Pioneering in Electronics
Chapter Four - Other Eggs in Other Baskets
One morning in the summer of 1934, a small group of U.S. Army Signal Corps engineers gathered at Atlantic Highlands, a promontory at the southern end of New York’s lower bay, to watch an experiment by Irving Wolff and Ernest Linder, of RCA’s Camden research staff. The two scientists had brought with them an odd-looking collection of apparatus—a transmitter, a small receiver, an audio amplifier, and two four-foot dish-shaped antennas.
As the engineers watched and listened, the RCA scientists directed the antennas toward a small boat passing half a mile or so away up the channel toward New York. An audible tone emerged from the amplifier as the boat went by. The antennas were turned to follow the vessel, and, once more the tone was heard, continuing steadily until the boat moved out of range.
The name of the boat was not recorded, but perhaps it should have been. For, in the words of the official Signal Corps history, “this may well have been the first successful use in the United States of microwave radar, or of what eventually became microwave radar."
The RCA radar work, initiated in 1932, grew out of Wolff’s interest in techniques employing wavelengths short enough to be (p. 83) focused in a narrow beam. It was one outstanding example of the many and varied contributions of RCA research through the 1930s. While substantial effort went into the achievement of an effective television system, there was ample time and talent available for a multitude of other fruitful projects whose total effect was a radical advancement of the electronic art as a whole.
Any attempt to lay out these varied accomplishments in order of importance would be doomed at the start. Such judgments always must be a matter of opinion, and in the case of scientific research they are likely to be premature. Experience shows, after all, that results from the laboratory may vary in value over the years, affected by changing needs and related discoveries.
Viewed from the standpoint of breadth alone, however, the results of RCA contributions to electron tube development deserve first attention. Strictly speaking, several important ones occurred even before the corporation had a tube research program of its own. Prior to 1930, tube research was carried out on behalf of RCA in the laboratories of General Electric and Westinghouse. This work was continued within RCA following the corporate changes of 1930–32.
Outstanding among the pre-1930 accomplishments in this category were the series of screen-grid tube developments by B. J. Thompson, E. W. Ritter, J. C. Warner, Nergaard and others, whose work at General Electric had supported the rapid growth of commercial radio during the 1920’s. Further important work was done by G. R. Shaw and E. A. Lederer in the development of tubes with indirectly heated cathodes (p. 84) for alternating current operation. This advance led to radical simplification in radio receivers by eliminating the need for storage batteries and associated equipment.
The gathering together of the various research talents permitted greater concentration on main objectives. In the early 1930s, few goals were more important than the development of tubes capable of functioning at ever higher frequencies, for application in point-to-point communication and in television. Television, as we have seen, required high-frequency transmission in order to function at all. In point-to-point communication, a shift into the higher frequencies was necessary largely in order to expand the space available for radio service, already crowding the lower part of the frequency spectrum with commercial broadcasting and international communications.
In recognition of this need, a primary aim of the new RCA research program was to extend the frequency range of electron tubes, the building blocks of all electronic circuits at the time. The burden fell initially upon the Electrical Research group at Radiotron in Harrison. As the decade progressed, further contributions would come from the staff at Camden, notably in the specialized fields of microwave communication and multiplier phototubes.
Up to the start of this effort, operation at frequencies higher than 20 megacycles (20 million cycles per second) had been achieved on a limited scale by modifying existing apparatus. To set the figure in modern perspective, 20 megacycles falls somewhat short of the very-high-frequency (VHF) range employed today by standard television service. For reference, it is helpful to bear the following categories in mind: (p. 85)
Today, these three frequency ranges accommodate all television and FM broadcasting services, all microwave communication systems and all standard radar systems. In addition, progress is being made in the exploration of yet higher frequencies, employing millimeter waves, for certain specialized functions related principally to radar. As a measure of progress in electronic science, it is remarkable that virtually no apparatus existed as recently as 25 years ago for operating in these extensive and useful portions of the radio spectrum.
The clear need for equipment and techniques for higher frequency operation had prompted research in many laboratories during the preceding decade, but there had been little result in the form of practical apparatus. Browder J. Thompson and George M. Rose, Jr., a colleague on the Radiotron research staff, looked over the previous work in this field and pointed out in 1933 that an apparent wall had been reached at wavelengths of 3 to 5 meters (about midway in today’s VHF range) as far as existing techniques were concerned, They referred to various studies of high frequency oscillation phenomena and noted that all attempts to make use of these phenomena (p. 86) had resulted in impractically complex techniques. The conclusion of their findings was that an effort should be made to reduce the lower wavelength limit of conventional tube types and circuits in order to retain their advantages of simplicity at wavelengths below 1 meter.
