A synchronized two-phase sinewave generator for AC metrology system compensations

A slave audio two-phase sinewave generator, which can be directly synchroni zed to a master generator, is described here, It can be used in ac metrolog y setups to provide additional "compensation" signals, traditionally derive d with expensive multidecade inductive voltage divider networks. The generator is based on two direct digital synthesis (DDS) chips, program med via the parallel printer PC interface; their clock is provided by a pha se-locked loop circuit, which ensures frequency and phase synchronization o f the DDS outputs with the master generator. The synchronization reference signal can be provided via an optical link reference channel, which avoids interference and ground loops, In its present implementation, the output voltage is V-peak = 10 V,frequenc y range 500 Hz-4 kHz, Total harmonic distortion is contained to -65 dB, and amplitude stability is better than 500 mu V/V over 24 h.