Efficient solutions for reducing electromagnetic interference in legacy electronic test equipment systems

Abstract

This paper presents a comprehensive methodology for reducing electromagnetic interference (EMI) and improving electromagnetic compatibility (EMC) during the modernization of legacy analog-digital mixed electronic test systems. The research addresses critical challenges encountered when replacing obsolete Soviet-era discrete components with modern commercial off-the-shelf (COTS) integrated circuits in precision optoelectronic testing equipment. A systematic approach combining signal integrity analysis, power distribution network (PDN) optimization, and multi-layer shielding techniques is proposed. Experimental results demonstrate successful EMI suppression achieving conducted emission levels below CISPR 11 Class B limits (66 dBμV at 150 kHz to 40 dBμV at 30 MHz) and radiated emission compliance with MIL-STD-461G RE102 requirements. The proposed methodology enables functional equivalence while maintaining measurement accuracy within ± 0.5% of original specifications across the operational bandwidth of 1 MHz to 100 MHz.