A microprocessor-based digital flickermeter

A flickermeter is an instrument able to simulate and measure the human optical sensation caused by illumination variations due to small-amplitude, low-frequency changes of mains power supply voltage. A flickermeter that has been designed, constructed, and found to meet the internationally agreed performance specifications set out by the IEC (International Electrotechnical Commission) is described. The system, already in commercial service, has been implemented around a microprocessor and presents a full range of I/O interfaces for possible applications in a variety of operational environments. Several unique and demanding design obstacles are related, along with experiences in achieving their solutions. Particular attention is directed to the matter of a nonlinear-phase filter design, task that required a novel Darwinian evolutionary approach which exploits non-equispaced frequency sampling in order to simultaneously satisfy both harsh step response and frequency response accuracy constraints