介绍了TFSK(Time Frequency Shift Keying)-MFSK(Multiple Frequency Shift Keying)的数据传输方法.该系统采用纠错能力很强的串行级联码对信号进行编码,串行级联码的外码选用(255,223)RS码,内码选用(2,1,7)卷积码,信号译码采用软判决维特比(Viterbi)译码方式.TFSK-MFSK调制改善了MFSK因M增加导致频带利用率低的情况,能够更加充裕地组合各个频率进行信号传输,组合信号方式可借鉴跳频扩频思想,不容易受限于频率范围非常窄的水声信道,有效地对抗信号的干扰和衰减.%This paper presents a data transmission technology based on Time Frequency Shift Keying (TFSK) and Multiple Frequency Shift Keying (MFSK). It takes serial concatenated codes with strong correction ability to signal encoding and the outer codes of serially concatenated code uses (255,223) RS codes, inner codes uses (2,1,7) convolution code. Signal decoding takes soft-decision of Viterbi codes. TFSK-MFSK modulation improves the situation that MFSK increases M resulting in low degree of utilization ratio of bandwidth so that it has more frequency combination ways which use the idea of frequency hopping and spread spectrum for reference to signal transmission. And it is not limited at acoustic channel with narrower frequency range and has more effective anti-jamming and low attenuation ability.
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