Nov 17, 2013

Nike Air Bedingfield

North of San Francisco with a great vantage point on the Pacific Ocean is the only Nike missile site that has been converted to a museum. It is within sight of Russian Hill in the city, not too far from the Russian River and an hour or so away from the southernmost point of Russian occupation long before California was claimed for Spain. For those who didn’t live through the Cold War, it’s hard to imagine that we needed missiles pointed toward the western sky to shoot down incoming Russian bombers.

To me, Nike means running shoes, basketball shoes, celebrity endorsements and Steve Prefontaine at the University of Oregon (and waffle irons – another story). To the U.S. Army, it was a network of installations to protect against the very real threat of 500mph Soviet jets flying at 60,000 feet with nuclear payloads. The inspiration for the names of those two, Nike, refers to the mythological Greek goddess of victory.

I’m well aware of analog computers using vacuum tube to calculate trajectories to shoot down planes in World War II. Twenty years later, that was no longer sufficient. Three radar systems were needed: one to look for enemy targets, one to track the target, and one to track the missile once the others were locked. In 1958, the U.S. Army began the development of the Nike missile system, with Bell Laboratories responsible for much of the early hardware design through Western Electric.

In the Continental United States the sites were numbered from 01 to 99 starting at the north and increasing clockwise. Nike Site SF-88L refers to the launcher area (L) of the battery located in the northwestern part (88) of the San Francisco Defense Area (SF). You and your Nike shoes can wander all over the site, now a museum. Each site had three parts: C for control, L for launcher, and A for administration. Part C, which no longer exists at SF-88 as far as I can tell, had the radar system which was a digitally-controlled phased array radar system for guiding the short and long-range interceptor missiles. I like phase array radar because it uses lots of Analog-to-Digital Converters (ADCs)!

Initially, the logic was resistor-transistor-logic (RTL) in hybrid packages. At the time, ADCs in general were rare and “high-speed” types were virtually non-existent – except to the deep pockets of the U.S. military. Early prototypes for the 8-bit 10MSPS ADC were developed at Bell Labs in North Carolina between 1963 and 1965. In 1966, two pioneers in high speed data conversion, John M. Eubanks and Robert C. Bedingfield, left Bell Labs and founded Computer Labs, Inc. The initial product was a commercial version of this ADC.

I am still researching these two, as well as the history of Bell Labs in North Carolina. Google Patents lists some key contributions in the area of high-speed data conversion:

  • John Eubanks patents a multi-waveform generator, at Bell Labs in Greensboro, NC, US patent # 3,274,396, filed May 16, 1962.
  • John Eubanks patents the peak detector at Bell Labs, US patent # 3328705, July 6, 1964 and a pulse amplifier also at Bell Labs, US patent # 3,439,286, July 29, 1965.
  • Robert Bedingfield patents a sample and hold circuit using an operational amplifier and a high impedance buffer connected by a switched diode capacitor circuit at Bell Labs (Greensboro, NC), US patent # 3,363,113, Aug. 2, 1965.

The first commercial ADC using folding Gray code architecture (Waldhaur's patent from Bell Labs) was the 8-bit, 10MSPS HS-810 from Computer Labs, Inc., in 1966, according to Walt Kester who worked there. Bell Labs researcher Frank Gray introduced the term reflected binary code in his 1947 patent application, now known as Gray Code. (Clever naming: HS-810, for a high-speed 8-bit, 10Msps converter.)
 The HS-810 used all discrete transistor circuits and was offered in a 19" rack-mount box for digital radar receiver applications. It contained its own linear power supply, dissipated nearly 150 watts, and sold for approximately $10,000. The next generation of Computer Labs' designs would take advantage of modular op amps (Philbrick, Analog Devices, et al), Widlar’s μA710/711 comparators (Fairchild) – they must have been so thankful for ICs – and 7400 TTL logic.

In 1978, Analog Devices acquired Computer Labs and continued developing board-level data converter products and hybrid ICs as the Computer Labs Division in Greensboro, NC, and eventually high-speed ADC ICs. And in outright gratuitous name-dropping, I will add that Nike’s biggest celebrity, Michael Jordon and his size 13 footsteps, led the University of North Carolina to a national championship in NCAA basketball in 1984. For which we have a near endless variety of Nike Air shoes. And we aren’t really worried about Russian bombers attacking San Francisco.


“ANALOG-DIGITAL CONVERSION”, "MT-024" and "MT-025", Analog Devices, tremendous gratitude for the contributions of Walt Kester.


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