Edwin Howard Armstrong
- a summary of the life of Edwin Armstrong, the man credited with several
radio inventions including the superhet or superheterodyne radio, the
regenerative receiver, and wideband FM.
Edwin Armstrong was a man who gave much to the development of
radio or wireless technology. Starting at a very young age, he developed the
first regenerative radio receiver, was the first to develop and construct a
superhet or superheterodyne receiver, and he also saw the benefits of wideband
FM which he again pioneered. Without Edwin Armstrong, radio technology would
have not developed as fast as it did.
Armstrong's early years
Edwin Howard Armstrong was born on 18 December 1890 and became one of the
foremost inventors in radio technology. However he was primarily a scientist and
not a businessman and as a result he did not gain as much financial reward from
his inventions as might have done. His name is well known to vintage wireless
enthusiasts as a man who brought the developed the regenerative radio receiver
as well as the superhet and wideband FM.
Armstrong had a keen interest in radio, building early radio
sets while still at high school. On graduating from high school he moved to
Columbia University to study engineering. It was while he was here that he made
his first discovery. He investigated the action of de Forest's Audion triode
valve that in these early days of wireless was not well understood. In the
summer of 1912 he devised a circuit that fed part of its output back into the
input to give what is called a regenerative circuit. So successful was this that
he could hear distant stations without the need for headphones. Although others
came up with the idea around the same time as Armstrong, he is normally credited
with the invention of the regenerative receiver. He received his degree in 1913
and filed a patent for his idea.
Armstrong's war service
When the USA joined the war in Europe, Armstrong was commissioned as an officer
in the Army Signals Corps. He was sent to Paris and started work on receivers
for detecting enemy transmissions. This work resulted in the development in 1918
of a new type of receiver that used the heterodyne principle to convert the
incoming signals down to a fixed intermediate frequency where they could be more
effectively amplified and filtered. This new type of receiver was called the
supersonic heterodyne or superhet receiver, because it used heterodynes above
the audible range for its operation.
The end of hostilities the need for his new type of receiver
dwindled. Broadcasting was in its infancy and the small number of stations meant
the need for the selectivity provided by his new set was not needed. As valves
(tubes) were very expensive it was not until the late 1920s that the rise in
broadcasting meant that superhet receivers were needed.
FM development
After the war Armstrong continued his researches. One of the major problems of
the time was that of static noise that reduced the quality of transmissions.
Rather than using the normal amplitude modulated signals, Armstrong devised a
system of using wideband frequency modulation. Unfortunately in the 1930s of the
depression, there was little enthusiasm for a new style of transmission.
Undaunted, Armstrong managed to gain permission to set up an FM station at his
own cost in 1940. It then took two further years before new frequency
allocations were given for this new mode that was proving popular.
Legal battles
Armstrong faced many legal battles over royalties and payments. Facing another
legal battle, Armstrong took his life on 31st January 1954, jumping from his
apartment window in New York. By the 1960s FM was firmly established as the
method to be used for high fidelity broadcast transmissions, and he was
posthumously elected to the line of electrical leaders by the International
Telecommunications Union in Geneva.
|
