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本文介绍一种高稳定度频移键控(FSK)调制解调方法,它的调制解调中心频率全部由晶体确定,其稳定度比传统的压控振荡器和锁相环实现方法提高3～4个数量级。当调制信号的任一逻辑电平在一个较宽范围内波动时,调制输出的FSK信号能够保持一个固定大小的频偏。作者用全数字TTL集成电路实现了这种调制解调器,并且在以电源线为介质组成的计算机通信网络中进行了成功的实验。
This paper introduces a high stability frequency shift keying (FSK) modulation and demodulation method, its modulation and demodulation center frequency all determined by the crystal, the stability than the traditional voltage-controlled oscillator and phase-locked loop method to improve 3 ~ 4 orders of magnitude. When any one of the logic levels of the modulated signal fluctuates over a wide range, the modulated output FSK signal maintains a fixed-size frequency offset. The author implemented this modem with an all-digital TTL integrated circuit and conducted successful experiments in a computer communication network composed of power lines.