Radio Engineering – 1890s to 1930s AD

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Radio Engineering

“At the same time, San Francisco’s inhabitants showed a voracious interest in the radio technology invented in Europe at the turn of the century. The Italian inventor Guglielmo Marconi, then in Britain, had galvanized the sector with his long-distance radio transmissions, beginning in 1897 and culminating with the radio message from the US President Theodore Roosevelt to the British king Edward VII of 1903. Marconi’s company set up radio stations on both sides of the Atlantic to communicate with ships at sea. However, it was not yet trivial how to create a wireless communication system.”

“In 1906 an independent with a degree from Yale, Lee DeForest, had built a vacuum tube in New York without quite understanding its potential as a signal amplifier. In fact his invention, the “audion”, was useful to amplify electrical signals, and therefore to wireless transmissions. (In 1904 the British chemist John-Ambrose Fleming had invented the two-element amplifier, or “diode”, and a few months before DeForest the Austrian physicist Robert von Lieben had already built a three-element amplifier, or “triode”). In 1910 DeForest moved to San Francisco and got into radio broadcasting, a business that he had pioneered in January when he had broadcast from New York a live performance by legendary Italian tenor Enrico Caruso. In fact, DeForest is the one who started using the term “radio” to refer to wireless transmission when he formed his DeForest Radio Telephone Company in 1907. However, his early broadcasts did not use the audion yet. Interest in radio broadcasting was high in the Bay Area, even if there were no mass-produced radios yet. A year earlier, in 1909, Charles Herrold in San Jose had started the first radio station in the US with regularly scheduled programming, including songs, using an arc transmitter of his own design. Charles Herrold had been one of Stanford’s earliest students and founded his own College of Wireless and Engineering in San Jose.

The Bay Area stumbled into electronics almost by accident. In 1909 another Stanford alumnus, Cyril Elwell, had founded the Poulsen Wireless Telephone and Telegraph Company in Palo Alto, later renamed the Federal Telegraph Corporation (FTC), to commercialize a new European invention. In 1903 the Danish engineer Valdemar Poulsen invented an arc transmitter for radio transmission, but no European company was doing anything with it. Elwell understood its potential was not only technological but also legal: it allowed him to create radio products without violating Marconi’s patents. Elwell acquired the US rights for the Poulsen arc. His radio technology, adequately funded by a group of San Francisco investors led by Beach Thompson, blew away the competition of the East Coast. In 1912 he won a contract with the Navy, which was by far the biggest consumer of radio communications. Thus commercial radiotelegraphy developed first in the US. The “startup” was initially funded by Stanford’s own President, David Starr Jordan, and employed Stanford students, notably Edwin Pridham. Jordan had just inaugurated venture-capital investment in the region.

In need of better receiver amplifiers for the arc transmissions, FTC hired Lee DeForest, who by 1912 had finally realized that his audion could be used as an amplifier. The problem with long-distance telephone and radio transmissions was that the signal was lost en route as it became too faint. DeForest’s vacuum tube enabled the construction of repeaters that restored the signal at intermediate points. The audion could dramatically reduce the cost of long-distance wireless communications. FTC began applying the audion to develop a geographically distributed radiotelegraphy system. The first tower they had built, in July 1910, was on a San Francisco beach and it was 90 meters tall. Yet the most impressive of all was inaugurated in 1912 at Point San Bruno (just south of the city), a large complex boasting the tallest antenna in the world (130 meters).

