He is one of several people who can claim to have invented television. He invented the picture tube and built the first all-electric TV set. He had built his first prototype in 1927, and presented it in 1928. For the next few years, Farnsworth fought a battle with RCA over his patents. By 1936, he was filming television programs. He did a lot of research in nuclear fusion. He also invented the modern method of air-traffic control.