Transparent Wideband Data Transmission in Digital Communication Networks

This paper presents a systematic study of the possibilities of time-transparent and of code-transparent binary data transmission in digital communication networks where PCM or differential PCM (DPCM) systems are employed for the encoding of speech or video signals. To describe the effects that occur if data signals instead of speech or video signals are sampled and transmitted by these two encoding methods, time-transparency and code-transparency are defined and are used as figures of merit. The occurrence of time-quantizing errors and amplitude errors at the decoder output is statistically analyzed. The limitations to be considered in the various applications are described, and time- and code-transparency are evaluated quantitatively. The predictions of the analysis are then compared with the results obtained through simulations. The comparison shows that for data rates below 10 percent of the bit rate (bits per second) in the digital channel, conventional PCM and DPCM encoding are acceptable for binary data transmission and have the advantage of easy signal integration. For higher data rates special data encoding is necessary. The encoding method analyzed here is dual-mode.