GB429007A - Improvements in or relating to arrangements for modulating high frequency carrier waves - Google Patents

Abstract

429,007. Modulating systems. LORENZ AKT.-GES., C., 1, Lorenzweg, Tempelhof, Berlin. Jan. 4, 1935, No. 338. Convention date, Jan. 6, 1934. [Class 40 (v)] Modulating systems of the kind described in Specification 363,480, in which the mean carrier level is varied according to the amplitude of the modulating signal, are provided with a time-delay circuit traversed by the signal, the frequency-discriminating effect of which circuit is compensated by an opposite distortion in the signal amplifier. The signal is applied to a transformer 1 with two secondaries 2, 3 the signal being fed through an amplifier V with a final stage 7 to the modulating-valve 9, whilst the secondary 3 feeds the signal through a rectifier 4 and smoother A, to a reversing valve 5, the output of which is tapped into the grid circuit of the modulating-valve 9. The combination C, R forming the coupling between the valves 7, 9 has a small time constant. This gives a time delay in the application of the rectified voltage to the valve 9 which delay is necessarily small in order to prevent over-modulation when the signal strength rises quickly. The combination C, R discriminates against the lower frequency components of the signal fed from the valve 7. This is compensated by arranging that such components are emphasized in the amplifier V. The plate current of valve 9 traverses a winding on an iron-cored choke coil 8 in a high-frequency circuit between the carrier wave generator S and an amplifier 6.