APPARATUS FOR AMPLITUDE AND FREQUENCY MODULATING A SIGNAL

摘要

Combined amplitude and frequency-shift-keying (AM-FSK) modulation of a carrier wave by the same baseband data signal achieves significant suppression of one of the sidebands to ease the design requirements of filters generally used in the transmission of FSK signals. Significant suppression effect is observed when the ratio of minimum to maximum amplitude of the envelope of the amplitude modulated carrier wave is restrained to be approximately between 0.6 and 0.9.