Understanding Noise in EMI Receivers

This application note explains how noise sets the sensitivity and usable dynamic range of EMI receivers and how to configure measurements accordingly. It covers the essentials on noise figure and system design for noise reduction, such as the preamplifier placement. The application note explains receiver settings, that all shape the displayed noise floor, and the dynamic-range trade-offs between attenuation, preamplification and preselection. It helps understanding effects on the noise floor and their consequences for compliance EMI measurements and explains how to interpret datasheet values such as DANL. Reading it helps EMC engineers set up receivers for maximum sensitivity, avoid overestimating emissions near the limit, correctly compare instrument datasheet specifications, and distinguish emissions from instrument-generated noise floor artifacts such as spurious responses or input mismatching.