The Allen Avionics HD-SDI-5 is a video hum and noise eliminator for HD-SDI applications. Hum eliminators work best when interference causes small differences in ground potential (less than 20VDC) or long cable runs have induced currents. HD-SDI units also work well when there are multiple power panels in a building that create differences in ground potential which induce ground loop current flow and 60Hz hum.