Process for the reduction of the parasitic noises in the modulation with phase shift and transmitters applicable

摘要

752,628. Frequency modulation. BOSE, J. H. Oct. 8, 1954 [Oct. 12, 1953], No. 29062/54. Drawings to Specification. Class 40 (5). Relates to frequency modulation transmitters in which a phase shift modulator is followed by a frequency multiplier and a band-pass filter. In such an arrangement the effect of random phase shifts in the early stages, which introduce noise, is reduced by using a band-pass filter which attenuates desired high side frequencies, a compensating network being provided in the modulation input circuit. The invention is described as applied to a multiplex system in which further channels are added by subsequent modulations of the modulated carrier by modulated sub-carriers. Specifications 668,030 and 670,967 are referred to.