A standard for accurate phase-angle measurements at audio frequencies.
Winston W Scott · 1966
A method is described for the measurement of phase angles from 0° to 360° (except for a band ±10° about the 180° point) with an uncertainty at audio frequencies of ±0.05° to ±0. 01°, depending on the phase-angle.The method utilizes readily available equipment which may be assembled and connected to serve as a standard.The principal advantage of this standard is in its potentially broad frequency-response; namely, 10 Hz to 10 kHz or higher.It makes use of inductive voltage dividers and thermal voltage converters to compare voltage magni- tudes, which are related to phase -angle by the law of cosines.The thermal voltage converters are compared with each other before each phase -angle measurement.Their outputs are connected so that short-time power supply variations do not affect the measurements.The repeatability of measurements with this standard at a phase-angle of 60° is within a range of 0. 001°.A model has been built which shows good measure- ment precision, but it has not been thoroughly tested or studied at many frequencies and phase-angles for sources of error.This report serves as a record of the development work completed on this standard to date.