Tracking generator of calibrated harmonics

A tracking generator of calibrated harmonics has been tested at the Istituto Elettrotecnico Nazionale Galileo Ferraris. This system acquires the sinusoidal input supplied by a precision ac calibrator, and the internal DSP produces, by means of a digital-to-analog converter (DAC), an output signal combination of calibrated harmonics components, which is added to the sinusoidal signal of the calibrator. In this way, an ordinary 12-bit DAC can produce a precision signal with an assigned THD less than 10%. Some algorithms for generating the signal and for tracking with high accuracy the internal reference to the external input signal have been developed, which allow the frequency and phase difference to be recovered within 10/sup -4/ rad in less than 0.1 s.