Part 1

4 Dec

          This is a memoir of my experiences at Bell Telephone Laboratories (aka Bell Laboratories or Bell Labs) during my 40 years there (37 as Member of Technical Staff, and three as Research Consultant.

         The basic research at Bell Labs was considered worthwhile for its scientific value — even if it had no immediate benefit to AT&T, its regional phone companies, or its manufacturing arm, Western Electric. The entire annual budget of Bell Labs was such a miniscule percentage of the Bell System revenue that just the public relations value to AT&T of this world-famous industrial research laboratory made good sense. Of course, many of the results did have a huge impact on telecommunion industry, but it was just the ‘Icing on the cake’ in the overall benefit of Bell Labs to AT&T.  In the research centers of Bell Labs, the policy was to hire the best people they could find in physics, chemistry, materials science, communication science, cognitive psychology, engineering, and mathematics and then let them pursue their particular field of interest. Such a favorable environment for basic research was rare indeed!

         I was fortunate to participate in a large variety of interesting projects at Bell Labs. This was not the case for many researchers there, particularly some I knew in research at Murray Hill, who had spent their entire Bell Labs careers in one particular area of expertise, and many became world-renowned in their specialties. One Vice President of Research told his technical staff, “I don’t care which field of research you work in, as long as you own the field!”  The atmosphere and excitement of the place was inspiring — researchers generally felt free to share ideas without fear that they would be claimed by others. In general, there was a great freedom of flow of information. A common wisdom was that you could get the answer, or at least the latest information, on any scientific question in only two phone calls within Bell Labs, and in my experience of making many such calls, it was true. The exception to this was in the military research and development work that Bell Labs was doing during World War II and the Cold War period afterward. In this work, the flow of information was restricted to those having the proper security clearance. All the military research projects I worked on have now been disclosed in the public domain, so I can openly talk about them.

         When I have felt the need for further comments, digressions, or explanations, I have attached them as notes at the end, rather than break up the narrative. Superscript numbers indicate references attached at the end. A short history and descriptions of the major innovations created at Bell Labs are also included in Appendix A. An account of my four-week visit to the Soviet Union in 1965 as part of a US delegation on a scientific exchange visit is attached as Appendix B.

 

 

Chapter 1: My Aerospace years: 1960-1966

         On July 1, 1960, I left my position as Assistant Professor at Columbia University to become a Member of Technical Staff (MTS) at Bell Laboratories. I started work in the Military Research Division at Whippany, NJ. My research specialties at Columbia were acoustics and control theory–a combination of physics and applied mathematics, analyzing the behavior of feedback systems that enables them to become ‘self-regulating’, i.e., able to keep a prescribed course and speed, as in an airplane auto-pilot, or simply maintain a desired condition, as in a home heating thermostat. Many of the pioneers in control theory (or feedback control systems, as it was originally called) did their research at Bell Labs. The negative-feedback amplifier, conceived in 1927 by Harold S. Black, provided reduced distortion in communication signals, and advanced the development of long-distance telephony. The amplifiers located in tandom along the long-distance lines each added successively more distortion to the original voice signals, and they eventually became unintelligible. Black’s amplifier sacrificed some amplification for greatly reduced distortion, so the distances possible for intelligible communication were greatly increased.

         Other Bell Labs researchers, notably Harry Nyquist and Hendrik Bode, developed the mathematical tools for insuring the stable behavior of feedback systems. Black’s amplifier had the problem of having unstable oscillations as its amplification was increased. Using Nyquist’s stability criterion, he was able to optimize design of his negative-feedback amplifier for maximally stable amplification. This research in feedback control also led to improvements at Bell Labs and Western Electric in radio receivers and recording sound systems.

         I was familiar with this pioneering work at Bell Labs because my college courses in feedback control theory used the Nyquist diagram in complex-variable space, and the Bode plots in amplitude/log-frequency space, to aid in the design of system parameters to ensure rapid, yet stable, control system response. Nyquist had retired before I arrived at Bell Labs, but at Whippany I sometimes sat in research seminars with Hendrik Bode, who was then the Vice-President of the Military Research Division. I often observed him at the end of the work day leaving with two bulging, battered briefcases, one in each hand. I later learned that one briefcase contained the administrative stuff  he had to do, and the other contained the technical stuff  he wanted to do. This was typical of the Bell Labs management — they were promoted because of their scientific and technical achievements, not their management skills. So they were always more interested in the technical merits of someone’s work than in its potential commercial value. While this method of selecting managers was generally beneficial to our research work, I did experience a couple of cases where better management skills would have been preferable.

         During my first six months, I was allowed to concentrate on writing two papers on my thesis work at Columbia, which was on the optimal design of sampled-data control systems through pulse-width modulation of the control signal6,7. I presented a talk on the first paper at the Joint Automatic Control Conference at MIT in September, 1960. At the same conference a paper was presented by Rudolf Kalman, a fellow graduate student of mine at Columbia, who by then was on the faculty of Johns Hopkins University in Baltimore. He and Richard Bucy had developed a recursive scheme for the optimal estimation of a physical system’s state (such as its position and velocity) by statistically combining a prediction from a mathematical model of the system, with successive measurements on the system. This method not only gave the maximum-likelihood estimate of the system state, but also the error covariance of that estimate, which allowed a confidence region to be established around each estimate. This technique had a profound influence on estimation and control methods, and it became known as the Kalman filter (why Bucy’s name was left off, I don’t know). I mention it here because it played a big role in much of the work I did later.

