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本文对由叉线所产生的调幅及调频波进行了比较。根据调制波每一频谱分量的功率含量的计算,确定了带宽及调制指数的最优值。证明了调制指数为1.8及带宽仅仅包含第一组边带的调频系统具有最高的有效信噪比。采用这个带宽及调制指数值时,与工作在相似条件下的调幅系统相比,调频系统在有效信噪比方面略占优势。尚若带宽及调制指数二者之一明显地偏离其最优值,则有效信噪比之优势即将失去。对叉线产生的各种调制波进行了计算。
This article compares the AM and FM waves generated by the fork lines. According to the calculation of the power content of each spectral component of the modulated wave, the optimal values of bandwidth and modulation index are determined. It is proved that FM system with modulation index of 1.8 and bandwidth only contains the first set of sidebands has the highest effective SNR. Using this bandwidth and modulation index values, the FM system is slightly more effective than the AM system operating under similar conditions. Still, if one of the bandwidth and modulation indices clearly deviates from its optimal value, the advantage of an effective signal-to-noise ratio is about to lose. Various modulation waves generated by the fork line were calculated.