Stereo generator

A stereo generator is an electronic device designed to encode stereophonic information for transmission over radio or television. It generally only refers to analog audio.

Radio

FM

;CCIR
FM stereo uses a double-sideband suppressed carrier (DSSC or DSB-SC) on a 38kHz subcarrier. This carries the "left minus right" (stereo difference) signal, while the baseband audio is the monophonic "left plus right" (stereo sum). It can be mathematically shown that time multiplexing the left and right audio channels (alternately switching between left and right) at a rate of 38 kHz and low-pass filtering at 54 kHz accomplishes the same effect. In both cases, the 19 kHz pilot is derived from the 38 kHz carrier and added to the result before the signal is passed to the FM modulator.;OIRTThe old Soviet system uses polar modulation.

AM

The most common method for AM Stereo is the Motorola C-QUAM system, which has been the de facto worldwide standard since the early 1990s. Previous systems for AM Stereo included Leonard Kahn's independent sideband system, as well as systems developed by Harris Corporation and Magnavox. These alternative systems fell out of use as various countries adopted C-QUAM as their official standard for AM Stereo, including Australia in 1985, Mexico and Canada in 1988, Japan in 1992, and the USA in 1993.

Television

NTSC

The main audio is on a separate carrier, but the stereo difference is a subcarrier of the "video" carrier. See multichannel television sound.

PAL

ÉCAM