Sound recording and reproduction 1920s when several radio-related developments in electronics converged to revolutionize the recording process. These included improved microphones and auxiliary devices such as electronic filters, all dependent on electronic amplification to be of practical use in recording. In 1906, Lee De Forest invented the Audion triode vacuum tube, an electronic valve that could amplify weak electrical signals. By 1915, it was in use in long-distance telephone circuits that made conversations between New York and San Francisco practical. Refined versions of this tube were the basis of all electronic sound systems until the commercial introduction of the first transistor-based audio devices in
John P. Costas (engineer) properties for the problem. Costas was made a fellow of the Institute of Electrical and Electronics Engineers (IEEE) in 1965 for "contributions to communications theory and techniques." Among Costas' most notable publications are the following, John P. Costas (engineer) John Peter Costas (1923 in Wabash, Indiana – 2008) was an American electrical engineer. Costas invented, among other things, the Costas loop and Costas arrays. Costas studied at Purdue University as an undergraduate. During World War II, he was involved in radar engineering, serving in the U.S. Navy as a radar officer. He was a graduate student at Massachusetts Institute of