用高信噪比渐近式研究调相通信系统的性能。用简单而又最理想的近似方法,导出相干及相位比较两种解调方式的误差概率。另外,导出简单的相位比较解调的渐近衰减表示式。当信号的每次取样比特数足够大时,发现组合的数字调幅与调相较单独的调相更有效地利用发射机的功率。在最小峰值功率或最小平均功率情形下,应用近似表达式来求误差概率,就可选出幅度电平数。在峰值功率情形下,能找到一个解析的解,最理想的是指数仅为2的数值解,而对于平均功率情况,亦该如此。因此表中列出在上述限制下的最佳电平数。 Asymptotic Analysis of Phase Modulation Communication Systems with High Signal to Noise Ratio. With the simple and ideal approximation method, the error probability of two demodulation methods of coherent and phase comparison is deduced. In addition, we derive the simple asymptotic attenuation representation of phase comparison demodulation. When the number of samples per sample is large enough, the combined digital amplitude modulation and phase modulation are found to make more efficient use of the transmitter power than phase modulation alone. In the case of the minimum peak power or the minimum average power, the approximation expression can be used to find the error probability to select the amplitude level number. In the case of peak power, an analytic solution can be found, ideally a numerical solution with an exponent of only 2, and for the average power case. Therefore, the table lists the best level under the above restrictions.