Modulator for generating an amplitude-modulated radio-frequency signal

To generate an amplitude-modulated radio-frequency signal from an unmodulated radio-frequency signal and an audio-frequency modulation signal (A3 modulation), the unmodulated RF signal is applied to the reference connection of a digital/analog converter with an R-2R resistance network. The audio-frequency modulation signal is digitized and from the digital signal, digital control signals are derived by means of tables which are preset in a read-only memory in a switchable manner, for the D/A converter which thus acts as digitally controlled amplitude modulator. The amplitude modulated radio-frequency signal is available at the analog output of the D/A converter.