There is a direct relationship between wavelength, on the one hand, and the size of the tube and the spacing of its elements, on the other. To Thompson and Rose, it appeared that the chief limitations of conventional tubes lay in the fact that the size of the tube became too large in comparison to the wavelength at which it operated. This led them to an approach that was generally regarded at the time as impossible—a three-fold reduction in all dimensions of the tube to permit something like a three-fold increase in operating efficiency.
This sounds far simpler than it really is, The question is far more than one of merely scaling down the size of the tube and its components, because the performance characteristics of the tube are grossly affected by the spacing of the internal elements. Thompson and Rose reasoned, however, that the job might be done if all linear dimensions in the tube and circuit were designed in proportion to the particular wavelength desired.
During 1933, the two scientists had achieved one of those rare developments that can be legitimately described as a breakthrough—a new tube of the conventional grid type, oscillating at frequencies never before attained by conventional types. Formed of two glass hemispheres placed together with the elements mounted within, the tiny experimental tubes resembled acorns, leading to their designation as "acorn" tubes. The initial types demonstrated in 1933 (p. 87) measured only 3/4-inch in their largest dimension and operated at wavelengths down to 30 centimeters, well within today’s UHF range. Not only were the new tubes far smaller than any previous types, but their design entailed elimination of the base in order to achieve the desired performance, with the incidental result of further economy in weight and space. In this respect, the acorn tube was an outstanding achievement in miniaturization, some years before miniaturization became an important concern in electronics.
Commercial production of such tubes at first presented major problems. These were overcome by intensive and ingenious engineering development, and by 1935 acorn tubes were standard items of international renown for the ultimate in performance at very-high and ultra-high frequencies. Operating up to about 500 megacycles, the tube initiated an era of receiving tube development leading to continuing further advance in shorter wavelength operations. The work of Thompson and Rose laid the foundation for all subsequent high-frequency tubes of miniature size, an area in which RCA research made further pioneering contributions continuing through World War II.
A development of equal importance in its own area was the pentagrid converter tube developed by D. G. Haines and J. C. Smith, with later contributions by E. W. Herold, W. A. Harris, and T. J. Henry, members of the Harrison group. Until the advent of the pentagrid converter in 1933, the superheterodyne radios used in the home tended to suffer from the hazards of interaction between the incoming signal and the local-oscillator frequency to an extent (p. 88) that interfered with neighboring receivers. The pentagrid converter overcame these defects to become the standard converter in all American equipment, establishing the principles used today in radio converter tubes.
The full scope of successful tube development by the groups under Thompson at Harrison and Zworykin at Camden, ranging far beyond the bounds of a brief historical account intended to cover all RCA research, resulted in a variety of fundamental advances in tube function and design relating to all types of electronic equipment. Among these might be mentioned the introduction of metal tubes of increased ruggedness and economy, the development of new miniature receiving tubes for many types of radio equipment, the pioneering work of P. T. Smith and Garner and others in the field of beam power tubes, and the phototube contributions of John Ruedy and his associates.
One further original tube contribution during this fertile period is of special interest as a departure from the general pattern of transmitting and receiving tube development. The point of origin in this case was Zworykin’s Electronic Research group at Camden. The motive was the desire for a low-noise or noise-free amplifier, primarily for boosting to useful levels the output of the Iconoscope in the television pickup system.
Noise is a perennial and annoying problem in electronic systems. In this sense, the word refers not simply to audible phenomena, but to all forms of interference that result from the operating characteristics of a tube or circuit. This type of noise is (p. 89) evidence of the effort being made by the tube or circuit to do its job. It is objectionable when it becomes great enough to have an appreciable effect on the output signal, whether the signal happens to be a television picture, a radar pulse, or the sound of a radio. This accounts for the constant preoccupation of the electronic specialist with “signal-to-noise ratio,” and his continued effort to find ways of increasing the signal relative to the interfering noise.
Seeking its low-noise amplifier, the Camden group turned to the phenomenon of secondary emission. This is the same effect that had created difficulties in the Iconoscope, as we have seen. In that case, as in a number of others, efforts had been made to suppress secondary emission as an undesirable form of interference. On the other hand, scientists had recognized as early as 1920 that secondary emission might be put to use in amplifying small initial electron currents, and some experimental work had been done along these lines in various laboratories.
