Manchester Line Decoder
Manchester Line Encoder
Answers to Questions
How to encode using Manchester?
A signal coded with Manchester is constituted of a logic 0 is indicated for a transition from the low level to the high level or a logical 1 for a transition from the high level to the low level.
The line coding can be modeled as a 'xor' ⊕, or logical exclusive with the signal of the synchronization clock.
Depending on the standard used, the binary code may be totally inverted. The IEEE 802.4 standard used for Ethernet buses is the opposite of what was originally proposed by G. E. Thomas as the inventor of Manchester coding.
The Manchester code, when written, takes 2 times more space than the original code (while the signal is in practice of the same length).
How to decrypt a Manchester line code
Deciphering consists in listing the transitions and decoding them thus: from high to low: logical 1, from low to high: logical 0. When the XOR is re-made with the synchronization clock, the original signal is found again.
|Original Signal||__¯¯||0 1|
In writing, the original code is 2 times shorter than the Manchester code (while the signal is in practice of the same length).
How to begin with a negative polarity?
The IEEE802.4 bus network Ethernet standard uses the Manchester code, but reverses the encoding (0 and 1). In this standard, a logical 1 is indicated for a transition from the low level to the high level and a logical 0 for a transition from the high level to the low level.
When Manchester coding has been invented?
G. E. Thomas was the first to have presented the Manchester coding in 1949.