Edwin Howard Armstrong

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Edwin Howard Armstrong, ca.1954

Edwin Howard Armstrong (born December 18, 1890 in New York City , † February 1, 1954 in New York City) was an American electrical engineer and inventor . He developed and invented devices and processes for radio technology . Some of these, like the superheterodyne receiver and frequency modulation , are commonplace these days (2011).

Life

Edwin Armstrong was the first of John Armstrong and Emily Smith Armstrong's three children. His father was a representative of the US branch of Oxford University Press , and his mother worked as a school teacher before they married.

Childhood and Adolescence (1890–1910)

As a 14-year-old boy, Armstrong showed, driven a. a. through the radio tests by Guglielmo Marconi , a strong interest in the newly discovered wireless technology. He was still a high school student (1905–1910) when he built his own antenna mast in his parents' garden to attempt reception. The young Armstrong experimented with every electronic part he could get, including the triode invented by Lee de Forest in 1906 .

Studies and University (1910–1917)

After graduating from high school, Armstrong attended Columbia University School of Engineering from 1909 to deepen his knowledge. In 1912, at the age of 21 and still a student at Columbia University, Armstrong made his first invention. He used de Forest's triode, which was previously only used as an audion , to amplify the weak radio signals by feeding a small portion of the tube's output current back to the control electrode . If he increased the amount of feedback , his circuit was to be used as an oscillator .

In 1913 he made his engineering degree. About six months after Alexander Meißner , he submitted his invention to the patent office on October 29, 1913 and received the patent for the regenerative circuit on October 6, 1914 . This patent was later challenged in a twelve year lawsuit by Lee de Forest .

After graduation, he worked at Columbia University and was an assistant to his mentor, Professor Michael Pupin . With him he applied u. a. At the end of 1917 a patent for a highly selective receiving circuit, which was granted in 1922.

During the First World War (1917-1919)

Major Armstrong

In 1917 Armstrong became a captain in the US Army Signal Corps . The Americans had not yet intervened in the fighting in World War I when Armstrong was posted to Paris in October 1917. The unit in which Armstrong served tested various French and American receivers in order to improve them, examined equipment from the enemy, and was supposed to detect enemy radio transmissions.

In 1918 he made his next major invention, the super heterodyne receiver, of which he built a prototype in Paris and tested it on the Eiffel Tower . This device had an unprecedented level of sensitivity. At the end of 1918 he applied for a patent for his invention in France and England. In the United States, Armstrong filed for it on February 8, 1919, and was awarded the patent on June 8, 1920. This invention was later challenged to him as well.

Towards the end of his service, Armstrong was raised to the rank of major and he was awarded the title "Knight of the Legion of Honor " by General Ferrié , the head of the French military intelligence service .

Back in America (1919-1940)

Back in America, Armstrong was able to sell the rights to its regenerative receiver and overlay receiver to Westinghouse Electric and Manufacturing Company for $ 335,000 in October 1920 . Even so, he continued to work at Columbia University.

On June 27, 1921, he applied for a patent for the super regenerative receiver, a further development of the regenerative receiver. Parts of this circuit principle were developed by John Bolitho, and Armstrong had bought the rights for them from him. On July 25, 1922, he received the patent and sold the rights to it to the Radio Corporation of America (RCA), newly formed in October 1919, for USD 200,000 and 60,000 RCA shares valued at USD 217,500. Linked to the sale to RCA was a right of first refusal for further inventions by Armstrong.

In 1923, Armstrong owned the largest proportion of RCA stock any single person held. During his business contacts he met Marion MacInnes, who was then secretary to David Sarnoff , president of RCA. Edwin Armstrong and Marion MacInnes married on December 1, 1923. His wedding present to her was a portable radio. His patents came under increasing attack during this period, and the resolution of the claims resulted in numerous lawsuits for Armstrong. Regardless of this, he continued to research and develop the improvement of radio technology. In 1934 he received a professorship at Columbia University.

A major problem with the technology at that time was the susceptibility of the amplitude modulation used to atmospheric interference on the transmission path. Armstrong realized that he could only deal with this problem with a different type of modulation . His deliberations resulted in the development of broadband frequency modulation . Against all odds, Armstrong succeeded in late 1939, early 1940 in obtaining permission to broadcast from the Federal Communications Commission (FCC) for a test FM transmitter . A long and expensive legal dispute also developed over the rights to FM technology.

