title: Microprocessor assisted real-time harmonic analysis by minicomputer.
abstract: A real-time signal averaging and harmonic analysis technique for low audio frequency waveforms is described that, although based on based on earlier software emulations of lock-in detection instruments, eliminates problems inherent in the earlier systems. Parallel processing is employed between a data acquisition minicomputer (HP-2116B) and a microcomputer (Z-80) to (1) replace an earlier chopper-type lock-in algorithm with a coherent Fourier transform, (2) digitally produce a pure (0.01% THD) modulation sine wave, (3) simplify system tune-up, and (4) produce a high-quality, flicker-free, real-time display of the averaged waveform and its harmonic content.
authors.affiliation: Physics Department, University of Oregon, Eugene, OR 97403, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Matheson
authors.forename: R J
authors.initials: RJ
authors.lastname: Higgins