Early in 1933, the problem was tackled by George Morton, Jan A. Rajchman and Malter. They investigated scores of materials that emitted secondary electrons upon exposure to bombardment by electrons from a primary source. Their next step was to apply electron optical principles to achieve new and effective multiplier tubes in which electrons initially entering in small quantities were focused upon successive emitting surfaces to produce major amplification of signals. The highly significant result, demonstrated to the Institute of Radio Engineers in October, 1935, by Zworykin, (p. 90) Morton, and Malter, was the secondary emission multiplier phototube, in which small amounts of light released an initial supply of electrons for amplification to useful levels.
Opening the way to new electronic techniques, the multiplier phototube lent itself ideally to use in systems concerned with high quality optical signals, such as motion picture sound recording and facsimile. It became familiar as well in the “electric eye” mechanism for performing such tasks as opening doors automatically. Further development by Rajchman and R. L. Snyder led to even more efficient types which achieved signal amplifications of two million or more times, leading to highly sensitive tubes which found postwar application in such functions as automatic dimming of automobile headlights. Carried forward in the postwar era, principally by Morton and Ruedy, the principles led to development of incredibly sensitive high-speed multiplier phototubes to function for scintillation counters in nuclear research.
There is one ironic touch. Large quantities of multiplier phototubes were produced during the war at the Lancaster, Pennsylvania, plant of the RCA Tube Division for military purposes that were not disclosed publicly at the time. Zworykin, proud of the low-noise characteristics of the tube and legitimately interested in all possible applications, inquired what the purpose might be. He was dismayed to learn that the Lancaster output was being used for amplifying random noise as a countermeasure against enemy radar. (p. 91)
An important share of RCA tube research during the 1930s produced benefits in the form of basic knowledge rather than immediately applicable devices. It was recognized from the start that maximum value could be gained from invention and engineering development only with some understanding of the physical phenomena that were involved. This type of understanding can be achieved only through basic studies and the formulation of theories that can explain observed events and pave the way for further invention.
A part of the Harrison program therefore went into a concentrated effort to understand what happens inside the electron tube. One monumental result was a series of theoretical computations by Dwight O. North and W. R. Ferris relating to transit time effects in tubes. This was of basic importance in clarifying the environmental limitations affecting the movement of electrons within a tube, and it confirmed the measured results of performance in the acorn tube in particular.
Further fundamental studies by North, Thompson, and W. A. Harris led in 1938 to a comprehensive set of findings related to fluctuation noise phenomena in tubes. These studies, published as a series of five consecutive papers in the RCA Review, explored every discernible source of noise in electron tubes and provided an invaluable guide for all current and subsequent tube development. (p. 92)
Radar and Related Matters
It was at Camden that the shift toward higher frequencies was pushed to perhaps its farthest extreme in the 1930s. The agent was Wolff who, in 1932, proposed a program of research in microwave transmission, a technique employing centimeter wavelengths and involving the use of a parabolic dish type of antenna for both transmission and reception.
“I felt that this was an area holding major opportunities for RCA,” he reported later. “Up to that time, very little research had been conducted in this field outside of Germany and Japan.”
With the approval of Engstrom, head of the General Research group, Wolff launched into his studies with the help of Ernest Linder, who was recruited specifically for this work. The initial objective was an effective point-to-point communications system using 9-centimeter waves—the general standard of present microwave systems.
At this time there were no transmitters, receivers or components designed for operation at such high frequencies, and the project had to begin with their development. New types of receiving tubes and oscillators were studied, and new measuring equipment and methods were devised. In important respects this early work laid foundations for the later development of microwave communications.
To generate and transmit the extremely short-wave signals, Linder designed a special tube, an end-plate magnetron, possessing high (p. 93) stability of output at the high operating frequencies that were required. Four-foot parabolic antennas were assembled for both the transmitter and the receiver, since, at these wavelengths, the signals could be focused in a narrow beam. The receiver consisted of a crystal attached to a small loop at the focus of the parabolic dish, with an output feed to an audio amplifier producing an audible signal. (p. 93 A)
In addition to its possible communications use, the rudimentary system showed an interesting tendency to receive its own signals back from various objects by reflection. In 1934, the U.S. Army Signal Corps invited Wolff and Linder to Atlantic Highlands primarily to test the communications aspect of the system over the 17-mile stretch of water to Brooklyn, and, perhaps incidentally, to demonstrate the reflection characteristics—an aspect upon which the Signal Corps had been doing some work of its own. The outstanding result was the pioneering radar experiment described above.
