| 摘要 |
PURPOSE:To relieve the line distance limitation in relation to the main equipment by correcting the line impedance of a key telephone system during a speaking between extensions to a specified value, and by making it conform to the impedance of a line of distance corresponding to the balancing circuit. CONSTITUTION:The distances of lines L1-Ln of the key telephone systems T1-Tn installed at optional places are calculated by terminal voltage detectors 6 and 9, and the resulting values are stored in a memory part 3. In case the telephone set T1 and that T2 are used for speaking utilizing a microphone 17 and a speaker 19, the controller 2 reads out the distances of the lines L1 and L2 from the memory part, and adds them together, and controls a switch controller part 14 to select an impedance from impedance correcting circuits 11-13 that conforms to the balancing circuit 15. In such way, a tone is unified for any optional length of line and a howling is prevented from occurring. |
