We ran across a claim that compromising emanations were
discovered in 1918:
http://www.tscm.com/TSCM101tempest.html
"TEMPEST was 'invented' in 1918 when Herbert Yardley and
his staff of the Black Chamber were engaged by the U.S. Army
to develop methods to detect, intercept, and exploit covert radio
transmitters. The initial research identified that "normal unmodified
equipment" was allowing classified information to be passed to the
enemy through a variety of technical weaknesses. A classified
program was then created to develop methods to suppress these
"compromising emanations". However, the actual acronym known
as TEMPEST was only coined in the late 60's and early 70's (and
is now considered an obsolete term, which has since, been
replaced by the phrase "Emissions Security" or EMSEC)."
About the author:
"James M. Atkinson is one of a small number of people who have
been formally certified and trained by the NSA as a TEMPEST
Engineer, and Cryptographic Technician. He has extensive
experience with the design and development of SIGINT systems
to exploit and/or control compromising emanations. Additionally,
he has many hours of experience working deep inside highly
classified U.S. and NATO cryptographic, communications, and
computer systems."
Has this claim been seen in any of the Yardley/Black Chamber
accounts?
