| 摘要 |
PURPOSE:To remarkably improve multiplexing efficiency by selecting a CODEC with low compressibility when traffic at a transmission line is less than a value set in advance, and switching the CODEC to the one with high compressibility when it arrives at the value set in advance. CONSTITUTION:The traffic of a transmission packet is measured at a traffic monitoring circuit 22, and the arrival of traffic to 99% of the effective maximum amount of transmission on the transmission line 23 is informed to a switch 16 and the CODECs 17, 18, and the next audio signal of one line is switched from the CODEC 17 for 16kb/s to the CODEC 18 for 8kb/s. After that, when the traffic is further increased, the audio signal is switched from 16kb/s compression to 8kb/s compression at every line. When the traffic is decreased and it becomes less than 98.5, a speech path is returned from 8kb/s compression to 16kb/s gradually within a range not exceeding 99.0%. |