Primary interest in the system thus became directed at an early stage upon its ability to indicate the location of objects. The 1934 equipment was, however, a long way from being radar as we would recognize it today. For one thing, the results came out in the form of audible sound rather than as the visual display of present-day radar. Furthermore, the early system indicated only the presence of an object in a given direction. It provided no means for determining the distance of the object.
The next objective for Wolff and Linder was a system of “radio vision” specifically for detecting objects at a distance by reflection of the centimeter waves back to the point of transmission. The matter of communication thus became secondary to the development of an effective radio detection system. The original transmitting equipment had sent out a continuous signal. Work was now started on apparatus that would generate a pulsed signal, consisting of a succession of rapid pulses each less than a microsecond in (p. 94) duration. Both Wolff and Zworykin had made independent proposals some time earlier for the use of pulsed signals in connection with aircraft altimeters. The idea was the same in both cases—to furnish a means for measuring distance. With the addition of the pulsing technique, the pioneer radar system acquired the ability to measure with some accuracy the distance of objects from which its signals were reflected.
Wolff and Linder, reinforced by Rene A. Braden and George W. Leck, were now ready to move on to a historic achievement—the first microwave scanning radar equipment capable of displaying visually the distance and angle of location of the objects that it detected. The apparatus was set up and demonstrated to RCA executives and military representatives on a roof at the Camden plant during 1937. The Philadelphia skyline, two miles away, and ships in the Delaware River were scanned by the pulsed beam. The reflected waves were picked up by the receiver and converted to a visual display on a cathode ray tube in the manner of modern radar systems.
After 1937, further RCA development of radar was swallowed up by the military services and kept from the public eye. By that time, however, the system had advanced in basic form beyond the laboratory stage. In 1938, radar equipment produced by the Naval Research Laboratory was installed aboard the battleship New York, while an additional set, built by RCA for Navy tests, went into operation on the U.S.S. Texas. In 1939, RCA received the first Navy service radar equipment order, leading to the installation of extensive shipboard systems during 1940. (p. 95)
While the question as to who “invented” radar is likely to remain buried forever beneath a mass of conflicting claims, the work at Camden during the 1932–37 period clearly made a basic contribution to the effective development of the system that was to have such a radical effect upon military and naval tactics in World War II. Testifying to this contribution, the Navy awarded to Wolff in 1949 the highest honor it can bestow upon a civilian—the Distinguished Public Service Award. With the award was this citation:
The radar work by Wolff and his associates coincided happily with an RCA program aimed at development of electronic equipment suited to the needs of the growing aviation industry. By 1937, the introduction of new economical aircraft and the increasing government interest in the establishment of air safety standards had launched commercial aviation into an era of new growth. At the same time, it was evident to both the airlines and the electronics industry that electronic techniques would be required on a growing scale in order to solve effectively the problems of air navigation and safety. (p. 96)
Against this background, the RCA organization projected a broad program of aviation radio research, with such specific objectives as the development of obstruction warning devices, new communications and direction-finding equipment, and instrument landing and position indicating systems. Among the projects developed under the program were an instrument landing system undertaken by Donald S. Bond and others in cooperation with the Sperry Gyroscope Company, and ultra-high-frequency direction-finding techniques which occupied a group under Vernon D. Landon.
In this context, the radar development looked like a logical candidate for possible application in an anti-collision system capable of detecting objects in the path of a plane. The possibility was discussed in a memorandum to [Ralph M.] Beal by Lewis M. Clement, then Vice-President in Charge of Research and Engineering at Camden. Clement noted that “it now appears that with the present flying technique, a device which would indicate with reasonable accuracy an obstruction at a distance of at least three or four miles would find a field of considerable usefulness.” The development of such a device was promptly undertaken by Wolff with an enlarged team including R. M. Smith, C. E. Hallmark, and W. D. Hershberger.
Among the odd properties of the company was a rugged and venerable tri-motor Ford plane made to order for this experimental work because, as Wolff noted, “we could carve all sorts of holes in its skin without weakening the structure.” After several months of intensive work in the laboratory, the research team equipped the Ford with an experimental 600-megacycle transmitter and antennas, and took off for flight tests over the PhiladelphiaCamden area with the first airborne radar system developed in the United States. (p. 97)
As an obstacle detector, the equipment was moderately satisfactory. It detected hills and picked up other planes at short distances. Its strongest point, however, turned out to be an ability to measure altitude above ground almost instantaneously and with extreme accuracy. While RCA’s initial intent had been the development of commercial equipment, this particular talent of the device logically awakened the interest of the military services, which were now in the throes of a major expansion in response to the outbreak of war in Europe in 1939.
