Signal processing technique which uses both compression and expansion to improve dynamic range and signal-to-noise ratio.
A signal is passed through a non-linear transformation prior to transmission. A reverse of this transformation occurs at reception. The transformation is such that quiet portions are boosted and loud portions reduced. Noise is reduced because the quiet signals are louder, compared to the noise in the transmission channel.
Used in digital, PCM, transmissions as well as analog applications. Dolby is a common example of a compander-based noise reduction system.