By the end of 1912 FTC had grown; it had stations in Texas, Hawaii, Arizona, Missouri and Washington besides California. However, the Poulsen arc remained the main technology for radiotelephony (voice transmission) and, ironically, FTC was no longer in that business. Improvements to the design by recent Cornell graduate Leonard Fuller (mostly during World War I, when the radio industry was nationalized to produce transmitters for the Navy) that allowed the audion to amplify a signal a million times eventually led FTC to create the first global wireless communication system. The audion was still used only for receivers, while most transmitters were arc-based. It was only in 1915 that DeForest realized that a feedback loop of audions could be used to build transmitters as well. DeForest had already (in 1913) sold the patent for his audion to Graham Bell’s AT&T in New York, and AT&T had already used it to set up the first coast-to-coast telephone line (January 1915), just in time for the Panama-Pacific International Exposition. Meanwhile, DeForest had moved to New York. There, in 1916, he stunned the nation by broadcasting the results of the presidential elections with music and commentary from New York to stations within a range of 300 kilometers, and this time using an audion transmitter. Radiotelephony would switch from the Poulsen arc to his audion during the 1920s. In due time Leo Fuller took Elwell’s place as chief engineer of FTC, and in 1920 Navy engineer and former Marconi engineer Haraden Pratt was hired to launch commercial wireless telegraph service, and sugar magnate Rudolph Spreckels bought control of FTC.

The wireless industry was booming throughout the US, aided by sensational articles in the mainstream press. Earle Ennis had opened a company (Western Wireless Equipment Company) to sell wireless equipment for ships. He also ran a radio broadcast to deliver news to ships at sea. In 1910 he organized the first air-to-ground radio message, thus showing that the same technology could be used by the nascent airline industry.

Because of its maritime business, the Bay Area became one of the largest centers for amateur radio. The Bay Counties Wireless Telegraph Association was founded in 1907 by (then) amateurs such as Haraden Pratt, Ellery Stone and Lewis Clement.

Quite a bit of innovation in radio engineering came from the “ham” radio amateurs. The first wireless communications were, by definition, done by independents who set up their own equipment. This was the first “virtual” community as they frequently never met in person. The first magazine devoted to radio engineering, Modern Electrics, was launched in April 1908 in New York by Hugo Gernsback, a 24-year-old Jewish immigrant from Luxembourg. It reached a circulation of 52,000 in 1911, the year when it started publishing science-fiction stories (thus also becoming de facto the first science-fiction magazine). Amateur wireless associations popped up throughout the country, such as the Radio Club of Salt Lake City in Utah, founded in September 1909, and the Wireless Association of Central California, formed in May 1910 in Fresno. From a social point of view, the beauty of ham radio was that it blurred class boundaries: they were known by codes such as 6ZAF, not by their last names, and it made no difference whether they were rural teenagers, Stanford PhD students or professional radio engineers. They were all on the same level.

Among the amateurs of the second decade were Charlie Litton, an eleven-year old prodigy who operated an amateur station in Redwood City in 1915, and Frederick Terman, a teenager who operated an amateur station in Palo Alto in 1917. Some of those amateurs went on to create small companies. Little did they know that their hobby would in time of war constitute a strategic industry for the Air Force, Navy and Army: during World War I (in 1918) Elwell’s technology would be a pillar of naval communications for the US. The Navy had set up radio stations all over the place. In January 1918 the President of the US, Woodrow Wilson, proudly spoke live to Europe, the Far East and Latin America.

Magnavox Corp. was founded in 1910 in Napa (north of the bay). It was the brainchild of Peter Jensen (one of the Danish engineers imported by FTC to commercialize the Poulsen arc) and Edwin Pridham (a Stanford graduate who also worked at FTC). In 1917 they introduced a new type of electrical loudspeaker.

Alas, after World War I it became obvious that radio technology was strategic, and it couldn’t be left in the hands of West-Coast independents. The US government basically forced a large East-Coast company, General Electric, to buy the US business of Marconi. The US government also helped the new company to acquire the most important radio patents. Thus a new giant, RCA, was born and soon became the dominant player in consumer electronics, as the number of radios grew from 5,000 in 1920 to 25 million in 1924. Hence FTC was doomed and other Bay Area-based radio companies had to live with only military applications.

