Very Low Data Rate Voice Communication.

摘要

The domain of very low data rate voice communication is not universally defined. For this discussion, the domain will be verbal communication at a maximum serial rate of a few hundred bits per seconds. Systems are ordered or under development which operate at 400 bps or less. Some areas of communication have a desperate need for very low rates. This compelling need arises from the laws of physics and the mathematical relationships inherent in the applications. Because of its traditionally higher data rate, digital voice hasn't been a practical choice for some of these areas until recently. I'll briefly describe a group of these applications in general and then cover the details in the next section. One application is using digital voice on narrow-band radio channels (as in the typical 3kHz wide single sideband voice channel in the VHF bands). Another is jam-resistance where massive redundancy or unique operating techniques require a low rate. A third use is balancing the relative load in integrated voice/data systems. A related application is in disguising a voice channel as a data channel. A final application is in multiplexing of several users onto one channel. Reprints. (RRH)