ManchesterKodierung

ManchesterKodierung, commonly known in English as Manchester encoding, is a line coding scheme used in digital communications to embed a clock signal in the data stream. Each bit is represented by a transition that occurs in the middle of the bit period, enabling the receiver to recover timing from the signal. The scheme is DC-balanced and self-clocking, which helps maintain reliable transmission over AC-coupled channels.

Encoding rules vary by standard. In the common convention, a logical 0 is encoded by a high-to-low transition in the middle of the bit period, while a logical 1 is encoded by a low-to-high transition. Some standards invert these meanings. The method is also known as bi-phase level or Manchester II coding.

Advantages and trade-offs: The mid-bit transition provides straightforward clock recovery but at the cost of reduced data density and increased bandwidth relative to non-return-to-zero signaling. It is simple to implement with basic digital or analog circuitry and is robust to DC drift, which makes it suitable for certain long or noisy transmission paths.

Historically, ManchesterKodierung played a key role in early Ethernet (10 Mbps) and other legacy networks, where DC balance and clock recovery were important. It remains a foundational concept in digital design and education, even though modern high-speed interfaces often employ other line codes to achieve greater efficiency.

See also: Differential Manchester encoding, Bi-phase code. Variants such as differential Manchester扱 different transition semantics while preserving self-clocking properties.