On Apr 20, 9:50�am, Tim Shoppa wrote:

A terminology question I suppose about the derivation of the term
"Superheterodyne" more than anything else:

Does the "Super" actually mean anything? Is there a Subheterodyne?

The heterodyning of two signals was barely known around 1902 to
1904 when very early entrepreneur-experimenter Reginald Fessenden
was fooling around in his lab trying to improve the sensitivity of
early coherer-type detectors. Fessenden tried mixing the output
of a very low-power spark transmitter with his simple receiver and
reported getting a clearer tone from a distant station. Fessenden
was keen on making himself known so he wrote that up and it was
published.

However, by 1906 the first audion tube was made and in a few years
later, some production units were available for experimenters,
namely a very young Armstrong...who went on to start gaining fame
with his regenerative tube receiver. By 1918, Amstrong was now a
Major in the US Army and stationed in Paris with WW One having
stopped. Armstrong remembered the Fessenden experiment and
remembered the 'heterodyning' process of mixing low-level RF signals
with higher-level RF (the 'Local Oscillator' as it became known),
getting two extra mixing products out of a 'mixer' stage (sum and
difference of the two main input frequencies). By now academics
had gone into the heterodyning process in more detail with at
least 14 years between Fessenden's experiment and Armstrong's tube
version.

Armstrong's patent application promised an equal-selectivity at
any antenna-input frequency, something not possible with TRF
receivers, narrower at lower frequencies, wider at higher ones.

I suspect that "Super" was more a marketing term than anything
else :-).

Might have been had there been ANY real "market" for radios back
then. Of course, anything RF done with vacuum tubes beat the pants
off any crystal detector and spark transmitter, so it was definitely
a 'super' thing. :-)

Actually, Ed Armstrong had a battle with various nations on the
patent for his superheterodyne, at least a year or two later with
someone in England and another in France. Patent suits would
continue to dog Armstrong until the end of his life, probably
causing the depression that, in turn, caused him to suicide.
Just the same, Armstrong had the chutzpah to promote his ideas
and he is truly the father of FM broadcasting allowing high-
fidelity music to any FM receiver. He was no slouch in getting
organized and promoting himself.

There's a whole lot of material on Edwin Howard Armstrong at
several websites, reachable through members of the Radio Club of
America, the oldest association (since 1909) and still going.
---------------
The three basic forms of modulation of a carrier (amplitude,
frequency, phase) were worked out by John Carson of AT&T in 1915,
before Armstrong got going on his 'superhet' idea. Whether or not
Ed saw those is unknown, but Carson had them worked out already.
Those very early 'radio' experimenters, from academics to amateurs,
were very very busy in the first two decades of 'radio' existance,
going from essentially nothing to several somethings. 'Radio'
stayed a fertile field for scientific-engineering innovation for
three more decades, spurred into a couple quantum jumps during the
World War II years.

Reginald Fessenden sort of faded into the woodwork after his
famous "Christmas Eve" sound broadcast of 1906...using a spark
transmitter whose antenna wire was modulated by a special carbon
microphone! I doubt that any AM broadcast station ever tried to
use that system since so it was an early curiosity in radio history.
Armstrong's name spread and so did his inventions...not just the
regen or superhet, but also the super-regenerative for high HF and
into VHF (note the 'super' addition by the extra oscillation) and,
of course, to FM broadcasting.

73, Len AF6AY