本文介绍光盘驱动器中使用的EFM(Eight to Fourteen Modulation)调制及解调系统,给出了该系统的调制码表及主要电路的逻辑图。该系统的调制码是综合了调制和解调二方面的实现难度,经计算机最佳化后得到的,因此解调系统的电路特别简捷。结合位的添加由简便的逻辑电路实现,从而提高了调制速度。 This article describes the EFM (Eight to Fourteen Modulation) modulation and demodulation system used in optical disk drives, and presents the system’s modulation code table and the logic diagram of the main circuit. The system modulation code is a combination of modulation and demodulation of the realization of the two aspects of difficulty, obtained by computer optimization, so the demodulation system circuit is particularly simple. The addition of a combination of bits is facilitated by a simple logic circuit, thereby increasing the modulation speed.