| 摘要 |
PURPOSE:To enable many many-subscriber calls by simplifying switching and connection processing by superposing and sending voice signals, received from other subscriber telephone sets via a digital subscriber line, to the subscriber telephone set. CONSTITUTION:Voice signals and control signals from subscriber telephone sets are digitally multiplexed to arrive at a many-subscriber calling device via digital subscriber line 3. They are demultiplexed by demultiplexer 43 and then converted into analog voice signals by D/A converters 45A-45C. Next, those signals are mixed by superposing device 47, whose output is sent to subscriber telephone set 1 via hybrid circuit 49. On the other hand, the control signal is inputted to signal circuit 41 and sent to telephone set 1. Circuit 41 detects the signal of telephone set 1 and sends it to A/D converters 44A-44C. The voice signal from telephone set 1 is passed through circuit 49 and then mixed with the output of superposing device 47 by superposing device 48. The resulting output is subtracted from by outputs of converters 45A-45C by subtracters 46A-46C and inputted to converters 44A- 44C. |
