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) stage. A variable filter is tuned to filter out everything but the desired radio station's carrier frequency. Along with the homodyne receiver, direct conversion was one of the earlier methods of building radios, both of which were superseded by the superheterodyne approach. See superheterodyne receiver.