The Telephone

On March 10, 1876, the telephone was born when Alexander Graham Bell called to his assistant, "Mr. Watson! Come here! I want you!" He was not simply making the first phone call. He was beginning a revolution in communications and commerce. It spread a web of instantaneous information across towns, then a continent, then the world, and has greatly accelerated economic development.

First Transcontinental Telephone Call

If you collect U.S. postage stamps, you might have noticed one issued in February 1998 to commemorate AT&T's 1914 construction of the first transcontinental telephone line.
AT&T began building the nation's original long distance network in 1885. Starting from New York, the network reached Chicago in 1892. But, because an electrical signal weakens as it travels down a wire, that distance was close to the limit for a line built of thick copper. With the 1899 introduction of loading coils, which slow the rate at which a signal weakens, construction proceeded west. By 1911, the network stretched as far as Denver, but had reached the distance limit for loading coils.
In 1908, AT&T President Theodore Vail had made a transcontinental telephone line a major goal, even though he knew the technology to build one did not exist. The next year, Chief Engineer John J. Carty raised the stakes when he announced in San Francisco that AT&T would open a transcontinental line in time for the city's 1915 exposition to mark the completion of the Panama Canal.
But, without a scientific breakthrough, AT&T couldn't make good on that bet. To improve the company's odds, Carty not only hired physicist Dr. Harold Arnold to study the amplification of electrical signals, he also spread the word in the scientific and electrical-engineering community that AT&T would pay handsomely for an electrical amplifying device.

With the development of vacuum tube amplifiers, it was possible to extend the New York-Denver circuit to San Francisco.

On Oct. 30, 1912, independent inventor Dr. Lee de Forest brought the audion, a three-element vacuum tube, to AT&T's engineering department. De Forest's invention provided a small amount of amplification, and then broke down into a bright blue haze. However, Arnold recognized almost immediately that the blue haze was caused by ionization of residual gasses in the tube. If he increased the vacuum, thereby removing most of the residual gasses, the audion would become a practical amplifier. So on Arnold's recommendation, AT&T bought the patent rights from de Forest. By summer 1913, AT&T had tested high-vacuum tubes on the long distance network. And that fall, the company began constructing the line west from Denver and upgrading the line to the east. On June 27, 1914, AT&T completed the line, erecting the last pole at Wendover, Utah.
Only one problem remained: AT&T had connected the continent before the Panama-Pacific exposition was ready. So the company waited, and on Jan. 25, 1915, opened the line with great fanfare and celebrations in San Francisco and New York.

Remembering Claude Shannon

 

Juggling Genius Claude Shannon Launched the Digital Age

Claude Shannon turned the world on its head by developing Information Theory, which blazed a trail toward digital communication.

Claude Shannon has been described as the "intellectual giant of the digital age." By the time of his death on Feb. 24, 2001, Shannon had collected a pile of prestigious prizes that proved it — the National Medal of Science, Japan's Kyoto Prize, the IEEE Medal of Honor among them. But, none of those awards quite measured up to the honor he received in October 1998, when AT&T Labs named its two-building, 387,000-square-foot complex in Florham Park, N.J., the Shannon Laboratory.
Perhaps that building's sign should have read "Shnon Lab," because as the Father of Information Theory, Shannon paved the path for digital communications by introducing ingenious concepts for efficiently packaging and transmitting data.
Birth of the theory

Considered the Magna Carta of communication, Shannon's Information Theory first appeared more than 50 years ago in his 1948 Bell System Technical Journal paper "The Mathematical Theory of Communication."
Information Theory describes an ideal communications system in which all information sources -- people speaking, computer keyboards, video cameras -- have a "source rate" measured in bits per second. The channel through which the source's data travels has a "capacity," also measured in bits per second. Information can be transmitted only if the source rate does not exceed the channel's maximum capacity, now known as the Shannon limit.
To approach the Shannon limit, communications engineers encode data, compress it to remove redundancy, and transmit only information essential to understanding. By posting the sign "Shnon Lab," for example, we would eliminate predictable, redundant symbols and send only those symbols that contain unpredictable news -- what Shannon called "information."
It sounds simple, but the complex mathematical formulas embedded in Information Theory have guided the discoveries of two generations of communications engineers. "Information Theory stimulated all kinds of intellectual energy," says AT&T Fellow Neil Sloane, whose research on the mathematical framework of communications is rooted in Information Theory. "Without Shannon's theory, we wouldn't have all the digital devices we depend on today -- wireless phones, fax machines, compact disks or the Internet." Shannon's ideas have even been applied in such diverse fields as psychology, linguistics, economics and biology.

Shannon does the math at Bell Labs, 1955.

