FFSK

The software method is introduced by employing DDFS technology to realize the transformation of digital signal into FFSK signal. The conventional DDFS technology is improved a lot to achieve its function on single chip micro-computer without using too much resources.

采用直接数字频率合成（DDFS）技术，实现数字信号转换成FFSK信号的软件方法，对常用DDFS技术进行改进，使其能够在通用型单片机上实现而无需占用太多资源。

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The results show that the FFSK has more virtues of phase continuation and higher band utilization than FSK and PSK/ DPSK.

结果表明：FFSK调制解调器具有相位连续、包络恒定的特征，频带利用率优于一般FSK和PSK/DPSK。

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Software Arithmetic of Sending FFSK Signal in Portable Shunting Unit

平调手台设备中发送FFSK信号的软件算法

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