Initially, it was the Navy that indulged this interest to the extent of contracting with RCA for the development of a pulse altimeter operating on radar principles. Working toward this new goal, Wolff and his associates achieved better equipment weighing some 90 pounds and having an accuracy of plus or minus 100 feet from a 20,000-foot altitude. A demonstration of the equipment at Wright Field in Dayton, Ohio, in early 1940 led to a further contract from the Signal Corps under a joint arrangement with the Navy and the Army Air Corps. According to the official Signal Corps history, the service officers at the demonstration found the RCA equipment especially attractive because “it looked the best of all they had seen thus far, even to offering a possibility of reviving the moribund double project for obstacle detection and collision prevention, because it could indicate objects in front of an airplane as well as below.” (p. 98)
Out of this research and development came a major contribution to the subsequent war effort—the RCA pulse altimeter, used as standard equipment in all Allied military planes during World War II. Further development by the RCA engineering staff and the Signal Corps brought still greater improvement, achieving equipment weighing only about 30 pounds and maintaining the same high accuracy up to 40,000 feet. The obstacle detection feature remained secondary, but a further modification was developed and widely used as a tail warning system for fighter planes, indicating the presence of other aircraft approaching from the rear where they were invisible to a fighter pilot.
The broad program of aviation electronics research also produced a fundamentally important advance of immediate and lasting value to commercial aviation. This was the omni-directional range, developed by Luck and a small group including Lowell B. Norton and J. R. Boswell.
Up to the latter 1930s, the standard type of radio range used by commercial air services to determine aircraft position provided the pilot with accurate information only if he happened to be close to one of four different courses that intersected near or over a ground radio beacon. Even at that, the pilot had no indication as to whether the beacon lay ahead of him or behind him. If he had to leave one of the fixed courses, he usually had to resort to a complex and time-consuming procedure to find it again. (p. 99)
Taking an entirely new approach to the problem, Luck and his associates worked out a VHF system that was flight-tested in 1939 in the ubiquitous Ford and an array of other craft ranging from a Goodyear blimp to an American Airlines DC-2. It worked this way:
The radio beacon station on the ground radiated a unidirectional rotating field. At the correct point of each field rotation—when the beam was in the true north position—an indicating signal was applied. The signal was reproduced in the plane on a visual indicator marked in the degrees of the compass, so that the pilot could read instantly his position with respect to the beacon.
At the start of the development, Luck and his colleagues explored the use of the 4-6 megacycle band. In response to the high-frequency requirements of the airlines, however, they had developed by late 1939 a system operating at 125 megacycles. Functioning at this frequency in the series of flight tests, it appeared capable of permitting pilots to fly practically any course by taking bearings on radio beacons set up in a pattern over the country.
After World War II, the principles of the omnidirectional range provided the basis for completing the standard radio range used in present-day commercial air service, making possible safer all-weather flying along the nation’s airways. Luck’s contribution was recognized subsequently with several awards, including the rank of Fellow in the Institute of Radio Engineers, and the Stuart Ballantine Medal of the Franklin Institute. (p. 100)
Progress in Acoustics
The listener who enjoys his high-fidelity concerts at home today owes a considerable debt to technical foundations laid by acoustical research during the 1930s. While a large part of the RCA research organization busily pursued higher-frequency techniques and devices, a substantial group of talents continued to concentrate on the bottom end of the frequency spectrum, within the range of human hearing.
The groundwork for a fruitful program of acoustical work had been laid, as we have seen, by the work of Olson, Weinberger, Wolff, and others at Van Cortlandt Park during the 1920s. These efforts had coincided with the birth of sound motion pictures and the swift expansion of broadcast radio, securing for RCA a position of leadership in sound pickup and reproduction.
Both the sound movies and radio broadcasting continued to develop with unabated vigor into the following decade, and to them was added another fertile area for acoustical development. This was the rebirth of the phonograph as a popular home instrument—an occurrence for which the RCA Victor engineering organization may claim a large share of the credit with its development of improved electrical pickup equipment and the design of attractive radio-phonograph combinations.
At the breakup of the Van Cortlandt Park organization, some of the acoustical work had migrated to the Photophone laboratories under Weinberger’s direction. While the stay at Photophone was (p. 101) brief, it was highly productive. In this interval, for example, Olson achieved the first of a long and continuing succession of improved unidirectional microphones for radio and sound motion picture pickup. Coming at a time when the velocity microphone was entering standard use in both areas, this first unidirectional type gave added versatility to sound pickup techniques and strengthened the position held by RCA in the commercially important field of acoustics.
