正则表达式是使用各种构件构建的复杂模式规范，并且随着模式变得越来越复杂，它看起来就像是调制解调器的线路噪声。
Regular expressions are complex pattern specifications built using building blocks that end up looking more like modem line noise as the pattern gets more complex.
由于BBS的复杂性、局限性，而且速度缓慢，早期系统的用户大半是愿意支付一大笔钱购买速度最快的调制解调器的计算机狂热者。
Because of the complexity, limitations and slowness of BBS, the early system was largely populated by computer enthusiasts willing to shell out big bucks for the fastest modems.
时钟同步和载波同步是接收机的关键问题，传统模拟解调可靠性、稳定性差，调试复杂。
Time synchronization and carrier synchronization are cruxes of receiver. The reliability and stability of traditional analog demodulation are bad, and adjustment is complex.
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