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In telecommunications, node-to-node data transfer is the movement of data from one node of a network to the next. In the OSI model it is handled by the lowest two layers, the data link layer and the physical layer. In most communication systems, the transmitting point applies source coding, followed by channel coding, and lastly, line coding. This produces the baseband signal. Some systems then use modulation to multiplex many baseband signals into a broadband signal. (The receiver un-does these transformations in reverse order: demodulation, trellis decoding, error detection and correction, decompression). Some communication systems omit one or more of these steps, or use techniques that combine several of these steps together. For example, a Morse code transmitter combines source coding, channel coding, and line coding into one step, typically followed by an amplitude modulation step. Barcodes, on the other hand, add a checksum digit during channel coding, then translate each digit into a barcode symbol during line coding, omitting modulation. ==Source coding== :''See main article Data compression'' Source coding is the elimination of redundancy to make efficient use of storage space and/or transmission channels. Examples of source coding are: *Huffman coding *Morse code *Binary coding 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Node-to-node data transfer」の詳細全文を読む スポンサード リンク
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