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在研制用于地面移动数字话音无线系统中存在着令人关注的兴趣和积极性。今后可以预料,所研制的新的无线设备,在通常情况下就可达高的比特速率,或者是减小通道间隔。作为研制工作者更直接的另一种手段就是在现有的标准移动设备上传输数字话音。本文叙述的第二种可能性就是开发现有设备的各种性能。数字话音无线系统一个重要的优点就是能达到高度的话音保密。数字话音设备的另一个潜在的优点是它与地面移动数字数据设备可实现兼容。数字话音设备的第三个优点是,和模拟话音设备相此时,对本网络的其它用户和对非本网络通道的其它明话与编码用户的潜在干扰似乎是非常小的。如果采用精确设计的数字编码,数字编码还可提供实现非扩展型编评码器、高效率的信号再生和增加抗多径衰落的多种可能性。本文分析了在现有移动无线电话设备上传输数字话的问题。首先给出了标准移动无线设备的某些特征,其次考虑影响选择适应移动无线话音编码方法的因素、并且就几种典型的自适应增量调制在主观试验和主观测试的基础上进行性能比较。第三,为了适应移动无线信道的特性,选择了改进型的双二进码作为数字话音信号的频谱形成。第四,提出测量数字话音发/收信机特性的概念,因此,我们就可以考虑数字话音技术(如自适应增量调制和二进制或改进型的双二进制FM)与现存的地面移动无线业务进行兼容的能力。
There has been a lot of interest and enthusiasm in the development of wireless systems for terrestrial mobile digital voice. In the future, it is expected that new wireless devices will be developed to achieve high bit rates under normal conditions or to reduce the channel spacing. Another way to be more direct as a developer is to transmit digital voice over existing standard mobile devices. The second possibility described in this article is to develop various capabilities of existing equipment. An important advantage of digital voice wireless systems is the high level of voice privacy. Another potential advantage of digital voice devices is that it is compatible with terrestrial mobile digital data devices. A third advantage of digital voice devices is that, at the same time as analog voice devices, the potential for interference with other users of this network and other plain-talking and coding users that are not this network channel seems to be very small. With precisely designed digital encodings, digital encodings can also offer many possibilities for implementing non-extender coders, efficient signal regeneration, and increased resistance to multipath fading. This article examines the issue of transmitting digital words over existing mobile radiotelephone devices. First, some characteristics of standard mobile wireless devices are given. Secondly, the factors influencing the selection of mobile wireless voice coding methods are considered. And some typical adaptive delta modulations are compared based on subjective and subjective tests. Third, in order to adapt to the characteristics of mobile radio channel, an improved dual binary code is chosen as the spectrum of digital voice signal. Fourth, the concept of measuring the characteristics of digital voice transceivers was proposed so that we could consider digital voice technologies (such as adaptive delta modulation and binary or modified dual-binary FM) with existing terrestrial mobile radio services Compatible ability.