现代通信系统要求通信距离远、通信容量大、传输质量好。作为其关键技术之一的调制解调技术一直是人们研究的一个重要方向。一个系统的通信质量, 很大程度上依赖于所采用的调制方式。因此,对调制方式的研究, 将直接决定通信系统质量的好坏 。 DBPSK 即差分相干二进制相移键控 用这种调制方法可以克服接收时由PSK所造成的倒∏现象，能够更好的减少接收时的误码率。DBPSK数字调制器是目前电子信息领域常用的调制器，它在数字通信，移动通信中都有应用。它与FSK,ASK等调制器相比有更加可靠的性能，并且误码率相比最低。因此在高速的数据传输时，往往DSPSK是最佳的选择。目前，在话带内以中速传输数据时,DBPSK是CCITT建议选用的一种数字调制方式。比如,在高速的无线通信中，运用DBPSK调试方式能够很好的高速传输数据，减少码元的误码率，提高整个系统的可靠性。
Modern communications systems require long communication distance, big communication capacity and good transmission quality. Modulation and demodulation, as one of the key technologies, has long been a research direction. The communicational quality of a system depends largely on what modulation means to adopt. Therefore, research on modulation methods will directly determine the quality of communications systems. DBPSK, namely differential binary phase shift keying, a modulation method by which to overcome the inverse π phenomenon caused by PSK during reception, is able to reduce error rate more effectively during reception. DBPSK digital modulator is commonly used in current field of electronic information, and is applied in both digital communications and mobile communications. It enjoys higher reliability and lower error rate than FSK, ASK and other modulators. So DBPSK tends to be an optimal choice in high-speed data transmission. At present, DBPSK is a digital modulation method in transmitting data at medium-speed within voice band recommended by CCITT. For example, in high-speed wireless communications, DBPSK modulation can be used to effectively transmit data at high speed, reduce error rate of code-element, and improve the overall reliability of system.
1,DBPSK调制器的原理及组成结构
1. Principle and composition of DBPSK modulator
BPSK信号中，相位的变化是以未调载波的相位作为参考标准的。由于它是利用载波的相位的绝对数值表示数字信息，所以称之为绝对相移。但BPSK信号的相干解调时，由于载波恢复中相位有0，∏模糊性，导致解调过程中出现“反向工作”现象，恢复出的数字信号“1”和“0”倒置，所以BPSK方式在实际中很难运用。为了克服这些缺点，提出DBPSK方式。
In BPSK signal, the phase of unmodulated carrier is taken as the reference for phase alteration, which is called absolute phase shift because it utilizes the absolute numeric value of the carrier’s phase to represent digital information. But during the coherent demodulation of BPSK signal, the “inverse working” phenomenon occurs that the regained digital signal reverses “1” and “0” because of the 0(s) in the phase of carrier when being regained. Thus BPSK mode is difficultly applied in reality. DBPSK method is proposed to overcome these shortcomings.
