When was FM radio invented?

FM radio was invented in 1933 by Edwin Armstrong. The technology uses frequency modulation to control noise static generated by Earth's atmosphere and electrical equipment to improve radio audio signals. Armstrong's invention of the FM radio is recorded as U.S. patent 1,342,885.

At the time of its invention, FM radio was not adopted by the radio industry. To prove the benefits of FM radio, Armstrong spent $300,000 of his own wealth to build a full-scale FM station in 1939. As of 2015, the FM format is the preferred system setup for radio stations and is a required channel for all broadcast television audio.