What are the hdb3 encoding rules?

The encoding rules are: 1. The number of consecutive 0s does not exceed 3, and the rules are the same as AMI; 2. If the number of consecutive 0s exceeds 3, then every 4 0s are regarded as a section, defined as B00V; 3 , B and V satisfy that V has the same polarity as the previous adjacent non-0 symbol. When not looking at V, the polarity alternates, and the polarity alternates between V and V; 4. Generally, the first B is 0, and the first non-0 symbol Take -1.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

1. Coding rules:

1. When the number of consecutive 0s does not exceed 3, the rules are the same as AMI, that is, 0 remains unchanged, 1 becomes -1, and 1 alternates;

2. If the number of consecutive 0s exceeds 3, each 4 0s will be regarded as a section and defined as B00V. B can be -1, 0, 1, and V can be -1, 1;

3. The specific values ​​of B and V meet the following conditions: V has the same polarity as the previous adjacent non-0 symbol; the polarity alternates when V is not looked at; the polarity alternates between V and V;

4. Generally, the first B is taken as 0, and the first non-0 character is taken as -1.

Extended information:

Principle: HDB3 code must contain the alternating characteristics of AMI so that the output has no DC characteristics, and must not have more than four consecutive zeros. Therefore, You can satisfy the latter first.

　1. Replace "0000" with a replacement stanza.

Rules: Separate "0000" first, the first "0000" directly becomes "000V", then count the number of "1"s between two adjacent "0000"s, and the odd number is becomes "000V", and even numbers become "B00V".

　2. Update symbols.

According to the textbook: B is always the opposite sign of the preceding 1 or V, V is always the same sign as the preceding 1 or B, and 1 is always the opposite sign of the preceding V or B, so you can program Symbol.

For example:

Message code: 1 0 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1

　Intermediate code: 1 0 0 0 V 1 0 0 0 V 1 1 B 0 0 V 1 1 B 0 0 V B 0 0 V 1 1 1 0 0 0 V 1

　HDB3 Code: 1 0 0 0 V -1 0 0 0 -V 1 -1 B 0 0 V -1 1 -B 0 0 -V B 0 0 V -1 1 -1 0 0 0 -V 1

2. Characteristics of HDB3 code:

1 The baseband signal determined by HDB3 code has no DC component and only a small low-frequency component; 2 The number of consecutive 0 strings in HDB3 is at most 3 , easy to extract timing signals.

　3 The encoding rules are complex, but the decoding is relatively simple.

3. Decoding rules

1. Find the point that destroys the polarity alternation in the received symbol sequence. It can be concluded that the symbol and the three preceding symbols must be consecutive 0 symbols, thus restoring 4 consecutive codes;

　2After converting all -1 to 1, you can get the original message code

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