During World War II (1939-1945)

In 1939 Armstrong was called in by the US Signal Corps as a civilian advisor on the use of FM-modulated military communications equipment. Between 1940 and 1941 he worked free of charge on some projects for the Signal Corps . During this time, in 1942, he received the Edison Medal from the Institute of Electrical and Electronics Engineers (IEEE).

In the years that followed until the end of the war, he took over work for the military against payment. His main contribution during this time was a long-range FM radar system , which was not yet completed by the end of the war. During the war years he gave his rights to use the FM patents free of charge to the US military. He received a Medal of Honor in 1947 for his services to military intelligence in World War II.

After 1945

Due to the decision made by the FCC in 1945 to shift the FM frequency band, and the lengthy legal disputes over the patent rights to the FM technology with RCA, Armstrong got more and more financial distress in the post-war years. He fell out with his wife Marion, and after 30 years of marriage, she left him in November 1953.

Edward Armstrong committed suicide on the night of January 31, 1954. He fell to his death from the 13th floor of his apartment. He left his wife a two-page farewell letter in which he regretted leaving his life in this way and professed his love for her.

(The information on Armstrong's death date is partly contradicting one another. Some sources cite January 31st, others February 1st, 1954, since he was not found on the roof of the building until 10:30 am that day. The article holds the date written on his tombstone.)

The evolution of FM radio

From 1927 to 1933 Armstrong filed four patents relating to the technology of frequency modulation, and received them on December 26, 1933. The principle of frequency modulation had been known since around 1922, but only attempts were made with narrowband FM . From the theory behind this and the results obtained, it was concluded that FM modulation was practically worthless.

Since Armstrong gave RCA the right of first refusal on future inventions in 1922, he demonstrated the technology to David Sarnoff and RCA technicians between 1933 and 1934. It was decided that further tests were necessary, and from May 1934 onwards, a station not yet used for television broadcasts by NBC , a subsidiary of RCA, was put into operation on the Empire State Building . The tests ran until October 1935. The broadband frequency modulation showed its advantages, even during severe thunderstorms the transmission was free of interference and had the best reproduction quality that had been achieved with radio transmissions up to then.

RCA and Sarnoff, however, reacted cautiously to its novelty - the necessary changes on the transmitter and receiver side seemed too great to use the new technology. Sarnoff also believed that the future would belong to television, which RCA had invested heavily in, not radio.

Armstrong came to the conclusion that he could only spread the benefits of the new technology with his own transmitter. He sold a portion of his RCA stock and had his own test FM transmitter built in Alpine , New Jersey for $ 300,000. After an initial rejection, he finally succeeded in getting permission from the FCC for the range 41 to 44 MHz towards the end of 1939. He had General Electric produce the first 25 FM receivers in late 1937 . General Electric also became the first licensee of its FM patents. The first broadcast of the station in Alpine was on July 18, 1939. The station ceased operations on March 6, 1954 after the death of Edwin Armstrong.

Armstrong developed a complete FM system with transmitters and receivers and tried to win other, smaller companies than RCA for the new technology. He was partially successful with General Electric as a licensee for radio sets. a. Western Electric , Stromberg Carlson, and Zenith . One of the first networks interested in broadcasting FM programs was John Shepard's Yankee Network . On July 24, 1939, the Yankee Network transmitter W1XOJ in Paxton, Massachusetts began broadcasting regularly on 43 MHz.

In the fall of 1939, the FCC had over 150 applications for FM broadcast stations. Because of the many applications, the originally allocated frequency range would soon have become too narrow, and so on May 20, 1940 the range for FM broadcasts was changed by the FCC to 42 to 50 MHz and approved for commercial broadcasters from January 1, 1941.

From 1939 receivers were produced almost exclusively for the military. That also had an impact on Armstrong's financial situation. By then, he had invested over USD 1 million in FM transmission, but had earned less than USD 500,000 in license fees, and no further income was generated because there were no longer any manufacturers producing for the private market. The war disrupted Armstrong's efforts to promote FM broadcasting. During this time he worked as a civil employee for the US military until 1945.

In 1945, after the war, the FCC decided to move the originally approved frequency band to the 88–108 MHz range due to feared interference from solar activity and the higher probability of overreach in the existing FM band. Strangely enough, the freed-up frequency range was released for television broadcasts. According to the FCC, television, which is even more susceptible to this type of interference, could certainly work on these frequencies.

The frequency shift made more than half a million FM radios and around 50 FM broadcasting stations that were in use up to that point unusable. The still young FM industry threw this back years. By 1950 there were over 600 FM stations active again, and Armstrong had earned just under $ 2 million in royalties from its FM patents. However, spending on his Alpine radio station, staff, and research was about as high.

Although the quality of FM broadcasts was far superior to AM broadcasts, it took decades before FM broadcasters (VHF) were able to hold their own against the well-represented AM stations (LW and MW).

Patent disputes in court

The license and patent situation in the early days of wireless radio transmission was confused and hardly transparent. Many claims from the inventions had to be clarified in court. The industry built devices with or without a license, kits for devices were sold in order to avoid license fees, companies cross-licensed each other or formed large license pools, and the rights of pending or disputed patent applications were bought and sold.

Edwin Armstrong's inventions and patents were repeatedly attacked by others, and all major patents were disputed in court. He was an excellent radio technician, but his approach to litigation was sometimes clumsy. Without his stubbornness z. B. the patent for the regenerative circuit was awarded to him and not de Forest. With some inventions, however, it was also the case that the underlying discoveries had already been made and others were simultaneously working on their further development, which inevitably led to similar developments.

Regenerative recipient

Switching of the regenerative receiver

Lee de Forest filed a patent for the regenerative circuit in 1915 and later sold the rights to AT&T . At the instigation of AT&T, the courts had to resolve the patent dispute over the regenerative recipient. Armstrong was supported by RCA and Westinghouse. The dispute went through several instances before the Supreme Court and finally ended in 1934. The patent was awarded to de Forest. A misunderstanding by the judges regarding the technology of the device is said to have been decisive. This patent dispute could have been settled in Armstrong's favor earlier, but Armstrong insisted that the almost bankrupt de Forest, who had lost the previous lawsuit, should pay the litigation costs. This then moved to the next instance, which ultimately decided for him.

Super heterodyne receiver

The French engineer Lucien Lévy had filed a patent application for the electrical transmission of energy on August 4, 1917 in France (No. 493,660) and on August 12, 1918 in the USA (US Patent No. 1,734,038) . a. described the basic principles of heterodyne reception. About six months before Armstrong, whose patent application was dated February 8, 1919, he filed his claims for this functional principle. After he later aligned the claims in his patent with those of Armstrong, the patent office had to deal with the two applications, since a patent on the same invention could not be issued twice. On November 5, 1929, the patent for the superheterodyne receiver was finally awarded to Lucien Lévy, as he had invented the basic principles of the circuit in the judgment after 1917. AT&T held the rights in America to Lévy's patent at that time.

FM patents

RCA had made Armstrong an offer of $ 1 million for the FM patent rights in 1940, but he refused. Armstrong only wanted to license the technology, not sell the patents. He also feared that RCA only wanted to prevent the spread of FM stations in order to protect their investments in AM technology. Many radio manufacturers paid license fees for FM sets, but RCA and their licensees did not pay, but they used FM technology for sound transmission in their television broadcasts and even had their own FM system patented. Armstrong, however, was dependent on the license income if he wanted to continue his research independently. In 1948 Armstrong sued RCA and NBC for infringement of its fundamental FM patents because, in his opinion, RCA's patents contained no new principles. This lawsuit would overshadow the rest of his life. During this time Armstrong is said to have said: " They will stall this thing until I am dead or broke " ("They will block this matter until I am dead or broke"). He should be right.

The protracted litigation worn Armstrong down and drained his savings more and more. Shortly before his death, Armstrong was ready to reach an agreement with RCA. He asked for $ 2.4 million, but RCA only offered 200,000, which wasn't even enough to cover the litigation costs incurred. He did not accept this offer. At the end of 1953, Armstrong had 21 lawsuits pending for infringement of its FM patents.

After his death, his widow reached an agreement with RCA in 1954 and received just over $ 1 million. She won two of the 21 lawsuits, and the remainder were settled in her favor. On October 9, 1967, there was the final decision against Motorola in this series of trials . Marion Armstrong received a total of approximately USD 10 million from the defendant companies.

List of relevant US patents

Armstrong's patents:

  • Patent US1113149 : Wireless Receiving System. Published in 1914 (regenerative receiver). ‌
  • Patent US1342885 : Method of Receiving High Frequency Oscillations. Published on 1920 (superheterodyne receiver / superimposition principle). ‌
  • Patent US1416061 : Radioreceiving System having High Selectivity. Published in 1922 (receiver with high selectivity). ‌
  • Patent US1424065 : Signaling System. Published on 1922 (super regenerative receiver). ‌
  • Patent US1539820 : Wave Signaling System. Published on 1925 (improvements for the super regenerative receiver). ‌
  • Patent US1539821 : Wave Signaling System. Published on 1925 (improvements for the super regenerative receiver). ‌
  • Patent US1539822 : Wave Signaling System. Published on 1925 (improvement of the selection of the super regenerative recipient). ‌
  • Patent US1541780 : Wave Signaling System. Published on 1925 (improvements for the super regenerative receiver). ‌
  • Patent US1941066 : Radio Signaling System. Released in 1933 (Signal-to-Noise Improvement for FM Receivers). ‌
  • Patent US1941067 : Radio Broadcasting and Receiving. Published on 1933 (A system to be able to hide unwanted advertising announcements. None of Armstrong's great inventions, but what is interesting is that this problem gave cause to think about countermeasures so early.). ‌
  • Patent US1941068 : Radiosignaling. Released in 1933 (FM modulation and demodulation). ‌
  • Patent US1941069 : Radiosignaling. Published on 1933 (increasing the range of high radio frequencies through FM modulation). ‌
  • Patent US1941447 : Radio Telephone Signaling. Published on 1933 (Avoiding fading and atmospheric disturbances by using FM modulation). ‌
  • Patent US2104012 : Multiplex Radio Signaling System. Published on 1938 (Method for multiplex FM transmissions (examples are the transmission of a radio program and the simultaneous transmission of facsimile content and the transmission of a radio program with two separate channels to achieve perspective transmission)). ‌
  • Patent US2630497 : Frequency Modulation Multiplex System. Released 1953 (Improvements to Multiplex FM Broadcasts). ‌

Patents de Forests:

  • Patent US841387 : Device For Amplifying Feeble Electrical Currents. Published on 1907 (The de Forest Triode). ‌
  • Patent US879532 : Space Telegraphy. Released in 1908 (audion with triode). ‌

Lévys patents:

  • Patent US1734038 : Electrical Transmission Of Energy. Published on 1929 (Lévy's principle of superimposition). ‌
  • Patent US1457069 : Receiving System For Electrical Waves. Published on 1923 (improvements to No.1,734,038). ‌
  • Patent US1466841 : Antiparasitic Selecting System. Published on 1923 (improvements to No.1,457,069). ‌

literature

  • Lawrence P. Lessing: Man of High Fidelity: Edwin Howard Armstrong . JB Lippincott Company 1956
  • Tom Lewis: Empire of the Air: The Men Who Made Radio . Harpercollins 1991. ISBN 0060182156

Web links

Commons : Edwin Howard Armstrong  - Collection of Images, Videos and Audio Files
  • Edwin H. Armstrong (Eng.) A very detailed page about the life of Armstrong with many historical documents

Individual evidence

  1. ↑ Patent DE291604 : Device for generating electrical vibrations. Registered on April 13, 1913 , inventor: Alexander Meissner ( Online @ DepatisNet ). ‌
  2. ↑ Patent US1113149 : Wireless Receiving System. Registered on October 29, 1913 , inventor: EH Armstrong. ‌
  3. ↑ Patent FR493660 . ‌
  4. ↑ Patent US1734038 . ‌
personal data
SURNAME Armstrong, Edwin Howard
BRIEF DESCRIPTION American electrical engineer, radio technician, and inventor
DATE OF BIRTH December 18, 1890
PLACE OF BIRTH New York City
DATE OF DEATH February 1, 1954
Place of death New York City