The Photophone period also was marked by a record-breaking half-million-dollar contract awarded by the U.S. Navy for sound film equipment to be placed aboard more than 200 combat vessels and at a number of important shore installations. The development of this extensive system called for a number of innovations, such as speakers with superior response characteristics, resistant to salt spray and other seagoing hazards. RCA gained considerable business by the contract, but it almost lost Olson. During tests of the equipment, he came perilously close to breaking his neck in a fall from a 20-foot tower erected on the abandoned Van Cortlandt Park property to simulate the location of speakers aboard a battleship. For the next week, he reported, “I felt as though I’d been playing football.” But the results compensated for the experience—the equipment developed by Olson and his colleagues led to the large-scale entry of acoustical gear into the Navy’s educational and recreation program. (p. 102)
At Camden, where all of the acoustical development was centered after 1932, the emphasis was placed upon the basic problems of obtaining uniform response frequency characteristics in sound reproduction, The aim was achievement of maximum fidelity in all sound systems. It was a goal that required fundamental studies of sound characteristics, performed on a continuing basis in connection with development of new microphones, speakers and recording techniques for professional and consumer use.
The scope of the effort needed to develop effective sound systems is indicated by the troubles that can crop up if only one out of the many elements fails to do its job. The results can be ruined by poor voices or enunciation, by bad acoustics in the location of sound pickup, by faulty performance in the microphone, by any malfunction in the recording amplifier in the case of disc recording or in the optical system in the case of sound track recording on film, faults in the material or processing of the record or in the duplicating of copies from the master record, malfunctioning in the recording pickup device, the turntable mechanism, or loudspeaker, or poor acoustics in the room or theater. Every one of these aspects had to be studied and worked upon at one time or another, or even repeatedly, in order to achieve fully effective systems.
Numerous scientists and engineers were involved in this program at Camden through the 1930s. One of these was Kellogg, whose earlier work at General Electric had brought fundamental advances in sound pickup and reproduction techniques. Following (p. 103) his development, with Rice, of the dynamic loudspeaker, he had originated the magnetic pickup for phonographs—one of the most significant contributions to high quality sound reproduction from records. Subsequently, he contributed extensively to the development of sound techniques applicable to motion picture and home systems. A large portion of his work at Camden was devoted to basic studies related to phonograph recording and playback, leading to development by his group of advanced long-playing techniques and equipment.
Among the notable results of phonograph and recording work in Camden during the early years of the decade were advances in fine-groove recording, the development of the vinylite unbreakable record, and long-playing home phonograph records and players. Much of this progress resulted from the work of F[rederic]. C. Barton, Albert A. Pulley and others in the Record Engineering Department. The vinylite record, a major advance over the breakable type previously used, was developed initially for motion picture sound recording but was subsequently produced for home use. A long-playing system, employing 33-1/3 rpm vinylite records and turntable, was placed briefly on the market by RCA in 1934. Beset by the nation’s worst depression, however, the public was buying few records and phonographs of any description in 1934. Not until the re-introduction of long-playing records and instruments by the industry after World War II did a 33-1/3 system come into its own, together with the popular postwar RCA 45 rpm record and player. (p. 104)
In another area of acoustics, outstanding developments came from Olson and his associates, including John Preston and Reginald A. Hackley, in a succession of high-performance microphones and speakers. One of the early projects at Camden involved the search for basic improvements in radio loudspeakers. By 1934, Olson had developed a new type of cone speaker capable of reproducing a broader range of sound, and at the same time incorporating simpler and more economical construction than in any previous type. Efforts then were directed at reducing the size of speakers for the new portable radios under development by Wendell L. Carlson and others. A number of miniature types, with diaphragms ranging from one to three inches in diameter, were completed for this application in 1938-39.
Microphone development was largely guided through the decade by the special demands of motion pictures and television for pickup devices that could function efficiently without intruding visually in the filmed or televised scene. To meet this need, Olson, Preston and others designed a series of small unidirectional and ultradirectional microphones capable of operating out of camera range. A typical example was the novel l5½-ounce unidirectional type developed by Olson and Preston in 1937 to provide the entertainment industry with a useful new device having better directional characteristics, yet several times smaller and lighter than any previous microphones. (p. 106)
A detailed review of the acoustical research effort and its results through the 1930s would amount to counting the trees and ignoring the forest. The forest in this case is an impressive advance in sound reproduction, applied widely in the fields of motion picture, radio, television, and phonograph. By devising new techniques and equipment applicable at various points throughout all sound systems, the Camden group was basically responsible for establishing new technical and esthetic standards for sound reproduction. By the advent of World War II, the results were evident in the extensive use of high-fidelity equipment in theaters and in professional recording and broadcasting. At the same time, the foundation had been laid for the phenomenal expansion of high-fidelity sound techniques for home listening, in which RCA was destined to play a leading role in the postwar era.
