USS Fessenden (DE-142)
She was named in honor of Reginald Aubrey Fessenden, born in Brome County, Quebec, Canada, 6 October 1866. He served as head chemist with Thomas Edison's East Orange, New Jersey, laboratories. In 1890 he began concentrating on electrical engineering, and through the next years made many important inventions and improvements in existing devices. His great contributions in the field of radio (particularly the invention of radio-telephony were of marked benefit not only to the Navy but to all seamen. He died 22 July 1932, at his home on Bermuda.
Radio receiver
In 1901 Reginald Fessenden had invented a better means of accomplishing this. In his "heterodyne receiver" an unmodulated sine wave radio signal at a frequency f" offset from the incoming radio wave carrier f" was applied to a rectifying detector such as a crystal detector or electrolytic detector, along with the radio signal from the antenna. In the detector the two signals mixed, creating two new "heterodyne" (beat) frequencies at the sum f" + f" and the difference f" − f" between these frequencies. By choosing f" correctly the lower heterodyne f" − "f" was in the audio frequency range, so it was audible as a tone in the earphone whenever the carrier was present. Thus the "dots" and "dashes" of Morse code were audible as musical "beeps". A major attraction of this method during this pre-amplification period was that the heterodyne receiver actually amplified the signal somewhat, the detector had "mixer gain".