Improvements in or relating to apparatus for phase modulating electric oscillations

Abstract

Abstract 745,908. Phase modulation. GENERAL ELECTRIC CO., Ltd. Nov. 9. 1953 [Nov. 7, 1952], No. 28125/52. Class 40 (5). Phase modulation is obtained by vectorially adding in adding means 1 a carrier input and a phase displaced carrier obtained from the output of the adding means through a 90 degrees phaseshifting network 5 and a balanced amplitude modulator 6 whose output is therefore a carrier with amplitude proportional to the modulating voltage. The output and added carrier being in phase quadrature, the phase deviation of the output is therefore sin<SP>-1</SP> x, where x is the ratio of modulation voltage to carrier input amplitude. The phase-modulated output, amplified and restored in a limiter 8 to the same amplitude of the carrier input, then further has vectorially added to it in adding means 3 a quadrature phase carrier from the balanced modulator attenuated to <SP>3</SP>#2 times the carrier input amplitude. The final phase deviation is therefore #=sin<SP>-1</SP> <SP>3</SP>#2.x+tan<SP>-1</SP> x and it is shown that # is linearly related to x except only for fifth and higher powers of it.

Inventors

• 👤 Joseph Easto Bryden
• 👤 John Davison Dolwin

Bibliographic Details