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A mechanical harmonic synthesizer-analyzer

Journal of the Franklin Institute
Publication Date
DOI: 10.1016/s0016-0032(39)90460-6
  • Musicology


Abstract A harmonic synthesizer is described that has thirty harmonic elements (fifteen sine components and fifteen cosine components) that operate simultaneously, and the sum of the thirty sinusoidal movements is recorded by a tracing point (pencil) on a drawing board that is driven uniformly past the pencil point. Analysis is accomplished by setting the amplitudes of the thirty elements to values that are determined from the values of selected ordinates from the curve to be analyzed, and the harmonic components of this curve are determined from selected ordinates of the auxiliary curve that is traced by the machine. Thirty-two equispaced ordinates from the curve to be analyzed furnish sufficient data whereby analysis is accomplished, by a single trace of the machine, that includes fifteen harmonic components (fifteen sine components and fifteen cosine components); or, sixty-four equispaced ordinates may be taken from the curve and the analysis will include thirty-one harmonic components that are obtained from two traces made by the machine (odd harmonics are determined from one auxiliary curve and even harmonics from the other curve); or, one hundred-and-twenty ordinates may be selected from the curve and the analysis is extended to fifty-nine harmonic components by tracing four auxiliary curves with the machine.

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