An oscilloscope includes a memory that stores instructions; and a processor that executes the instructions. When executed by the processor, the instructions cause the oscilloscope to obtain a measurement of a first radio frequency signal; perform a first Fourier transform to compute a first new spectrum based on the measurement of the first radio frequency signal; and compute a first waveform of the first new spectrum with noise of the oscilloscope reduced by performing a first inverse Fourier transform based on the first new spectrum.