Spectrum analysis of random noise generators

A method is introduced for evaluating the spectrum shape of random noise generators. This method uses only one selective filter and a variable chopper-carrier to select within a wide band, the frequency which is of interest. The random noise at the frequency selected is then squared and averaged over a sufficient length of time. This process being repeated at various frequencies yields the spectrum shape. The spectrum to be examined by the variable-chopper scheme is preshaped by a wide-band filter of known characteristic. The deviations of the output of the selective filter from the wide-band characteristic indicates the deviation of the original spectrum from a flat-shaped spectrum.