Reginald Fessenden was an American engineer, physicist, and inventor who was a pioneer in radio and echo-sounding. He is thought to have broadcast the first radio program (using speech signals, not Morse code in 1906 from a transmitter he constructed at Brant Rock, Massachusetts. Fessenden developed a new type of wireless system using continuous waves. Among his 500 or so patents were amplitude modulation (AM), the high-frequency alternator, the electrolytic detector, the heterodyne system of radio detection, and the fathometer.