HDB3 Code: Advantages, Applications, and Comparison to AMI Code

Academic paraphrasing: HDB3 code stands for 'high-density bipolar 3rd order code', which is an improved version of AMI code. Its purpose is to maintain the advantages of AMI code while overcoming its limitations by limiting the number of consecutive zeros to no more than 3. HDB3 code retains the advantages of AMI code and is useful for error detection and extraction of timing signals. HDB3 code is the most widely used code type and is used for A-law PCM interface code types below 4th order group, while µ-law PCM interface code types below 4th order group use scrambled AMI code to reduce the number of consecutive zeros.