Line code意思
"Line code" is a term used in telecommunications and electronics to refer to the encoding scheme used to represent digital data as electrical signals for transmission over a communication line. The line code defines how the binary data (bits) are converted into a form that can be sent over a physical medium, such as a copper wire or a fiber optic cable.
There are several types of line codes used in different applications, depending on the characteristics of the transmission medium and the requirements for error rate, bandwidth efficiency, and signal integrity. Some common line codes include:
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Non-Return-to-Zero (NRZ): In NRZ, a binary 1 is represented by a constant positive voltage, and a binary 0 is represented by a constant negative voltage. There is no change in voltage level to indicate the start or end of a bit.
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Manchester encoding: In this scheme, each bit is represented by a change in the signal level that occurs at the middle of the bit time. The transition at the start of a bit represents the data bit, and the transition at the middle is used for clock recovery.
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Differential Manchester encoding: Similar to Manchester encoding, but the transition at the start of the bit is not used for data. Instead, the absence of a transition indicates a binary 0, and a transition indicates a binary 1.
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Biphase mark encoding (BPM): In BPM, each bit is represented by a phase change in the signal. A binary 0 is represented by a signal that does not change phase, and a binary 1 is represented by a phase change.
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8B/10B encoding: This is a block coding technique used in high-speed data transmission to ensure DC balance and to provide a means of synchronization and error detection. It encodes 8-bit bytes into 10-bit symbols.
The choice of line code can affect the quality of the signal transmitted, the amount of bandwidth required, and the ability to detect and correct errors. Line codes are an important consideration in the design of communication systems to ensure reliable and efficient data transmission.