Stereodecodering

Stereodecodering is a process used in audio engineering to extract stereo sound from a signal that has been encoded in a particular way. This encoding is often used in broadcasting, particularly for FM radio, to transmit two audio channels (left and right) using a single carrier wave. The most common method for this is called the matrix encoding system, where the left and right channels are combined into a single monaural signal for transmission, along with additional information to allow for reconstruction of the original stereo image at the receiver.

The decoder at the receiving end, such as a stereo radio, performs the inverse operation. It takes the transmitted signal, which contains the sum of the left and right channels (often referred to as the "sum" or "M" signal) and a difference signal (often referred to as the "difference" or "S" signal), and uses them to recreate the original left and right channels. The sum signal carries the information present in both the left and right channels, while the difference signal contains the information that is unique to either the left or the right channel. By adding and subtracting these two signals in specific proportions, the decoder can accurately reconstruct the separate left and right audio signals, allowing the listener to experience stereo sound. This process is crucial for maintaining the spatial qualities and depth of the original stereo recording.