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一、概述频移键控(FSK)是数字通信中一种主要数字调制方式,它具有实现容易,设备比较简单,抗衰落性能好的特点。在海上无线电通信中,不管是采用 Morse 电码形式还是采用无线电纠错直接打字电报都采用 FSK 调制技术进行对话、通信。在 ARQ 系统(Automatic Request for Repetition 自动请求重发)中,FSK 信号的中心频率为1700Hz(或1500,1900Hz),最大频率偏移为±85Hz,对调制速率为100Baud 的基带信号,传号时发出 f_0-85Hz 的载波信号.空号时发出 f_0+85Hz 的载波信号。
I. Overview Frequency Shift Keying (FSK) is a digital communication in a major digital modulation, it has easy to implement, the device is relatively simple, anti-fading performance and good features. In maritime radio communications, FSK modulation techniques are used to conduct conversations and communications, whether in the form of Morse code or direct error correction by radio. In the ARQ system (Automatic Request for Repetition), the FSK signal has a center frequency of 1700 Hz (or 1500, 1900 Hz) and a maximum frequency offset of ± 85 Hz. The baseband signal is transmitted with a modulation rate of 100 Baud f_0-85Hz carrier signal. When empty number issued f_0 +85 Hz carrier signal.