A microprocessor-controlled phase-locked signal source

The paper outlines the principles behind an approximating frequency synthesizer based on continued fractions to derive the data required for the addressable counters of the digital phase-locked loops. A hardware implementation is described based on a cheap microprocessor and calculator chip combination for the digital content and integrated circuit phase-locked loops for the analogue section. The prototype operates over the frequency octave 400<f<800 kHz with a resolution of 0.1 Hz.