Zero IF frequency modulator.

摘要

An apparatus for frequency-modulating telecommunication carriers (7) with baseband signals (4) includes an arrangement (2) for generating two quadrature-related baseband signals in two separate channels (A, B), wherein each of the quadrature-related baseband signals is a sinusoidal function of the instantaneous angle of the message signal to be transmitted. The apparatus further includes and arrangement (3) for producing a frequency-modulated carrier from the quadrature-related baseband signals, this arrangement including a device that provides two quadrature-related carrier-frequency waveforms, two mixing devices each for individually mixing one of the quadrature-related carrier-frequency waveforms with one of the quadrature-related baseband signals in one of the channels, and a combining device which combines the output signals from the two channels into a single frequency-modulated carrier-frequency output signal (8).