Encoder and Decoder
| Collection | GlossariumBITri |
|---|---|
| Author | José María Díaz-Nafría |
| Editor | José María Díaz-Nafría |
| Year | 2010 |
| Volume | 1 |
| Number | 1 |
| ID | 18 |
| Object type | Concept |
| Domain | Communication Theory Telecommunication Transdisciplinary |
| es | codificador / decodificador |
| fr | codificateur / decodificateur |
| de | Kodierer / Dekodierer |
Encoder is a device for converting data or signals by using a specific code. It is normally used with four clearly differentiated purposes: 1) To remove redundancy or anything that is not going to be perceived by the information receiver or remain beyond the quality goals of the received signal, typically named source encoder; 2) To increase redundancy, so that the decoder can eventually detect and correct the errors occurred within the reception of signals or symbols, named channel encoder; 3) To make the coded data unreadable, except if the recipient knows the code, by using encryptors or ciphers; 4) To allow the transmission of data through a channel with certain resources and limitations, corresponding in the MTC communication model to the transmitter-encoder, also named modulator -especially in telecommunications-.
The decoder is the device performing the inverse operation of the encoder, whatever the purpose of the code: 1) the source decoder tries to restore the eliminated redundancy; 2) the channel decoder removes the redundancy that has been introduced by the corresponding encoder, and correct those errors being detected; 3) the unencryptor makes the data readable; and 4) the demodulator or receiver-decoder identifies the symbol transmitted through the channel –normally according to a maximum likelihood criterion– and restate the data into its original form, i.e., how it was before the modulator.
References
- SHANNON, C. E. (1948). “A Mathematical Theory of Communication”. The Bell System Technical Journal, Vol. 27, pp. 379–423, 623–656, July, October, 1948.
- SHANNON, C. y WEAVER, W. (1949). The mathematical theory of communication. Urbana: The University of Illinois Press, 1949.
- SKLAR, Bernard (2001). Digital Communications. Fundamentals and Applications. New Jersey: Prentice Hall.