Improvements in or relating to circuits including electric signal transmission linesin communication systems

摘要

787,824. Substation circuits. WESTERN ELECTRIC CO., Inc. Dec. 20, 1955 [Dec. 30, 1954], No. 36452/55. Class 40 (4). The output of the transmitter T is applied to a transistor amplifier 9; compensation for the greater attenuation by the line of higher frequencies is effected by a circuit 6, 7 in the feedback path of the amplifier. The resistor 6 and capacitor 7 are variable to adjust the frequency response as required. An inductance 2 has a high impedance for voice-frequency currents but provides a low-resistance D.C. path so that the transmitter-energizing D.C. does not have to pass through the transistor. A thermistor 4 compensates for variations in line impedance and an anti-side-tone network 12 is provided. The transistor 9 is preferably of the junction type. Specifications 694,705 and 700,231, [Group XL (c)], are referred to.