RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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By now, most people involved with spread
spectrum communications are (or should be) aware that Hollywood starlet
Lamarr is credited for being the first to suggest a frequency hopping scheme
for secure communications. If you do a Google search on Hedy Lamarr and spread spectrum,
you see that except for a few mentions on tech websites, it has only been in the
news since the end of the last decade. Scientific American magazine ran
an article titled, "Hedy Lamarr: Not Just a Pretty Face," in 2008.
Google honored her on November 9 (her birthdate), 2015, with a
"The most beautiful woman in the world," with the assistance of her co-inventor-composer
George Antheil, came up with the idea while working on a piano piece. Ms. Lamarr
and Mr. Antheil were concerned about the massive torpedo attacks by German
U-boats against not only naval ships but passenger
and merchant ships in the northern Atlantic ocean. The objective was to discourage
supply shipments to Europe, which was already under siege by the Third Reich. Radio-controlled
torpedoes were used by Allied forces against Axis warships and submarines, but the
signals were easily jammed by high power transmitters broadcasting on the same frequency
as the controller. Frequency hopping would allow the controller to change frequency
faster than the enemy could keep up with to block. Both the transmitter and the
receiver are given an identical schedule of frequencies and times for synchronization
(using a player-piano type of tape for programming). Just as your ears
and brain can pick out known notes to a melody while ignoring other non-related
notes playing simultaneously, the spread spectrum receiver heeds only information
on its frequencies and ignores all others.
Lamarr and Antheil share the patent titled "Secret Communication System" (US2292387)
which was granted on August 11, 1942; however, the military did not adopt the scheme
for tactical use until nearly two decades later. Interestingly, the patent application
was filed on June 10, 1941 - six months prior to the Japanese bombing of Pearl Harbor
that marked America's official entrance into World War II. Note also that the
inventors are listed as George Antheil and Hedy Kiesler Markey. Hedy Lamarr was
her screen name, Markey was her married name, and her birth name was Hedwig Eva
"Bombshell: The Hedy Lamarr Story," produced by
Zeitgeist Films, is just now showing in select theaters around the country, so it
will be a few months before it is available online or on DVD. I realize that the
double entendre created by using the the term "https://www.merriam-webster.com/dictionary/bombshell" refers
to both explosive torpedoes and the common vernacular for a very attractive woman.
However, it is notable that a film meant at least partly to quash the concept of
recognizing women for their beauty rather than for their brains would choose to
make such a blatant comparison. Surrendering of core principles is often done in
the pursuit of profit (aka hypocrisy).
Bombshell: The Hedy Lamarr Story
Secret Communication System - U.S. patent
"This invention relates broadly to secret communication systems involving the
use of carrier waves of different frequencies, and is especially useful in the remote
control of dirigible craft, such as torpedoes.
An object of the invention is to provide a method of secret communication which
is relatively simple and reliable in operation, but at the same time is difficult
to discover or decipher.
Briefly, our system as adapted for radio control of a remote craft, employs a
pair of synchronous records, one at the transmitting station and one at the receiving
station, which change the tuning of the transmitting and receiving apparatus from
time to time, so that without knowledge of the records an enemy would be unable
to determine at what frequency a controlling impulse would be sent. Furthermore,
we contemplate employing records of the type used for many years in player pianos,
and which consist, of long rolls of paper having perforations variously positioned
in a. plurality of longitudinal rows along the records. In a conventional player
piano record there may be 88 rows of perforations, and in our system such a record
would permit the use of 88 different carrier frequencies, from one to another of
which both the transmitting and receiving station would be changed at intervals.
Furthermore, records of the type described can be made of substantial length and
may be driven slow or fast. This makes it possible for a. pair of records, one at
the transmitting station and one at the receiving station, to run for a length of
time ample for the remote control of a device such as a torpedo.
The two records may be synchronized by driving them with accurately calibrated
constant speed spring motors, such as are employed for driving clocks and chronometers.
However, it is also within the scope of our invention to periodically correct the
position of the record at the receiving station by transmitting synchronous impulses
from the transmitting station. The use of synchronizing impulses for correcting
the phase relation of rotary apparatus at a receiving station is well-known and
highly developed in the fields of automatic telegraphy and television."
Posted January 23, 2018
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