Ham-radio amateurs were the first “garage nerds” of the San Francisco Bay Area, a place isolated from the rest of the country (reaching any other city required a long journey by ship, by train or by coach). Bill Eitel presided the Santa Clara County Amateur Radio Association, formed in 1921, before he went on to launch his own “startup”. The First National Radio Conference took place in Washington in February 1922, and it pitted the five big corporations that owned all the patents (American Telephone & Telegraph, General Electric, Western Electric, Westinghouse and RCA) against the ham-radio amateur clubs. That conference established their legal legitimacy. A few weeks later, in April 1922, the first transpacific two-way amateur communication was established between 6ZAC (Clifford Down) in Hawaii and 6ZAF (A.H. Babcock) in Berkeley. The ham-radio operators became heroes in countless cases of natural disasters, especially in the Western states, at a time when there was no other way to communicate rapidly with the aid workers. A teenager, known as 6BYQ, sent out the first alarm when a dam broke in 1928 in Santa Paula, near Los Angeles, causing a flood that caused massive destruction. Ham-radios helped in September 1932 when a landslide wiped out the mining town of Tehachapi, east of Los Angeles, and in March 1933 when an earthquake struck Long Beach, south of Los Angeles. Ham-radios were the first “consumers” of the vacuum tubes made in the Bay Area.

Radio engineering created two worlds in the Bay Area that would greatly influence its future: a high-tech industry and a community of high-tech amateurs.

SEE ALSO: Electrical Engineering – Early 1900s

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History Software Engineering

William Shockley’s Silicon Transistor – 1947 A.D.

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Silicon Transistor

John Bardeen (1908–1991), Walter Houser Brattain (1902–1987), William Shockley (1910–1989)

“A transistor is an electronic switch: current flows from one terminal to another unless voltage is applied to a third terminal. Combined with the laws of Boolean algebra, this simple device has become the building block for microprocessors, memory systems, and the entire computer revolution.

Any technology that can use one signal to switch another on and off can be used to create a computer. Charles Babbage did it with rods, cogs, and steam power. Konrad Zuse and Howard Aiken did it with relays, and ENIAC used tubes. Each technology was faster and more reliable than the previous.

Likewise, transistors have several advantages over vacuum tubes: they use less power, so they generate less heat, they switch faster, and they are less susceptible to physical shock. All of these advantages arise because transistors are smaller than tubes—and the smaller the transistor, the bigger the advantage.

Modern transistors trace their lineage back to a device manufactured by John Bardeen, Walter Brattain, and William Shockley at AT&T’s Bell Laboratories in 1947. The team was trying to build an amplifier that could detect ultra-high frequency radio waves, but the tubes that they had just weren’t fast enough. So they tried working with semiconductor crystals, as radios based on semiconductor diodes called cat’s whiskers had been used since nearly the birth of radio in the 1890s.

A cat’s whisker radio uses a sharp piece of wire (the “whisker”) that’s jabbed into a piece of semiconducting germanium; by moving the wire along the semiconductor and varying the pressure, the semiconductor and the wire work together to create a diode, a device allowing current to pass in only one direction. The Bell Labs team built a contraption that attached two strips of gold foil to the crystal and then applied power to the germanium. The result was an amplifier: a signal injected into one wire was stronger when it came out of the other. Today we call this device a point-contact transistor.

For their discovery of the transistor, Bardeen, Brattain, and Shockley were awarded the Nobel Prize in 1956.”

SEE ALSO Semiconductor Diode (1874), First LED (1927)

“The first transistor ever made, built in 1947 by John Bardeen, William Shockley, and Walter H. Brattain of Bell Labs.”

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DevSecOps-Security-Privacy History

Vernam Cipher – 1917 A.D.

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Vernam Cipher

Gilbert Vernam (1890–1960), Joseph Mauborgne (1881–1971)

“Most encryption algorithms are computationally secure. This means that while it’s theoretically possible to crack the cipher by trying every possible encryption key, in practice this isn’t possible because trying all of the keys would require too much computational power.

