Not exactly. FM was proposed first by Edwin Howard Armstrong in 1935 paper: "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation"
Class D amplifier was proposed first by P.J Baxandal in 1959.
First commercial class D amplifier was designed by Gordon Edge and manufactured by Clive Sinclair in 1964 under name X-10.
www.nvg.ntnu.no/sinclair/audio/gallery/x-10_boxed.jpg
www.nvg.ntnu.no/sinclair/audio/gallery/x-10_ad.jpg
It was Hi-Fi amp - it says so on the box (LOL)
Class D amplifier was proposed first by P.J Baxandal in 1959.
First commercial class D amplifier was designed by Gordon Edge and manufactured by Clive Sinclair in 1964 under name X-10.
www.nvg.ntnu.no/sinclair/audio/gallery/x-10_boxed.jpg
www.nvg.ntnu.no/sinclair/audio/gallery/x-10_ad.jpg
It was Hi-Fi amp - it says so on the box (LOL)