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 which can be a source of annoyance and a potential health hazard. Here we describe a flickermeter which has been designed, constructed, and found to meet the internationally agreed performance specifications set out by IEC (International Electrotechnical Committee). 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 nonlinearphase filter design task that required a novel "Darwinian" evolutionary approach which exploits non-equispaced frequency sampling in order to sumultaneously satisfy both harsh step response and frequency response accuracy constraints.