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差动相干移相键控(DPSK)一般用于提供频率耗散信道的数据通信。为了得到更高的数据速率,可增加相位数或使用复合调幅调相。本文中我们对多电平DPSK的特性与带有相加噪声的频率耗散信道Ⅰ型调幅调相的特性进行了比较。对于Ⅰ型系统来讲,差动调制用于对单个比特进行幅度编码,而普通的DPSK用于从单个直至四个相位比特进行编码。本文给出了幅度编码比特和相位编码比特的比特差错率对信道有效信噪比的曲线。从这些曲线中可获得高速率Ⅰ型系统中所使用的幅度调制的适当数值。尔后,在发射机平均功率和峰值功率相等的条件下,对多电平DPSK和Ⅰ型调制的特性进行了比较。
Differential coherent phase shift keying (DPSK) is commonly used to provide frequency-dispersive channel data communications. To get higher data rates, increase the number of phases or use composite amplitude modulation. In this paper, we compared the characteristics of multilevel DPSK with the frequency-dependent channel type I AM with additive noise. For type I systems, differential modulation is used to amplitude encode a single bit, whereas normal DPSK is used to encode from up to four phase bits. This paper gives the curves of the bit error rate of the amplitude-coded bits and the phase-coded bits versus the effective signal-to-noise ratio of the channel. From these curves, appropriate values for the amplitude modulation used in high-rate type I systems are available. Then, the characteristics of multi-level DPSK and type I modulation were compared under the condition that the average transmitter power and the peak power were equal.