| 摘要 |
PURPOSE:To decrease the hardware and also to attain effective utilization of a multiplexed signal line by replacing a detector installed individually to a subscriber circuit with one detector to be installed in a line concentrator, and utilizing time division multiplex function. CONSTITUTION:The detector DETB is provided to the output side of a multiplexer MPXV. In calling a telephone set, an AC signal TRP2 is generated to the output of a level converting circuit LVC and the signal TRP2 is fed to the input of a coder/decoder CODEC by a swtich SW1. No signal is generated to the T side output from the A-B line side of a current supply circuit BSH by a switching circuit RT. The signal train VT of the coder/decoder CODEC is information converted with the signal TRP2. The line concentration circuit LCC multiplexes the signal train VT in time division, selects the signal of a subscriber circuit SLIC out of the multiplexed signal during calling, the detector DETB eliminates the AC components and detects the DC components and obtains an RTP output. When no telephone set is called, the switching circuit RT and the swtich SW1 are opened and only a voice signal is supplied to the CODEC. |