More than a century ago, Gilbert Vernam and Joseph Mauborgne came up with a cryptographic system that is theoretically secure: even with an infinite amount of computer power, it is impossible to crack a message encrypted with the Vernam Cipher, no matter how fast computers ever become.

Vernam’s cipher, today called a one-time pad, is unbreakable because the encrypted message, decrypted with an incorrect key, can result in a plausible-looking message. Indeed, it can result in every possible message, since the key is the same length as the message. That is, for any given ciphertext, there is a key that makes it decrypt as a verse from the Bible, a few lines from Shakespeare, and the text on this page. Without a way to distinguish a correct from an incorrect decryption, the cipher is theoretically unbreakable.

Working at American Telephone and Telegraph Company (now AT&T®) in 1917, Vernam created a stream cipher that encrypted messages one character at a time by combining each character of the message with a character of a key. At first Vernam thought that key could be simply another message, but the following year, working with Joseph Mauborgne, a captain in the US Army Signal Corps, the two realized that the key must be random and nonrepeating. This improved security substantially: if the key were another message, it would be possible to distinguish a probable key from one that was improbable. But if the key was truly random, then any key was equally possible. Together, the two inventors created what we now call a one-time pad, one of only two known encryption systems that are provably unbreakable (the other being quantum cryptography).

As it turns out, a banker named Frank Miller had also invented the concept of the one-time pad in 1882, but his pen-and-paper system was not widely publicized or used.”

SEE ALSO Manchester SSEM (1948), RSA Encryption (1977), Advanced Encryption Standard (2001)

One-time pad device used with SIGTOT cipher system used aboard President Roosevelt’s Douglas C-54 airplane.

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History Software Engineering

Floating-Point Numbers

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Floating-Point Numbers

Leonardo Torres y Quevedo (1852–1936), William Kahan (b. 1933)

“Leonardo Torres y Quevedo was a Spanish engineer and mathematician who delighted in making practical machines. In 1906, he demonstrated a radio-controlled model boat for the king of Spain, and he designed a semirigid airship used in World War I.

Torres was also a fan of Babbage’s difference and analytical engines. In 1913, he published Essays in Automatics, which described Babbage’s work and presented the design for a machine that could calculate the value of the formula a(y–z)2 for specified values of a, y, and z. To allow his machine to handle a wider range of numbers, Torres invented floating-point arithmetic.

Floating-point arithmetic extends the range of a numerical calculation by decreasing its accuracy. Instead of storing all of the digits in a number, the computer stores just a few significant digits, called the significand, and a much shorter exponent. The actual “number” is then computed using the formula: significand × baseexponent

For example, the gross domestic product of the United States in 2016 was 18.57 trillion dollars. Storing that number with a fixed-point representation requires 14 digits. But storing it in floating point requires just 6 digits: $18.57 trillion = 1.857 × 1013

Thus, with floating-point numbers, sometimes called scientific notation on modern calculators, a 10-digit register (a mechanical or electronic gadget that can store a number) that would normally be limited to storing numbers between 1 and 9,999,999,999 instead can be partitioned into an 8-digit significand and a 2-digit exponent, allowing it to store numbers as small as 0.0000001 × 10–99 and as large as 9.9999999 × 1099.

Modern floating-point systems use binary rather than decimal digits. Under the standard developed by Canadian mathematician William Kahan for the Intel 8086 microprocessor and adopted in 1985 by the Institute of Electrical and Electronics Engineers (IEEE 754), single precision floating point uses 24 bits for the significand and 8 bits for the exponent.”

For his work, Kahan won the Association for Computing Machinery’s (ACM) A.M. Turing Award in 1989.”

SEE ALSO Binary Arithmetic (1703), Z3 Computer (1941), Binary-Coded Decimal (1944)

Portrait of Leonardo Torres y Quevedo by Argentinian cartoonist and illustrator Eulogia Merle (b. 1976).”

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