Digital amplitude modulating circuitry.

摘要

A digital circuitry is provided for modulating the amplitudes of sinusoidal carrier frequency signals in the phase domain. Thereto, a phase accumulator (2) delivers a digital phase signal in response to a carrier frequency signal to be modulated. A modulating phase signal is derived from an analog modulating signal by means of A/D-converter (70), a ROM (60) containing phase data and a polarity generator (50). The phase signals from the phase accumulator (2) and from the polarity generator (50) are added, converted into sinusoidal amplitude signals and are converted into analog signals having phase modulated signal components with higher frequencies and amplitude modulated signal components with lower frequencies. A low-pass filter (120) delivers the desired analog amplitude modulated output signal.