but it’s astoundingly simple and in the early years of the 20th century it offered a huge improvement over the much simpler tuned radio frequency (TRF) receivers that were the order of the day.

Also called a "tuned radio frequency" (TRF) receiver, it is a radio receiver that detects and demodulates the carrier signal broadcast by the station without using an intermediate frequency (IF ...

Early radio receivers worked on a principle called Tuned Radio frequency (TRF), patented in 1916. They weren’t very easy to use, requiring each stage to be tuned to the same frequency (until ...

In 1960, radio astronomer Frank D. Drake ... and would constitute a universal “hailing frequency.” A single 100 Hz channel receiver was slowly tuned up and down the dial to cover 400 kHz. Drake ...