| 摘要 |
<p>A data communications system includes a standard tele-communications apparatus (1) arranged to transport analogue signals in a form of Adaptive Differential Pulse Code Modulated (ADPCM) digital signals generated from Pulse Code Modulated (PCM) digital signals representative of the analogue signals. A mapping data processor (13) coupled to a source (14) of digital data and to an ADPCM encoder (3) of the standard telecommunications apparatus (1), generates PCM coded symbols representative of the digital data in accordance with a predetermined mapping function. An unmapping data processor (15) connected to an ADPCM to PCM decoder (10) of the apparatus (1) operates to re-generate the digital data from communicated PCM signals. The mapping and unmapping data processes are arranged in combination with the PCM and ADPCM encoding and decoding operations to provide a substantial increase in a rate of data communication, with respect to a data rate which would be achieved if the digital data were to be converted into analogue signals and fed to a PCM encoder of the standard telecommunications equipment. <IMAGE></p> |