"Because Information Theory was such a profound development, history will remember Shannon as one of the great thinkers in the field of electrical engineering," says AT&T Fellow Larry Greenstein, who relied on Shannon's theories in researching point-to-point radio and wireless communication channels. "He broke the mold in the field of communications and did something unlike anything that came before -- not just an extension or improvement."
The cycling scholar

Just as unique as the theory was the theorist himself. Born in 1916, Michigan native Shannon arrived at AT&T in 1941 after producing what's been called the century's most important master's thesis and earning a Ph.D. at the Massachusetts Institute of Technology. His work on anti-aircraft and digital-encryption systems during World War II planted the seeds for Information Theory. Shannon reasoned that the same types of digital codes that protect sensitive information could be used to safeguard it from noise, static or interference
While pondering such deep thoughts, Shannon often pedaled a unicycle through the halls of Bell Labs. In the early 1950s, his intellectual journey veered toward the relationship between people and machines, and he helped found the field of artificial intelligence. Among the first applications he devised in this area was Theseus, a mechanical mouse that solved mazes in search of a brass "cheese." During this period, Shannon also published one of the earliest proposals for a chess-playing computer.

By "teaching" an electrical mouse to find its way through a maze, Shannon helped stimulate Bell Labs researchers to think of new ways to use the logical powers of computers for operations other than numerical calculation.

After leaving AT&T in 1956, Shannon joined the faculty at MIT. He formally retired in 1978 and pursued his longtime passions — gadgets and juggling. In fact, one of his favorite creations was a juggling gadget — a robot in the likeness of comedian W.C. Fields.
"I've always pursued my interests without much regard to financial value or value to the world. I've spent lots of time on totally useless things," Shannon said in 1983, perhaps referring to such gizmos as a gasoline-powered pogo stick, a rocket-powered Frisbee, and THROBAC (THrify ROman numerical BAckward-looking Computer), a computer that calculates in Roman numerals.
"He had a wonderful sense of humor and was a great builder of gadgets," Sloane says. "His house was filled with toys, including one device that displayed all the gowns he wore to receive his dozen or more honorary doctorates. He hung them on a circular clothes line, and when he'd flip a switch, the gowns marched around and around."
The man who caused so much excitement died quietly at age 84. But in one of his last papers, Shannon continued pointing the way toward communications' far horizons: "Our government might consider ... listening for evidence of intelligent life on other star systems. Who knows, perhaps E.T. would have words of wisdom for all of us."

1st Air-to-Ground / Ground-to-Air Radio Comm..

The first air-to-ground and ground-to-air radio communications were accomplished by AT&T engineers at Langley Field in Virginia.

In the early days of aviation, pilots relied upon primitive means of communication during flight, including hand signals and flags. But during World War I, the U.S. military desperately needed radio communication between airplanes and the ground and between the planes themselves.
So in May 1917, General George Squier of the U.S. Army Signal Corps contacted Western Electric, AT&T's manufacturing subsidiary, to request an airplane radio telephone with a 2,000-yard range. On June 5, AT&T engineers met with the military to gather technical requirements, only to discover that there was practically no information about such essentials as the wavelengths desired, antennas and power supplies.
Undaunted and spurred on by wartime urgency, AT&T engineers designed the equipment using solid hunches, available circuitry and a few field tests. On July 2, they made their first air-to-ground transmission over a distance of about two miles. And on July 4, they accomplished a ground-to-air transmission over the same distance. By August 20, they had achieved two-way communication between planes in flight. Western Electric began shipping radio telephone sets abroad in October.
Although few of those sets ever actually saw service, AT&T had proved that rapid voice communication between military vehicles in the air or on the sea was possible.
AT&T employees (from left) Edward Craft, 1st Lt. Ralph Bown, Maj. Nathan Levinson and Col. N. H. Slaughter watch an early aircraft-radio test. Many AT&T and Bell System employees entered the U. S.Army Signal Corps during World War I.

Fax Service

 

In 1918 H. Nyquist began investigating ways to adapt telephone circuits for picture transmission. By 1924 this research bore fruit in "telephotography" - AT&T's fax machine.

The principles used in 1924 were the same as those used today, though the technology was comparatively crude. A photographic transparency was mounted on a spinning drum and scanned. This data, transformed into electrical signals that were proportional in intensity to the shades and tones of the image, were transmitted over phone lines and deposited onto a similarly spinning sheet of photographic negative film, which was then developed in a darkroom. The first fax images were 5x7 photographs sent to Manhattan from Cleveland and took seven minutes each to transmit. 

The Artificial Larynx

The first artificial larynx developed by AT&T Bell Labs was purely mechanical. A metallic reed vibrated inside a tube that was connected, by the speaker, between the mouth and the stoma, an artificial opening in the speaker's throat. Air forced up the windpipe, through the tube and across the reed, was then manipulated in the speaker's mouth to create artificial speech.

In 1960, AT&T Bell Labs replaced the mechanical artificial larynx with an electronic version. This required no stoma, and could simply be held against the speaker's throat. A vibrating driver in the larynx replaced the sounds made by vocal cords, which could then be formed into words by the speaker. AT&T made it available at cost worldwide. 
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