Communication principle coding
Non-return-to-zero code NRZ
0 is 0, 1 is 1.
Return to zero code RZ
The level jumps back to 0 before the symbol ends.
That is, 0 is 00, and 1 is 10. Anyway, when the symbol ends, it will become 0.
Manchester Encoding (Biphase Code) Manchester
01 represents 0, 10 represents 1
Or 10 for 0 and 01 for 1.
A man named GE Thomas proposed the first one in 1949.
The second type is proposed in IEEE 802.4 (Token Bus) and the low-speed version of IEEE 802.3 (Ethernet).
Not to mention which one to use, basically the second one is the default.
I refer to
an article for you to understand - Manchester Coding
Mark Alternate Inverse Code AMI
0 is 0, and 1 is alternately represented by +1 and -1.
For example, 100001000011100011
is +10000-10000+1-1+1000-1+1
Mark Inversion CMI
0 is represented by 01, and 1 is represented alternately by 11 and 00.
Three-order high-density bipolar code HDB3
First change the fourth 0 of all four consecutive 0s in the code to V.
Then find the range with an even number of 1s between two adjacent Vs, find the first 1 from the last V in this range, change the 0 behind the first 1 into B, and change all the values in this way Range B.
Finally, V has the same polarity as the previous non-zero symbol (1 or B), B has the opposite polarity to the previous non-zero symbol, and 1 has the opposite polarity to the previous symbol. If it continues, it will alternate positive and negative. The above rules go to write the plus and minus signs. (The first 1 starts with the + sign)
Miller
To put it bluntly, 1 is jumping between 10 and 01, and 0 is 11 or 00. They all have to pick up with the previous one, except for consecutive 0's that jump back and forth.
Explanation diagram:
