A frequency-shift modulation device includes an oscillating circuit, a phase-locked loop and a digital frequency modulation circuit. The oscillating circuit is connected to the phase-locked loop in order to produce a fixed-frequency clock signal. This clock signal is used for timing the frequency modulation circuit. A standard model crystal oscillator can be used in the oscillating circuit, given that the RF frequency of a wireless transmission signal which is produced by the modulation device is determined digitally.