 4-channel audio, digital pictures, and computer graphics. Everything from dictionaries, textbooks, magazines, and shopping catalogs to computer programs and video games could be disseminated.
The existing CD format will remain intact, but in CD ROM the data area currently used for audio will be used for general-purpose, digital-data storage. The subcode on the track will not be changed. Players will be substantially the same, but digital outputs and video interfaces will have to be added as built-in features or made available as accessories. Presto-your CD player will become a mass-data storage device, and each disc will hold a ton of information. That 20-gram piece of reflective plastic will cost a lot less than the equivalent 500 to 1,000 conventional floppy discs it will replace. It will save a lot of space, too. With a 12-cm disc holding 12,000 sheets of documentation, we could all be walking encyclopedias. Which reminds me-CD Walkman, look for it soon. I saw a battery-operated prototype player, half the size of a book, and it sounded great. And, yes, the special LSI ICs used to achieve size reduction in the portable players will permit proportional cost reduction. And the cost of discs-on the way down, too. CD ROM will greatly extend the CD's product life, but Mr. Ohga noted that he expects the CD to be a viable format only until the 21st century; with the rapid pace of storage technology development, the CD is just the beginning... .
The next evolutionary step for the CD is the DRAW system, which is a write once medium. Similar to film in a camera, a disc is used to record once. DRAW would use a format compatible with the CD, but would require an enhanced player/recorder. The prototype DRAW disc is a magneto-optical disc on which a laser beam is focused through a current loop; it uses a 30-cm disc with a pit density of 3 x 10^5 kilobits per square inch (KBPI^2), yielding 1.89 gigabytes of storage. Recordable and erasable disc systems are also under development, and I was privy to demonstrations of prototypes. Like the DRAW disc, the erasable disc is magneto-optical, and it offers the read/write advantages of a floppy disc but with much greater storage capacity (the prototype holds 5.2 gigabytes). Cost would initially limit this medium to high-end computer systems, although the appeal of a recorded library on one disc, with access time of 100 mS, might attract more than a few high-end consumers. And perhaps professional recording studios would welcome the chance to abandon tape recording in favor of digital disc.
Will we thus roll into the third millennium on discs? Yes, but at least a few of us will be carrying tape machines as well. Just when you thought it was safe to buy a Compact Disc player as the last piece of audio gear you'd ever have to buy, they had to start work on the technology for a digital audio cassette. Manufacturers are currently meeting to discuss the question of format, and they likely will decide on a standard by the end of the year. The billion-dollar question is: Should a stationary or rotary head be employed in the consumer digital audio cassette? While many people feel instinctively more comfortable with the simpler looking stationary-head system, home video recorders have proven the reliability of the rotating-head design. From an engineering standpoint, both systems offer advantages as well as a few pitfalls; the smart money is allocating R & D to both systems.
The stationary-head digital cassette recorder as prophesized by Sony would use 1/8-inch tape (with stricter tolerances) and a shell similar to the standard analog cassette shell. A recorder could sample at 32, 44.1 or 48 kHz at 2.38, 4.76, and 5.18 cm/S respectively; it is expected that 44.1 kHz will emerge as the standard rate. Quantization would be 16-bit (12-bit at 32 kHz), and playing time on a cassette would be 2 to 4 hours. Twenty data tracks would be used, with a recording density of 63 KBPI2. The secret of longitudinal recording is the thin-film recording and magneto-resistive playback heads. This technology is already proving itself in professional multi-track digital audio recorders.
The rotating-head system would also use 1/8-inch tape, but the helical scan would permit a slower tape speed of 7.2 mm/S, the shell would be about half the size of a standard cassette (70 x 50 x 10 mm), and maximum playing time would be 3 hours. Sixteen-bit quantizing would be used at 32, 44.1 or 48 kHz, with Reed-Solomon error correction. The drum diameter would be 30 mm, with a wrap of 90° and 12 micron track pitch; head life is estimated to be 5,000 hours.
With both the rotaryand stationary head systems, the wide bandwidth would permit storage of still pictures. Just as the LP is giving ground to the Compact Disc, the days of the analog cassette are numbered... While disc and tape systems will remain popular for years to come, the third millennium will see both the proliferation of new media and the enhancement of existing systems. New developments in television and video, cable, and satellite systems are afoot. The videotape recorder will be supplanted by a digital VTR with digital audio tracks, of course. Digital television receivers have been developed; non-interleaving scanning will double the number of lines to give a higher resolution picture; large, internal memories could be used for still-picture projection, and multiple pictures on one CRT-up to nine simultaneous channels-are already possible. In the future, CATV systems will be used to distribute digital audio and data transmission. The Sony CADA (CAble Digital Audio) system uses one CATV channel to transmit a variety of program services, including one channel of CD-format audio, 32 channels of monaural low-fidelity audio, facsimile data, computer software, and videotext. DBS (Direct Broadcast Satellite) systems will give households access to transmissions from geostationary satellites. The Japanese broadcasting network, NHK, has a satellite which has begun transmission, the BS-IIa at 110° east. Sony is marketing a 50-cm parabolic antenna to catch the 12 gigahertz microwave signal and a PLL FM tuner to demodulate the signal into video and audio components. For more remote areas, 75-cm and 1.2-m dishes are available. The tuner uses demodulation circuits similar to those used in Sony's CD-701 CD player. Two audio modes are available from the satellite system: The A mode offers 4 channels of 10or 14-bit sampling at 32 kHz, and the B mode has 2 channels sampling at 48 kHz with 16-bit quantizing. In addition to NTSC television broadcasts, high-definition television could be transmitted on existing channels with data compression and compensation. The parabolic dish may be easily installed by the consumer and aligned with a simple diagnostic display on the television screen. The price of the antenna and tuner (in Japan) is about $1,150, putting the price of an earth station within many consumers' reach.
Thus, unparalleled technology is rapidly becoming available to the con sumer. Digital disc and tape systems (both playback-only and recordable), digital video recorders and televisions, new cable services, and Direct Broadcast Satellite systems are all entering the consumer marketplace. Our access to entertainment and information will be multiplying year after year. Though my visit to Sony underscored that corporation's commitment to new product development, companies worldwide are similarly looking ahead. The 21st century is still a few years away, but after a tour of Sony's research labs, I can state that I have seen the future. And it is now.
Also see:
Philips Oversampling System for Compact Disc Decoding (April 1984)
(adapted from Audio magazine, Aug. 1984; KEN POHLMANN )
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