This tutorial video gives the basics of the typical amplitude units used on a spectrum analyzer. It gives a basic description of the electronic definition of the decibel (dB), some of the properties of the dB, why it is used. It describes that the dB is a relative measurement. These relative measurements can be expressed as absolute measurements when a known reference is used/implied. This is where the terms dBm, dBu, dBmv, etc. come from. Finally, the term dBc is described. Each of the descriptions is followed with practical examples and demonstrations on an oscilloscope and spectrum analyzer. Notes from the video are here: