| 摘要 |
<p>Bit rate compression in a digital communications system is provided by transmitting voice information from n telephone circuits over the capacity conventionally allocated for transmission of voice information from n/2 circuits without appreciable degradation in quality. Alternatively, a doubling of the number of voice circuits may be provided with transmission at the same bit rate required for conventional transmission of voice information. Each frame period, at the transmitter, all n circuits are serviced and, utilizing an adaptive predictive encoding scheme, a maximum of only 3/8 n unpredictable samples in the given frame are transmitted over the available channel capacity. A sample assignment word (SAW), which identifies the circuits corresponding to the unpredictable samples, is transmitted therewith. Upon reception of the transmitted frame comprising the SAW and the unpredictable samples, the receiver updates the stored samples which were transmitted during previous frames as unpredictable samples by substituting the received unpredictable samples for the stored samples in accordance with the channel routing information provided by the SAW, thereby enabling proper reconstruction of all samples in the given frame. Means are provided for effectively recirculating the servicing sequence of the n circuits to optimize the adaptive predictive encoding scheme.</p> |
