A Signal That Could Jump
Imagine trying to send a secret message over the radio while someone is trying to drown it out with noise. During World War II, inventor and actor Hedy Lamarr and composer George Antheil worked on an idea to make that kind of interference harder. Their invention used a signal that changed frequencies again and again.
A radio frequency is one of the channels over which a radio signal can travel. If a message stays on one frequency, an enemy who finds that frequency can send a stronger signal over it. This interference, called jamming, can keep the intended receiver from hearing the message.
Lamarr and Antheil designed a system in which the sender and receiver would switch frequencies together. Think of two people moving through a long row of doors in the same order. If both know which door to use next and when to move, they can stay together. Someone who does not know the pattern has a harder time following them.
A wartime problem
The inventors hoped their system could help guide a torpedo, a weapon that travels underwater toward a target. Radio signals sent to the torpedo could carry instructions about where to go. But if an enemy jammed the signal, those instructions might not get through.
- interference:
- Something that gets in the way of a signal or activity.
- intended:
- Meant for a particular person or purpose.
- pattern:
- An arrangement or sequence that follows a rule.
- mechanisms:
- Parts of equipment that work together to do a job.
- equipment:
- Tools or devices used for a particular job.
- techniques:
- Ways of doing a particular task.
- wireless:
- Able to send information without connecting wires.
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Preview questions from this passageShowHide
- 1What problem did Lamarr and Antheil hope their invention would solve?
- 2Why is a message that stays on one frequency easier to jam?
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About this explanatory article passage for Upper Elementary
“A Signal That Could Jump” is a explanatory article reading passage about Frequency-hopping communication, written for Upper Elementary. It takes about 3 minutes to read (483 words) and comes with an interactive quiz and a printable worksheet with comprehension questions and an answer key.