Frequency modulator

Abstract

Abstract The frequency modulator is suitable for the frequency modulation of a radio-frequency carrier, particularly with digital modulation signals. It comprises a voltage-controlled oscillator (VCO) (3) which, in terms of its frequency-modulated output frequency, is stabilised by a reference oscillation with the aid of a phase-locked loop, comprising a frequency multiplexer (4), a Swallow frequency divider (5) controlled by the modulation signal and the radio-frequency signal, an adder (11) for the modulation voltage and control voltage, a control voltage filter (10) and a phase comparator (9). The modulation signal is fed, on the one hand, via a modulation filter (1) to a control circuit (12) for the Swallow frequency divider and, on the other hand, to a level controller (2) in front of the adder (11). As a result, the VCO is modulated with the desired frequency swing according to the instantaneous amplitude of the modulation signal, both directly by the modulation signal and indirectly due to the changeover of the Swallow frequency divider and thereby due to the control voltage. <IMAGE>

Inventors

• 👤 Heinrich Dipl.-Ing. Beyrich (Fh)
• 👤 Reiner Tanner

Bibliographic Details