The radio spectrum scope (also radio panoramic receiver, panoramic adapter, pan receiver, pan adapter, panadapter, panoramic radio spectroscope, panoramoscope, panalyzor and band scope) was invented by Marcel Wallace - and measures and shows the magnitude of an input signal versus frequency within one or more radio bands - e.g. shortwave bands.[1] [2] A spectrum scope is normally a lot cheaper than a spectrum analyzer, because the aim is not high quality frequency resolution - nor high quality signal strength measurements.
The spectrum scope use can be to:
Modern spectrum scopes, like the Elecraft P3, also plot signal frequencies and amplitudes over time, in a rolling format called a waterfall plot.