Abstract
The method of harmonic analysis described in this paper is of the selected ordinate type. It is similar to the Fischer Hinnen analysis in that a different spacing of ordinates is used for each harmonic component to be determined, and no multiplications are necessary. The basis of derivation is the assumption that the curve to be analyzed can be replaced by a parabola passing through certain ordinates in each half period of the harmonic component. A spacing of these ordinates is then found such that the sum of the ordinates is proportional to the harmonic component of the parabolas replacing the original curve.
Spacings have been determined for 3, 5, and 7 ordinates per half period, corresponding to parabolas of second, fourth, and sixth orders. In the five and seven ordinate rules it is necessary to use a multiplying factor of 1/2 for the end ordinates.
In use a set of transparent charts with the ordinates for each component are constructed. Laid over the curve to be analyzed, the ordinates can be quickly summed on a strip of paper.
The accuracy of the method is relatively high and in use it is of the utmost simplicity, so that with a set of charts once prepared, correct results can be obtained by the most unskilled computer.
