The receiver un-does these transformations in reverse order: demodulation, trellis decoding, error detection and correction, decompression.
Source coding is the elimination of redundancy to make efficient use of storage space and/or transmission channels.
[citation needed] Examples of source coding are: In digital telecommunications, channel coding[3] is a pre-transmission mapping applied to a digital signal or data file, usually designed to make error-correction (or at least error detection) possible.
Types of channel coding include: Line coding consists of representing the digital signal to be transported, by an amplitude- and time-discrete signal, that is optimally tuned for the specific properties of the physical channel (and of the receiving equipment).
The waveform pattern of voltage or current used to represent the 1s and 0s of a digital signal on a transmission link is called line encoding.