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移频键控(FSK)是目前短波数传的重要方式,由于信道噪声及多径传输中选择性衰落的影响,误码率高是个未曾解决的问题。本文提出了用窄带锁相环路解调的方案,并给出了初步的实验结果。进而论述了此种解调方式可以减小白高斯噪声、多径传输中时间选择性衰落及频率选择性衰落的影响,使误码率降低的原理,提出了增高短波 FSK 方式传输速率的可能性。通过理论计算,获得了白高斯噪声作用下的误码率曲线,将它与普通的相干与非相干解调方式相比,可以看出本文提出的解调方式,误码率有明显的降低。
Frequency shift keying (FSK) is an important way of shortwave data transmission. Due to channel noise and selective fading in multipath transmission, the high bit error rate is an unsolved problem. In this paper, a scheme of demodulation with a narrowband PLL is proposed and the preliminary experimental results are given. Furthermore, the principle that this demodulation method can reduce the effects of white Gaussian noise, time-selective fading and frequency selective fading in multipath transmission and reduce the bit error rate is proposed, and the possibility of increasing the transmission rate of the short-wavelength FSK mode is proposed . Through theoretical calculation, we get the error rate curve under the effect of white Gaussian noise. Compared with the common coherent and non-coherent demodulation methods, we can see that the proposed demodulation method and bit error rate are significantly reduced.