OK, my take on spectrum measurements :)This kind of picture is a result of Fast Fourier Transform (FFT) - mathematical transformation of the input signal.Fourier says - every input signal (whatever form it is) can be represented as a combination of sine waves.Each "stick" on the spectrum diagram represents a single sine wave of particular frequency and amplitude. Thus, every component is characterized by Amplitude (V) and Frequency (F).Now - some explanation for each picture: 1) Typical FFT diagram. Base frequency component represents the test signal (1KHz sine wave) - set to 0db. A small (sometimes not so small :P) stick...