Gregory W. Wornell Dept. Electrical Engineering and Computer Science - - PowerPoint PPT Presentation

Gregory W. Wornell

• Dept. Electrical Engineering and Computer Science

Massachusetts Institute of Technology

June 16, 2010 WITHITS Session International Symposium on Information Theory

How can radio-control of torpedoes be made jam-resistant?

Frequency-hopped spread spectrum.

• Hedwig (Hedy) Eva Maria Kiesler, b. 1913, Vienna
• high-school dropout with mathematical bent
• in 1930, started studying acting in Berlin
• in 1932 (age 19), appears in Czech film Ecstacy
• made worldwide cinematic history for what was not in the film
• in same year, married Fritz Mandl – older, wealthy,

prominent, (and domineering) Austrian munitions dealer (to Germany and Italy)

• spent time helping entertain customers; learned about weapon

systems engineering

• becomes disenchanted with Mandl, and Nazis
• escaped from her maid, ended up in Hollywood via

London; new life

• signs with Louis Mayer (MGM), 1939
• new name (Lamarr), “wholesome” films, star
• gets involved with composer George Antheil
• Antheil uses 16 player pianos in sync in a concert
• she makes a connection to anti-jam torpedo radio

control

• patent enbodiment uses Tx and Rx player piano rolls

perforated with identically (88-frequency) hopping patterns

“…it is veritably impossible for an enemy vessel to `jam’ or in any way interfere with the radio-direction

• f such a previously synchronized torpedo because,

simply, no ship may have enough sending stations aboard or nearby to `jam’ every air-wavelength possible or to otherwise succeed except by barest accident to deflect the course of the oncoming radio controlled torpedo – unless, of course, it happened to have the exact synchronization pattern between sender-ship and torpedo.”

• Navy couldn’t use – 20 years ahead of its time
• gave the patent to the US government; turned

to promoting war bonds

• patent withheld from public until 1981
• cited by >1000 US Patents as prior art
• Sylvania enabled with transistor circuit, 1957
• first used in the 1962 Cuban embargo
• concept now used everywhere, from Milstar to

IS-95 to bluetooth

• Bob Price (RAKE receiver) learned of Lemarr’s invention

from his (author) sister, who’d run across her name

• about the time the patent was declassified (1981)
• wasn’t known at the time of Scholz’ “Origins of Spread-

Spectrum Communications” May 1982 TCOM article

• Price interviewed Lemarr August 1982; appeared in

Price’s “Further Notes and Anecdotes” follow-up Jan. 1983 TCOM article

• son accepted 1997 Electronic Frontier Foundation Award

for “contribution to pioneering electronics” on her behalf; she lived (modestly) until 2000

• the value of taking the path less chosen, an

independent streak, and being self-sufficient and resourceful

• didn’t “play it safe”; wits, confidence, instinct
• the aesthetic appeal of practical solutions to real

problems, and the satisfaction that accompanies their pursuit

• just as much theory as needed and no more
• the dignity of life without self-promotion
• dedication to a broader cause than personal gain