NTT Develops Wristwatch PHS

No, that guy on the corner isn't necessarily holding a conversation with his wristwatch. From NTT comes a lightweight, compact, voice-activated PHS unit that you can strap to your wrist. by Noriko Takezaki The US may have taken an early lead in the development of "wearable computers," acknowledges NTT (Nippon Telegraph and Telephone Corp.), but that is not the case when it comes to wearable communications tools. To prove it, NTT has announced a wristwatch-type PHS (personal handyphone system) unit featuring a voice-recognition dialing function so that the user can place a hands-free call. "The Japanese are good at producing very compact and sophisticated tools," says Tetsuma Sakurai, senior research engineer at NTT's Speech and Acoustics Laboratory. "So there is high potential that Japan can lead the world in the field of wearable communications devices." A "wristwatch" PHS unit NTT's compact "wristwatch" PHS unit (also available with a necklace pendant case) contains an embedded LSI chip and miniature lithium-ion battery; it weighs just 45 grams. The user can activate the unit's hands-free voice-dial function by preregistering the phone number to be dialed with his or her own voice into the PHS memory. The unit's dialing function is then activated by announcing either the number to be dialed or its associated registered name, such as "uchi" (my home) for the user's home phone number, into the PHS microphone. According to NTT, the unit's voice recognition function can handle any language, so long as the voice-dial registration was done in that language. The PHS also supports pushbutton input of abbreviated (quick dial) numbers. NTT's Sakurai says that the key to the unit's success lies in its LSI chip, which enables high voice recognition performance and suppression of howling (noise picked up by the microphone from the unit's speaker), as well as low power consumption and low cost. "The voice recognition precision of this PHS unit is quite high," he claims; "more than 95% precision in a quiet indoor setting, and 70% to 80% even in a noisy outdoor environment." The LSI consists of an MT-CMOS (Multi-Threshold Complementary Metal-Oxide Semiconductor) device and incorporates two transistors with high and low threshold values. The transistor with the higher threshold functions as a barrier against current leakage during circuit idling, while that with the lower threshold is used during normal operation. This helps reduce the device's power consumption and enables the unit to support calls of up to 60 minutes duration or to function for 100 hours in standby (call-available) mode. With the cooperation of a semiconductor manufacturer (Sakurai would not disclose the name, saying only that NTT had evaluated both foreign and Japanese RISC chip manufacturers), NTT spent one year designing and developing the requisite LSI. Sakurai recalls that the critical point in selecting a chip manufacturer was not the performance of the chips themselves, but the availability of an evaluation toolkit (including simulator, emulator, in-circuit emulator, and target board) to assess the application development work at NTT. Even though some companies offered chips with excellent performance, few offered an adequate evaluation tool kit, notes Sakurai. "This is something that semiconductor manufacturers should seriously consider [to extend their market share]," he says. An Olympic field test NTT has a long history in voice recognition R&D, dating from the early 1980s. NTT researchers were confident, therefore, of their level of technology; they were not so sure, though, about the commercial application of this technology to a wearable PHS unit. The basic question was whether people would be willing to speak into a wristwatch PHS in public. For those too shy to speak loudly into the wrist unit, NTT developed a compact earphone-type microphone/receiver. The optional earphone unit features separate microphones for better voice transmission -- one that picks up the user's voice normally through airborne sounds, and one that picks up voice via conduction by the speaker's facial bones. During the product's field trials, carried out at the Nagano Olympic Games site in February, NTT was pleased to find that the number of people willing to use the wristwatch PHS unit far exceeded its expectations. Moreover, few of the field trial users bothered to employ the optional microphone/receiver unit. Sounding out the future NTT is the first to apply voice-recognition technology to a wearable PHS unit. It is too early to say, though, whether PHS will be a key player in the wearable communication device market of the future. That shouldn't pose a problem, since the technology can be easily applied to cellular phone systems as well. The main reason that NTT selected PHS to showcase its voice recognition technology at this time was in part to widely promote PHS, including at the Nagano Olympic site where the field trials were conducted. NTT is eager to improve the image of PHS, which has often been criticized for poor performance and connectivity, and thus help its money-losing PHS affiliates. NTT says that its target for commercialization of a voice-activated PHS unit is two years. For successful market release, however, the product still requires some improvements, such as cost reduction to the level of standard PHS units (in the ´20,000 range) and an improved terminal design that offers easy operation (current button operation remains slightly complicated). NTT's voice-recognition technology is first rate, but high quality Technology alone doesn't sell products. Ultimately, the most important factor for successful sales of NTT's wristwatch PHS will be the short-and long-term success of Japan's PHS market.. Back to the table of contents