PSEUDO-INCOMMENSURATE 2-STIMULUS GENERATOR

A signal generator is described that provides two oscillations of ''al most'' incommensurate frequencies, along with their sum and difference frequency. There is no phase drift between the outputs since all sign als are generated from a single master clock. The concept is based on Fibonacci approximands to the golden mean. Technical implementation re quires ordinary digital frequency dividers and a single phase-locked-l oop frequency multiplier. Applications are measurements of weak nonlin earities in ''almost linear'' transfer functions. (C) 1997 American In stitute of Physics.