page 5 of 6
Inventing the Internet Again

As ADC technology continues to advance, however, it will relieve pressure on the mixer, opening the way to still cheaper and lower power solutions. With the expiration of Steinbrecher’s patent on the paramixer, the business is opening up. Watkins-Johnson has created a tiny mixer device in gallium arsenide the size of your smallest fingernail. So has Mini-Circuits of Brooklyn, New York. “It has 50% less performance than Steinbrecher’s, but it costs only 10% as much. Many customers say, ‘It’s a deal,’“ observes former Steinbrecher CEO and president R. Douglas Shute, now contemplating a startup.

AD converters are now edging toward microwave frequencies. Both Analog Devices and Comlinear, a National Semiconductor company, have introduced 40-megasample-per- second products at a resolution of 12 bits. This allows more of the mixing to move into digital multipliers. The first of the digital downconvertor chips came from Harris Corporation of Melbourne, Florida. Harris now has parlayed its expertise in RF and mixers into the creation of a sophisticated programmable machine that demonstrates the management of multiple modulation schemes in one cellular radio. Introduced on the floor of the Fifth Annual Wireless Symposium Exhibition in late February in Santa Clara, California, the Harris smart radio showcases its programmable HSP50214 digital downconvertor chip and is run from a PC. With an array of displays, the machine is designed to allow configuration and testing of smart transceivers from a Windows PC.

With high-powered digital signal processors and leading- edge ADCs, Analog Devices is a paragon of the digital radio paradigm. At the CTIA (Cellular Telecommunications Industry Association) meeting in San Francisco during the first week of March, Analog introduced a wideband smart radio tuned to the cellular band but applicable through the PCS band as well. A reference design to be used by infrastructure manufacturers, it displays an array of new chips from Analog comprising a specialized ADC called the 6600, tunable filters called the 6620 and the 6640 that function as a digital tuner, a SHARC DSP chip that performs the modem and channel-coding role (any advanced DSP will do), and a “sinfully cheap” Watkins-Johnson mixer chip the size of your fingernail. Incorporating an automatic gain control and a received signal strength indicator, the ADC is customized for smart radio applications.

The antenna is from Radio Shack (most any will do). From a Windows PC using Visual Basic, Analog engineers can move from one cellular channel to another and from GSM to CDMA to DECT 1900 to IS-136 to the Japanese Personal Handyphone system (PHS). As manufacturers around the globe converge on a single intermediate frequency of 70 megahertz, the reference radio could adapt to any cellular band, from 850 megahertz on up. All you would have to do is change or retune the mixer. According to Tom Gratzek, Analog Devices’s director of base station marketing at the Analog communications center in Greensboro, North Carolina, customers say, “Shazaam!”

The Rush to Cash In... Who Wins, Who Loses
Interest is acute at all major telecom equipment manufacturers, from Ericsson to Motorola, and champions include every telecom company that thinks it may have guessed wrong in the GSM, TDMA, CDMA wars. BellSouth, for example, is slipping into a GSM ghetto, but it dreams of deploying smart radios that can play any popular standard and allow it to filch (i.e., service) CDMA customers. Also a TDMA orphan, AT&T could buy cheap, all-purpose base stations that allow it to sell any favored brand of service. Ericsson is using the technology to create indoor GSM base stations that can fit in a closet, and if worst comes to worst (as it will), Ericsson will also offer CDMA, perhaps initially as an overlay for data.

By drastically enhancing efficiency in the use of spectrum, broadband digital radios will lend new force to the industry’s move up the frequency ladder toward bandwidth abundance. They enable the seamless convergence of the cellular band not only with the PCS band but also with an array of other applications such as the low-powered ISM (industrial, scientific, and medical) bands at 900 megahertz used by Baran’s Metricom startup, the 24-gigahertz band of Associated Communications, the 28-gigahertz band of Local Multipoint Distribution Service (LMDS) used by CellularVision for wireless cable, and the 38-gigahertz band of WinStar. This up-spectrum bias assures the continued success of companies pressing the frontiers of microwave integrated circuits, low-noise amplifiers, power amplifiers, and other devices that function in the gigahertz.

Going over the cliff of costs, the industry can introduce radically new products. We have just undergone the epoch of the personal computer, climaxing in 1996 with PCs outselling TVs in units for the first time. We are now entering a new era when a new form of PC will be dominant. It may not do Windows, but it will do doors. Tetherlessly transcending most of the limitations of the current PC era, the most common PC will be a digital cellular phone.

It will be a dataphone, as faithful readers of these pages will know. It will be as portable as your watch and as personal as your wallet. It will recognize speech and convert it to text. It will plug into a slot in your car and help you navigate streets. It will consult electronic yellow pages and give directions to the nearest gas station, restaurant, police headquarters, or hotel. It will collect your news and your mail and, if you wish, it will read them to you. It will conduct transactions and load credit into a credit chip on a smart card, which can be used like cash. It can pay your taxes, or help you avoid them, or soothe you with soft music as you do your calculus homework. It will take digital pictures and project them onto a wall or screen, or dispatch them to any other dataphone or computer. It will have an Internet address and a Java run-time engine that allows it to execute any applet or program written in that increasingly universal language. Or it will dock in a more powerful machine to perform more demanding functions. It will link to any compatible display, monitor, keyboard, storage device, or other peripheral through infrared pulses or radio frequencies.

And, oh yes, it will unlock your front door or car door, open your garage door, or even play Jim Morrison songs, if you are old enough to care for those swinging Doors of the 1960s (amazingly enough, my teenage daughters do).

[ back to top ] [ page | 1 | 2 | 3 | 4 | 5 | 6 ]