A Calibration Method of a Range Finder With a Six-Port Network

A calibration method is proposed for a range finder with a six-port phase frequency discriminator. Calibration equations are derived that include phase errors resulting from both the imperfections in a six-port network and the different diode characteristics. The equations allow a simple and accurate calibration of the range finder with the six-port network. Calibration parameters are calculated from dc outputs, which are measured as the output frequency is varied. The maximum error of a distance measurement from 0.5 to 3 m is ~ 2%.