APPARATUS FOR OBTAINING THE PHASE OF A FUNDAMENTAL FREQUENCY FROM PHASE VALUES OF HARMONICS THEREOF

摘要

An apparatus for obtaining indications of the phase of a fundamental signal from received indications of phase angle of its fifth, sixth, eighth and ninth harmonics, in which the phase angles are converted into numerical indications and are numerically processed by multiplication and merger to yield a multiplicity of numerical indications of the fundamentals phase angle. The various indications thus obtained are combined to perform a mean. Each merger operation requires the multiplication of a numerical indication of phase angle at a lower frequency by an appropriate integer to yield an indication at a frequency for which a second estimate of phase angle is available in only fractional form, and adopting for the merged indication the integer value taken from the multiplied indication and the fractional part from the other estimate. Minimising the effects of differential phase distortion of the phase angles of the various harmonics is achieved.