Facsimile Research and Development
An added feature cropped up at a Washington demonstration of RCA television in 1940 to an audience of Congressional leaders, the FCC and various other dignitaries. It was a neat cabinet, inscribed “RCA Facsimile,” from the top of which issued a tabloid-size sheet carrying the news of the day, relayed by radio from New York. The visitors were interested and impressed. A few were also puzzled. One Senator watched the operation silently for a few moments, contemplating the fresh print and pictures appearing on the sheet. Finally he turned to C. J. Young, of RCA’s Camden research staff. (p. 106) “Say,” he asked, “what kind of microphone do you talk into to make it come out like that?”
Actually, facsimile was neither as new nor as strange as all that. It had a long and honorable history, extending back 100 years or more. What was new on this occasion was RCA’s proposed use of the facsimile to provide a news service for the home.
Any broad research program will produce along with its successes a few results that fall short of the mark in the business sense for technical or economic reasons beyond the control of the sponsor. The product may be too advanced for its time, or it may mature too late to fit into a changing environment. In the case of RCA’s facsimile research and development, we find an ambitious program that produced many useful and important innovations, but that matured in the form of a proposed consumer service for which there was no longer any real demand.
Facsimile, the art of transmitting photos and printed matter by radio for reproduction at a distant point, is a concept that originated more than a century ago and achieved its first practical form in the early part of the present century as a rudimentary system employing telegraph wire transmission. The concern of RCA with facsimile as a communications service is almost as old as the corporation itself.
R. H. Ranger, of the communications engineering group in New York, initiated the RCA facsimile program during the early 1920s at the suggestion of Owen D. Young, then RCA Chairman of the Board. Ranger carried on through the decade with the objective, (p. 107) as he stated it in 1925, of producing “an economic solution rather than essentially the purely mechanical problem of producing a machine that would work.”
By the middle and late twenties, limited broadcast tests were under way from New York to locations along the east coast and in the mid-west. The copy used in the tests was received from England by radio and retransmitted from the long-wave RCA transmitter at New Brunswick, N.J., to facsimile receivers at department stores in Boston, Philadelphia, Pittsburgh, Chicago, Indianapolis, and Cincinnati. The system used a drum type of scanner on which transparent subject copy was placed for electrical scanning and conversion into radio signals. At the receiving end, reproduction was achieved by any one of several techniques, including hot wax pen, hot air, or ink vapor recording.
At the same time, Alexanderson’s group at General Electric had shown interest in facsimile and had developed a system using an optical scanner and a recorder employing 8-inch photographic paper on a roll. This equipment was tied in during 1928 with an early experimental short-wave circuit to San Francisco, sending a page of newspaper—in three strips—across the continent. The results interested C. J. Young, then in the General Electric Radio Engineering Department, and prompted his suggestion for a broadcast facsimile service supplying a radio “newspaper” for the home, through a receiver incorporating both the regular home radio and a facsimile recorder.
Young also figured that the reproduction process might be simplified and improved by employing carbon paper recording, and (p. 108) equipment of this type was built and tested in the Radio Engineering Department with the help of Maurice Artzt.
With the reorganization of 1930, the various approaches were pulled together in an RCA development program headed by Young. The principal objective became the development of the proposed facsimile service for the home. At the same time various other commercial applications were devised and tested, among them a simple and effective shore-to-ship system for transmitting weather maps and news information to ships at sea.
The status of facsimile development during 1935–36 showed sufficient promise to warrant an intensive study of potential markets for a leased broadcast service in urban areas. Young, Artzt and their associates by now had developed a possible home system including a VHF radio, a carbon printer, and a device for cutting off the recorded pages and stacking them in a tray. It was entirely automatic, starting on a signal from the broadcast station to which it was tuned, and stopping at the end of the program. The speed of delivery was three 12-inch pages per hour, which was felt to be sufficient for nighttime transmission of a newspaper for reading at breakfast.
