| 摘要 |
738,319. Telephone transmission systems. MOULON, J. M. March 6, 1953 [Sept. 19, 1952], No. 6336/53. Class 40 (4). [Also in Group XL (c)] The attenuation of a two-wire line 30 is reduced by the use of a negative impedance in series or in parallel with the line. The transformer-coupled amplifier employing transistors 31, 32 feeds a Wheatstone bridge of resistors 6, 7, 8 and the series impedance of the transmission line 30. By changing over the switches 27, 28 and 29 the negative impedance is altered to suit the parallel connection across the line 30. The circuit is adjusted by disconnecting the feedback circuit from the input, terminating it with an impedance equal to the input impedance of the amplifier, connecting a predetermined resistance in place of the line 30 and adjusting the bridge for balance. |