         During the winter of 1961-62, I was involved in Bell Labs Telstar project, which was the world’s first active communication satellite. There was concern that after the Telstar satellite was launched from Cape Canaveral, the large, narrow-beam, high-gain antenna [Note 1-1], located on the coast of  Brittany in France, might not be able to lock onto the satellite signal, because the small, wide-angle guidance antenna might not have sufficient gain (i.e. sensitivity) to pick up the satellite beacon signal.  If the small antenna didn’t detect the satellite beacon signal as it came over the horizon, it would not be able to direct the large, narrow-beam antenna to lock-on to the

satellite signal and establish two-way communication. (This is like being unable to find a small  bird with high-power binoculars until your eyes can spot the bird and aim the binoculars in the right direction.) Since the small antenna’s receiver used an FM with feedback circuit, I was asked to analyze the receiver and advise the project manager whether it could capture the beacon signal. I was able to show how to optimize the control parameters of the receiver so it would have enough gain to pick up the satellite signal as soon as it appeared over the horizon at the French tracking station8. When the launch date came, the small antenna’s receiver did detect the beacon signal from the Telstar satellite. It successfully aimed the big antenna to pick up the satellite and transmit to it the world’s first live trans-Atlantic television broadcast signal, and there was great relief and jubilation at the French station and at Bell Labs [Note 1-2].

         After that, I was promoted to supervisor of the control systems research group in the Military Research Division. My group eventually consisted of five PhDs and several technical assistants. We worked on the design of control systems for guided missiles, satellites, and anti-ballistic missile systems. As this work was classified secret by the government, most of it could not be published, but we still managed to do some publishable control theory research2-6. In one of the projects, Ron Sherman and I were able to apply the Kalman filter to the optimal tracking of radar targets, using a ballistic model of the target’s motion, and the range and bearing measurements from three ground radar sites2. Using the estimated statistical errors on the range and bearing data, the three-dimensional confidence region on the maximum-likelihood estimate is an ellipsoid, as indicated (not to scale) in the diagram below.

 

 

         During this period, I was active in the American Automatic Control Council, serving on several committees, and helping in reviewing papers submitted to their conferences. In the summer of 1965, I was invited to be part of a delegation of American and European scientists invited for a scientific exchange visit with control-scientists in the Soviet Union and their Eastern European bloc (Appendix B). There was supposed to be a second exchange visit in the US the following year but, probably due to cold-war tensions, it didn’t happen. Professor Alexander Letov, who was our USSR Academy of Sciences host during our Russian visit, did manage to get permission to visit some institutes and universities in the US. I met him when he arrived at Newark airport, and brought him home for dinner with my family. He seemed to enjoy it greatly, and favored us with a rendition of “Autumn Leaves” with my daughter Kristin accompaning on the guitar. The next day I took him to Bell Labs at Murray Hill, where we had prepared a tour of our research facilities.

 

 

 

 

CHAPTER 1 NOTES

 

1-1. A similar large high-gain antenna was first built at Bell Labs in Holmdel, NJ. Because of its narrow field of view and high gain which was very efficient in capturing very weak radio signals, it was used by Arno Penzias and Robert Wilson to investigate the background radio interference that appeared to be coming from all directions in space. After eliminating all other possible sources, they along with colleagues at Princeton University, finally concluded the mysterious noise was the leftover radiation from the “Big Bang” at the creation of the universe. This research led to Nobel prizes in 1978 for Penzias and Wilson. (I think the colleagues at Princeton University should have also been included) 

 

1-2. The TELSTAR satellite was launched by NASA aboard a Delta rocket from Cape Canaveral on July 10, 1962, It was the first privately sponsored space launch into a low-orbit, which required receiving stations in Andover, Maine, Pleumeur-Bodou, France, and other locations in Asia and Austrailia to maintain continuous contact with the satellite. The 23,000 mile stationary orbits now used by all communication satellites were ruled out by Bell Labs scientists, notably John Pierce, because they felt that the few seconds of time delay, due to the long distance path, would be unacceptable for normal telephone conversations. They didn’t foresee the future of television and data transmissions, for which the slight delay would be insignifigent. In spite of this short-sightedness, the TELSTAR project did demonstrate the feasibility of communication satellites.

 

 

REFERENCES

1. Bell Laboratories: Innovation in Telecommunications, 1925-1977 (7 vols.)

     Bell Telephone Laboratories, Inc., 1979

2. A History of Engineering and Science in the Bell System, Bell Telephone Laboratories, Inc., 1975

3. Mabon, Prescott C, Mission Communications:The Story of Bell Labs, Bell Telephone Laboratories, Inc., 1975

4. Gregor, Arthur, Bell Labs:Inside the World’s Largest Communications Center, Scribner, 1972

5. Gahani, Narain. Bell Labs: Life in the Crown Jewel of AT&T, Silicon Press

6. Nelson, W.L.,“Pulse-width relay control in sampling systems”,Jour.of Basic Eng’g,Trans.ASME,Series D,

    83,  65-76 (1961).

7. Nelson, W.L., “Optimal control methods for on-off sampling systems”,Jour.of Basic Eng’g,Trans.ASME,Series

    D 84, 91-100 (1962).

8. Nelson, W.L., “Phase-lock loop design for coherent angle-error detection in the “Telstar” satellite tracking

     system”, Bell System Tech. Journal, 42, 1941-1976 (1963).

 

 

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