Between 1937 and 1940, several broadcasting stations received experimental licenses from the FCC for facsimile operation during the early morning hours. RCA sold about twelve (p. 109) scanners and three hundred receivers, principally to newspaper-owned broadcasting stations, during this period. Experience in the field showed that the speed of reproduction was too slow, that the unit cost of receivers was still too high to encourage volume sales, and that commercial operations were unlikely to be approved by the FCC without the adoption of common facsimile standards throughout the country. Subsequently, a number of technical improvements were made by the Camden group in time for demonstration at the New York World’s Fair in 1940. Further commercial development was then postponed by the shelving of most peacetime electronic activities in order to meet war requirements.
While there is no guarantee that a broadcast facsimile service may not one day find wide application, the conditions of the postwar era discouraged further activity in this particular field. By 1946, the growth of commercial television and the improved distribution of newspapers eliminated to a large extent the need for a supplementary broadcast facsimile news service into the home.
Yet every research and development program seems to produce a number of useful results—and the extensive facsimile work of the 1930s is no exception. RCA facsimile is employed today in several commercial services and by the military in special communication tasks. Many of the techniques developed during the 1930s also have found application in other areas. For example, Artzt developed a means for synchronizing shaft speeds (p. 110) between transmitter and receiver by means of electrical signals, solving a critical problem in facsimile. This experience helped later in his development of synchronizing techniques for the television magnetic tape system developed at RCA Laboratories in the postwar era. Furthermore, a continuation of work by Young and his associates in search of better facsimile recording techniques for special application led to further useful advances. Among these were contributions to the high-speed “Ultrafax” system developed by Donald Bond for operation at speeds of more than a million words per minute, and the “Electrofax” high-speed electronic printing process developed by Young, Harold G. Greig and others at RCA Laboratories after the war.
Something New in Microscopes
Everything that has been considered so far in these pages was clearly relevant to RCA’s primary business of communications. Inevitably, however, a truly broad research program will generate by-products that seem to have little or nothing to do with the sponsoring company’s standard line of products and services. Sometimes these by-products launch a new business either for the company or for its licensees.
There were few such by-products from the RCA research program of the 1930s. This does not reflect upon the effectiveness of the program or the ingenuity of the research staff. Rather, it reflects the expansion of RCA’s interest in the broadening field (p. 111) of electronics as opposed to the communications aspect alone. The corporate sights were steadily raised to keep pace with a rapidly developing technology.
In the late 1930s came a major technical development that would have seemed far out in left field relative to RCA’s interest only a few years earlier. This was the design and development of the first practical electron microscope for commercial use.
Pioneering work with the Iconoscope and other aspects of television had both drawn upon and contributed to knowledge in electron optics. At the same time, research in Germany, Belgium, England, and Canada had applied electron optical techniques in the field of microscopy, with concrete results in the form of several rudimentary and complex instruments. Perhaps the most successful of these was the first working electron microscope to be built in North America—a two-stage instrument developed in 1938 by James Hillier and Albert Prebus at the University of Toronto. This device achieved magnifications far beyond the limits of the light microscope, which cannot detect anything smaller than the wavelength of light.
Zworykin, at Camden, had been interested for some time in the potentialities of the electron microscope. He had, in fact, been instrumental in obtaining for RCA the services of Ladislaus Marton, who had pioneered in certain aspects of electron microscopy at the University of Brussels, Belgium. With Marton’s participation, some technical advances were achieved at Camden, but the project remained largely inconclusive. (p. 112)
Following the Canadian success, a new team was set up under Zworykin, combining the talents of Hillier, who was brought in from Toronto, and A[rthur]. W. Vance. The result, achieved in 1940, was a rugged and practical electron microscope for commercial use, incorporating a radically improved power supply of unprecedented stability, developed by Vance. Making its appearance just prior to the outbreak of World War II, the instrument was enthusiastically received by the scientific world as an important new research tool for medical science, chemistry and metallurgy, probing into areas never before within the range of human observation.
High-frequency tubes and techniques, radar, airborne electronics, acoustics—these were the partial ingredients of the broad creative research program, supported by a research-conscious management, that played so large a part in the transformation of RCA through the 1930s into a major electronics enterprise. Looking back over the prewar decade, David Sarnoff reflected in these words to RCA’s stockholders in 1940:
At this point, however, the bright promise of further advance in commercial electronics was being dimmed, by the start of war in Europe and by the dark prospect of a world conflict. By 1940, virtually all research work at Camden and Harrison in the fields of navigational equipment and ultra-high-frequency communications was directed to military needs. At the same time, the growing national defense program and the demands of the Lend-Lease effort to aid Britain and France had brought increased pressure upon RCA’s production facilities. To gear the corporation to these new developments, another change was in order. It was not long in coming. . . (p. 114)
|Home | Back to Top||
This website is supported by and