Hedy Lamarr's Radio Invention
Written by Studio AM.
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Hedy Lamarr became famous as a film actress in the 1930s and 1940s. She also worked on inventions outside her acting career. During the Second World War, she collaborated with composer George Antheil on a problem involving radio-controlled torpedoes.
A torpedo receiving commands on one radio frequency could lose its instructions if an enemy jammed that frequency with interference. Lamarr and Antheil proposed changing frequencies repeatedly. The transmitter and receiver would follow the same sequence at the same time, so they could keep communicating.
Their design used mechanisms like player-piano rolls to coordinate the changes. Each roll stored a pattern, much as a music roll stored instructions for playing notes. Someone monitoring just one frequency would receive only a fragment of the changing signal. Hopping frequencies could make interference more difficult, though it did not make communication impossible to disrupt.
The pair received a patent in 1942, but the Navy did not put their design into wartime use. Lamarr's contribution to wireless communication received wider recognition decades later. Her inventing work showed an ability that her public image as a movie star did not fully reflect.
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Questions
Choose an answer. The explanation appears after you answer.
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Question 1 of 4
Which statement best expresses the main idea?
The answer is C: Lamarr and Antheil designed a radio system that changed frequencies to resist interference.
Most of the passage explains the problem, their frequency-changing design and its later recognition.
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Question 2 of 4
What problem were Lamarr and Antheil trying to solve?
The answer is A: Interference on one frequency could block a torpedo's commands.
The control signal could be blocked by interference. Their design moved communication between frequencies.
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Question 3 of 4
What would likely happen if the receiver followed a different sequence from the transmitter?
The answer is D: The devices would often use different frequencies and lose contact.
The design relies on both devices changing frequencies together. Different sequences would break that coordination.
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Question 4 of 4
In the passage, 'transmitter' means:
The answer is B: the device that sends out the radio signal
The transmitter sends the commands; the receiver picks them up. Both must follow the same frequency sequence.
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