Manchester Coding and differential Manchester Coding

Manchester Encoding(Manchester Encoding), also known as Phase Encoding (PE), is commonly used for LAN transmission. In Manchester Coding, there is a hop in the middle of each bit. The hop in the middle is both a clock signal and a data signal. However, in different books, in Manchester encoding, the value of the level beat expression is different, which produces many ambiguities:
1. Network Engineer ExaminationAnd related materials:
Bit CenterThe jump from high to low indicates "0 ";
Bit CenterThe jump from low to high indicates "1 ".
2 《 Computer NetworkIn books:
Bit CenterThe jump from high to low indicates "1 ";
Bit CenterThe jump from low to high indicates "0 ".
The "computer communication and network tutorial" and "Computer Network (version 4th)" published by Tsinghua University are also said in this regard. We call this as a standard. Standard Manchus Encoding. As for the first type, we will call it here Manchester Encoding. However, remember to be flexible in different situations. Otherwise, the score will be deducted by the teacher.. The two are the opposite. Do not confuse them. What we want to talk about now is Differential Manchester Encoding:
Letter Number Start TimeDoes not change the Signal Polarity, indicating the series "1"
Letter Number Start TimeChanges the polarity of the signal, indicating the logic "0 ";
【 Note]: If at the initial signal, that is First SignalHour:
If the intermediate bit level is from low to high, it indicates 0;
If the intermediate bit level is from high to low, it indicates 1;
The next one (from the second one) is determined by the absence of hop changes at the beginning of each signal bit:
Here is an example to compare the standard Manchester encoding, Manchester encoding, and differential Manchester encoding: