The HP 8559A displays the amplitude and frequency of each component of an input signal on a CRT. This display gives quantitative information often not available from a conventional oscilloscope. The HP 8559A is capable of measuring signals from - 112 dBm to + 30 dBm over a frequency range of 10 MHz to 21 GHz. The complete measuring system includes the HP 8559A Spectrum Analyzer plugged into a compatible Hewlett-Packard display mainframe.