实验案例，? 1.了解HDB3码的编译码原理 ? 2.通过仿真验证HDB3码的原理 ? 3.分析HDB3码的优缺点(Experiments, 1. Understanding the encoding and decoding principles of HDB3 codes 2. Verify the principle of HDB3 code by simulation 3. Analysis of the advanta